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1- Statistical analysis
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Error bars are a graphical representation of the variability of data
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 mean is just the average
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3- State that the term standard deviation is used to summarize the spread of values around the mean, and that
68% of values fall within one standard deviation of the mean
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4- Explain how the standard deviation is useful for comparing the means and spread of data between two or more
samples
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 the larger the t value (converted to % chance) means that there's a significant difference in statistics
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6- Explain that the existence of a correlation does not establish that there is a causal relationship between two
variables
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1- Cell theory
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1- Outline the cell theory
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 first point (all organisms are composed of at least one cell)
o use of a microscope, observing living things and calling them "animalcules"
o plants and animals are made of "independent, separate beings"
 second point (smallest units of life)
o we haven't been able to find a living entity that isn't made up of at least one cell
 third point (all cells come from pre-existing cells)
o after sterilizing chicken broth by boiling, Pasteur showed that living organisms can't spontaneously
reappear
o life was only able to re-establish itself after exposure to pre-existing cells
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3- State that unicellular organisms carry out all the functions of life
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4- Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles and cells, using
appropriate SI units
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𝑠𝑖𝑧𝑒 𝑜𝑓 𝑖𝑚𝑎𝑔𝑒
𝑜𝑓 𝑠𝑝𝑒𝑐𝑖𝑚𝑒𝑛

magnification= 𝑠𝑖𝑧𝑒

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6- Explain the importance of the surface area to volume ratio as a factor of limiting cell size
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The multicellular organisms show emergent properties
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 many cells in multicellular organisms are able to reproduce themselves, allowing growth and replacement of
damaged or dead cells
 they start out as a single cell after sexual reproduction which has the ability to reproduce at a very rapid rate
 then, these cells differentiate to produce all of the required cell-types necessary for the well-being of the
organism
 the differentiation process is the result of the expression of certain genes but not others
 each cell contains all the genetic information for the production of the complete organism, but each cell
becomes a different type of cell depending on which DNA segment becomes active
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9- Sate that stem cells retain the capacity to divide and have the ability to differentiate along different pathways
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10- Outline one therapeutic use of stem cells
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2- Prokaryotic cells
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1- Draw and label a diagram of the ultrastructure of Escherichia coli as an example of a prokaryote
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 cell wall
o protects and maintains the shape of the cell
 plasma membrane
o controls the movement of materials in and out of the cell
o plays a role in binary fission
 pili
o joining bacteria cells for reproduction
 flagellum
o allows cell motility
 ribosomes
o sites of protein synthesis
 nucleoid region
o contains DNA

o cell control and reproduction
o some contain plasmids which help the cell adapt to unusual circumstances
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3- Identify structures from 2
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1 in electron micrographs of E
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p19
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4- State that prokaryotic cells divide by binary fission
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p20
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2- Annotate a diagram with the functions of each named structure
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p20
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4- Compare prokaryotic and eukaryotic cells
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Plant cells
Animal cells
Chloroplast in cytoplasm
No chloroplast
Cell wall
No cell wall
Store carbohydrates as starch
Store carbohydrates as glycogen
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6- Outline two roles of extracellular components
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4- Membranes
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1- Draw and label a diagram to show the structure of a membrane
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 hydrophilic: the area that is polar and so water soluble
 hydrophobic: the area that is not polar and so not water soluble
 this causes phospholipids to always align as a bilayer
 the fatty acid tails don't strongly attract one another so the membrane is fluid and flexible
 re-attachment of membrane after endocytosis (not possible if membrane wasn't fluid)
 water tends to form hydrogen bonds, maintaining the overall structure of the membrane
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3- List the functions of membrane proteins
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 Diffusion: passive movement of particles from a region of high concentration to a region of low concentration
 Osmosis: passive movement of water molecules across a partially permeable membrane from a region of lower
solute concentration to a region of higher concentration
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5- Explain passive transport across membranes by simple diffusion and facilitated diffusion
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 Active transport: movement of substances against a concentration gradient, and therefore need energy in the
form of ATP
 sodium-potassium pump
o three intercellular sodium ions bind to specific protein pump
o this causes phosphorylation by ATP
o the protein to change its shape and expels the 3 sodium ions into extracellular matrix

o
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2 extracellular potassium ions bind to different regions of the protein, causing release of the phosphate
group
the protein's original shape is restored, causing release of potassium ions into intracellular matrix

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7- Explain how vesicles are used to transport materials within a cell between the rough endoplasmic reticulum,
Golgi apparatus and plasma membrane
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 the fatty acid tails are loosely connected to each other, making the membrane fluid and able to change shape,
break and re-form during endocytosis and exocytosis
 the hydrophobic and hydrophilic regions of the phospholipid molecules make the membrane stable in an
aqueous environment
 during endocytosis, the membrane literally breaks and reforms
 during exocytosis, the vesicle is actually part of the plasma membrane

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 Interphase
o G1: first growth phase
o S: replication of DNA (synthesis phase)
o G2: second growth phase to prepare for mitosis (number of organelles increase, DNA condenses from
chromatin to chromosomes and microtubules begin to form)
 Mitosis
o replicated chromosomes separate and move to opposite poles of the cell
o cytoplasm divides to form two daughter cells
o four phases: prophase, metaphase, anaphase, telophase
 Cytokinesis
o occurs after nuclear division
o animal cells: inward pinching of fluid plasma membrane to form cleavage furrows
o plant cells: form a cell plate, separating outwards in opposite directions
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2- State that tumours (cancers) are the result of uncontrolled cell division and that these can occur in any organ or
tissue
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 Interphase is an active period in the life of a cell when many metabolic reactions occur, including protein
synthesis, DNA replication and an increase in the number of mitochondria and/or chloroplasts
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 Prophase
o chromatin fibres become more tightly coiled to form chromosomes (sister chromatids)
o nuclear envelope disintegrates and nucleoli disappear
o mitotic spindle forms
o the spindle attaches to the centromere
o centrosomes move towards opposite poles of the cell due to elongation of microtubules
 Metaphase
o sister chromatids move to equator of the cell, due to microtubules
o centrosomes are now at opposite poles
 Anaphase
o two sister chromatids split
o chromosomes move to opposite poles of the cell, due to shortening of microtubules
 Telophase
o chromosomes are each pole
o nuclear envelop forms around each set of chromosomes
o chromosomes elongate to form chromatin
o nucleoli reappear
o spindle apparatus disappears
o cell is elongated, ready for cytokinesis
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5- Explain how mitosis produces two genetically identical nuclei
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 Embryonic development, tissue repair and asexual reproduction involve mitosis
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1- Chemical elements of water
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1- State that the most frequently occurring chemical elements in living things are carbon, hydrogen, oxygen and
nitrogen
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2- State that a variety of other elements are needed by living organisms including sulfur, calcium, phosphorous,
iron and sodium
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(CPISS)
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3- State one role for each of the elements mentioned in 3
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p47
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5- Outline the thermal, cohesive and solvent properties of water
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(above)

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 organic compounds
o contain carbon found in living organisms
o carbohydrates, lipids, proteins
 inorganic compounds
o contain no carbon or contain inorganic carbon compounds
o (oxides of carbon, carbonates, hydrocarbonates)
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2- Identify amino acids, glucose, ribose and fatty acids from diagrams showing their structure
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Carbohydrate
Examples
Monosaccharides
Galactose, glucose, fructose (GGF)
Disaccharides
Maltose, lactose, sucrose (MLS)
Polysaccharides
Starch, glycogen, cellulose (SGC)
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4- State one function of glucose, lactose and glycogen in animals, and of fructose, sucrose and cellulose in plants
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 the following show hydrolysis reactions, using water to create smaller products
 the opposite would be condensation reactions which would result in the creation of water and a larger molecule
Polysaccharides + water  disaccharides/monosaccharides
Disaccharides + water  monosaccharides
Triglyceride + 3 water  glycerol + 3 fatty acids
Protein + water  amino acids
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6- State three functions of lipids
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Lipids
Carbohydrates
 store energy for long periods of time
 store energy for short periods of time
 contain more energy so stores are lighter
 more easily digested so energy stored can be released
more quickly
 insoluble in water so they don't cause problems with
osmosis
 soluble in water to they're easier to transport

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2- State the names of the four bases in DNA
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 two single strands of DNA interact to form a double helix
 the two bases in the middle are like rungs on a ladder and are complimentary to each other
 complimentary base pairs: adenine-thymine and cytosine-guanine
 adenine and thymine are held together by 2 hydrogen bonds and cytosine and guanine are by 3 bonds
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5- Draw and label a simple diagram of the molecular structure of DNA
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4- DNA replication
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1- Explain DNA replication in terms of unwinding the double helix and separation of the strands by helicase,
followed by the formation of the new complementary strands by DNA polymerase
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 ensures that 2 identical copies of DNA are produced from one
 the original DNA molecule had complimentary pairs of nucleotides and when it was unzipped, nucleotides
complimentary to each strand came to form 2 identical strands
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2- State that DNA replication is semiconservative
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DNA
Sugar is deoxyribose
Nitrogenous bases: adenine, thymine, cytosine, guanine
Double stranded

RNA
Sugar is ribose
Nitrogenous bases: adenine, uracil, cytosine, guanine
Single stranded

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2- Outline DNA transcription in terms of the formation of an RNA strand complementary to the DNA strand by
RNA polymerase
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 the mRNA molecule produced by transcription represents a complimentary copy of one gene of DNA
 the nucleotides making up the genetic code have enough information to make one polypeptide
 every 3 bases is enough information to code for 1 of the 20 amino acids
 triplet: any set of 3 bases that determines the code for 1 amino acid
 triplet is called codon in mRNA molecules
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4- Explain the process of translation, leading to polypeptide formation
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 the process continues until the ribosome reaches the last codon triplet (which doesn't act as a code for an amino
acid)
 the polypeptide molecule breaks away from the final tRNA molecule and becomes a free-floating polypeptide in
the cytoplasm
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5- Discuss the relationship between one gene and one polypeptide
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6- Enzymes
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1- Define enzyme and active site
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 the active sit of an enzyme matches a substrate like how glove fits a hand or how a key (substrate) fits a lock
(active site)
 this is how active sites of enzymes and substrates are specific to each other
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3- Explain the effects of temperature, pH and substrate concentration on enzyme activity
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 temperature is high enough the break the intramolecular bonds in an enzyme, causing it to lose its 3D shape
 it's sometimes permanent and sometimes temporary
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5- Explain the use of lactase in the production of lactose-free milk
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7- Cell respiration
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1- Define cell respiration
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 In cell respiration, glucose in the cytoplasm is broken down by glycolysis into pyruvate, with a small yield of ATP
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 Alcoholic fermentation
o yeast converts both 3-C molecules of pyruvate to 2-C molecules of ethanol
o the 'lost' carbons turn into two molecules of carbon dioxide
o ex: baker's yeast
 Lactic acid fermentation
o when humans can't supply enough oxygen to their cells (ex
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 it's the most efficient pathway
 the two pyruvate molecules enter a mitochondrion to be further metabolized
 each pyruvate loses a carbon dioxide and becomes acetyl-CoA
 each acetyl-CoA enters the Krebs cycle

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some ATP is directly generated and some is indirectly through a later series of reactions involving oxygen
completely oxidizes (breaks down) a glucose molecule and the end-products are carbon dioxide and water
aerobic cell respiration is more efficient because its molecules are completely oxidized, unlike ethanol and lactic
acid which represent portions of the original glucose that was not oxidized
it also leaves no by-products and has a much higher yield of ATP per glucose

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Photosynthesis involves the conversion of light energy into chemical energy
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Light from the Sun is composed of a range of wavelengths (colours)
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Chlorophyll is the main photosynthetic pigment
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 chlorophyll is a green pigment
 when a plant leaf is hit by sunlight, it absorbs red and blue wavelengths for photosynthesis and reflects green
wavelengths of light
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5- State that light energy is used to produce ATP, and to split water molecules (photolysis) to form oxygen and
hydrogen
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6- State that ATP and hydrogen (derived from the photolysis of water) are used to fix carbon dioxide to make
organic molecules
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7- Explain that the rate of photosynthesis can be measured directly by the production of oxygen or the uptake of
carbon dioxide, or indirectly by an increase in biomass
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 Light intensity
o straight increase: positive correlation between light intensity and photosynthetic rate
o flat: enzymes are working at their maximum rate
 Temperature
o curved increase: increase molecular collisions
o drop down: enzymes/other proteins become denatured
 Carbon dioxide concentration
o straight increase: positive correlation between carbons dioxide concentration and photosynthetic rate
o flat: rate of reaction reaches a plateau unless light or temperature is also increased

4- Genetics 1
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Eukaryote chromosomes are made of DNA and proteins
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 Gene: a heritable factor that controls a specific characteristic

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Allele: one specific form of a gene, differing from other alleles by one of a few bases and occupying the same
gene locus as other alleles of the gene
 Genome: the whole of the genetic information of the gene
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3- Define gene mutation
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 The consequence of changing one base could mean that a different amino acid is placed in the growing
polypeptide chain
 This can result in mutations
 A mutation is sometimes found in a gene which creates haemoglobin for red blood cells
 This leads to a change in the shape of the haemoglobin, which leads to the change in shape of red blood cells
 The mutated red blood cell looks like a sickle, not a flattened disk pinched in the middle
 Therefore, the condition that results in this mutation is called sickle cell anaemia
 Sickle cell anaemia is a base substitution mutation
 One base is substituted for another so that the codon GAG becomes GTG
 So during translation, instead of adding glutamic acid, valine is added instead
 The resulting polypeptide chain is modified, and so the shapes of haemoglobin and red blood cells are modified
 Oxygen can’t be carried as efficiently by the irregularly-shaped red blood cells
 The haemoglobin also tends to crystallize in the blood cells, causing them to be less flexible
 The blood cells can get stuck in capillaries so blood flow can be slowed or blocked
 Symptoms of sickle cell anaemia
o Weakness
o Fatigue
o Shortness of breath
 People with sickle cell anaemia have a risk of passing the mutated gene to their offspring

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Meiosis is a reduction division of a diploid nucleus to form haploid nuclei
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 Homologous chromosomes
o In a diploid human cell, the 46 chromosomes can be grouped into 23 pairs of chromosomes
o 23 come from the father and 23 from the mother
o Homologous means similar in shape and size and the 2 homologous chromosomes carry the same genes
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3- Outline the process of meiosis, including pairing homologous chromosomes and crossing, followed by two
divisions, which results in four haploid cells
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 Non-disjunction: when two or more homologous chromosomes stick together instead of separating
 This causes an unequal distribution of chromosomes
 In trisomy 21, non-disjunction happens in the 21st pair of chromosomes
 The child receives 3 instead of 2 of the 21st chromosomes
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5- State that, in karyotyping, chromosomes are arranged in pairs according to their size and structure
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6- State that karyotyping is performed using cells collected by chorionic villus sampling or amniocentesis, for prenatal diagnosis of chromosome abnormalities
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7- Analyse a human karyotype to determine gender and whether non-disjunction has occurred
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3- Theoretical genetics
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1- Define genotype, phenotype, dominant allele, recessive allele, codominant alleles, locus, homozygous,
heterozygous, carrier and test cross
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Steps
 Indicate letter to show the alleles: A for dominant allele, a for recessive allele
 Determine the parents’ genotypes: Aa, aa
 Determine the gametes that the parents could produce: A, a and a, a
 Draw a Punnett grid
 Deduce the chances for each genotype and phenotype: 25%, 50%, 75%
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3- State that some genes have more than two alleles (multiple alleles)
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4- Describe ABO blood groups as an example of codominance and multiple alleles
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 Sex chromosomes: 23rd pair of chromosomes determine a person’s gender
 X and Y are chromosomes
 XX is female and XY is male
 All female eggs have one X chromosome
 Half of male sperm contain one X chromosome and half contain one Y chromosome
 That’s why there’s a 50/50 chance that it’ll be a boy/girl
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6- State that some genes are present on the X chromosome and absent from the shorter Y chromosome in
humans
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7- Define sex linkage
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Colour blindness and haemophilia are only formed on X chromosome so there’s no subscript for Y chromosome
Xb colour blindness, XB no colour blindness
Xh haemophilia, XH no haemophilia
All possible genotypes for colour blindness (could also be for haemophilia if H and h replace B and b
o Not colour blind: XB XB
o Colour blind: Xb Xb
o Not colour blind: XB Xb
o Not colour blind: XB Y
o Colour blind: Xb Y
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9- State that a human female can be homozygous or heterozygous with respect to sex-linked genes
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10- Explain that female carriers are heterozygous recessive alleles
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 You can use Punnett grids for normal, ABO blood groups and sex-linked traits
 Remember steps
o Choose letters to represent dominant and recessive alleles
o Determine the genotypes of the parents
o Determine their gametes
o Draw a Punnett grid to determine offspring
o Interpret the grid for ratios
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12- Deduce the genotypes and phenotypes of individuals in pedigree charts
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4- Genetic engineering and biotechnology
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1- Outline the use of polymerase chain reaction (PCR) to copy and amplify minute quantities of DNA
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In gel electrophoresis, fragments of DNA move in an electric field and are separated according to their size
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Gel electrophoresis of DNA is used in DNA profiling
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DNA profiling is the process of matching an unknown sample of DNA with a known sample to see if they
correspond
 DNA profiling in paternity
o if the pattern of bands formed are similar, it means both come from the same individual
 DNA profiling in forensic investigations
o if the pattern of bands formed are identical, it means both come from the same individual
o Gel electrophoresis is used to determine to compare the collected DNA from a crime scene with the
suspects of the crime
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5- Analyse DNA profiles to draw conclusions about paternity or forensic investigations
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 In traits that aren't sex linked, it is difficult to find which of the 22 chromosomes the gene is found in; with
genome libraries of genetic diseases, doctors can find out exactly where to look if they think one of their
patients might possess a disease carrying allele
 new medicine can be produced by copying and distributing genes which control the synthesis of beneficial
molecules
 ancestry, how humans have migrated and how their genes have mixed can be revealed by comparing the
genetic makeup of populations around the world
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7- State that, when genes are transferred between species, the amino acid sequence of polypeptide translated
from them is unchanged because the genetic code is universal
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8- Outline a basic technique used for gene transfer involving plasmids, a host cell (bacterium, yeast or other cell),
restriction enzymes (endonucleases) and DNA ligase
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coli
 they are cut by restriction enzymes (endonucleases) at target sequences
 DNA fragments from another organism are cut using the same restriction enzyme
 these pieces are pasted to the open plasmid that has sticky ends by DNA ligase
 the recombinant plasmids formed can be inserted into new host cells and cloned
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9- State two examples of current uses of genetically modified crops or animals
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Genetic modification of crops
Benefits: 5
Harmful effects: 8
 improved food production
 unknown effects of GM organisms in the wild
 crops produce their own pest-control substances so it
 GM plants could be integrated into wild species, giving
benefits the environment because pesticides don't
them an unnatural advantage over other species
have to be used
 genes could cross species and this has unknown effects
 farmers have more control on the crops they produce
 Bt-crops which produce toxins to kill pests could be
because there is less ambiguity
harmful to humans
 multinational companies who make GM plants say
 risk of allergies
they'll help developing nations to reduce hunger by
 large portions of the human food supply might be in
using pest-resistant crops
the hands of a few corporations
 using GM organisms to produce rare proteins for
 high-tech solutions are not necessarily better than
medications or vaccines could be less expensive and
simple solutions (like teaching farmers how to use
less damaging to the environment than synthesizing
natural fertilizers more efficiently)

proteins in labs



proliferation of GM organisms could decrease
biodiversity

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11- Define clone
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Cloning using a differentiated animal: Dolly the sheep
 original donor sheep was cloned by taking a somatic cell from the udder
 this cell was cultured and the nucleus was removed
 an unfertilized egg was collected from another sheep and its nucleus was also removed
 an electrical current was used to fuse the nucleus of the udder cell with the egg cell
 the embryo was placed in the womb of a surrogate mother sheep
 Dolly the sheep was born
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13- Discuss the ethical issues of therapeutic cloning in humans
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1- Communities and ecosystems
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1- Define species, habitat, population, community, ecosystem and ecology
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 Autotroph: an organism that synthesizes its organic molecules from simple inorganic substances
 Heterotroph: an organism that obtains organic molecules from other organisms
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3- Distinguish between consumers, detritivores and saprotrophs
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 Food chain: a sequence showing the feeding relationships and energy flow between species (the direction of
each arrow shows the energy flow)
 Examples
o grass→ grasshopper→ toad→ hognose snake→ hawk
o algae→ mayfly larva→ juvenile trout→ kingfisher

o diatoms→ copepods→ herring→ seal→ great white shark
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5- Describe what is meant by a food web
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Trophic level: refers to an organism’s position in a food chain
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7- Deduce the trophic level of organisms in a food chain and a food web
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p117
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9- State that light is the initial energy source for almost all communities
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10- Explain the energy flow in a food chain
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Energy transformations are never 100% efficient
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 Pyramid of energy in kJm-2y-1
 Since energy is lost, each level is always smaller than the one before
 Pyramid of energy is not pyramid of population sizes at each trophic level
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13- Explain that energy enters and leaves ecosystems, but nutrients must be recycled
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Saprotrophic bacteria and fungi (decomposers) recycle nutrients
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2- The greenhouse effect
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1- Draw and label a diagram of the carbon cycle to show the processes involved
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 Since plants and decomposers are more active in the summer months so more carbon dioxide is extracted from
the atmosphere (less in the atmosphere)



Over the decades, human pollution has produced enough carbon dioxide to considerably raise its percentage in
the planet’s atmosphere
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3- Explain the relations between rises in concentrations of atmospheric carbon dioxide, methane and oxides of
nitrogen and the enhanced greenhouse effect
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 If the effects of human-induced change would be very large (perhaps catastrophic), those responsible for the
change must prove that it will not harm the environment before proceeding
 This is the reverse of the normal situation, where those who are concerned about the change would have to
prove that it will do harm in order to prevent such changes going ahead
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5- Evaluate the precautionary principle as a justification for strong action in response to the threats posed by the
enhanced greenhouse effect
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 Increased rates of decomposition of detritus previously trapped in permafrost

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Expansion of the range of habitats available for temperate species
Loss of ice habitat
Changes in distribution of prey species affecting higher trophic levels
Increased success of pest species and pathogens

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 Natality and immigration: increased population size
 Mortality and emigration: decreased population size
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2- Draw and label a graph showing a sigmoid (S-shaped) population growth curve
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 Exponential growth phase
o Plentiful resources (food, space, water, light)
o Little or no competition from other inhabitants
o Favourable abiotic factors like temperature
o Little or no predation or disease
 Transitional phase
o Increasing population and so increasing competition for resources
o Predators are attracted by a growing food supply
o Limited space, so more opportunities for diseases to spread
 Plateau phase
o Limited supply of food and so smaller number of offspring
o Predators and disease increase mortality and so the growth curve starts to level off
o Natality and immigration equals mortality and emigration
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4- List three factors that set limits to population increase
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4- Evolution
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1- Define evolution
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 Fossil record
o Palaeontologists collect and classify fossils
o Life in the past was very different from what it is now
o The top predators today didn’t exist in the time of the dinosaurs or before
o Life on earth is constantly changing
 Selective breeding of domesticated animals
o Provides a record of recent changes in heritable characteristics
o Breeders learn to choose the males and females with the most desirable genetic characteristics and
breed them together

o

After doing this for a long time, breeders realize that certain varieties of animals have unique
combinations of characteristics that didn’t exist before
o The driving force for these changes is human choice
o But this artificial selection isn’t the driving force of evolution
 Homologous structures
o Homologous anatomical structures are similar in form and function but are found in seemingly dissimilar
species
o Common example: 5 fingered limb found in humans, whales and bats
o This means these organisms have a common ancestor
o The basic shape and position of the limbs are the same
5
...
3- State that populations tend to produce more offspring than the environment can support
...

5
...
4- Explain that the consequence of the potential overproduction of offspring is a struggle for survival
...
4
...

The members of a species show variation
...
4
...

 There are two ways in which genes are mixed
o 1: Meiosis
o 2: Fertilization
 There’s a random distribution of chromosomes when the cells split during meiosis so each egg and sperm have a
different combination of genes
 Of the many sperm cells, only one will fertilize the one egg and so an amount of chance and luck is required
5
...
7- Explain how natural selection leads to evolution
...
4
...

 Antibiotic resistance in bacteria

o
o
o
o



Overuse of antibiotics can lead to the production of resistant strains of bacteria
A bacterium modifies its genetic makeup to become resistant to the antibiotic that was given
If the bacterium continues to modify its genetic makeup, it could become resistant to all the antibiotics
Two sources of possible change of genetic makeup
 Mutations
 Plasmid transfer
Pesticide resistance in rats
o Due to natural variation, a few rats are slightly different and aren’t affected by the pesticide
o These resistant rats survive and reproduce
o To kill the rats, a new pesticide must be used

5
...
5
...

 Binomial means two names
 First name
o Refers to the genus
o Capitalized
 Second name
o Refers to species
o Uncapitalized
 Always typed in italics or underlined when written by hand
5
...
2- List seven levels in the hierarchy of taxa- kingdom, phylum, class, order, family, genus and species-using an
example from two different kingdoms for each level
...
5
...

Phyla of plants
External recognition features
Bryophyta (moss)
Non-vascular
No leaves
Produce spores
Filicinophyta (ferns)
Vascular
Leaves
Produce spores
Coniferophyta (conifers)
Woody stems
Vascular
Leaves are in the form of needles/scales
Pollination (mostly by seed cones/scales)
Angiospermophyta (flowering plants)
Flowers and fruit
Pollination by pollen

5
...
4- Distinguish between the following phyla of animals, using simple external recognition features: Porifera,
Cnidaria, Platyhelminths, Annelida, Mollusca and Arthropoda
...
5
...

 Start by putting things in groups and ask yourself why you did so
 Identify the characteristics which make up each group

6- Human health and physiology 1
6
...
1
...

 Digestion solves a problem of molecular size
o food molecules must be small enough to pass through the membrane of you intestines and then
through the membrane of a capillary to get into the bloodstream
o therefore food must be chemically digested to a suitable size
 Digestion allows you to turn molecules into "your own"
o foods are composed of plant or animal cells and therefore contain molecules not characteristic of
human beings
o ex
...
1
...

 enzymes are protein molecules which act as catalysts for digestion
 their function is to lower the activation energy of the reactions they catalyse
 humans maintain a stable body temperature of 370C which is enough to maintain good molecular movement
 with the aid of enzymes, it provides low enough activation energy for metabolic reactions including digestion

 digestive enzymes also catalyse hydrolysis reactions
 enzymes don't cause reactions but they make them more likely to occur at physiologically normal temperatures
6
...
3- State the source, substrate, products and optimum pH conditions for one amylase, one protease and one lipase
...
1
...

p154
6
...
5- Outline the function of the stomach, small intestine and large intestine
...
coli are also in the small intestine (examples of mutualistic
organisms within us)
o we provide them with nutrients, water and a warm environment while they synthesize vitamin K and
maintain a healthy environment in the large intestine
o any food undigested by us or the bacteria is eliminated from the body as solid waste or faeces
6
...
6- Distinguish between absorption and assimilation
...
1
...

 digested nutrients in the lumen of the small intestine enter the villus epithelium which is single-cell layer
 the nutrients enter the capillary bed or lacteal
 the villus creates a very large surface area for absorption
 blood enters the capillary bed from an arteriole
 blood rich in nutrients leaves via a venule

6
...
2
...

p158
6
...
2- State that the coronary arteries supply heart muscle with oxygen and nutrients
...

6
...
3- Explain the action of the heart in terms of collecting blood, pumping blood and opening and closing of valves
...
2
...

 myogenic muscle contraction
o cardiac muscle spontaneously contracts and relaxes without nervous system control
 the myogenic activity of the heart needs to be controlled for timing
 sinoatrial node (SA node)

o in the right atrium
o acts as a pacemaker
o sends electrical signals to initiate the contraction of both atria
 atrioventricular node (AV node)
o in the right atrium
o receives the signal from the SA node, waits 0
...
2
...

Arteries
Capillaries
Veins
Take blood away from the heart to
Blood enters a capillary bed through
Collect blood from capillaries and
reach capillaries
an arteriole
return it to the heart
Thick smooth muscle layer
Through which all chemical exchanges Thin walled and larger internal
occur
diameter
Muscle used by autonomic nervous
Wall is one cell thick
Internal passive valves that help keep
system to change the inside diameter
the blood moving towards the heart
which helps to regulate blood
pressure
High internal blood pressure
Low internal pressure
Low internal pressure
6
...
6- State that blood is composed of plasma, erythrocytes, leucocytes (phagocytes and lymphocytes) and platelets
...

6
...
7- State that the following are transported by blood: nutrients, oxygen, carbon dioxide, hormones, antibodies,
urea and heat
...
3- Defence against infectious disease
6
...
1- Define pathogen
...
3
...

 antibiotics are chemicals that take advantage of the differences between prokaryotic and eukaryotic cells
 one type of antibiotic might selectively block protein synthesis in bacteria or inhibit the production of a new cell
wall (thus preventing them from growing and dividing) but have no affect on our own cells
 this is why antibiotics have no effect on viruses
 viruses make use of our own body cell's metabolism to create new viruses
 so any chemical that could inhibit this would be damaging our own body cells
 antibodies can thus kill prokaryotic cells without damaging eukaryotic cells or their metabolism
6
...
3- Outline the role of skin and mucous membranes in defence against pathogens
...
3
...

 leucocytes (white blood cells) help us fight off pathogens and also provide immunity for many pathogens that
we encounter a second time
 one type of leucocyte is a macrophage: large white blood cells that are able to change their shape to surround
an invader and take it through the process of phagocytosis
 macrophages can squeeze out of small blood vessels
 macrophages determine whether something is 'self' or 'not self' by the collections of proteins on the surface
 if it's 'not self', the macrophage engulfs the invader by phagocytosis
 phagocytes contain many lysosomes to chemically digest what they've engulfed
 this type of response is called non-specific because the identity of the pathogen hasn't been determined
6
...
5- Distinguish between antigens and antibodies
...
3
...

 each type of antibody is different and specific for just one type of antigen
 each antibody is a Y-shaped protein and at the end of each of the forks is a binding site where it attaches itself
to an antigen and thus is attached to the pathogen
 the leucocytes that produce antibodies are called B lymphocytes
 each type of B lymphocyte can produce one type of antibody
 steps for antibody production
o specific antigen type is identified
o specific B lymphocyte is identified that can produce an antibody which will bind to the antigen
o the B lymphocytes clone themselves by mitosis to increase the number
o now they begin antibody production
o the antibodies circulate the bloodstream and eventually find their antigen match
o antibodies help eliminate the pathogen
o some cloned B lymphocytes remain in the bloodstream and give immunity from a second infection by
the same pathogen (memory cells)
6
...
7- Outline the effects of HIV on the immune system
...
3
...

 it's very difficult to find a vaccine or cure for the infection caused by the virus
 HIV hides away inside its host cells for many years
 during this time, the body continues to fight against other pathogens but not against HIV which is already inside
a body cell waiting for a signal to be activated
 HIV mutates relatively quickly and so the body's immune responses or vaccines might not even recognize it after
it has mutated several times
 HIV was often associated with sexual activity and drug abuse which lead to some reluctance to allocate money
towards HIV research
 HIV is transmitted from person to person by body fluids (including exchanges during sex and drug injections)
 at one time, blood for transfusions wasn't tested for blood-borne diseases like HIV
 blood is routinely tested in countries with reasonable medical care
 AIDS was originally labelled as a disease affecting homosexuals and drug abusers but it is rapidly spreading by
way of heterosexual encounters
 individuals who have been diagnosed as being HIV positive might be discriminated against in terms of
employment, insurance, education access, social acceptance and many other forms of discrimination
 not every country has the education and medical facilities to deal with the disease and in some countries
inadequate medical care sometimes leads to an increase in infection rates

6
...
4
...

 ventilation
o breathing air in and out
o each breath in and out replenishes the gases within the lung tissues so that diffusion continues
o oxygen diffuses into the lung tissue and carbon dioxide diffuses out
 gas exchange
o the diffusion of gases
o occurs in the lungs where oxygen moves from the air of the lungs into the bloodstream and carbon
dioxide moves from the bloodstream into the air of the lungs
o the opposite occurs in a capillary bed somewhere else where oxygen diffuses out of the bloodstream
and into a body cell and carbon dioxide diffuses out of the body cell and into the capillary bed
 cell respiration
o biochemical pathway in which chemical bonds within a glucose molecule are broken to release energy,
which is stored in molecules of ATP
o in aerobic organisms, the process requires oxygen molecules
o each of the six carbons of glucose are given off as carbon dioxide
 steps
o ventilation: oxygen diffuses into alveolus
o gas exchange: oxygen diffuses into lung capillary and then diffuses out of body capillary

o

cell respiration: oxygen enters body cell and is a reactant for aerobic cell respiration; carbon dioxide is a
product of aerobic cell respiration
o gas exchange: carbon dioxide diffuses into body capillary and diffuses out of lung capillary
o ventilation: carbon dioxide enters lungs and diffuses out of alveolus
6
...
2- Explain the need for a ventilation system
...
4
...

Adaptation of alveoli
Advantage
Spherical shape
Provides a large surface area for gases to diffuse
Flattened, one cell thickness
Prevents gases from having to diffuse through more cell layers
Moist inner lining
Allows for efficient diffusion
Nearby capillary bed
Gases don't have to diffuse far to reach capillaries
6
...
4- Draw and label a diagram of the ventilation system, including trachea, lungs, bronchi, bronchioles and alveoli
...
4
...

 an increase in volume leads to a decrease in pressure
 Inspiration
o diaphragm contracts (moves down)
o abdominal and intercostal muscles help to expand rib cage
o this increases the volume of the thoracic cavity, which decreases the pressure
o since there's less pressure exerted on the lungs
o air is inhaled to counter the partial vacuum within the lungs
o the volume in the lungs increases
 Expiration
o diaphragm relaxes (moves up)
o abdominal and intercostal muscles help rib cage get smaller
o this decreases the volume of the thoracic cavity, which increases the pressure
o since there's more pressure exerted on the lungs
o this increases the pressure inside the lungs, causing air to be exhaled

6
...
5
...

The nervous system consists of the central nervous system (CNS) and peripheral nerves, and is composed of cells called
neurons that can carry rapid electrical impulses
...
5
...

p174

6
...
3- State that nerve impulses are conducted from receptors to the CNS by sensory neurons, within the CNS by relay
neurons, and from the CNS to effectors by motor neurons
...

6
...
4- Define resting potential and action potential (depolarization and repolarisation)
...
5
...

p177
 Resting potential
o polarized area
o Na+ actively transported out
o K+ actively transported in
o this occurs only on the length of the axon
o results in net positive charge outside and net negative charge inside
 Action potential
o depolarized area
o Na+ diffuse in
o K+ diffuse out
o this occurs because of concentration gradient
o results in action potential
o this area initiates the next area to open channels
 Return to resting potential
o depolarized areas cannot carry on action potentials so they are repolarized with active transport
o refractory period: time it takes for a neuron to send an action potential and then repolarize
6
...
6- Explain the principles of synaptic transmission
...
Ca2+ diffuse into the terminal buttons
2
...
neurotransmitter diffuses across the synaptic cleft from the presynaptic to the postsynaptic neuron
4
...
this initiates an action potential in the postsynaptic neuron
6
...
neurotransmitter fragments diffuse back across the gap to be reassembled in the terminal button of the
presynaptic neuron
p179
6
...
7- State that the endocrine system consists of glands that release hormones transported in the blood
...

6
...
8- State that homeostasis involves maintaining the internal environment between limits, including blood pH,
carbon dioxide concentration, blood glucose concentration, body temperature and water balance
...


6
...
9- Explain that homeostasis involves monitoring levels of variables and correcting changes in levels by negative
feedback mechanisms
...
5
...

 the hypothalamus controls temperature
 high temperature
o hypothalamus receives information from thermoreceptors in skin, activating cooling mechanisms
o increasing activity of sweat glands results in a cooling effect
o arterioles in skin dilate, filling skin capillaries with blood so that heat can leave skin, cooling the body
down
 low temperature
o hypothalamus receives information from thermoreceptors in skin, activating warming mechanisms
o constricting skin arterioles so that blood is diverted to deeper organs and there is less heat loss
o stimulate skeletal muscles to start shivering
6
...
11- Explain the control of blood glucose concentration, including the roles of glucagon, insulin and a and B cells in
the pancreatic islets
...
5
...

 Type 1
o caused when B cells in the pancreas don't produce enough insulin
o controlled by injection of insulin
o autoimmune disease which destroys B cells
o most often develops in young people
o 10%
 Type 2
o when body cell receptors don't respond properly to insulin
o controlled by diet
o result of insulin resistance
o genetics, obesity, age, race, lack of exercise
o 90%

6
...
6
...

Male p185
Female p186
6
...
2- Outline the role of hormones in the menstrual cycle, including FSH (follicle stimulating hormone), LH (luteinizing
hormone), oestrogen and progesterone
...
6
...

p188
 FSH level rises to stimulate follicle development and estrogen secretion by the cells of the follicle
 more estrogen which makes endometrium highly vascular
 estrogen rises to peak and stimulates the secretion of LH
 LH rises to peak and causes ovulation
 negative feedback: LH causes follicle cells to produce less estrogen and more progesterone
 LH causes follicle to develop into corpus luteum
 the corpus luteum secretes the progesterone, which causes the endometrium to prepare for an embryo
 negative feedback: high progesterone and estrogen levels inhibit the secretion of FSH and LH
 if no embryo is formed, progesterone and estrogen levels fall (menstruation), allowing the secretion of FSH, LH
 FSH level rises again to stimulate follicle development
6
...
4- List three roles of testosterone in males
...
6
...

 women injected with FSH for 10 days to develop many follicles
 HCG injected to loosen oocytes
 oocytes harvested surgically
 man ejaculates sperm cells into a container
 eggs and sperm cells mixed in culture dishes
 overnight in incubator
 2/3 embryos selected and placed in uterus
6
...
6- Discuss the ethical issues associated with IVF
...
1- DNA structure
7
...
1- Describe the structure of DNA, including the antiparallel strands, 3’-5’ linkages and hydrogen bonding between
purines and pyrimidines
...
1
...

 A nucleosome consists of DNA wrapped around 8 histone proteins, held together by another histone protein
...
1
...

Nucleosomes help to supercoil chromosomes and help to regulate transcription
...
1
...

 Highly repetitive sequences (satellite DNA)
o makes up 5-45% of the genome
o there are 5-300 base pairs per repetitive sequence, which can be replicated 100 000
o function is unknown
 Single-copy genes
o Provide base sequences essential to produce proteins
o Any base sequence is carried from the nucleus to the ribosomes by mRNA
o Exons: coding fragments
o Introns: non-coding fragments; are removed after transcription to form mature mRNA in eukaryotes
7
...
5- State that eukaryotic genes can contain exons and introns
...


7
...
2
...

DNA replication occurs in a 5' to 3' direction
...
2
...

 Helicase unwinds the double helix at both replication forks to create “bubbles”
 Leading strand (3’ to 5’)
o Assembled continuously toward the progressing replication fork
o Primer (RNA nucleotides) is produced at the replication fork
o Primase allows the joining of RNA nucleotides to match the DNA bases at the point of replication
o DNA polymerase III adds DNA nucleotides in a 5’ to 3’ direction
o DNA polymerase I replaces the primer with DNA nucleotides
 Lagging strand (5’ to 3’)
o Assembled away from the replication fork and therefore is in Okazaki fragments
o Primer, primase, and DNA polymerase I and III are needed as for the formation of each fragment
o Once the Okazaki fragments are assembled, DNA ligase joins the Okazaki fragments to the strand
7
...
3- State that DNA replication is initiated at any points in eukaryotic chromosomes
...


7
...
3
...

Transcription is carried out in a 5' to 3' direction
...
3
...

 Sense strand: coding strand that has the same base sequence as mRNA but with uracil instead of thymine
 Antisense strand: template, the strand that’s subscribed
7
...
3- Explain the process of transcription in prokaryotic, including the role of the promoter region, RNA polymerase,
nucleoside triphosphates and the terminator
...
3
...

Eukaryotic RNA needs the removal of introns to form mature mRNA
...
4- Translation
7
...
1- Explain that each tRNA molecule is recognized by a tRNA-activating enzyme that binds a specific amino acid to
the tRNA, using ATP for energy
...
4
...

 Ribosome is composed of one large and one small subunit
 It is composed of rRNA and proteins
 Ribosomes are constructed in the nucleolus and exit through the membrane pores
 Decoding of the strand of mRNA to produce a polypeptide occurs in the space between the 2 subunits
 Binding of the mRNA and tRNA is carried out by the rRNA
 There are three binding sites for tRNA (2 can bind at a time)
o A: holds tRNA carrying the next amino acid to be added to the polypeptide chain
o P: holds tRNA carrying the growing polypeptide chain
o E: tRNA that lost its amino acid is discharged
7
...
3- State that translation consists of initiation, elongation, translocation and termination
...

7
...
4- State that translation occurs in a 5’ to 3’ direction
...

7
...
5- Draw and label the structure of a peptide bond between two amino acids
...
4
...

 Initiation
o Activated amino acid combines with small ribosomal subunit in the P site
o The small subunit moves down the mRNA strand until it reaches the start codon (AUG)
o Hydrogen bonds form between anticodon and codon
o A large ribosomal subunit now combines with this complex

o Proteins called “initiation factors” also join the complex using energy from GTP
o another tRNA binds the next codon in the mRNA
 Elongation
o Protein called “elongation factors” assist in binding the tRNA to the A site
o a peptide bond forms between the amino acids of tRNA in the A site and P site
o the growing polypeptide detaches from the tRNA in the P site
o Translocation
o the tRNA in the P site moves to the E site and exits the ribosome
o the tRNA in the A site moves to the P site
o they switch sites when the large subunit moves a codon down the chain, followed by the small subunit
o Translation occurs in a 5’ to 3’ direction so the ribosomal complex moves towards the 3’ end
o Polysome: a string of ribosomes
 Termination
o When the stop codon appears at the open A site
o Protein called “release factor” comes into the A site and catalyses the hydrolysis of the bond linking the
tRNA and the polypeptide in the P site
o Polypeptide is released from the ribosome
o Ribosome splits into its 2 subunits
o tRNA is detached
o If proteins are synthesized by free ribosomes, they’re used within the cell
o If proteins are synthesized by ribosomes bounded by the rER, they’re secreted by the cell or used as
lysosomes
7
...
7- State that free ribosomes synthesise proteins for use primarily within the cell, and that bound ribosomes
synthesize proteins primarily for secretion or for lysosomes
...


7
...
5
...

 Primary organization
o A chain of amino acids attached by peptide bonds
o 20 amino acids can be arranged in any order
o The order is determined by the nucleotide base sequence in the DNA of an organism
o The primary structure determines the next three levels of protein organization
o Changing one amino acid can completely alter the structure and function of a protein
 Secondary organization
o Formation of hydrogen bonds between the oxygen from the carboxyl group of one amino acid and the
hydrogen from the amino group of another amino acid
o Alpha-helix and beta-pleated sheet both have regular repeating patterns
 Tertiary organization
o The polypeptide chain bends and folds over itself to create a 3D shape
o Interactions among R-groups and the peptide backbone
 Disulphide bridges: covalent bonds between sulphur atoms
 Hydrogen bonds between polar side chains
 Van der Waals forces among hydrophobic side chains
 Ionic bonds between positively and negatively charged side chains
o Important in determining the specificity of enzymes



Quaternary organization
o Involves multiple polypeptide chains which combine to form a single structure
o Not all proteins have a quaternary structure
o All the bonds from the primary, secondary and tertiary structures are involved
o Some proteins contain non-polypeptide groups to form conjugate proteins
7
...
2- Outline the difference between fibrous and globular proteins, with reference to two examples of each protein
type
...
Collagen in connective tissue for structure
 Ex
...
Actin in muscle for contraction
 Ex
...
5
...

 Non-polar amino acids are found in regions of proteins that are linked to a hydrophobic area of the cell
membrane; hydrophobic R groups
 Polar amino acids are found in regions of proteins that are exposed to water and therefore have hydrophilic
properties; hydrophilic R groups





Membrane proteins have polar amino acids towards the interior and exterior of the membrane, making them
water soluble
amino acids on the inside of membrane protein are non-polar, making the structure stable
These amino acids create hydrophilic channels in proteins through which polar substances can move
non-polar amino acids cause proteins to stay embedded in the membrane




Polar and non-polar amino acids are important in determining the specificity of an enzyme
The fitting of the substrate to the active site of an enzyme involves the general shape and polar properties of the
substrate and of the amino acids exposed in the active site
7
...
4- State four functions of proteins, giving a named example of each
...
6- Enzymes
7
...
1- State that metabolic pathways consist of chains and cycles of enzyme-catalysed reactions
...

7
...
2- Describe the induced-fit model
...
6
...

 Activation energy is the energy necessary to destabilize the existing chemical bonds in the substrate of an
enzyme-substrate catalysed reaction
 Enzymes lower the activation energy and so they cause chemical reactions to occur faster
 the substrate is changed into transition state, different from if enzyme isn't involved
 a lower activation energy is possible because the transition state has less energy
7
...
4- Explain the difference between competitive and non-competitive inhibition, with reference to one example of
each
...
The use of sulfanilamide to kill bacteria during an
makes the enzyme not function
infection
Ex
...
6
...

End-product inhibition
 Prevents the cell from wasting chemical resources and energy by making more of a substance than needed
 Many metabolic reactions occur in steps, each step catalysed by a different enzyme
 When there’s an insufficient amount of the end-product, it is used up by the cell and the first enzyme is
reactivated
 When there is a sufficient amount of the end-product, it is used to inhibit the action of the first enzyme in the
metabolic pathway by attaching itself to the allosteric site
 The enzyme that is reactivated and inhibited is the allosteric enzyme

8- Cell respiration and photosynthesis
8
...
1
...

Oxidation
Reduction
Loss of electrons
Gain of electrons
Gaining oxygen or losing hydrogen
Losing oxygen and gaining hydrogen
8
...
2- Outline the process of glycolysis, including phosphorylation, lysis, oxidation, and ATP formation
...
1
...

p76 of study guide
8
...
4- Explain aerobic respiration: the link reaction, the Krebs cycle, the role of NADH + H+, the electron transport
chain and the role of oxygen
...
1
...

 Chemiosmosis involves the movement of protons to provide energy so that phosphorylation can occur
 Called oxidative phosphorylation because it involves an electron transport chain
 ATP synthase uses energy of an ion gradient to allow the phosphorylation of ADP to ATP
 Protons are pumped from the matrix to the intermembrane space as electrons are transported along the chain
 The protons move passively through ATP synthase into the matrix
 ATP synthase takes the energy produced by this movement and uses it to convert ADP to ATP

Summary ATP Production in Cell Respiration
Process
ATP used
Glycolysis
2
Krebs cycle
0
Electron transport chain
0
and chemiosmosis
Total
2

ATP produced
4
2
32

Net ATP gain
2
2
32

38

36 (actually like 30)

8
...
6- Explain the relationship between the structure of the mitochondrion and its function
...
2- Photosynthesis
8
...
1- Draw and label a diagram showing the structure of a chloroplast as seen in electron micrographs
...
2
...

Photosynthesis consists of light-dependant and light-independent reactions
...
2
...

 In the grana of the chloroplast
 Photosystem
o Pigments that absorb light are organized on the membrane of thylakoids
o Includes chlorophyll a molecule, accessory pigments and a protein matrix
 Reaction centre of a Photosystem
o Includes a pair of chlorophyll a molecules, a protein matrix and a primary electron acceptor
 Photosystem I and II work together to bring about a non-cyclic phosphorylation/ electron flow
 Steps
o In Photosystem II, a photon of light is absorbed by a pigment and is passed to accessory pigments until it
reaches the reaction center where it excites one of the chlorophyll a electrons to a higher energy state
o This electron is captured by the primary acceptor in the reaction centre
o Photolysis: water is split by an enzyme, producing hydrogen ions, oxygen and electrons
o The electrons are supplied to the chlorophyll a molecules one by one in the reaction centre
o The excited electrons pass from the primary acceptor down the electron transport chain, losing energy
at each exchange
o The energy lost brings about phosphorylation of ADP to ATP
o In Photosystem I, a photon of light is absorbed by a pigment and is passed to accessory pigments until it
reaches the reaction centre where it excites one of the chlorophyll a electrons to a higher energy state,
transferring it to the primary acceptor
o The de-energized electron from Photosystem II fills in the void left by the newly energized electron
o This energized electron is passed down a second electron transport chain (with carrier ferredoxin)
o The enzyme NADP reductase catalyses the transfer of the electron from ferredoxin to NADP+ (2
electrons are required to reduce NADP+ to NADPH)
 Final products are NADPH and ATP
 They supply chemical energy for the light-independent reaction to occur
 Photophosphorylation because light is used to drive chemiosmosis
8
...
4-Explain photophosphorylation in terms of chemiosmosis
...
2
...

 Calvin cycle
 In the stroma
 ATP and NADPH produced in the light-dependent reactions are used
 End product is glucose
 Steps
o Carbon fixation: rubisco catalyses the reaction between ribulose biphosphate (RuBP) and carbon
dioxide, making the 5C RuBP into unstable 6C compound
o This unstable 6C compound breaks down into 2 GP
o Reduction: the 2 GP react with ATP and NADPH to form 2 TP
o Some TP leave the cycle to form sugar phosphates and complex carbohydrates but most continue the
cycle to reproduce RuBP, which requires ATP
 One glucose is produced by
o 6 RuBP
o 12 TP
o 18 ATP
o 12 NADPH
8
...
6- Explain the relationship between the structure of the chloroplast and its functions
...
2
...

 Various pigments of photosynthesis absorb photons of light from specific wavelengths of the visible spectrum
 Not all wavelengths are absorbed equally because pigments are specific to that plant
 A spectrophotometer is used to measure absorption at various light wavelengths
 This results in the absorption spectrum of the plant
 The absorption spectrum is the combination of all the absorption spectra of all the pigments in the chloroplasts
 Blue light and red light show the greatest absorption and they also represent the peaks in the rate of
photosynthesis
 Low absorption of green light corresponds to lower rate of photosynthesis
8
...
8- Explain the concept of limiting factors in photosynthesis, with reference to light intensity, temperature and
concentration of carbon dioxide
...
1- Plant structure and growth
9
...
1-Draw and label diagrams to show the distribution of tissues in the stem and leaf of a dicotyledonous plant
...
1
...

Monocots
Dicots
Parallel venation in leaves
Netlike venation pattern in leaves
3 flower parts or multiples of 3
4 or 5 flower parts or multiples of 4 or 5
Seeds contain 1 cotyledon
Seeds contain 2 cotyledon
9
...
3- Explain the relationship between the distribution of tissues in the leaf and the functions of these tissues
...
1
...

 Roots
o Storage roots
 Specialized cells within the root store large quantities of carbohydrates and water
 Stems
o Bulbs
 Vertical, undergrounds stems consisting of enlarged bases of leaves that store food
o Tubers
 Horizontal, underground stems that are modified as carbohydrate-storage structures
 Leaves
o Tendrils
 Structures that coil around objects to aid in support and climbing
9
...
5- State that dicotyledonous plants have apical and lateral meristems
...


9
...
6- Compare growth due to apical and lateral meristems in dicotyledonous plants
...
1
...

 Phototropism means plant growth in response to light
 It’s important for seedlings to grow toward the sunlight so that photosynthesis may occur more efficiently
 Auxins are plant hormones that cause the positive phototropism of plant shoots and seedlings
 They increase the flexibility of plant cell walls in young developing shoots by pumping hydrogen ions into to cell
walls and loosening the connections between cellulose fibres, allowing cell expansion
 it does this on the shadier side so that the shoot will bend towards the light
 auxin reflux carriers are distributed unevenly so that they can redistribute auxin in a tissue
 when auxin binds to an auxin receptor, transcription of specific genes is promoted

9
...
2
...

 Root hairs branching increase the surface area over which water and mineral ions are absorbed
 roots hairs only absorb be active transport because there is a high concentration of nutrients inside the root
than in the soil
 therefore, they have many mitochondria to supply ATP and they also need oxygen
 The root cap protects the apical meristem during primary growth of the root in the soil
 Three zones of branch development
o Cell division: new cells are formed
o Elongation: cells are enlarging
o Maturation: cells become functional to the plant
9
...
2- List ways in which mineral ions in the soil move to the root
...
2
...


 Often there is a higher concentration of various mineral ions inside the plant than outside
 Therefore active transport is needed to transport minerals from the soil into the roots of plants
 Proton pump is used for active transport
 Proton pump uses energy from ATP to pump certain ions out of the cell, creating a negative charge inside
 This gradient results in the diffusion of other ions back into the cell
 The voltage difference is called a membrane potential
 These forms of potential energy can be used to absorb mineral ions
9
...
4- State that terrestrial plants support themselves by means of thickened cellulose, cell turgor and lignified xylem
...

9
...
5- Define transpiration
...

9
...
6- Explain how water is carried by the transpiration stream, including the structure of xylem vessels,
transpirational pull, cohesion, adhesion and evaporation
...
2
...

Guard cells can regulate transpiration by opening and closing stomata
...
2
...

Plant hormone abscisic acid causes the closing of stomata
...
2
...

Environmental factor
Effect
Light
Speeds up transpiration by warming the leaf and opening
stomata
Temperature
Increase in temperature causes greater transpiration
because more water evaporates
Wind
Increases the rate of transpiration because humid air near
the stomata is carried away
Humidity
Decreasing humidity increases transpiration because of the
greater difference in water concentration
9
...
10- Outline four adaptations of xerophytes that help to reduce transpiration
...
2
...

 Active translocation
 Sugar from the source is loaded into the phloem sieve tube, causing water to enter by osmosis
 This causes a pressure and results in the movement of phloem sap
 Sugar is then removed at the sink from the phloem sieve tube at the sink, causing water to leave the tube by
osmosis
 This diminishes the pressure
 The water is carried back from the sink to the source

9
...
3
...

p257
9
...
2- Distinguish between pollination, fertilization, and seeds dispersal
...
3
...

 Testa
 Micropyle
 Cotyledons
 Embryo shoot
 Embryo root
p259
9
...
4- Explain the conditions needed for the germination of a typical seed
...
3
...

 The starchy seed absorbs water
 Gibberellin is formed in the seed's cotyledon
 This stimulates the production of amylase, which catalyses the breakdown of starch to maltose
 Maltose diffuses to the embryo to release energy (when converted into glucose) and for growth
 food stores aren't needed when light can reach leaves and plant can perform photosynthesis
9
...
6- Explain how flowering is controlled in long-day and short-day plants, including the role of phytochrome
...
1- Meiosis
10
...
1- Describe the behaviour of the chromosomes in the phases of meiosis
...
1
...

 during prophase I, the process of synapsis brings together 2 homologous chromosomes
 in this bivalent, one chromosome is from the father and one from the mother
 the mixing of genetic material between the 2 non-sister chromatids occurs when the chromatids intertwine and
break (the locations of the breaks must be identical on either non-sister chromatid)
 the 2 segments connect to the opposite chromatid
 the places where they connect are called the chiasmata
10
...
3- Explain how meiosis results in an effectively infinite genetic variety in gametes through crossing over in
prophase I and random orientation in metaphase I
...
1
...

 Mendel's law of independent assortment states that when gametes are formed, the separation of a pair of
alleles between the daughter cells is independent of the separation of another pair of alleles
 one allele doesn't follow another when it's passed down to a gamete
 alleles which determine different characteristics will be transmitted independently to the next generation
 traits get passed down independently of each other
 but some genes so go hand in hand (linkage group)
10
...
5- Explain the relationship between Mendel’s law of independent assortment and meiosis
...
2- Dihybrid crosses and gene linkage
10
...
1- Calculate and predict the genotypic and phenotypic ratio of offspring of dihybrid crosses involving unlinked
autosomal genes
...
2
...

 autosomes: 22 chromosomes
 sex chromosomes: XX, XY
10
...
3- Explain how crossing over between non-sister chromatids of a homologous pair in prophase I can result in an
exchange of alleles
...
2
...

 linkage group: a group of genes inherited together because they are found on the same chromosome
 any 2 genes that are found on the same chromosome are said to be linked to each other
 the linkage group is passed on to the next generation together
 linked genes are the exception of Mendel's law of independent assortment
 in dihybrid crosses, they don't give the ratio 9 : 3 : 3 : 1
10
...
5-Explain an example of a cross between two linked genes
...
2
...

 find gametes of parents
 cross them over in dihybrid cross
 for test cross, cross with homozygous recessive to figure out
 recombinants are those that are different from either parent
 without crossing over, G would always be inherited with L because they're linked

10
...
3
...

 Polygenic inheritance
o involves 2 or more genes influencing the expression of a trait
o with 2 or more pairs of alleles are found at different loci, the number of possible genotypes is greatly
increased
10
...
2- Explain that polygenic inheritance can contribute to continuous variation using two examples, one of which
must be human skin colour
...
1- Defence against infectious diseases
11
...
1- Describe the process of blood clotting
...
1
...

 The following are principles of immunity
 Challenge and response
o During the first infection, the immune system is challenged by an antigen
o The response of macrophages, helper-T cells and B cells respond, leading to immunity to this pathogen
 Clonal selection
o Immune system selects the type of B cell that will be useful and initiates the cloning of that cell
 Memory cells
o Provide long-term immunity
o To achieve true immunity, you must experience a pathogen once in order to produce memory cells
11
...
3- Define active and passive immunity
...
1
...

 Among the leucocytes in your bloodstream, there are many different types of B lymphocyte
 Each B lymphocyte (B cell) is capable of synthesizing a specific antibody which binds to a specific antigen
 The problem is that there are not enough of each type of B lymphocyte
 Therefore, B cells are cloned
 The first type of leucocyte that encounters an antigen is the large, phagocytic cell called the macrophage (found
inside and outside the bloodstream)
 When a macrophage encounters a “not self” antigen, it engulfs the possible pathogen by phagocytosis and only
partially digests it
 Leucocytes called helper-T cells (form the bloodstream) chemically recognize the antigen and become activated
 Helper-T cells turn the immune response from “not self” to antigen-specific by identifying the antigen
 These cells then activate the specific B cell type able to produce the antibody needed
 The specific B cell then begins a series of cell divisions, known as cell cloning
 There are two types of cloned B cell
o Antibody-secreting plasma cells: immediately secrete antibodies and help fight off the first infection
o Memory cells: remain in the bloodstream waiting for a subsequent infection
11
...
5- Describe the production of monoclonal antibodies, and their use in diagnosis and in treatment
...
1
...

 You can’t be immune to a pathogen without being exposed to it at least once
 We have developed vaccines that act as the first exposure to the pathogen
 A vaccine is developed by weakening a pathogen and then injecting it into the body
o Select a particularly weak strain of pathogen
o Heat the pathogen
o Or chemically treat the pathogen
 The leucocytes will recognize the pathogen as “not self” and the primary immune response takes place
o Memory B cells are formed which will produce antibodies very quickly if there’s a later infection
 Vaccination doesn’t prevent infection but with exposure to the pathogen the secondary immune response is
quicker and more intense than the primary immune response
 In this way, most people have only very mild symptoms
P288
11
...
7- Discuss the benefits and dangers of vaccination
...


11
...
2
...

 Bones
o Provide a hard framework to support the body
o Allow protection of softer tissue and organs
o Act as levers for body movement
o Form blood cells in the bone marrow
o Allow storage of minerals like calcium and phosphorous
 Tendons
o allow the attachment of skeletal muscles to bones
 Muscles
o Provide the force necessary for movement
 Ligaments
o Connect bone to bone
o Strengthen the joint
o Provide stability
 Nerves
o Allow constant monitoring of positions of the joint parts
o Prevent over-extension of joint parts

11
...
2- Label a diagram of the human elbow joint, including cartilage, synovial fluid, joint capsule, named bones and
antagonistic muscles (biceps and triceps)
...
2
...
2
...

Elbow joint part
Function
Cartilage
Reduces friction and absorbs compression
Synovial fluid
Lubricates to reduce friction and provides nutrients to cartilage
Joint capsule
Surrounds the joint, encloses the synovial cavity and unites connecting bones
Tendons
Attach muscle to bone
Ligaments
Connect bone to bone
Biceps
Contracts for flexion of the arm
Triceps
Contracts for extension of the arm
Humerus
Lever that allow anchorage of muscles of the elbow
Radius
Lever for biceps
Ulna
Lever for triceps
11
...
4- Compare the movements of the hip joint and the knee joint
...
2
...

 Striated muscle fibres
 Responsible for skeletal movement
 Muscle cells are called muscle fibres because of their elongated shape
 There is connective tissue beside the muscle fibres
 Blood vessels and nerves penetrate the muscle body
 Sarcolemma
o Plasma membrane
o Multiple nuclei are just underneath
o Has transverse or T tubules that penetrate the interior of the cell
 Sarcoplasm
o Cytoplasm
o Has a large number of glycosomes that store glycogen
o Has large amounts of the protein myoglobin
o mitochondria
 Sarcoplasmic reticulum
o Organelle that surrounds the muscle myofibrils
 Myofibrils
o Rod-shaped bodies that run the length of the cell
o Have many mitochondria between them
o Contractile element of muscle cells and the reason why striated muscle has a banded pattern
o Made up of sarcomeres which allow muscle movement

o

Light and dark banding of sarcomeres within myofibrils
Actin and myosin are contractile proteins
o Z lines mark ends of sacromere
o A band is dark and extends the entire length of the myosin filaments
o H zone is in middle of A band and contains only myosin
o Supporting protein holds the myosin filaments together at the middle, producing an M line
o I bands are light and only contain actin
11
...
6- Draw and label a diagram to show the structure of a sarcomere, including Z lines, actin filaments, myosin
filaments with heads, and the resultant light and dark bands
...
2
...

 Motor neuron carries action potential to neuromuscular junction
 The neurotransmitter acetylcholine is released into the gap between the axon terminal and the sarcolemma
 Acetylcholine binds to receptors on the sarcolemma, causing sarcolemma ion channels to open which allow
sodium ions through the membrane
 This generates an action potential, which moves along the membrane and through the T tubules
 (After generation of the action potential, acetylcholine is broken down by the enzyme acetylcholinesterase)
 This causes the release of calcium ions from the sarcoplasmic reticulum into the sarcoplasm
 Myosin heads are activated by splitting ATP, causing a change in the position of the heads
 Myosin heads are attracted to and attach to the exposed binding sites of actin to form cross-bridges, releasing
inorganic phosphate
 As myosin forms a cross-bridge, ADP is released, causing myosin to lose energy and bend towards the centre of
the sacromere, causing the actin to move inwards (power stroke)
 Myosin binds to ATP, allowing detachment of myosin heads from the actin binding sites
p298
11
...
8- Analyse electron micrograph to find the state of contraction of muscle fibres
...
3- The kidney
11
...
1- Define excretion
...
3
...

p300
11
...
3- Annotate a diagram of a glomerulus and associated nephron to show the function of each part
...
3
...

 Blood is ultrafiltered within the Bowman’s capsule
 Afferent arteriole brings unfiltered blood to the nephron
 The afferent arteriole branches into a capillary bed called the glomerulus
 When blood pressure is increased, the fenestrations in the glomerulus open
 Increased blood pressure is caused when the efferent arteriole (which drains blood from the glomerulus) has a
smaller diameter than the afferent arteriole (takes blood to the arteriole)
 Fluid that is ultrafiltered from the glomerulus passes through the basement membrane which prevents large
molecules from being a part of the filtrate
 Filtrate enters the proximal convoluted tubule
 The blood cells, proteins and other molecules that didn’t become a part of the filtrate move through the
efferent arteriole out of the Bowman’s capsule
11
...
5- Define osmoregulation
...
3
...

 Reabsorption recovers needed substances to the bloodstream
 Substances leave the tubule filtrate and enter the bloodstream through the peritubular capillary bed (called
peritubular because it surrounds the tubule)
 Microvilli line the inside of the proximal convoluted tubule which increase the surface area for reabsorption


Salt ions
o First actively transported into the tubule cells and then outside the tubule into the intercellular fluid and
then into the peritubular capillary bed
 Water
o The reabsorption of salt ions causes the water to follow the same route by osmosis
 Glucose
o All of the glucose that is in the filtrate is reabsorbed into the bloodstream by active transport
11
...
7- Explain the roles of the loop of Henle, medulla, collecting duct and ADH in maintaining the water balance in
the blood
...
3
...

 Proteins are too large to fit through the basement membrane within the Bowman's capsule and so they are a
part of blood plasma but not the filtrate or urine
 Glucose becomes a part of the filtrate but all of it is moved back to the peritubular capillary bed by active
transport (mainly in the proximal convoluted tube)
 The relatively high concentration of urea in urine is due to the reabsorption of water in the collecting duct
11
...
9- Explain the presence of glucose in the urine of untreated diabetic patients
...
4- Reproduction
11
...
1- Annotate a light micrograph of testis tissue to show the location and function of interstitial cells (Leydig cells),
germinal epithelium cells, developing spermatozoa and Sertoli cells
...
4
...

 spermatogenesis occurs in the seminiferous tubules
 spermatogonia (2n) undergoes
o DNA replication
o growth
o meiosis I: 2 cells (n)
o meiosis II: 4 cells (n)
 each differentiates into a motile spermatozoon (plural: spermatozoa) and attaches to Sertoli cells for nutrients

11
...
3- State the role of LH, testosterone and FSH in spermatogenesis
...
4
...

 germinal epithelium: diploid germ cells which grow larger to become primary oocytes
 primary follicles: primary oocytes surrounded by single layer of follicle cells
 Graafian follicle: secondary oocyte and 2 rings of zona pellucida with fluid between
 secondary oocyte: haploid oocyte after meiosis I (n)
p311
11
...
5- Outline the processes involved in oogenesis within the ovary, including mitosis, cell growth, the two divisions
of meiosis, the unequal division of cytoplasm and the degeneration of the polar body
...
4
...

p311
11
...
7- Outline the role of the epididymis, seminal vesicle and prostate gland in the production of semen
...
4
...

Spermatogenesis- 7
Oogenesis- 7
Millions of sperm produced/day
One secondary ooctye ovulated/menstrual cycle
4 gametes produced per germinal cell (spermatogonia)
1 gamete produced per germinal cell (oogonia) which
which begins meiosis
begins meiosis (plus 3 polar bodies)

Resulting gametes are very small
Occurs in testis
Spermatozoa released during ejaculation
Haploid nucleus from meiosis
Continues all through life starting at puberty

Resulting gametes are very large
Occurs in ovaries
Secondary oocyte released during ovulation
Haploid nucleus from meiosis
Ovulation starts at puberty, occurs with each menstrual
cycle and stops during menopause

11
...
9- Describe the process of fertilization, including the acrosome reaction, penetration of the egg membrane by a
sperm and the cortical reaction
...
4
...

 human chorionic gonadotrophin
 secreted by embryo
 HCG enters the mother's bloodstream to get to the corpus luteum, maintaining the secretory functions of the
gland beyond the length of a normal menstrual cycle
 so the corpus luteum continues to secrete oestrogen and progesterone and the endometrium is maintained

11
...
11- Outline early embryo development up to the implantation of the blastocyst
...
4
...

 the embryo and maternal endometrium create the placenta
 it is part of molecule exchanges
From fetus to mother within placenta
From mother to fetus within placenta
Carbon dioxide, urea, water, hormones (WUCH)
Oxygen, nutrients/vitamins/minerals, water, hormones



(NHOW)
acts as endocrine organ important in second half of pregnancy
o when the corpus luteum stops producing and secreting the two hormones, the placenta does it instead



structure
o thick disk plate
o placental villi
 large surface area for exchange
 capillaries flow with fetal blood
o inter-villous space
 mother`s blood flows through (brought by uterine arteries and taken by uterine veins)
o endometrium (through which placenta grows)
o umbilical arteries
 deoxygenated fetal blood flows to placenta
 oxygenated fetal blood flows to fetus
11
...
13- State that the fetus is supported and protected by the amniotic sac and amniotic fluid
...

11
...
14- State that materials are exchanged between the maternal and fetal blood in the placenta
...

11
...
15- Outline the process of birth and its hormonal control, including the changes in progesterone and oxytocin
levels and positive feedback
...
1- Stimulus and response
E
...
1- Define the terms stimulus, response and reflex in the context of animal behaviour
...
1
...

 receptors
o receive stimulus and generate nerve impulse in sensory neurons
 sensory neurones
o carry impulse to spinal cord
o axon enters spinal cord in the dorsal root and sends a chemical message across a synapse to a relay
neuron
 relay neurons
o located in grey matter of spinal cord

o synapses with motor neuron and transfers impulse chemically across synapse
 motor neuron
o located in grey matter of spinal cord
o carries impulse to effector through ventral root of spinal cord
 effector
o performs response
E
...
3- Draw and label a reflex arc for a pain withdrawal reflect, including spinal cord and its spinal nerves, relay
neuron, motor neuron and effector
...
1
...

 European blackcaps
o usually migrate from Germany to Spain
o 50 years ago, some blackcaps came to the UK instead of Spain and went back to Germany 10 days earlier
than the ones in Spain
o the earlier the birds came, the more territory they had and the more eggs they laid, hence having an
advantage
o UK has warmer winters, increasing survival rate
o eggs from both UK and Spain were taken
o birds migrated to where their parents had gone and therefore genetically programmed to fly in a certain
direction
o something in genetic variation causes birds going to the UK return to Germany earlier
 Sockeye salmon
o some from Lake Washington migrate to Cedar River
o river and lake have very different environments
o over 60 years, 13 generations have been produced
o river and lake salmon have stopped interbreeding
o lake conditions favour one set of traits and river conditions favour another
o lake salmon (beach-spawning)
 females lay eggs on beaches
 males have large bodies fit for deep lake waters, not efficient for navigating fast river currents
o river salmon (river-spawning)
 females lay eggs on bottom of river
 males have thinner bodies, fit for fast river currents

E
...
2
...

 Mechanoreceptors
o stimulated by mechanical force or pressure
o pressure receptors in arteries to detect change in blood pressure
o pressure receptors in inner ear to give information about equilibrium
o stretch receptors in lungs to detect degree of lung inflation
o proprioceptors in muscle fiber, tendons, joints and ligaments to maintain posture and balance
 Chemoreceptors
o respond to chemical substances
o we can taste and smell
o monitor pH changes in blood vessels and signal body to adjust breathing rate
o pain receptors respond to chemicals released by damaged tissues, causing pain reflex
 Thermoreceptors
o respond to change in temperature
o warmth receptors when temperature rises and cold receptors when temperature drops
 Photoreceptors
o respond to light energy in eyes
o rod cells respond to dim light causing black and white vision
o cone cells respond to bright light causing colour vision
E
...
2- Label a diagram of the structure of the human eye
...
2
...

Notes of annotating
 rod cells: photoreceptor cells that receive stimulus of even dim light and synapse with a bipolar neuron
 cone cells: photoreceptor cells that receive stimulus of bright light and synapse with a bipolar neur on
 bipolar neurons: cells in retina which carry impulses from rod or cone cells to ganglion cells to optic nerve (called
bipolar because they each have two processes extending from the cell body)
 ganglion cells: cell bodies of optic nerve that synapse with bipolar neurons and send impulses to the brain
p467

E
...
4- Compare rod and cone cells
...
2
...

 Edge enhancement
o use of optical illusions to study the neurobiology of vision
o Hermann grid illusion
 areas where you see are grey are in peripheral vision, where there are fewer light-sensitive cells
than in the centre of the retina
 this sends the message of grey instead of white
 when you look directly, you use the centre of the retina which has a high concentration of lightsensitive cells
o this demonstrates how we have a special mechanism for seeing edges, called edge enhancement
o light-sensitive receptors in your eye switch off their neighbouring receptors, making edges look more
distinct because of extreme contrast between light and dark
 Contralateral processing
o contralateral (opposite side) processing is due to the optic chiasma
o nerve fibres bringing information from right and left half of each visual field converge at optic chiasma
and pass to the opposite side of the brain, and vice versa
o information ends up in visual cortex of brain and the image is inverted and reversed
o patients with lesions in the right side of the brain cannot recognize an object
o patients with lesions in the left side of the brain can describe the function of an object but not the name
o therefore it takes both sides of the brain to have a correct vision which is able to recognize an object
and understand what it is
E
...
6- Label a diagram of the ear
...
2
...

 outer ear catches sounds waves, causing the eardrum to vibrate slightly
 vibration moves to bones of ear and is multiplied 20 times
 stapes strikes oval window, causing it to vibrate and is passed to fluid in cochlea, which causes hair cells to
vibrate
 hair cells are receptors and release a chemical message across a synapse to the sensory neurons of the auditory
nerve and the chemical message is transported to the brain
 the wave of the fluid of the cochlea dissipates as it reaches the round window

E
...
3
...

Innate behaviour
Develops independently of environmental context
Controlled by genes
Inherited from parents
Developed by natural selection

Learned behaviour
Dependent on environmental context
Not controlled by genes
Not inherited from parents
Develops by response to an environmental stimulus

Increases chance of survival and reproduction

May/may not increase chance of survival and reproduction

E
...
2- Design experiments to investigate innate behaviour in invertebrates, including either a taxis or a kinesis
...
3
...

 the behaviour of isopods is to move randomly and quickly in a dry environment until they come to rest in the
humid environment
 humidity is important for their survival
 this ensures survival and enhances the ability to reproduce
E
...
4- Discuss how the process of learning can improve the chance of survival
 learning from parents or trial and error
 imprinting is how young animals become attached to their mother within the first day or so after hatching
 this ensure that the young stay close to their mother for protection and as a source of food
 improves chance of survival
 animals hoard food which is a learned strategy, allowing them to stay nourished even when there are shortages
 birdsong is learned and is used to attract mates and deter rival males; the best song promotes survival of his
particular genes
 grizzly bears learn to catch slippery salmon in rivers
E
...
5- Outline Pavlov’s experiments into conditioning of dogs
...
3
...

 birdsongs have both inherited and learned components
 a crude template of birdsong is inherited but the development of a mature adult song is learned
 memorization phase
o when a hatchling listens to the song of adults to modify the inherited template
o occurs within 100 days of hatching (sensitive phase)
 second phase
o young birds practice the song they have learned (motor phase)
o tries to shape the song to match his father's
o as he becomes sexually mature, the song will become perfected and he'll begin to search for a mate

E
...
4
...

Some presynaptic neurons excite postsynaptic transmission and others inhibit postsynaptic transmission
...
4
...

 if the sum of signals in a neuron is inhibitory, the axon doesn't fire and if the sum of signals is excitatory, the
axon fires
 the CNS makes decisions based on the summation of messages
 neurotransmitters released by exocytosis


Excitatory neurotransmission
o generates an action potential
o increase the permeability of postsynaptic membrane to positive ions, causing Na+ to diffuse into the
postsynaptic neuron from the synaptic cleft
o depolarization occurs: net positive charge inside compared to outside
o this causes the next area to depolarize and so the impulse is carried along
o the membrane depolarization must be raised above the threshold



Inhibitory neurotransmitters
o inhibit action potentials
o causes hyperpolarisation of the neuron, causing the inside to be more negative than the outside
o inhibitor binds to specific receptor, causing Cl- to move across the membrane into the postsynaptic
neuron OR causing K+ to move out of postsynaptic neuron

E
...
3- Explain how psychoactive drugs affect the brain and personality by either increasing or decreasing postsynaptic
transmission
...
4
...

 Excitatory drugs
o nicotine
o cocaine
o amphetamine


Inhibitory drugs
o benzodiazepines
o alcohol

o tetrahydrocannabinol (THC)
E
...
5- Explain the effects of THC and cocaine in terms of their action at the synapses in the brain
...
4
...

 addiction: chemical dependency on drugs where the drug has "rewired" the brain and has become an essential
biochemical in the body


genetic predisposition
o studies of male twins show that if one twin has an addiction to alcohol or drugs, the rate of addiction in
the second twin is 50% greater among identical twins than fraternal twins
o genetically determined deficiency of dopamine receptors predisposes some people to addiction
o alcohol-preferring rats had 20% less dopamine receptors than normal rats



social factors
o can determine a child's vulnerability to substance abuse
 family addiction
 family parenting skills
 mental health problems of family or child
 peer pressure (very influential over adolescents)



dopamine secretion
o dopamine is the neurotransmitter which activates the 'reward pathway' and gives a sense of pleasure
and satisfaction

o

tolerance
 during drug addiction, over-stimulation of dopamine receptors decreases the number of
receptors and the remaining receptors become less sensitive to dopamine
 exposure to the drug causes less response than before and so more of the drug is needed
 this neuroadaptive change causes addiction

E
...
5
...

p490

E
...
2- Outline the functions of each of the parts of the brain listed above
...
5
...

 brain lesions
o lesions can indirectly tell us about the function of that part of the brain
o can tell differences between right and left side of the brain
o right and left hemispheres are connected by a thick band of axons called the corpus callosum
o

left hemisphere
 important for communication





damage can cause difficulty speaking or doing complicated movement of arms and hands
injury to Broca's area interferes with ability to vocalize words
injury to Wernicke's area affects ability to put words in a sentence

o

o





right hemisphere
 helps understand words
 specializes in receiving and analysing information which comes from our senses
 helps understand what we hear and see
 damage on right side causes problems in identifying faces and locating an object correctly in
space
splitting of corpus callosum to relieve symptoms of epilepsy
 left side receives info from right visual field
 right side receive info from left visual field
 person is asked to stare at the centre of a picture with the left side being a woman and right
side being a man
 the information of the picture of the woman went to the right side so the person points to the
woman's face when asked to point to what they saw
 the information of the picture of the man went to the left side so that person says that they saw
a "man" when asked to say what they saw
 this shows how the left side of the brain is responsible for verbal communication and the right
side of the brain for the recognition of objects

functional magnetic resonance imaging (fMRI)
o shows blood flow of brain
o researchers examine how the brain performs a task exposed to various stimuli
o can determine when regions of the brain become active and for how long they remain active
o used by doctors to determine
 a plan for surgery
 treatment for a stroke

animal experiments
o expose animals to addictive substances because they respond in similar ways to humans
 want more and more of the substance
 spend a lot of time and energy getting it
 keep taking it despite adverse conditions
 have withdrawal symptoms
 go back to it when stressed
 go back to it with another exposure
o self-administration experiment is conducted to fit the above model
 animal is trained to press a lever to get a reward
 in doing so, it is given an injection of the addictive substance
 2 levers: one which gives substance and one that doesn't
 if animal presses lever with substance more frequently, it is addictive
E
...
4- Explain sympathetic and parasympathetic control of the heart rate, movements of the iris and flow of the blood
to the gut
...
pain reflux arc)
 autonomic system
o involuntary
o regulates activities of glands, smooth muscle and the heart
o consists of the sympathetic system and parasympathetic system (they are antagonistic)
Sympathetic system
Parasympathetic system
Important in emergency
Important in returning to normal
Response is "fight or flight"
Response is to relax
Neurotransmitter is noradrenalin
Neurotransmitter is acetylcholine
Excitatory
Inhibitory
Increases heart rate and stroke volume of heart
Decreases heart rate and stroke volume of heart
Dilates bronchi to give more oxygen
Breathing slows down
Dilates pupil by contraction of radial muscles in iris
Constricts pupil by contraction of circular muscles in iris to
(relaxation of circular muscles)
protect retina (relaxation of radial muscles)
Blood flow to the gut is restricted by causing blood vessels Blood flow returns to digestive system by causing blood
to narrow
vessels to widen
E
...
5- Explain the pupil reflex
...
5
...

 life support, but person is dead
 it is possibly to artificially maintain the body without the impulses which would normally come from the brain
 functions like heart rate, breathing, body pressure, blood pressure and fluid retention can be controlled without
a functioning brain
 legal description of brain death: when a doctor has determined that the brain and brain stem have irreversibly
lost all neurological function
 pupil reflex must be absent for someone to be brain dead (tested with shining light)
E
...
7- Outline how pain is perceived and how endorphins can act as painkillers
...
6- Further studies of behaviour
E
...
1- Describe the social organization of honey bee colonies and one other non-human example
...
6
...

 natural selection in the case of social organisms acts on the colony as a whole
 the selected genes are those which promote social organization
 the "worker" gene in the case of working bees
E
...
3- Discuss the evolution of altruistic behaviour using two non-human examples
...
g
...
6
...

 Small mouth bass
o can forage for minnows or crayfish
o minnows contain more energy per unit weight and easier to digest but crayfish are easier to catch
o they switch back and forth and ensure the energy they take in is higher than the energy they expend
 bluegill sunfish
o eat Daphnia
o forage for larger but go with smaller if the larger ones are far away
o when density is low, it will not care about size but when density is high, it will choose the larger ones
E
...
5- Explain how mate selection can lead to exaggerated trait
...
6
...

Animals show rhythmical variations in activity
...
6
...

 reef-building species of coral
o release millions of gametes in a synchronized mass spawning ritual each year
o increases the chance of fertilization
 North American ground squirrel
o flies at night
o gets the most food and the least competition

H- Further human physiology
H
...
1
...

Hormones are chemical messengers secreted by endocrine glands into the blood and transported to specific target cells
...
1
...

Steroids: oestrogen
Tyrosine derivatives: thyroxin
Proteins: insulin

H
...
3- Distinguish between the mode of action of steroid hormones and protein hormones
...
1
...

 The pituitary is controlled by the action of the hypothalamus
Posterior lobe of pituitary
 Contains axons of cells called neurosecretory cells (dendrites in hypothalamus)
 The dendrites and cell bodies of the neurosecretory cells are located in the hypothalamus and the axons extend
down to the posterior pituitary
 Hormones are produced at the cell body end and travel down the axon into the posterior pituitary
Anterior lobe of pituitary
 The hypothalamus contains capillary beds which take in hormones produced by the hypothalamus itself, which
are called releasing hormones
 The capillary beds join together to form a blood vessel called a portal vein which extends down to the anterior
pituitary
 It then branches out into a second capillary bed, which allows the releasing hormones to reach the target cells in
the anterior pituitary
 The releasing hormones cause the anterior pituitary to secrete specific hormones, which enter through the same
capillary beds that the releasing hormones used to exit
p603
H
...
5- Explain the control of ADH secretion by negative feedback
 ADH (antidiuretic hormone) controls how much water is reabsorbed from the collecting duct into the
bloodstream
 ADH secreted: collecting duct becomes more permeable to water so water leaves it by osmosis into the highly
hypertonic medulla of the kidney; then the water is reabsorbed back into the bloodstream
 ADH not secreted: collecting duct is impermeable to water so urine contains a relatively high content of water
 ADH is produced by the dendrites of the neurosecretory cells
 The hormone extends down the axon and is stored in membrane-bound granules within the synaptic end of the
neurosecretory cell
 The secretion of ADH from these granules depends on the action potential of the hypothalamus





Osmoreceptors in the hypothalamus monitor the water content of the blood as it passes through capillary beds
in the hypothalamus
If water content is low, an action potential is sent to the posterior pituitary to secret ADH, so water is
reabsorbed into the bloodstream which goes to the kidneys
If water content is high, no action potential is sent, so no ADH is secreted and urine is relatively dilute

H
...
2
...

Digestive juices are secreted into the alimentary canal by glands, including salivary glands, gastric glands in the stomach
wall, the pancreas and the wall of the small intestine
...
2
...

 An exocrine gland is a collection of cells that produce and secrete a product (often a protein) which is carried to
a specific location in the body by way of a duct
Recapping steps of protein synthesis
 mRNA transcribed from a gene of DNA
 mRNA translated at a ribosome in the cytoplasm of a cell
 ribosomes attached to rough endoplasmic reticulum (rER)
 synthesized proteins at ribosomes move through ER channels and reach a Golgi apparatus, which package
protein into a vesicle (larger vesicles are called secretory granules)
 vesicles fuse with plasma membrane and release their contents outside the cell (exocytosis/secretion)
 these cells usually contain an above average amount of mitochondria because ATP is needed in this process


Therefore, endocrine gland cells contain extensive ER, many ribosomes, Golgi apparatus, vesicles/granules and
mitochondria

The arrangement of exocrine gland cells into acini and ducts
 Example: cells in the pancreas that secrete digestive enzymes
 Acini: exocrine gland cells surround the end of a very small branch (ductile) of the pancreatic duct and secrete
digestive enzymes into it
 The ductile takes the secretion into larger and larger ducts until the pancreatic duct is reached
P607
H
...
3- Compare the composition of saliva, gastric juice and pancreatic juice
...
2
...

 The sight or smell of food will initiate the secretion of gastric juice from the stomach
 Once food enters the stomach, receptors in the stomach wall are stimulated and send sensory signals to the
brain, which responds by causing the stomach to secrete even more gastric juice
 This results in the production of the hormone gastrin, which leads to the sustained release of gastric juice
(especially the hydrochloric acid component)
 initial release: nerve stimulation
 sustained release: secretion of the hormone gastrin when food enters stomach
H
...
5- Outline the role of membrane-bound enzymes on the surface of epithelial cells in the small intestine in
digestion
...
2
...

 Mammals do not produce an enzyme able to digest cellulose (a polysaccharide carbohydrate composed of
thousands of glucose monosaccharides)
 Grazers (mammals) contain mutualistic microorganisms which produce enzyme (to hydrolyse cellulose into
glucose)
 However, the relative energy yield from plant material is small so they spend hours each day eating
 Humans have mutualistic association with intestinal bacteria but we don’t have a relationship with the type of
bacteria that produce cellulose
 Therefore, the plant material we eat largely exits our alimentary canal as faeces
H
...
7- Explain why pepsin and trypsin are initially synthesized as inactive precursors and how they are subsequently
activated
...
2
...

 The fluid in our stomach can be as acidic as pH 2
 Before, it was assumed that excess production of hydrochloric acid, perhaps brought on by stress was the cause
of stomach ulcers
 However, the bacteria Helicobacter pylori survive in the stomach and infect the stomach lining
 Helicobacter pylori produce the enzyme urease to create ammonia and neutralize stomach acid
 Helicobacter pylori infection of the stomach leads to gastritis and stomach ulcers
 people with gastritis are much more prone to stomach cancers
 antibiotics help for stomach ulcers
 most common bacterial infection in the world
H
...
9- Explain the problem of lipid digestion in a hydrophilic medium and the role of bile in overcoming this
...
3- Absorption of digested foods
H
...
1- Draw and label a transverse section of the ileum as seen under a light microscope
...
3
...

 Microvilli
o the surface area of each villus has microvilli which increased the surface area for greater absorption


Mitochondria and pinocytotic vesicles
o some molecules are absorbed using active transport and therefore there are mitochondria in epithelial villi
cells to provide ATP
o pinocytotic vesicles are active transport mechanisms



Tight junctions
o if intercellular fluid and small molecules moved between epithelial cells, nutrients have no selective
barrier to pass through to the capillary bed and lacteal
o therefore, the cells are tightly sealed to each other

H
...
3- Explain the mechanisms used by the ileum to absorb and transport food, including facilitated diffusion, active
transport and endocytosis
...
3
...

 cellulose
 lignin
 bile pigments
 bacteria
 intestinal cells
 (BBLIC)

H
...
4
...

p614
 Liver received blood from hepatic artery (oxygenated) and hepatic portal vein (nutrient-rich), carrying it to the
sinusoids
 hepatocytes remove substances from and add substance to the blood entering
 the deoxygenated blood is drained by the hepatic vein
o blood is low pressure because it has already been through a capillary bed
o varying quantities of nutrients depending on the type of food and timing of ingestion, digestion and
absorption of foods within the small intestine
o not as much variation as the nutrients in the hepatic portal vein
Sinusoids
 Hepatocytes (liver cells) remove and add a variety of substances
 When blood enters the sinusoids, exchange occurs between the blood and the hepatocytes
 Sinusoids are different from the capillary beds
o wider
o Lined with epithelial cells with gaps between them, allowing large molecules to be exchanged and
allowing hepatocytes to be in direct contact with blood

o
o

Contain Kupffer cells which help break down older red blood cells to recycle
receive a mixture of oxygenated blood and nutrient-rich blood which drains into small branches of
hepatic vein

H
...
2- Explain the role of the liver in regulating levels of nutrients in the blood
...
4
...

 (GADI)
 Glycogen: polysaccharide carbohydrate, regulate blood sugar levels
 Iron: removed and stored following breakdown of erythrocytes and haemoglobin molecules
 Vitamin A: good vision (first signs of deficiency is ‘night blindness’)
 Vitamin D: often added to milk and milk products
H
...
4- State that the liver synthesizes plasma proteins and cholesterol
...

H
...
5- State that the liver has a role in detoxification
...

H
...
6- Describe the process of erythrocyte and haemoglobin breakdown in the liver, including phagocytosis, digestion
of globin and bile pigment formation
...
4
...

 The hepatic portal vein brings alcohol to the sinusoids in the liver and any alcohol not removed is brought back
to the sinusoids through the hepatic artery
 Each time alcohol passes, hepatocytes try to remove it from the blood stream, which is why alcohol
consumption has a more magnified effect on the liver than on other organs
 Long-term alcohol abuse can result in
o Cirrhosis: scar tissue left when areas of hepatocytes, blood vessels and ducts have been destroyed
o Fat accumulation: damaged areas of the liver build up fat instead of normal liver tissue
o Inflammation: swelling of damaged liver tissue (aka alcoholic hepatitis)
 Females are more susceptible to liver damage
 Small liver damage can be partially reversible but too much can be fatal

H
...
5
...

 Cardiac cycle=one heartbeat
 Heart rate measured in cycles per minutes
 A chamber contracts when the cardiac muscle of the chamber receives an electrical signal
 This causes an increase in pressure on the blood inside the chamber so it leaves (systole)
 When the cardiac muscle is relaxed, it's called diastole
 Both atria undergo systole at the same time, both ventricle too
 Atrioventricular valves between atria and ventricles
 Semilunar valves through which blood leaves the ventricles
p619
What prevents blood from flowing back into vena cava and pulmonary veins when atria undergo systole?
 Vena cava and pulmonary veins have internal, passive flap valves which close down if blood attempts to flow
backwards
 The atria exert low pressure relative to the ventricles
Sounds of the heart for 72 beats per minute (1 heartbeat=0
...
1 seconds into CC at end of atrial
systole and beginning of ventricle
systole
Dub
0
...
5 seconds: 0
...
1 seconds of the next cycle

closing of atrioventricular valves

closing of semilunar valves

H
...
2- Analyse data showing pressure and volume changes in the left atrium, left ventricle and the aorta, during the
cardiac cycle
...
5
...

Myogenic control-p623
 Resting heart rate controlled by the heart itself
 Sinoatrial (SA) node located close to entry of superior vena cava
 The action potentials cause atria to undergo systole
 Atrioventricular (AV) node located in septum: receives an action potential from SA node, delays for 0
...
5
...

Atherosclerosis
 Atherosclerosis is a slow build-up of plaque (lipids, cholesterol, cell debris and calcium)
 It typically takes many years to become a serious problem
 As arteries begin to build up plaque, they become harder
 Endothelium: inside lining of an artery
 Build up of plaque causes the decrease in diameter of the blood vessel and therefore decreases the amount of
oxygen-rich blood that is supplied to organs
 Also, the damaged part of the blood vessel can cause of blood clot, which further decreases the diameter
Coronary arteries
 Three major coronary arteries (branches of the aorta) supply the heart with oxygen-rich blood
 The heart muscle demands a lot of oxygen so there is a serious problem if even one coronary artery is blocked
 This is what happens when atherosclerosis leads to stenosis of the coronary arteries
 A travelling blood clot can also come into these arteries
H
...
5- Discuss factors that affect the incidence of coronary heart disease (CHD)
...
6- Gas exchange
H
...
1- Define partial pressure
...

H
...
2- Explain the oxygen dissociation curves of adult haemoglobin, fetal haemoglobin and myoglobin
...
6
...

 carbon dioxide diffuses out of a respiring cell and eventually enters a nearby blood capillary
 it is carried in three ways through the blood stream
o as carbon dioxide gas dissolved in plasma
o as carbon dioxide bound to haemoglobin
o as hydrogen carbonate ions dissolved in blood plasma
 the cytoplasm of erythrocytes contains the enzyme carbonic anhydrase which catalyses the synthesis of
carbonic acid from carbon dioxide and water
 carbonic acid then dissociates into a hydrogen carbonate ion and hydrogen ion
 hydrogen carbonate ion
o exits the cell through protein channels by facilitated diffusion in exchange for a chlorine ion which
enters the cell
o chloride shift: keeps a balance of charges on either side of the erythrocyte cell membrane
 hydrogen ion
o pH buffering: removal of hydrogen ions prevents a large change in the pH of blood
o buffered: stay within the erythrocyte and become temporarily bound to haemoglobin
o buffered: some leave and become bound to plasma protein
o the hydrogen ions are only temporarily removed
p632
H
...
4- Explain the role of Bohr shift in the supply of oxygen to respiring tissues
...
6
...

 the use of skeletal muscle requires more ATP molecules, increasing the rate of cell respiration
 therefore, more oxygen is consumed and more carbon dioxide is absorbed
 the ventilation rate is therefore increased to supply oxygen
 the breathing centre of the medulla oblongata of the brainstem controls the ventilation rate
 breathing centre mechanisms
o chemoreceptors in the aorta and carotid arteries detect the increase of carbon dioxide level and
subsequent decrease in pH and send action potentials to the breathing centre
o the medulla has chemosensors which detect the increase of carbon dioxide level and subsequent
decrease in pH as blood passes through capillary beds in the medulla
 to increase the ventilation rate, the breathing centre sends action potentials to the diaphragm, intercostal
muscles and abdominal muscles to increase breathing rate and tidal volume
 increased heart rate supplies body tissues with oxygen
 chemosensors send action potentials leading to a decrease in ventilation rate when physical exertion decreases
H
...
6- Outline the possible causes of asthma and its effects on the gas exchange system
...
6
...

 at high altitudes there is low air pressure which means that molecules in the air are more spread out so less
oxygen enters the bloodstream
 symptoms of altitude sickness
o fatigue
o vision problems
o nausea
o high pulse rate
o difficulty thinking clearly
o serious: fluid accumulation around brain or in lungs
 bodies compensate first by increasing ventilation and heart rate
 acclimatization occurs: increase in
o number of erythrocytes and amount of haemoglobin
o capillaries in lungs and muscles
o lung size and surface area for oxygen and carbon dioxide exchange
o myoglobin within muscle tissue



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