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IB BIOLOGY SL
07 April 2014
21:15

Biology Page 1

KEYWORDS
07 April 2014
21:16

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Arithmetic Mean
Casual
Correlation
Error Bar
Relationship
Significance
Spread
Standard Deviation
T-Test
Value
Variability
Variable

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○ 95% of all values usually lie within the range of the mean ± 2 S
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State that error bars are a graphical representation of the variability of data
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State that the term standard deviation is used to summarize the spread of values around the
mean - that 68% of values fall within one standard deviation of the mean and 95%
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Deduce the significance of the difference between two sets of data using calculated values for 't'
and the appropriate tables
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etc
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○ There is still a chance of correlation between the two values
• If a standard deviation is calculated for a set of data, a minimum of 5 repeats per value is required
• If the standard deviation of values do not overlap (the error bars) then they are significantly different

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Outline the cell theory
Discuss the evidence for the cell theory
State that unicellular organisms carry out all the functions of life
Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles
and cells using appropriate SI unit
Calculate the linear magnification of drawing and the actual size of specimens in images of known
magnification
Explain the importance of the surface area to volume ratio as a factor limiting cell size
State that multicellular organisms show emergent properties
Explain that cells in multicellular organisms differentiate to carry out specialized functions by
expressing some of their genes but not others (switches)
State that stem cells retain the capacity to divide and have ability to differentiate along different
pathways
Outline one therapeutic use of stem cells

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coli) as an example of a
prokaryote
• Annotate the diagram with the functions of each named structure
• Identify structures from 2
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1 in electron micrographs of E
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Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell
Annotate the diagram with the functions of each named structure
Identify structures from 2
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1 in electron micrographs of liver cells
Compare prokaryotic and eukaryotic cells
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4
• Draw and label a diagram to show the structure of membranes
• Explain how the hydrophobic and hydrophilic properties of phospholipids help to maintain the
structure of cell membranes
• List the functions of membrane proteins
• Define diffusion and osmosis
• Explain passive transport across membranes by simple diffusion and facilitated diffusion
• Explain the role of protein pumps and ATP in active transport across membranes
• Explain how vesicles are used to transport materials within a cell between the rough endoplasmic
reticulum, Golgi Apparatus and Plasma Membrane
• Describe how the fluidity of the membrane allows it to change shape, break and re-form during
endocytosis and exocytosis
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Cells Page 4

• State that 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
• Describe the events that occur in the four phases of mitosis (prophase, metaphase, anaphase and
telophase)
• Explain how mitosis produces two genetically identical nuclei
• State that growth, embryonic development, tissue repair and asexual reproduction involve mitosis

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1 Cell Theory
14 April 2014
18:26

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1 Cell Theory:
The cell theory embraces four ideas:
• The cell is the building block of structures in living organisms - basically, all living things are made
up of cells
• The cell is derived from other cells by cell division - basically, they come from other cells
• The cell contains hereditary material which contains information which is used as instructions for
growth, development and functioning - basically, they contain genetic information
• The cell is the functioning unit of life (nothing smaller than the unit of the cell can survive) the
chemical reactions of life take place within cells - basically, they're the smallest units of life
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2 Evidence for Cell Theory:
• All living things are made of cells --> when living beings are observed under a microscope, they
consistently appear to be composed of cells
• The cell is the smallest unit of organization that can show all the characteristics of living processes
○ Organelles often require the cooperation of other organelles for their successful function
• Cells carry out a form of cell division - mitosis in eukaryotic cells and binary fission in prokaryotic
cells
○ This brings about the idea that all cells have a common ancestor - this also suggests that all
organisms are related
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3 Unicellular Organisms Carry out all the Functions of Life:
• Unicellular organisms are able to carry out processes which are characteristics of living things such
as:
○ Metabolism including respiration, the synthesis of ATP
○ Response to a change in the environment
○ Homeostasis - the maintenance and regulation of internal cell conditions
○ Growth - an increase in cell size and volume for unicellular organisms
○ Reproduction - for a unicellular organism, it is largely asexual - cell division is used to form a
clone
○ Nutrition - the synthesis of organic molecules or the absorption of organic matter
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4 Compare the Relative Sizes of Molecules, Cell Membrane Thickness etc
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Cells Page 6

• Magnification = (measured length of the image / measured length of the specimen)
○ = (image size / real size)
• Occasionally, they will provide a scale bar
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A cube of 1 cm3 will have a surface area of 6 cm2
 Resulting in a ratio of 6:1 (surface area to volume ratio)
○ A cube of 8 cm3 will have a surface area of 24 cm2
 Resulting in a ratio of 3:1 (surface area to volume ratio) and etc
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○ Example: Gaseous Exchange for Oxygen
 If a cell is too big, they will not be able to obtain sufficient oxygen to satisfy the
demands of the cell - the volume of oxygen obtained for each unit of cell volume is
actually decreasing
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7 Multicellular Organisms and Emergent Properties:
• The whole is greater than the composition of its parts:
○ The growing complexity of living things as you progress from a cellular level to an organ
system etc
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9 State that Stem Cells Retain the Capacity to Divide and have the Ability to Differentiate Along
Different Pathways:
• A stem cell retains the capacity to divide and has the ability to differentiate along different
pathways
• A stem cell is able to divide but has not yet expressed genes to specialize to a particular function
○ They can be induced to express particular genes and differentiate into a particular type of
cell under given circumstances
• Stem cells can be obtained from a variety of different places including the blastocyst
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Cells Page 7

• Example Used: Cancer:
○ A patient requires heavy does of radiation/chemotherapy - this will destroy health blood
tissue as well as diseased tissue
 Chemotherapy supplies toxic drugs to kill cancerous cells - chemotherapy and
radiation are used simultaneously as over time, the cancerous cells grow adapted to
one form of treatment
 Bone marrow can be removed from the treatment, and can be transplanted back to
produce blood cells again
○ Procedure:
 Blood is filtered for the presence of stem cells - they are then removed
 Bone Marrow can be removed before treatment of radiation and chemotherapy
which will result in the destruction of many health tissues and cells
 Treatment is applied
 Health stem cells or marrow cells can be transplanted back to produce blood cells
again
• Example Used: Therapeutic Cloning:
○ This is a method of treating an individual without generating an immune system response
as the human body recognizes and destroys foreign cells - this is a serious barrier to stem
cell therapy
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 This new egg cell behaves like a fertilized egg and develops into blastocyst - Stem cells
can be harvested from here
○ Procedures:
 A cell is taken from an individual
 Take an egg cell and discard its nucleus - then fuse it with the nucleus of the somatic
cell
 This will create a fertilized egg that is genetically identical to the individual
 The cell is then stimulated to divide forming a clone
 This will eventually lead into the formation of a blastocyst from which stem cells can
be harvested
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Cells Page 8

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Coli as an example of a Prokaryote:

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2 Annotate the Diagram from 2
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1 with the Functions of each Named Structure:
• Cell Wall:
• Plasma Membrane: Controls the entry and exit of substances, pumping some of them in by active
transport
• Cytoplasm: Contains all the enzymes needed for all metabolic reactions since there are no
organelles
• Ribosome: Used in protein synthesis which is part of gene expression
• Nucleoid: Region in the cytoplasm that contains DNA
• Flagella: Generally considered for movement
• Pilli: More numerous than the Flagella and are associated with different types of attachment - in
some cases, they can even prevent phagocytosis
• Slime Capsule: Thick polysaccharide layer outside the cell wall used for sticking cells together
• Plasmids: Extra nucleoid DNA - also used for anti biotic resistance
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3 Identify Structures from 2
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1 in Electron Micrographs:
• Just remember the structures in 2
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1 and 2
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4 State that Prokaryotic Cell Divide by Binary Fission:
• Prokaryotic cells divide by binary fission - an asexual method of reproduction
• Hence why the cells are genetically identical
• Process of Reproduction goes like this:
○ Reproduction Signal
○ Replication of DNA
○ Segregation of DNA
○ Cytokinesis

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3 Eukaryotic Cells
07 April 2014
22:03

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1 Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell

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N: Nucleus
PM: Plasma Membrane
M: Mitochondria
rER: Rough Endoplasmic Reticulum
GA: Golgi Apparatus
L: Lysosome
MV: Microvilli

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2 Annotate the diagram from 2
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1 with the functions of each named structure
• Nucleus: Largest of the organelles - contains the genetic information of the cell
• Plasma Membrane: Controls which substances enter and exit a cell - its fluid structure can change shape
• Mitochondria: Location of aerobic respiration and a region of major synthesis of ATP
• Rough Endoplasmic Reticulum: Protein synthesis and packaging into vesicles
• Ribosomes: Produces proteins for internal use within the cell
• Golgi Apparatus: Modifies proteins prior to their secretion
• Lysosome: Digests and recycles used cell components - used in defense to protect the cell from outside invaders
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3 Identify structures from 2
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1 in electron micrographs of live cells
• Nucleus: Largest of the organelles
• Plasma Membrane: The junction between liver cells
• Mitochondria: Double outer membrane
• Rough Endoplasmic Reticulum: Has dark spots all around it
• Golgi Apparatus: A stack of membrane envelopes on top of each other
• Lysosome: Just a white dot
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4 Comparison of Prokaryotic and Eukaryotic Cells
Prokaryotic

Eukaryotic

Small cells ( < 5um)

Large Cells (> 10 um)

Always unicellular

Often Multicellular

No nucleus - has a naked loop called a nucleoid

Always has a nucleus and linear DNA

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Cells Page 11

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They also
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act as receptors in cell signaling
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These properties make
the heads suited to the large water content of the tissue fluid and cytoplasm on opposite sides of
the membrane
• Fatty acid tails are non-charged, hydrophobic
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Cells Page 12

external 'water' environments of the cell - they effectively create a barrier to the movement of
charged molecules
• Individual phospholipids are attracted to each other through their charges - this gives some
stability
• Stability can be increased by presence of cholesterol
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3 List the functions of membrane proteins
Membrane Protein Function
Channel Protein

Allow the movement of large molecules across the plasma membrane - included
within this are the passive and active membrane pumps arriving at cells

Receptor Protein or These proteins detect hormones arriving at cells to signal changes in function
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Cells Page 13

the plasma membrane
• The vesicle fuses with the plasma membrane and secretes its contents out of the cell - this process
is called exocytosis
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8 Describe how the fluidity of the membrane allows it to change shape, break and re-form during
endocytosis and exocytosis
• Exocytosis: Vesicle Membrane fuses with the plasma membrane
• Endocytosis: A vesicle is formed by the in-folding of the plasma membrane
○ Phospholipid molecules can change places in the horizontal plane - this creates the so
called fluid property of the membrane
○ Phospholipid molecules cannot change places in the vertical plane - this maintains the
integrity of the membrane - this is further reinforced by the presence of cholesterol
• Fusion Process:
○ Membranes approach
○ Phospholipid heads flow together starting the process of fusion - this requires the presence
of additional molecules
○ At the point of contact, there is a single lipid bilayer
○ The pore is open and the membranes are now continuous

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5 Cell Division
20 April 2014
22:22

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1 Outline the stages in the cell cycle, including interphase (G1, S, G2), mitosis and cytokinesis
• Interphase: The longest phase which itself occurs in 3 stages
○ G1: Cell performs its normal differentiated function
○ S: DNA replication - mass of DNA in the cell has doubled at this point
○ G2: Preparation for cell division
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2 State that tumors are the result of uncontrolled cell division and that these can occur in any
organ or tissue:
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3 State that 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
• During G1, the cell performs its normal differentiated function (protein synthesis)
• During S, the cell replicates its own DNA
• During G2, preparation for mitosis occurs which involves the replication of mitochondria or in the
case of plants, chloroplasts
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4 Describe the events that occur in the four phases of mitosis (prophase, metaphase, anaphase
and telophase)
• Prophase:
 Early Prophase:
□ Spindle Microtubles grow
□ Chromosomes are becoming shorter and fatter by supercoiling
 Late Prophase:
□ Each chromosome consists of two identical chromatids formed by DNA replication and
held together by a centromere
□ Spindle Microtubles extend from each pole to the equator
Metaphase:
 Nuclear membrane has broken down and chromosomes have moved to the equator
 Spindle microtubles from both poles are attached to each centromere on opposite sides
• Anaphase:
 The centromeres have divided and the chromatids have become chromosomes
 Spindle microtubles pull the genetically identical chromosomes to opposite poles
• Telophase:
 Early Telophase:
□ All chromosomes have reached the poles and nuclear membranes form around them
□ Spindle Microtubles break down
 Late Telophase:
□ The cell divides (cytokinesis) to form two cells with genetically identical nuclei
□ Chromosomes uncoil and are no longer individually visible
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5 Explain how mitosis produces two genetically identical nuclei:
• The process of cell division produces genetically identical daughter cells
• Conservation of chromosome number - the chromosome number in each of the daughter cell is
the same as that of the original parental cell
• During S phase each chromosome is copied exactly - the two copies of each chromosome is held
together by a protein structure known as a centromere
• Prior to mitosis, there is double the number of chromosomes present in a cell

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Cells Page 16

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Chemistry of Life Page 17

• Transport Medium:
○ Blood carries nutrients, gases, wastes which are dissolved in the water of the blood

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2 Monomers and Polymers of Organic Molecules
20 April 2014
23:03

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1 Distinguish between organic and inorganic compounds:
• Organic compounds are based on compound - have a carbon backbone - there are however a
number of exceptions i
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CO2
• Inorganic compounds are by default all the molecules other than those in the category above
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2 Identify amino acids, glucose, ribose and fatty acids from diagrams showing their structure:
• Glucose: Six Carbon Sugar
• Ribose: Five Carbon Sugar
• Fatty Acids: CH3 at one end (hydrophobic) and COO or COOH on the other end
• Amino Acids: NH2 on the left, R group on the top, COOH on the right
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4 State one function of glucose, lactose and glycogen in animals, and of fructose, sucrose and
cellulose in plants
Carbohydrate

Plant Example Plant Function Animal Example Animal Function

Monosaccharide Fructose

Fruit Sugar

Glucose

Disaccharide

Sucrose

Energy Storage Lactose

Milk Sugar

Polysaccharide

Cellulose

Cell Walls

Energy Storage

Glycogen

Respiration

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5 Outline the role of condensation and hydrolysis in the relationships between monosaccharide's,
disaccharides and polysaccharides, between fatty acids, glycerol and triglycerides, between amino
acids and polypeptides
• Condensation Reaction: H2O is formed (fusion)
• Hydrolysis Reaction: OH and H is formed (breaking up)
• Dimers:
○ Two monomers are bonded together to form a dimer
○ Water is removed during this reaction (condensation)
○ A dimer can be split by hydrolysis but needs water to be added
• Polymerization:
○ Polymers can be digested back to monomers by hydrolysis reaction
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6 State three functions of lipids
• Buoyancy
• Energy Storage
• Thermal Insulation
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7 Compare the use of carbohydrates and lipids in energy storage
Carbohydrates

Lipids

Carbohydrates are more easily digested energy can be released more rapidly

Lipids contain more energy per gram than carbohydrates they are a lighter source of energy

Carbohydrates are soluble in water and
therefore easy to move around the body

Lipids are insoluble in water and therefore do not cause
problems with osmosis in cells

CARBS WIN

Lipids require more oxygen per molecule therefore can
only be utilized during lower levels of energy demand

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3 DNA Structure
20 April 2014
23:22

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1 Outline DNA nucleotide structure in terms of sugar (deoxyribose), base and phosphate
• Deoxyribose: Differs freom ribose in having one less oxygen on carbon 2
• Phosphate: PO4-3 group
• Base: Bases are nitrogen based ring structures of which there are 4 different kinds
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2 State the names of the four bases in DNA
Base Name Nucleoside Abbreviation
Cytosine

Cytidine

C

Thymine

Thymidine T

Adenine

Adenosine A

Guanine

Guanosine G

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3 Outline how DNA nucleotides are linked together by covalent bonds into a single strand
• The phosphate group creates a bridge connecting the C5 on one pentose sugar (deoxyribose) with
the C3 of the next pentose sugar
• The bond is a phosphodiester bond which indicates that there are two covalent bonds formed
between the -OH and the acidic phosphate group
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4 Explain how a DNA double helix is formed using complementary base pairing and hydrogen
bonds
• DNA is composed of two polynucleotide chains
• Adenine combines with Thymine (2 hydrogen bonds)
• Cytosine combines with Guanine (3 hydrogen bonds)
○ Since these are complementary base pairings, this creates two anti-parallel chains hence the
double helix
○ DNA is shaped into a spiral to avoid the molecules from bumping into one another
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5 Draw and label a simple diagram of the molecular structure of DNA

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Chemistry of Life Page 21

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Chemistry of Life Page 22

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Chemistry of Life Page 23

• One gene is transcribed and translated to produce one polypeptide
○ There is a gene for each type of polypeptide
• Some proteins are composed of a number of polypeptides and in this theory, each polypeptide
has its own gene

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6 Enzymes
21 April 2014
00:26

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1 Define Enzyme and Active Site
• An enzyme is a biological catalyst - speeds up biological reactions
• Active site is the position on the enzyme occupied by the substrate
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2 Explain Enzyme-Substrate Specificity
• Enzyme specificity is due to the complementary shape of the active site and the substrate basically specific substances have specific enzymes
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3 Explain the effects of temperature, PH and substrate concentration on enzyme activity
• PH - PH affects the rate of reaction of an enzyme catalysed reaction
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Should the PH be too far from the optimum, the enzyme will denature and 0 reactions will
occur - bonds are formed or changed because of electromagnetic forces
• Concentration - As substrate concentration increases so will the rate of reaction - there are more
collisions between the substrate and the enzyme
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Sooner or later, this increase in rate of reaction will level off as all enzymes will then be
occupied and an increased substrate concentration will be of no use
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However, once kinetic energy is too great, the
enzyme stability decreases and the enzyme atoms vibrate too much, resulting in the hydrogen
bonds breaking and causing the active site to change shape - this results in 0 reactions
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4 Define Denaturation:
• Denaturation is a structural change in a protein that results in the loss of its biological properties this loss is usually permanent
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5 Explain the use of lactase in the production of lactose-free milk
• Lactose -- (Lactase) --> Glucose + Galactose
○ First, the lactase is immobilized in alginate beads
○ The beads are placed in a container over which the milk is passed
○ Milk is re-circulated to convert any remaining lactose to glucose and galactose
○ Circulation is maintained until all lactose is converted into glucose and galactose

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7 Respiration
21 April 2014
00:26

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1 Define Cell Respiration
• Cell respiration is the controlled release of energy from organic compounds in cells to form ATP
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2 State that, in cell respiration, glucose in the cytoplasm is broken down by glycolysis into
pyruvate, with a small yield of ATP
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3 Explain that, during anaerobic cell respiration, pyruvate can be converted in the cytoplasm into
lactate, or ethanol and carbon dioxide, producing little ATP
• Anaerobic respiration is the oxidation of organic compounds without oxygen
• It is less efficient than aerobic respiration
• The lactic pathway is so inefficient though that is not done under normal circumstances
○ The ATP produced is just a supplement to that produced by aerobic respiration
• Technically, the oxidation of glucose simply creates lactic acid or in the case of yeast, ethanol
and CO2
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4 Explain that, during aerobic respiration, pyruvate can be broken down in the mitochondrion into
carbon dioxide and water with a large yield of ATP
• The production of ATP in the aerobic pathway is much greater than in either glycolysis or the
anaerobic alternatives
• Oxidation of pyruvate occurs, resulting in the formation of CO2 + H2O and a large amount of ATP this is done in the mitochondria

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8 Photosynthesis
21 April 2014
00:26

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1 State that photosynthesis involves the conversion of light energy into chemical energy
• Light energy --> Chemical Energy
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2 State that light from the sun is composed of a range of wavelengths
• Light from the sun is composed of a range of wavelengths
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3 State that chlorophyll is the main photosynthetic pigment
• Chlorophyll is the main photosynthetic pigment
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4 Outline the differences in absorption of red, blue and green light by chlorophyll

• Main color absorbed chlorophyll is red and blue
• Main color reflected is green - hence why plants appear green
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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
• Light energy is used to produce ATP and make photolysis of water occur
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6 State that ATP and hydrogen (derived from photolysis) are used to fix carbon dioxide to make
organic molecules
• ATP and Hydrogen from photolysis is used to fix CO2 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
uptake of CO2 or indirectly, by an increase in biomass
• Oxygen is a product of photosynthesis
• Carbon Dioxide is a component required for photosynthesis
• An increase in biomass occurs when carbon fixation occurs --> this is after photosynthesis occurs
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8 Outline the effects of temperature, light intensity and CO2 concentration on the rate of
photosynthesis:
• Look back to enzyme notes
• Temperature - Rate of photosynthesis will occur due to increase in kinetic energy of molecules however, too much will cause the enzymes to denature as the atoms of the enzyme will vibrate
too much
• Carbon Dioxide - There will be an initial increase that slowly levels off as there is a saturation level
(too few enzymes for too many CO2 molecules)
• Light Intensity - Like CO2 concentration, there will be an initial increase that slowly levels off until
it reaches a maximum - plants cannot harvest light at extremely high intensities and chlorophyll
can be damaged by this

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1 Chromosomes, Genes, Alleles and Mutations
07 April 2014
22:03

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1 State that eukaryote chromosomes are made of DNA and proteins
• A chromosome is composed of two main molecules:
○ DNA
○ Proteins called histones
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2 Define gene, allele and genome
• Gene - A heritable factor that controls a specific characteristic
• Allele - One specific form of a gene differing from other alleles by one or a few bases - also
occupies the same gene locus as other alleles of the gene
• Genome - Whole genetic information of the organism
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3 Define Gene Mutation
• Gene mutation is a change in the base sequence of the allele
○ This may result in the production of a different amino acid during translation
○ Changed base sequence will not change the protein due to the degenerate nature of the
genetic code
○ Expression of the gene may or may not be beneficial to the organism
○ Substances that causes mutation are called mutagens (includes chemicals and radiation)
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4 Explain the consequence of a base substitution mutation in relation to the processes of
transcription and translation, using the example of sickle-cell anemia
• Sickle cell anemia is a genetic disease
○ 2 of the four proteins inside normal hemoglobin is changed in the mutation
○ Normal biconcave disc shape of the blood cell is changed into a 'sickle' shape --> can result
in blood clots and possibly necrosis
...

• Gene loci for the normal beta chain of hemoglobin is on chromosome 11
• Normal allele carries the triplet GAG at the sixth amino acid position for the beta chain (Glutamic
Acid)
• The mutation changes GAG --> GTG (one single base is changed)
○ This results in the production of Valine

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2 Meiosis
21 April 2014
16:07

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1 State that meiosis is a reduction division of a diploid nucleus to form haploid nuclei
• Meiosis is a reduction division of a diploid nucleus to form a haploid nucleus
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2 Define Homologous Chromosomes
• They are chromosomes which have the same pattern of genes
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3 Outline the process of meiosis, including pairing of homologous chromosomes and crossing over,
followed by two divisions which results in four haploid cells
• Interphase:
○ G1 - Nucleus is still intact
○ S - DNA molecules replicate - each pair of sister chromatids are held together at the
centromere
○ G2 - Preparation for cell division
• Prophase 1:
○ Early Prophase:
 Nuclear membrane breaks down
 Spindle microtubles form at opposite ends of the cell
 DNA is supercoiling
 Crossing over occurs here - the point at which the chromosomes exchange genetic
information is called the chiasma
○ The pair of sister chromatids attach to the spindle microtubles at the centromere
• Metaphase 1:
○ Metaphase is marked by all pairs of sister chromatids being aligned on the equator
• Anaphase 1:
○ Early Anaphase:
 Spindle microtubles contract and pull the homologous pairs apart
○ Late Anaphase:
 The pair of chromatids are moving towards the poles
• Telophase 1:
○ Chromosomes are now in the opposite ends of the cells
○ Spindle microtubles break down
○ In some species, a nuclear membrane may form whereas in others it progresses straight to
Prophase 2
○ The cell will divide in half through cytokinesis
• Prophase 2:
○ Nuclear membrane of the now two cells break down (if present)
○ Spindle microtubles reform
○ Spindle microtubles will attach to the sister chromatids
• Metaphase 2:
○ All sister chromatids aligned on the equatorial plate of the cell
• Anaphase 2:
○ Spindle fibers contract pulling the pair of sister chromatids separate
• Telophase 2:
○ Nuclear membranes begin to form around each of the haploid cells
○ Cytokinesis occurs here and now you have 4 gamete cells
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Genetics Page 29

reference to Down Syndrome
• Non-disjunction is an error in meiosis which produces cells with unusual combinations of
chromosomes -this usually occurs during anaphase when the attachment of spindle microtubles to
the centromeres goes wrong and may pull more or less sister chromatids to one end of the pole
○ Technically, failure of separation causes an irregular number of chromosomes in a gamete
cell
• Down syndrome occurs when 3 copies of chromosome 21 is present - the gamete has 24
chromosomes instead of the normal 23 due to the (23 + 1 extra chromosome 21)

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3 Theoretical Genetics
21 April 2014
16:33

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1 Define genotype, phenotype, dominant allele, recessive allele, codominant alleles, locus,
homozygous, heterozygous, carrier and test cross
Genotype

Alleles possessed by an organism

Phenotype

Characteristics possessed by an organism

Dominant Allele An allele that has the same effect on the phenotype regardless of being in a
homozygous or heterozygous state
Recessive Allele An allele that only has an effect on the phenotype when present in the homozygous
state
Codominant
Allele

Pairs of alleles that both affect the phenotype when present in the heterozygous
state

Locus

Particular location of a gene on a chromosome

Homozygous

Having two identical alleles

Heterozygous

Having two different alleles

Carrier

An individual that has a recessive allele of a gene that does not have an effect on the
phenotype

Test Cross

Testing a suspected heterozygote by cross breeding it with a known homozygous
recessive

4
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2 Determine the genotypes and phenotypes of the offspring of a monohybrid cross using a
Punnett grid
• Example: (WE ALWAYS USE THE GENOTYPES IN THE PUNNET GRID DIAGRAM)
○ We have two alleles S and s
○ S = smooth allele
○ s = rough allele
○ Dominance is represented by a capital letter
○ Recessive is represented by a lower case letter
○ So when we cross two heterozygous pairs
S

s

S

SS

Ss

s

Ss

ss

Genotypes 1(SS) : 2(Ss) : 1(ss)
Phenotypes 3 Smooth : 1 rough
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3 State that some genes have more than two alleles
• Some genes can have more than two alleles
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4 Describe ABO blood groups as an example of codominance and multiple alleles
Phenotype Genotype
O

ii

A

IAIA or iIA

B

IBIB or iIB
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Genetics Page 32

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4 Genetic Engineering and Biotechnology
21 April 2014
17:28

4
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1 Outline the use of polymerase chain reaction (PCR) to copy and amplify minute quantities of
DNA
• PCR is the cloning of DNA
• Copies are made and the amount of DNA can be rapidly increased
• Temperature is used to separate the strands instead of enzymes such as helicase (95°C)
• DNA polymerase protects the DNA against the reactions caused by temperature
4
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2 State that in gel electrophoresis, fragments of DNA move in an electric field and are separated
according to their size
• Fragments of DNA during gel electrophoresis are separated according to their size
4
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3 State that gel electrophoresis of DNA is used in DNA profiling:
• Gel electrophoresis of DNA is used in DNA profiling
4
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4 Describe the application of DNA profiling to determine paternity and also in forensic
investigations
• DNA profiling is used to identify the biological parents of the child - this is done by comparing the
bands and where they are in the gel
• Bands presents in the child must come from either the mother or father
• DNA profiling is also used for identifying criminals should scraps of their DNA be available in the
crime scene
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5 Analyze DNA profiles to draw conclusions about paternity or forensic investigations
• Common sense
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6 Outline three outcomes of the sequencing of the complete human genome
• Identified all approximate 30,000 genes in human DNA
• Determine the sequences of the 3 billion chemical base pairs that make up human DNA
• Improve tools for data analysis
• Transfer related technologies to the private sector and market
4
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7 State that, when genes are transferred between species, the amino acid sequence of
polypeptides translated from them is unchanged because the genetic code is universal
• Genetic code is universal hence when genes are transferred between species, amino acid
sequence translated is unchanged
4
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8 Outline a basic technique used for gene transfer involving plasmids, a host cell, restriction
enzymes and DNA ligase
• First, obtain the gene for transfer - restriction enzymes are used to cut out the useful gene that is
to be transferred
○ Note the sticky ends of unattached hydrogen bonds
• Second, a vector must be prepared for the to be transferred gene - Plasmids
○ These can be cut with the same restriction enzymes above, leaving the same
complementary sticky ends for the useful gene
• Thirdly, the useful gene and plasmid are combined using DNA ligase creating recombinant DNA
• Fourthly, the recombinant DNA is introduced into the host cells, many cells remain
untransformed - some cells however, are transformed due to the recombinant DNA
• Fifthly, the transformed bacterial cells are isolated to be cloned

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Genetics Page 35

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of arrows in sequence before organism + 1
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8 Construct a food web containing up to 10 organisms

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of trophic levels are limited as energy is reduced at higher levels
5
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11 State that energy transformations are never 100% efficient
• Energy transformations are never 100% efficient
5
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12 Explain the reason for the shape of pyramids of energy
• Due to the 10% efficiency of energy transfer per trophic level, a pyramid like shape is formed
when energy is visually displayed
5
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13 Explain that energy enters and leaves ecosystems, but nutrients must be recycled
• Movement of energy and matter through ecosystems are related because both occur by the
transfer of substances through feeding relationships
• Energy however cannot be recycled - must be powered by a continuous influx of new energy from
an external source
• Nutrients are constantly being recycled within an ecosystem as food
○ Autotrophic activities of the producers produce organic materials from inorganic sources
which are then fed on by consumers
○ Heterotrophic organisms die, these inorganic nutrients are returned to the soils to be
reused by the plants
○ Thus energy flows through ecosystems whereas nutrients are recycled
5
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14 State that saprotrophic bacteria and fungi recycle nutrients
• Saprotrophic bacteria and fungi recycle nutrients

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2 The Greenhouse Effect
23 April 2014
21:54

5
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1 Draw and label a diagram of the carbon cycle to show the processes involved
5
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2 Analyze the changes in concentration of atmospheric carbon dioxide using historical records
• Data suggests that atmospheric CO2 levels have risen steadily in the past 30 years
• CO2 levels appear to be currently higher than at any time in the last 400,000 years
5
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3 Explain the relationship between the rises in concentrations of atmospheric carbon dioxide,
methane and oxides of nitrogen and the enhanced greenhouse effect
• Carbon dioxide, methane and nitrogen oxides are known as greenhouse gases
...
Greenhouse gases the ability to absorb these long wave radiations, trapping energy in
earth's atmosphere
• If too much energy is trapped within earth's atmosphere, earth's global temperature will rise
5
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4 Outline the precautionary principle
• The precautionary principle states that when a human-induced activity raises a significant threat
of harm to the environment or human health, precautionary measures should be taken even if
there's no scientific consensus regarding cause and effect
5
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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
• Arguments for Action:
○ Risk of inaction are potentially severe - more drastic and severe weather conditions
○ Higher temperatures will increase the spread of diseases
○ Loss of habitat = Loss of biodiversity
○ May affect food production
• Arguments for Inaction:
○ Cutting greenhouse emissions may development for LEDCs
○ Loss of economy - create significant job losses
○ Political tension - LEDCs think its unfair that these principles should be applied when they
haven't even begun properly developing whereas MEDCs have already finished
5
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6 Outline the consequences of a global temperature rise on arctic ecosystems
• Remember CREDIBLE threat
○ Changes in arctic conditions
○ Rising sea levels
○ Expansion of temperate species increasing competition with native species
○ Decomposition of detritus previously trapped in ice will significantly increase greenhouse
gas levels
○ Increased spread of pest species and pathogens
○ Behavioral changes in native species
○ Loss of habitat
○ Extinction and resultant loss of biodiversity

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3 Populations
23 April 2014
22:31

5
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1 Outline how population size is affected by natality, immigration, mortality and emigration
• Natality - Increases population size through reproduction
• Immigration - Increases population size from external populations
• Mortality - Decrease population size as a result of death
• Emigration - Decreases population size as a result of loss to external populations
5
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2 Draw and label a graph showing the sigmoid population growth curve

5
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3 Explain reasons for the exponential growth phase, the plateau phase and the transitional phase
between these two phases
• Exponential Growth Phase:
○ There is a rapid increase because there are abundant resources and limited environmental
resistance
• Transitional Phase
○ Competition increases for resources as population grows
○ Natality rates fall and mortality rates rise
• Plateau Phase
○ Eventually Mortality Rate = Natality Rate
○ Population has reached the carrying capacity of the environment (K)
○ Limited resources, predation and disease keep the population fairly constant
 There will be fluctuations but they will always converge towards (K)
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4 List three factors that sets limits to population Increase
Factors affected by Population Density Factors unrelated to Population Density
Predation and parasites

Natural Disasters

Availability of resources

Climate

Nutrient Supply

Availability of Light, CO2 and O2
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Ecology and Evolution Page 40

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○ Indirect: Footprints, tooth m arks, tracks, burrows etc
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Ecology and Evolution Page 41

○ Environmental pressures lead to differential reproduction
○ Organisms with beneficial adaptations will be better suited to their environment and are
more likely to survive and pass on their genes
○ Over generations, there will be a change in allele frequency in a population
5
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8 Explain two examples of evolution in response to environmental change; one must be antibiotic
resistance in bacteria
• Example 1: Staphylococcus Aureus
• Variation: Antibiotic Resistance
• Environmental Change: Exposure to anbitiotic (methicillin)
• Response: Methicillin susceptible S
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Aureus survive and
pass on their genes
• Evolution: Over time, the frequency of antibiotic resistance in the population increases
• Example 2: Peppered Moth
• Variation: Coloration
• Environmental Change: Pollution from industrial activities caused trees to blacken during
industrial revolution
• Response: Light colored moths died from predation whereas darker colored ones were
camouflaged and survived to pass on their genes
• Evolution: Over time, the frequency of the darker colored moths increased

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5 Classification
23 April 2014
23:44

5
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1 Outline the binomial system of nomenclature
• Genus is written first and is capitalized i
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Homo
• Species follows and is written in lower case i
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Homo sapiens
• Some species may also have a sub-species designation i
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Homo sapiens sapiens
• Conventions: When typing, names should be in italics whereas in writing, it should be underlined
5
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2 List the seven levels in hierarchy of taxa - kingdom, phylum, class, order, family, genus and species
Taxa

Kingdom Phylum

Mnemonic King

Class

Example 2 Plantae

Family

Genus

Species Common Name

Came

Over

For

Group

Sex

Mamalia

Philip

Example 1 Animilia Chordata

Order

Primates Horminidae

Homo

Sapiens Human

Angiospermophyta Dicotyledoneae Ranales

Rananculacae Ranunculus Acris

Buttercup

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3 Distinguish between the following phyla of plants, using simple external recognition features: bryophyta, filicinophyta,
coniferophyta and angiospermophyta
Filicinophyta

Coniferophyta

Angiospermophyta

Leaves, Roots, No 'true' leaves or roots
Stems

Bryophyta

Have leaves, roots and nonwoody stems

Have leaves, roots and
woody stems

Have leaves, roots and
woody/non-woody stems

Reproductive
Features

Spores in sporangia on
underside of leaf

Seeds found in cones

Seeds found in fruits

Other Features Anchored by rhizoids

Have large leaves (fronds)
that are divided into leaflets

Leaves usually narrow
with a thick waxy cuticle

Have flowers

Example

Ferns

Conifers and pines

Flowering plants and
grasses

Spores produced in a
capsule at end of stalk

Mosses and liverworts

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4 Distinguish between the following phyla of animals, using simple external recognition features: porifera, cnidaria,
platyhelminthes, annelida, mollusca and arthropoda
Symmetry

Body Layers

Porifera

Asymmetrical No mouth or anus

Cnidaria

Radial

Other Features

Example

Pores through body

Sponges

Mouth but no anus May have tentacles with stinging cells

Jellyfish and anemones

Platyhelminthes Bilateral

Mouth but no anus Flat, softened body

Flatworms and tapeworms

Annelida

Bilateral

Mouth and anus

Segmented body

Earthworms and leeches

Mollusca

Bilateral

Mouth and anus

Muscular foot and mantle - May have a shell Squids, slugs and snails

Arthropoda

Bilateral

Mouth and anus

Jointed appendages - Exoskeleton

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5 Apply and design a key for up to eight organisms

5
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1 Digestion
07 April 2014
22:03

6
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1 Explain why digestion of large food molecules is essential
• Most food is solid and in the form of large complex molecules which are insoluble or chemically
unusable
• Food is synthesized by other organisms and thus some of these molecules are not suitable for
human tissue
○ These need to be separated and removed
○ These small useful molecules can be reassembled into new products (amino acids)
6
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2 Explain the need for enzymes in digestion
• Enzymes are biological catalysts which speed up the rate of reactions by lowering the activation
energy
• Enzymes allow digestive processes to occur at body temperature and at sufficient speed to meet
the organism's survival requirements
• Enzymes are specific for a given substrate so can allow digestion of certain molecules to occur
independently of others
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3 State the source, substrate, product and optimal pH conditions for one amylase, one protease
and one lipase

Enzyme
Type

Example

Source

Substrate

Product

Optimum pH

Amylase

Salivary
Amylase

Salivary
Glands

Starch

Maltose

pH - 7 (neutral)

Protease

Pepsin

Gastric Juice

Protein

Short
Polypeptides

pH - 2 (highly
acidic)

Lipase

Pancreatic
Lipase

Pancreas

Lipids
(triglycerides)

Glycerol, fatty
acids

pH - 8 (slightly
alkaline)

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4 Draw and label a diagram of the human digestive system
Alimentary Canal:
Accessory Organs:

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5 Outline the function of the stomach, small intestine and large intestine
• Stomach:
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Human Health and Psychology Page 45

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Human Health and Psychology Page 46

○ They have a very wide lumen (keeps pressure low and allows greater flow of blood)
○ The walls of tissue surrounding the vein are thin (blood is not travelling in rhythmic pulses)
○ They have valves to prevent blood pooling at extremities
• Capillaries:
○ Capillaries are involved with material and gas exchange with the surrounding body tissue
○ Blood pressure is relatively low ( 15 mm Hg) and they have a very small diameter (5
micrometers wide)
○ Single cell thick walls to allow for diffusion
○ Also contains pores to aid the transport of material

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6 State that blood is composed of plasma, erythrocytes, leukocytes and platelets
• Blood is composed of:
○ Plasma
○ Red blood cells (erythrocytes)
○ White blood cells (leukocytes)
○ Platelets
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7 State that the following are transported by blood: nutrients, oxygen, CO2, hormones, antibodies,
urea and heat
• Blood carries:
○ Nutrients
○ Oxygen
○ Carbon Dioxide
○ Hormones
○ Antibodies
○ Urea
○ Heat

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3 Defense Against Infectious Disease
25 April 2014
20:38

6
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1 Define Pathogen
• A pathogen is a disease-causing microorganism, virus or prion
6
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2 Explain why antibiotics are effective against bacteria but not viruses
• Antibiotics target the metabolic pathways of prokaryotes - this kills them
• Virus do not carry out metabolic reactions hence why antibiotics are ineffective against them
6
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3 Outline the role of skin and mucus membranes in defense against pathogens
• Skin:
○ Protects external structures
○ Contains biochemical defense agents
○ Also secretes acidic substances - creates lower pH preventing bacteria from growing
• Mucus membranes:
○ Protect internal structures
○ Release fluids to wash away pathogens
○ Contains biochemical defense agents (lysosome)
6
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4 Outline how phagocytic leucocytes ingest pathogens in the blood and in body tissue
• Phagocytic leukocytes circulate the blood but may move to body tissue in response to infection
• Pathogens are engulfed when cellular extensions surround the pathogen and then fuse,
sequestering it in an internal vesicle
• The vesicle then fuses with the lysosome to digest the pathogen
○ Some of the pathogen's antigenic fragments may be presented on the surface of the
macrophage (phagocytes), in order to stimulate antibody production
• This is called phagocytosis
6
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5 Distinguish between antigens and antibodies
• Antigen: A substance that the body recognizes as foreign and that can evoke an immune response
• Antibody: A protein produced by certain white blood cells in response to an antigen
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6 Explain antibody production
• B lymphocytes are antibody producing cells that develop in the bone marrow to produce a highly
specific antibody that recognizes one type of antigen
• When wandering macrophages encounter a pathogen, they devour it and present their antigenic
fragments to helper T lymphocytes
• These cells activate the appropriate B cells which divides and differentiates into short-lived plasma
cells that produce massive quantities of antibody (2000 molecules per second)
• A small portion of B cell clones to develop into memory cells, which may survive for years
providing long-term immunity
6
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7 Outline the effect of HIV on the immune system
• The human immunodeficiency virus is a retrovirus that infects helper T cells
• Reverse transcriptase allows viral DNA to be produced from its RNA code - this helps it integrate
into the host cells genome
• After years of inactivity (during which the infected T cells reproduce), the virus becomes active
and begins to spread, destroying the T cells in the process
• This results in lower immunity as antibody production is compromised - the individual is now
susceptible to opportunistic infections

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Human Health and Psychology Page 49

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Human Health and Psychology Page 50

○ The pressure of the air in the lungs is decreased below atmospheric pressure
○ Air flows into the lungs to equalize the pressure
• Exhalation:
○ Diaphragm muscles relax and diaphragm curves upwards
○ External intercostal muscles relax allowing the ribs to fall
○ This decreases the lung volume
○ Pressure of the air in lungs is increased above atmospheric pressure
○ Air flows out of the lungs to equalize the pressure

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5 Nerves, Hormones and Homeostasis
26 April 2014
20:47

6
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1 State that the nervous system consists of the central nervous system and peripheral nerves, and
is composed of cells called neurons that carry rapid electrical impulses
• The nervous system consists of the CNS and PNS - they are composed cells called neurons and
carry rapid electrical impulses

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2 Draw and label a diagram of the structure of the motor neuron

6
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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
• Sensory neurons conduct nerve impulses to the CNS from the receptor
• Relay neurons conduct nerve impulses within the CNS
• Motor neurons conduct nerve impulses from the CNS to the effector

6
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4 Define resting potential and action potential
• Resting Potential: The charge difference across the membrane when a neuron is not firing ( -70
mV)
• Action Potential: The charge difference across the membrane when a neuron is firing (30 mV)
• Depolarization: The change from a negative resting potential to a positive action potential
(opening sodium channels and letting sodium in)
• Repolarization: The change from a positive action potential back to a negative resting potential
(opening potassium channels and letting potassium out)
○ POLARIZED = NEGATIVE
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5 Explain how a nerve impulse passes along a non-myelinated neuron
• Generating a Resting Potential:
○ The sodium-potassium pump maintains an electrochemical gradient of the resting potential
(-70 mV)
It is a trans-membrane protein that uses active transport to exchange Na+ and K+ ions across
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Human Health and Psychology Page 53

• Sweat glands release sweat, which absorbs heat from the body and evaporates thus cooling the
body
• Shivering expends energy through muscle movement - this produces heat in small amounts
through cell respiration
6
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11 Explain the control of blood glucose concentration, including the roles of glucagon, insulin and
the alpha and beta cells in the pancreatic islets
• Insulin and glucagon are responsible for controlling blood glucose levels in the body
○ These hormones are released from different group of cells and act primarily on the liver
• Insulin is released from beta cells in the pancreas and causes a decrease in blood glucose
concentration - this may involve glycogen-synthesis in the liver promoting the uptake of glucose
by the liver
• Glucagon is released from the alpha cells in the pancreas and cause an increase in blood glucose
concentration - they break glycogen down in the liver promoting glucose release
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12 Distinguish between type 1 and type 2 diabetes
Type 1

Type 2

Insulin-Dependent Diabetes Mellitus

Non Insulin-Dependent Diabetes Mellitus

Usually occurs during childhood

Usually occurs during late adulthood

Body does not produce enough insulin

Body does not respond to insulin

Caused by destruction of beta cells

Caused by down-regulation of insulin receptors

Requires insulin injection to regulate glucose levels Can be controlled with a carefully monitored diet

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6 Reproduction
26 April 2014
21:40

6
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1 Draw and label diagrams of the adult male and female reproductive systems

l

6
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2 Outline the role of hormones in the menstrual cycle, including FSH (follicle stimulating hormone), LH (luteinizing
hormone), estrogen and progesterone
Hormone

Secreted From

Function

Follicle Stimulating Hormone Anterior Pituitary • Stimulates follicular growth
• Stimulates Estrogen secretion

Estrogen

Ovaries

• Development of endometrium
• Stimulates LH secretion
• Inhibits LH and FSH

Luteinizing Hormone

Anterior Pituitary • Surge causes ovulation
• Stimulates progesterone secretion
• Development of corpus luteum

Progesterone

Ovaries

• Thickening of endometrium
• Inhibits LH and FSH

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3 Annotate a graph showing hormone levels in the menstrual cycle, illustrating the relationship between changes
in hormone levels and ovulation, menstruation and the thickening of the endometrium

• Follicular Phase:
○ FSH stimulates growth of several follicles
○ Dominant follicle secretes estrogen
○ Estrogen inhibits growth of other follicles
Estrogen stimulates development of the endometrium

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Human Health and Psychology Page 56



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