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Biology IGCSE
Section A: The Nature and Variety of Living Organisms
Chapter 1: Characteristics of Living Organisms
1) What are the 7 basic characteristics all living organisms follow?
Movement
Respiration
Sensitivity
Growth
Reproduction
Excretion
Nutrition

Chapter 2: Characteristics of Living Organisms
1) List the 6 different kingdoms of organisms (6):
Plants, animals, fungi, bacteria, protoctists and (virus)
...

-They contain chloroplasts and are able to carry out photosynthesis
...

-They store carbohydrates as starch or sucrose
...

b) Animals (6):
-These are multicellular organisms
...

-They have no cell walls
...

-They often store carbohydrate as glycogen
...

c) Fungi (7):
-Some are multi-celled some are single-celled
...

-Their body is usually organized into a mycelium made form threadlike structures called hyphae, which contain many nuclei
...

-They feed by extracellular secretion of digestive enzymes onto food
material and absorption of the organic products (saprotophic
nutrition)
...

1

-For example yeast and mushroom
...

-They have a cell wall, cell membrane, cytoplasm and plasmids
...

-Some bacteria can carry out photosynthesis but most feed off other
living or dead organisms
...

e) Protoctists (3):
-These are microscopic single-celled organisms
...

-A pathogen example is plasmodium, responsible for causing malaria
another example is algae
...

-They are parasitic and can reproduce only inside living cells
...

-They have a wide variety of shapes and sizes
...

-For example the influenza virus that causes “flu” and the HIV virus
that causes AIDS
...


Section B: Structures and Functions in Living Organisms
Chapter 3: Levels of Organisation
1) Define the following levels of organisation within organisms and
give 2 examples for each (5):
a) Organelle:
A tiny cell structure that carries out a specific function within the
cell, for example mitochondria and chloroplasts
...

c) Tissue:
A group of similar cells doing a common function for example muscle
and skin tissue
...

e) Organ system:
Several organs working together for example respiratory system and
digestive system
...
It is where DNA is located
...

c) Cell membrane:
Controls what substances can get in and out of the cell
...

e) Chloroplast (2):
Where photosynthesis happens
...

f) Vacuole:
Contains a liquid called cell sap, which keeps the cell firm
...


Chapter 5: Biological Molecules
1) What chemical elements are present in the following? (3)
a) Carbohydrates (3):
Carbon, hydrogen and oxygen
...

c) Lipids (3):
Carbon, hydrogen and oxygen
...

3) How do you test for starch and what is the result? (2)
-Test:
Add iodine to the solution or substance
...

4) How do you test for glucose and other reducing sugars and what is
the result? (2)
-Test (2):
Add some Benedict’s solution onto it in a test tube
...

-Result (4)s:
If glucose is present it should turn:
Yellow  Green  Orange  Red (from low to high)
...

6) How do you test for protein and what is the result? (2)
-Test (2):
Biuret test
...

6) What are enzymes? (2)
They are biological catalysts in metabolic reactions
...

7) How does temperature affect enzymes? (3)
Most enzymes work best in body temperature
...
If the temperature gets to high
the enzymes denature and can’t help any longer
...


Chapter 6: Movement of Substances In and Out of Cells
1) What are the 3 ways to exchange materials in organisms?
Diffusion, osmosis and active transport
...
It is passive and uses kinetic
energy
...

-Distance to cross
...

-Temperature
...

4) Where is the ratio of surface area greater, in a small or a big
organism?
In a small organism
...

6) In Polar Regions of the earth is it better to be large or small?
Large, because the larger the animal the less ratio of surface area
there is and the slower diffusion will be
...

7) What is osmosis (2)?
A type of diffusion
...

8) Give the words that describe different concentrations of solutes:
a) High solute:
Hypertonic
...

c) Equal solute:
Isotonic
...

-The movement of water across the wall of the large intestine
...

11) What does each of the following terms mean?
a) Shrivelled:
When an animal cell contains very little water and shrinks
...

c) Plasmolysed:
When a plant cell contains very little water and shrinks
...

e) Turgid:
When a plant cell contains a lot of water and expands
...

13) Where does active transport get its energy from?
Respiration
...

15) Examples of active transport (2):
-Glucose in small intestine
...
g
...


Chapter 7: Nutrition
Nutrition for flowering plants:
1) What do plants do during the night and day?
During the night they respire
...

2) What is photosynthesis?
It is the process by which plants make food
...

3) What is the word equation and balanced chemical symbol equation
for photosynthesis in a plant?
-Photosynthesis:
Carbon Dioxide + Water  Oxygen + Glucose + Energy
...

5) How is the structure of the leaf adapted for photosynthesis? (6)

6

-Palisade cells, which contain most chloroplasts, are near to the
surface of the leaf
...

-Leaves are thin so that sun’s rays can pass through them easily to
reach to the chlorophyll as quick as possible
...

-Leaves have air spaces to allow gas exchange by diffusion
...
Also sunlight reflects off the wax, which protects it
...

7) Why does the intensity of light affect the rate of oxygen
produced by a plant?
Because the more light there is, the faster photosynthesis occurs
...
So if there is more
photosynthesis the amount of oxygen produced by a plant increases
...

Carbohydrate, protein, lipid, vitamin, mineral, water and fibre
...

-Found in potatoes, rice and pasta
...

-Found in milk, eggs and meat
...

-Found in butter, cheese and peanuts
...

-Found in citrus fruits
...

-Found in sunlight
...

-Found in milk and eggs
...

-Found in spinach and liver
...

-Found in cereals and dark bread
...

-Found in fruits and drinks
...

11) What is ingestion?
The taking in of substances through the mouth
...

13) What is absorption?
When the digested food is absorbed in the blood through the villi
...
(3)
-The products of digestion are absorbed into your bloodstream in the
small intestine
...

-They have a large surface area, a good blood supply to maintain
steep concentration gradient and short diffusion distances
...

16) Describe the process of assimilation
...

-They are used for energy and to build up into chemicals needed by
the cells
...

18) Describe the process of egestion
...

-Water is removed
...

19) How does food get transported through your gut?
By muscular contractions called peristalisis
...

-They break down starch to glucose
...

-They break down proteins to amino acids
...

-They break down lipids to fatty acids and glycerol
...

22) What is the role of bile?
It neutralises stomach acid and helps in digesting lipids
...


Chapter 8: Respiration
1) What does the process of respiration do in living organisms?
It releases energy
...

-Anaerobic:
-Without oxygen
...

-C6H12O6 + 6O2  6CO2 + 6H2O + Energy
...

b) Plants:
-Glucose  Carbon Dioxide + Ethanol + Energy
...

-Carbon dioxide diffuses from the bloodstream into the air in the
alveoli
...

-The oxygenated blood travels back to the heart to be pumped
around the body
...
During the day they photosynthesise
...

-6CO2 + 6H2O  6O2 + C6H12O6 + Energy
b) Respiration:
-Oxygen + Glucose  Carbon Dioxide + Water + Energy
...

4) How is the structure of the leaf adapted for gas exchange? (3)
-Plant leaves are thin and flat so that the distances that gases need
to diffuse are very short
...

-Leaves have a waxy surface so that if it rains the water doesn’t go
into the stomata and block it, but instead lets the water run down
the leaf
...

Gas exchange in humans:
6) What are the parts of the respiratory system? (12):

10

Nose, mouth, larynx, trachea (has rings of cartilage to keep it open),
bronchi, bronchioles, alveoli, intercostals muscles, ribs, left lung,
right lung and diaphragm
...

-Lined of cells making mucus and ells with cilia which move the mucus
away from the lungs
...

c) Intercostals muscles:
Help form and move the chest wall
...

e) Bronchioles:
Smaller airways that send the air on to the inside walls of the lungs
to the alveoli
...

g) Diaphragm:
Sheet of muscle with a fibrous middle part which is domed; it helps
make breathing movements and separates the thorax from the
abdomen
...

8) What is the role of the intercostal muscles and the diaphragm in
ventilation? (5)
-During inhalation the diaphragm muscles contract and the external
intercostal muscles contract increasing the volume of chest cavity
-The pressure is now lower than outside the body, so air enters the
lungs
...

-The pressure is now higher than outside the body, so air is pushed
out of the lungs
...

9) How are alveoli adapted for gas exchange? (4)
-They have a large surface area so more gas can be exchanged at
once
...

-They are moist so the gas can diffuse through them easily
...

10) How does smoking affect the circulatory system? (3)
-Causes an increased risk of heart attacks and strokes
...

-In pregnant women carbon monoxide deprives the fetus of
oxygen and can lead to smaller babies and stillbirths
...

-Cilia are destroyed, which leads to mucus accumulation so dirt
and bacteria are not removed
...

This is called emphysema
...
Since breathing is the
intake of oxygen, it increases since you need more oxygen for your
muscles
...

2) Why do multi-celled organisms need a transport system?
Because they are too big and not all of their cells have contact with
the external environment
...

2) What are the differences between both?
a) Xylem (7):
-A hollow tube
...


12

-Transports water and minerals only
...

-Has thick walls stiffened with lignin (protein)
...

-Located in the inner part of the stem
...

-Transports nutrients only (sugars, fats and hormones)
...

-Cells have perforated end walls
...

-It is living tissue
...

-Located in the outer part of the stem
...

-Both sets of
(ii)
go to every part of the plant, but they are
totally
(iii)
...

b) Phloem tubes transport
(iv) :
-Made of
(v)
cells with perforated
(vi)
to allow stuff to
flow through
...

-They carry
(ix) ,
(x) ,
(xi)
etc
...

c) Xylem Tubes take
(xv)
up:
-Made up of
(xvi)
cells joined end to end with no end walls
between them
...
This gives the plant
(xx)
...

d) The Phloem and Xylem extend into the
(xxiv) :
-The
(xxv)
carries substances down to the roots for
(xxvi)
or for
(xxvii) , and may later carry them back up
again
...

14

Answers:
i) tubes
...
iii) separate
...
v) living
...

vii) food
...
ix) fats/sugars/hormones
...
xi) fats/sugars/hormones
...

xiii) root/shoot
...
xv) water
...
xvii)
thick/strong/stiff
...
xix) lignin
...
xxi) water/minerals
...
xxiii)
roots
...
xxv) phloem
...
xxvii)
storage/growth
...
xxix) minerals
...

5) How is water absorbed into plants?
Plants absorb water from their root hairs on the root via osmosis, it
is then transports to other parts of the plant (via the network of
xylem vessels) through transpiration
...

7) What factors affect the rate of transpiration?
Wind speed, humidity, temperature and light intensity
...

-This is because then the water droplets are blown off faster from
the stomata
...

-This is because the concentration of water particles in the air is
higher than the concentration of water particles in the plant and that
means osmosis works at a much slower rate
...

-This is because then the particles gain kinetic energy and move
faster
...

-This is because the stronger the light is, the more the stomata’s
open and the more they open the more they transpire
...

10) Where is the most water lost on a leaf and why?

15

At the lower surface because that is where most of the stomata are
because when it rains the water would go into the air spaces
...

12) What is the function of blood plasma?
To transport carbon dioxide, digested food, urea, hormones and heat
energy
...

14) What special features do red blood cells have to help them carry
out their job? (4)
-They don’t have a nucleus because like this they have more space
for carrying oxygen
...

-They are flexible so can squeeze through smallest capillaries
...

15) What is the function of white blood cells?
To protect your body from invasion of foreign substances such as
bacteria and viruses
...

-They release antibodies to destroy pathogens
...

-They can change shape
...

19) What are the three steps how phagocytes engulf microbes when
there is a wound and how lysosome then breaks them down? (4)
-They migrate to the site of injury
...

-Pseudopodia (“false-foot”)
...

20) What are the two types of lymphocytes?

16

B cells (produce antibodies) and t cells
...

-They split open pathogens
...

23) What is the function of blood platelets:
To clot blood
...

25) Where does the blood go in the:
a) Pulmonary Artery:
From the heart to the lungs
...

c) Aorta:
From the heart to the head and body
...

26) Draw and label the heart:

27) Describe the 7 steps of blood flow through the heart
-Blood enters the atria (left and right) passively
...

·The atrio ventricular valves open
...

-Blood fills space in the ventricles
...

-Ventricle muscles contract:
·Volume decreases
...

·Blood forced out through the arteries (aorta and pulmonary artery)
...

-Semi-lunar valves prevent the backflow of blood into the heart
...
So, the heart starts pumping faster to oxygen more
quickly around the body
...

29) What is the structure and function of the following transport
tubes in humans¿
a) Arteries:
-Structure (3):
-Have thick walls and muscles that withstand the pressure of the
blood
...

-They don’t have valves
...

b) Veins:
-Structure (1):
-They include pocket valves that prevent the blood from flowing in
the wrong direction
...

-Transports blood under lower pressure than arteries
...

-Capillary walls are only one cell thick,
-Function (1):
-This permits exchange of oxygen, carbon dioxide, water, salts,
etc
...


18

Chapter 11: Excretion
Excretion in Flowering plants:
Look at gas exchange
Excretion in Humans:
1) Name three organs that have an excretory function
...

2) What is excretion? 3 examples
...

3) Name four substances that have to be excreted from the body
...

4) Draw and label the excretory system (5 parts) and arrows
...

6) What is the kidneys’ function? (4 examples)
They filter the blood and remove any harmful or excessive substances
e
...
urea, water, salts and hormones
...

8) What transports blood from the heart to the kidneys?
Renal artery
...


19

10) What are nephrons?
They are millions of tiny structures inside the kidney
...

12) Where do they all eventually drain in to?
The ureter
...


14) Draw and label a nephron (8 parts):

15) What is the glomerulus?
A network of blood capillaries in the Bowman’s capsule
...
Only small molecules will pass through the blood
vessel (called glomerulus)
...

c) Which small particles pass through (7)?
Water, urea, salts, glucose, drugs, hormones and toxins
...

17) What can you also call the first and second coiled tubules?
Proximal and decimal convoluted tubule
...
The arterioles enter into the
(B)
...
This forces
everything small enough, to leave the blood and cross the
(D)
of
the adjoining cells, called the
(E)
...
After the filtrate trickles down from
the Bowman’s capsule into the first coiled tubule, it contains (6
things),
(G)
...
The remaining liquid,
called
(J)
passes down the
(K)
and collects in the
(L)
before being expelled from the body
...
(B) cortex
...
(D) partially permeable
membrane
...
(F) Bowman’s Capsule
...
(H) nephron
...
(J)
urine
...
(L) bladder
...

20) How and where is ADH produced?
By the pituitary gland in the centre of the brain
...

22) What happens when you don’t drink enough? (4)
-You hypothalamus detects this via osmoreceptors
...

-The ADH travels in the blood stream all around the body until it
reaches its target organ, the kidney
...

24) What happens when you drink too much? (4)
-You hypothalamus detects this via osmoreceptors
...

-The collecting ducts become less permeable to water
...


Chapter 12: Coordination and Response
1) Are organisms able to respond to changes in their environment?
Yes
...

3) Name 2 examples of homeostasis (2):
-Water content (osmo-regulation)
...

4) What does a coordinated response need?
A stimulus, a receptor and an effector
...

6) What is a respond to a stimulus called?
Tropism
...

8) How do plants respond to stimuli?
By growing to or away from them
...

12) What is negative phototropism?
When something does not grow in the direction of light
...

14) Where is it made?
In the cells in the tip of a growing shoot
...

16) What happens when a shoot gets light from above or all around?
(5)
-Auxin is produced
...

-The cells in the tip divide
...

-This makes the shoot grow towards the direction of the light
...

-There are more auxins on the shaded side of the shoot
...

-This makes the shoot curve to the direction of the light
...

19) What do root tips respond to?
Gravity
...

21) What will this make the root do?
Curve down
...

23) What is negative geotropism?
When something doesn’t go with gravity
...

-Chemical reaction
...

-More universal
...

-Physical reaction
...

-More specific
...

26) Why are the reactions so quickly in the nervous system?
Stimulation of receptors in the sense organs sends electrical impulses
along the nerves into and out of the central nervous system, resulting
in rapid responses
...

29) Draw the eye and label it (11):

30) What are the functions of each of the parts of the eye? (11)
a) Blind spot:
-Area of no receptors
...

-The blood supply gives nutrition to the various parts of the eye
...

d) Fovea:
-It gives the sharpest vision
...

f) Optic nerve:
24

-It connects the retina to the brain
...

h) Sclera (2):
-It maintains the shape
...

i) Lens (3):
-It is transparent to provide a clear medium through
...

-It provides clear images of objects over a wider range of distances
...

k) Pupil:
-The size of it regulates the amount of light entering the eye
...

-Suspensory ligaments loosen, so there is no tension on the lens
...

32) What happens to the lens where there is distance vision? (3)
-Ciliary muscles relax, so they move away from the centre
...

-Stretches the lens to become thinner and longer
...

-Target:
Collecting duct (nephron)
...

b) Adrenaline:
-Source:
Adrenal glands
...

-Breathing centre
...


25

-Faster and deeper breathing
...

-Target (2):
-All cells
...

-Allows glucose to become glycogen in liver
...

-Target (2):
-Testes
...

-Effects (2):
-Sperm production in testes
...

e) Progesterone:
-Source:
Ovaries
...

-Effects:
Maintains the uterus’ lining
...

-Target:
Uterus
...


Section C: Reproduction and Inheritance
Chapter 13: Reproduction
1) What are the five differences between sexual and asexual
reproduction? (2)
-Sexual (5):
-Two parents take part
...


26

-Fertilization takes place
...

-Mixing of hereditary material
...

-Offspring are genetically identical to each other and to their
parent
...

-No gametes
...

2) What is fertilisation? (4)
It is the fusion of a male and female gamete, to produce a zygote
that undergoes cell division and develops into an embryo
...

-Wind-pollinated:
Outside petals, so wind can blow pollen away
...

-Wind-pollinated:
Outside petals, to catch pollen blowing in the wind
...

d) Size of petals (2):
-Insect-pollinated:
Large to attract insects
...

e) Colour of petals (2):
-Insect-pollinated:
Bright to attract insects
...

f) Nectaries (2):
-Insect-pollinated:
Present to attract insects
...

g) Pollen grains (2):
-Insect-pollinated:
Large and sticky to stick to insects
...

4) What happens after pollination? (3)
-A pollen tube grows down into the ovary to carry the male nucleus
to the ovules
...

-After this seeds and fruit form
...

Reproduction in humans
6) What are the parts of the male reproductive system? (6)
Glands, testacies, scrotum, bladder, penis and vas deferens
...

b) Testacies (2):
They produce sperms and testosterone
...

d) Bladder:
Stores urine
...

f) Vas deferens:
It transports mature sperm to the urethra in preparation for
ejaculation
...


28

9) Give the functions for each part of the male reproductive system
(5):
a) Ovary (2):
Produces eggs and hormones
...

c) Cervix:
Directs sperm into the uterus during sexual intercourse
...

e) Fallopian tube:
Tunnels that allow the egg to travel from the ovaries to the uterus
...
(2)
FSH (Follicle Stimulating Hormone) and LH (Luteinising Hormone)
...

12) What does LH do?
Stimulates development of corpus luteum from the remains of the
follicle
...

14) What happens then?
The lining breaks down
...

16) Name 4 female secondary sexual characteristics
...

-Increased growth of breasts
...

-Growth of hair in the pubic region and in armpit
...
(4)
-Testes start to produce sperm
...

-Voice deepens (breaks)
-Growth of hair in the pubic region and in armpit
...

2) Where is DNA found? (3)

29

In the nucleus and small amounts are found in mitochondria and
chloroplasts
...

4) What is the name given to lots of nucleotides joined together? (2)
Polynucleotide (polymer)
...

6) Draw a nucleotide:

7) How does the sister strands of the DNA molecule run? (2)
In opposite direction (anti-parallel)
...

9) What are the 4 types of bases in DNA?
Adenine (A), Thymine (T), Guanine (G) and Cytosine (C)
...

11) What are the bases joint by?
By hydrogen bonds
...

13) Draw two chains of polynucleotides together:


...


30

15) Name 5 things that genetics cause (5)
Hair colour, hair texture, eye colour, skin colour and height
...

17) Where is the information stored for someone?
In the chromosomes
...

19) What are alleles?
The alternative form of a gene
...

21) What is another word for the human egg and sperm cell?
Gamete
...

23) What happens when fertilisation occurs?
The gametes fuse together to make a single cell called a zygote
...

25) What are the male sex chromosomes?
xy
...

27) What is the chance of getting a girl or a boy?
50:50 chance
...

29) What is meant by a recessive allele?
An allele that will determine a characteristic only if there are no
dominant ones
...

31) What is heterozygous?
A pair of chromosomes being made of two different alleles of a gene
...

33) What is the phenotype?
The trait that you physically see
...

35) In what order to you do a monohybrid cross for something? (7)
Parental phenotype, parental genotype, gametes, punnet square, x
generation genotype, x phenotype and proportions
...

-F1 phenotype: Blue
...

37) What is the outcome of a cross between two of the F1
generation? (7)
-Parental phenotype: blue eyes x blue eyes
-Parental genotype: Bb x Bb
-Gametes: B b x B b
-Punnet square:
B
b
B
BB
Bb
b
Bb
bb
-F1 genotype: BB, Bb, Bb, bb
...

-Proportions: 75% blue and 25% brown eyes
...

b) What are they?
-Sperm and egg cell
...

d) So what can you call them?
Haploids
...

39) Answer these questions on all body cells (6):
a) What are they called?

32

Somatic cells
...

c) What is this process called?
Mitosis
...

e) How many chromosomes do they have?
46
...

40) Explain mitosis in 4 steps (4):
-The cell starts off with 46 chromosomes
...

-Chromosomes split and move equally to two cells
...

41) Explain meiosis in 6 steps (6):
-The cell starts off with 46 chromosomes
...

-Chromosomes split and move equally to two cells
...

-These two cells then split
...

42) Name differences between meiosis and mitosis:
-Mitosis (4):
-Used for growth and repair
...

-Cells with identical number of chromosomes
...

-Meiosis (2):
-Used to produce gametes for sexual reproduction (eggs and sperm)
...

43) What is mutation?
A rare, random change in genetic material that can be inherited
...

45) Describe the process of evolution by natural selection:

33

Evolution is the development of new species from existing ones, and
this evolution is driven by natural selection, which acts on the
variations within a population
...

47) How can mutations be (3):
a) Harmful:
Mutations can harm protein in the cell, which lead to cancer
...

c) Neutral:
It can be neutral by neither causing cancer nor giving the organism
antibiotic resistance
...

b) Community:
All the populations of living organisms living in an ecosystem at a
particular time
...

d) Ecosystem:
A distinct, self-supporting system of organisms interacting with each
other and with their physical environment
...

3) What is quantitative sampling?
It counts the number of organisms present using a quadrat
...

5) What can it be used to measure?
Frequency (number) and percentage cover
...


34

7) How do you determine it? (3)
Repeat sampling in a certain area at least 5 times
...
This is called the
percentage cover
...


Chapter 16: Feeding Relationships
1) Define the following terms (9):
a) Producer (2):
Usually plants
...

b) Primary Consumer:
An animal that eats producers
...

d) Terciary Consumer:
An animal that eats secondary consumers
...

f) Carnivore:
An animal that only eats animals
...

h) Top carnivor:
An animal that is not eaten by anything else
...

2) What does  represent?
The flow of energy (direction of energy transfer)
...

4) What would happen if they weren’t in the ecosystem? (3)
The plants would not get essential nutrients
...
This is called nutrient recycling
...

6) What is a scavenger?
Animals that find dead animals or plants and then eat them
...

8) Where does the energy come from?
The sun
...

10) Where is the energy lost to?
Heat (from respiration) and faeces/urine (undigested matter)
...

12) Where is the energy lost?
When it reflects or passes through the leaf
...

14) What does the pyramid of numbers show?
The drop in numbers at each trophic level in a food chain
...

16) In what kind of an example are there inverted pyramids?
When there is an oak tree where a lot of caterpillars are feeding
off
...


Chapter 17: Cycles within Ecosystems
1) Describe the following carbon cycles (5):
a) From Carbon Dioxide to respiration in plants:
Carbon dioxide in the atmosphere and oceans  photosynthesis 
plants  respiration
...

c) From Carbon Dioxide to combustion of fossil fuel animals:
Carbon dioxide in the atmosphere and oceans  photosynthesis 
plants  feeding and assimilation  animals  fossilisation  fossil
fuels  combustion
...

e) From Carbon Dioxide to decomposers through death and decay:
Carbon dioxide in the atmosphere and oceans  photosynthesis 
plants  feeding and assimilation  animals  death and decay 
decomposers
...

2) What are the biological consequences of polluted air? (2)
Damaged crops and forests and it acidified sensitive soils and still
waters, killing many animals
...

3) Name 5 greenhouse gases:
Water vapour, carbon dioxide, nitrous oxide, methane and
chlorofluorocarbons (CFCs)
...

-Using refrigerators, which produce CFCs
...

-Many factories produce long-lasting industrial greenhouse gases
...

-It re-radiates some of this heat back into space
...

-The energy radiated back from the Earth is in the form of long
wavelengths (infrared) much of which is absorbed by the atmosphere
...

-It lets in light and heat from the Sun through, but reduces the
amount of heat that escapes
...

-This means the temperature increases and it can lead to global
warming
...
(5)
-Leached minerals from fertilisers go in a lake or other body of
water (usually still)
...

-This makes aquatic plant life unable to photosynthesis because the
algae block the sun, so the plants die
...

7) What are the effects of deforestation? (4)
Leaching, soil erosion, disturbance of the water cycle and of the
balance in atmospheric oxygen and carbon dioxide
...
(4)
a) Leaching (2):
Cutting down large areas of forest leaves the soil exposed
...

b) Soil erosion:
Normally plants in the forest hold onto water, but deforestation
removes this characteristic and makes nutrients get washed away
...

d) Disturbance of the balance of atmospheric oxygen and carbon
dioxide (3):
Trees take in carbon dioxide and produce oxygen when they
photosynthesise
...
Also, the trees are often
burned, using up oxygen and putting even more carbon dioxide into
the atmosphere
...


38

3) How can they increase the yield?
By increasing the temperature, by increasing the amount of Carbon
Dioxide in the air, by using fertilisers, by using pesticides or by using
biological pests
...

5) What are pesticides?
They are chemicals that farmers spray on crops to kill the pests
...
(1)
They are very effective
...
(4)
-They are expensive
...

-They can cause environmental damage
...

8) What is biological pest control?
It uses another organism to control a pest
...

It reduces the numbers to a level where they are not causing
significant crop damage
...

11) What is biotechnology?
The use of living organisms to make useful chemicals and products or
to perform an industrial task
...

13) What is the word equation for fermentation?
Glucose  ethanol + carbon dioxide
...

1
...
They make amylase to digest starch
...
Seed are killed and dried to make malt
...
Malt is ground up and mixed with water in a mash tun
...

4
...

5
...

6
...

7
...

15) What is the role of yeast in the production of beer?
When yeast respires anaerobically it produces ethanol, the chemical
that acts as a drug in alcoholic drinks
...

-Add yeast to a sugar solution, made up with boiled water that
contains air
...

-The carbon dioxide produced is collected via a gas syringe or upward
collection
...

2) What else has to be controlled? (5)
-The numbers of fish have to be carefully controlled to avoid too
much competition between members of the same species
...

-The quality of food is controlled
...

-Selective breeding is used to produce fish that grow as fast as
possible
...

-The waste from the fish and the excess of food can cause water
pollution, including eutrophication
...

2) How does selective breeding work?
-People choose animals or plants with a desirable characteristic, such
as a good milk yield for a cow or a big seed yield in wheat
...

3) What is selective breeding used for in plants? (3)
To give characteristics such as resistance to disease, heavy cropping
and the ability to survive in difficult conditions
...


Chapter 21: Genetic Modification
1) What happens in genetic modification?
A gene from one organism is cut out and added to the DNA of
another organism, often of a different species
...

3) What is an organism that receives a new gene from a different
species known as? (2)
Transgenic organism or genetically modified (GM) organism
...

5) What are ligase enzymes?
They are the enzymes used to stick the gene into the DNA of
another organism
...

7) What are genetically modified bacteria used for?
In making insulin
...

9) Where are they grown?
They are grown in a fermenter
...

-To be resistant to weed killers, frost, pests and diseases
...

-To produce human antibodies
...

-To tolerate drought, high and low temperatures and high salt levels
...

Chapter 22: Cloning
1) What is micro-propagation?
Tissue culture
...

-This is grown in a special nutrient media
...

-These are transferred to compost in a greenhouse until they become
establish plants
...

-Species that are hard to grow in other ways can be propagated
...

-Tiny plants can be stored until needed
...

4) How was Dolly the sheep created?
-Cell taken from the udder of an adult sheep, and the diploid nucleus
taken
...

-Nucleus from the udder cell inserted into unfertilised egg cell
...

-The cell developed into an early embryo
...

-There it grew and developed into Dolly
...


Extra Questions:
1) In the experiment to investigate Carbon Dioxide production by
yeast via anaerobic respiration, what is the oil layer for?
So the oxygen does not come in, and so that the fungi only respires
anaerobically not aerobically
...
(3)
a) Dependent variable:
What you measure in the experiment, for example the amount of

42

Carbon Dioxide produced by yeast in anaerobic respiration
...

c) Controlled variable:
What you keep the same, for example the amount of food given to
the yeast
...

b) Phosphor (2):
For respiration and helps in growth (especially root growth)
...

d) Magnesium (3):
Helps with photosynthesis and makes chlorophyll green
...

5) What are the advantages of chemical pesticides against biological
pest control? (4)
Pesticides are easy to obtain, cheaper, easy to apply and are very
effective
...

7) What is meant by a recessive allele?
It is only expressed if homozygous
...

-Result:
A blue-black colour results if starch is present
...
In the ileum, the acids are neutralised to an optimum
pH
...


43

Organism- what organisms will be involved and what similarities do
they need to have for example same sex, age, health etc
...

Standard- what are you going to keep the same? Light intensities,
diet time, temperature, oxygen etc
...

13) Label the parts of a flower:

14) Describe the process of selective breeding (2):
Farmers select organisms that have desired characteristics, like high
milk production on cows
...
The process is repeated for several generations
...

Short stem in wheat
...

17) Fill in this table for starch and glucose:
Soluble
Found in
Broken down Small
Absorbed
in water animal cells by amylase
molecule in stomach
Starch
No
No
Yes
No
No
Glucose
Yes
Yes
No
Yes
No
18) What is insect-pollination?
The transfer of pollen by insects from an anther to a stigma
...

Stimulus  Receptor  Sensory neurone  Brain (relay neurone) 
Motor neurone  Effector  Response
...

20) What is the stimulus response pathway for a reflex? Write it for
when you blink when an object is approaching your eye
...

Light  Retina  Optic nerve  Spinal cord (relay neurone) 
Motor neurone  Ciliary Muscles  Blink of eye
...
(5)
-An electrical impulse travels along an axon
...

-These chemicals diffuse across the synapse (the gap) and bind with
receptor molecules on the membrane of the next neuron
...

-This stimulates the second neuron to transmit the electrical impulse
...

-Green and yellow vegetables
...

-Citrus fruits

45

c) Vitamin D:
-Helps absorb calcium for strong teeth and bones and prevents
rickets
...

23) Name the two parts of the small intestine:
Duodenum and ileum
...

Carbohydrase for example amylase or maltase
...
In digestion, metabolic waste products like carbon dioxide,
urine and sweat are removed by the kidney, lungs and skin
...

27) How are the villi structured to help in absorption?
They have a large surface area so faster absorption
...
They are thin so substances don’t have to travel far
...

28) How do you remember what happens in inhalation and exhalation?
When you inhale, you…

Relax your
Intercostal muscles and
Contract your
External intercostal muscles
When you exhale, your…

External muscles
Relax and your
Intercostal muscles
Contract
29) What happens during inhalation? (6)
-Your diaphragm contracts and flattens
...

-Your ribs move upwards and outwards
...

-This decreases the pressure in your body making it lower than the

46

pressure outside
...

30) What happens during exhalation? (6)
-Your diaphragm relaxes and arches upwards
...

-Your ribs move downwards and inwards
...

-This increases the pressure in your body making it higher than
pressure outside
...

31) What is selective reabsorption?
CHECK AFTER EXAM
...

a) Hormonal system:
-Effect is widespread
...

-Duration of reaction is longer
...

b) Nervous system:
-Effect is local
...

-Duration of a reaction is shorter
...

34) Name an example of a runner:
Strawberries
...

36) Draw the eye:

47

37) Draw a diagram of a flower:

38) What is the diploid number of chromosomes in human cells?
46
...

40) What actually separates during mitosis?
The chromosome not the nucleus
...

42) What happens to a dead body in a few months of it dying?
48

Decomposers break down the body tissues using enzymes
...
These decomposers then release carbon dioxide and
mineral ions
...

43) How do fungi obtain their food?
They secrete extracellular enzymes onto food, which breaks it down
...
They use their hyphae to do
this and they feed on dead material
...

45) How does the blood leaving the glomerulus differ from the blood
entering the glomerulus?
The blood leaving the glomerulus contains less glucose, less water,
fewer amino acids, less urea and fewer salts
...

47) Name two examples of a vector used in genetic modification
...

48) What is a herbicide?
A substance that kills plants
...

50) Why are some people concerned about GM crops? (4)
Crops could alter food chains
...
GM crops could take over the ecosystem
...

51) What is a gene?
A gene is a section of a molecule of DNA and codes for a specific
protein
...

54) Define the following:
a) Population:
The number of an organism
...

c) Habitat:
Where an organism lives
...

56) What happens in a leaf when it is destarched?
The starch is removed and converted into glucose
...

57) What has to be done to the leaf before it is tested for starch?
It has to have its green pigment in the leave cells removed safely
...

59) How is food moved through the gut?
Via muscular contractions, squeezing the food down
...

61) Where are they expelled?
Anus
...

63) Why might a transplanted kidney be placed in the lower abdomen
instead of in the kidney’s usual location?
Because that makes it nearer to the bladder so there is easier
access

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