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Year 11 summary notes


Year 11 revision: When looking at the following questions tick answer you are 100%
sure you know, cross answer you need to get help with, and put a question mark beside
answer you are unsure about.

Make use of the MY GCSE Science website

Any other websites you use

Check the specification; http://filestore.aqa.org.uk/subjects/AQA-4405-W-SP-14.PDF

In the topics of cells can you??
1. Label a plant and animal cell, bacterial cell and yeast cell
2. Compare the above cells, similarities and differences
3. Know what an organelle is
4. Explain the job of the different parts of a cell
5. Learn the job of 2 new organelles, ribosome and mitochondria
6. Explain the term specialised cell
7. Explain how some cells are specialised (structures and the function of these structures for purpose)
8. Explain what a tissue is and give three examples (glandular, epithelial and muscle) and their jobs
9. Explain what an organ is (and explain how the stomach tissues that make up the organ enable it to
do its job)
10. Explain the term diffusion and some factors that affect the speed of diffusion

Environment and sampling can you???

1. Suggest some factors that affect the distribution of organisms and explain why??
2. Explain how to randomly sample (quadrats) and systematically sample (transect)?

In the topics of enzymes can you??

1. Explain what enzymes are what they are made of, what they are sensitive to
2. Explain what the active site is and what a substrate is
3. Can you sketch a diagram for the lock and key model?
4. Suggest some of the jobs enzymes carry out in our bodies
5. Explain why enzymes are catalysts
6. Can you describe and explain the effect of temperature on rate of enzyme activity (sketch a graph too)
7. Can you explain how pH affects an enzymes activity and sketch a graph
8. Can you explain the term denaturing?
9. Can you name the key digestive enzymes, site of production, site of activity and products produced?
10. Could you write a detailed 5/6 mark answer to explain the complete digestion of fats, carbs and protein
11. Can you explain the role of bile, where it is produced and stored?
12. Could you label key organs in the digestive system?
13. Do you understand the term optimum conditions relating to enzymes?
14. Can you give as much detail as possible about the uses of enzymes in industry?
15. Can you give reasons for and against the use of enzyme sin industry?
16. Can you give some examples of uses of enzymes in medicine?
17. Give some examples of proteins in the body (beyond enzymes)

In the topic of respiration can you??

1. Explain aerobic and anaerobic
2. Write the equations for both aerobic and anaerobic respiration
3. Can you write the formula equations (C6H12O6 + 6O2 6CO2 + 6H2O)
4. Explain where most steps of respiration occur and how the organelle is adapted for the process
5. Explain the purpose of respiration and name the storage sugar in the muscles and liver
6. Explain how the energy from respiration is used
7. Recognise that it is controlled by enzymes and thus is sensitive to temp and pH
8. Explain how the body changes during exercise (heart and lungs)
9. Explain why the heart and lungs change in the way they do
10. What characteristics would a fit person have compared to a less fit?
11. Can you compare and contrast aerobic and anaerobic respiration
12. What is oxygen debt?
13. Explain how the heart will change with exercise over a long period making it more efficient
14. Explain the term muscle fatigue
In the topic of speciation and fossils can you???
1. Explain what a fossil is
2. Explain how they provide evidence for evolution
3. Explain the limitations of the fossils as evidence for evolution
4. Explain how fossils are made
5. Give some reasons for extinction
6. Explain speciation
7. Define speciation
8. Define a species

In the topic of inheritance can you????

1. Explain mitosis and meiosis in 5 points each
2. Compare these two types of cell division
3. Explain the following terms, gene, DNA, chromosomes, allele, homozygous dominant, homozygous
recessive, heterozygous, recessive, dominant, haploid, diploid, stem cell, gamete, mitosis, meiosis,
clone, genotype, phenotype, pure breed, homologous chromosomes
4. Do you know the chromosomes for a male and female?
5. Explain how a gene controls the development of a protein
6. Do you know what polydactyly is and what allele causes it?
7. Do you know what causes cystic fibrosis and how it affects people?
8. Suggest some treatments for cystic fibrosis and reasons for them, why antibiotics are given and
enzymes (problem with taking enzymes orally)
9. Do you know how many chromosomes a human has?
10.Where the chromosomes are found
11.How many pairs of chromosomes a human has
12.What is genetic fingerprint and how could you use one to match an unknown DNA sample with a
known sample
13.What genetic screening may be used for
14.Give some positive and negative thoughts on genetic screening
15.Who was Mendel and what did he do and say
16.What are stem cells, how can they be used, pros and cons of using them
17.Explain why meiosis and mitosis are important
18.Can you show using a genetic cross how the inheritance of gender is 50% chance of boy or girl

In the topic of photosynthesis can you?????

1. Write the word and symbol equation for photosynthesis
2. Name three limiting factors for the process
3. Explain the uses of the glucose produced by the plant
4. Explain how the cross section of the leaf is adapted for photosynthesis
5. Explain how the palisade cells are adapted for photosynthesis
6. Label the different parts of the cross section of the leaf
7. Give examples of plant tissues
8. Recall that plants respire all the time but only photosynthesis in the presence of light
9. Name the storage sugar in plants
10. Explain how the leaf as an organ can function effectively in photosynthesis
Most human and animal cells have the following parts:

A nucleus, which controls the activities of the cell

Cytoplasm, in which most of the chemical reactions take place
A cell membrane, which controls the passage of substances into and out of the cell
Mitochondria, which are where most energy is released in respiration
Ribosomes, which are where protein synthesis occurs.

Plant cells have these and also

Chloroplast: which contain a green pigment Chlorophyll that absorbs light energy for photosynthesis
Cell wall: made of cellulose which strengthens the cell (supports the cell)
A permanent vacuole: This contains the cell sap

Bacterial cells: have a cell wall (though not made of cellulose), they do not have a nucleus but do have genetic
material, they have a cytoplasm, cell membrane and contain smaller ribosomes (than plant or animal cells)

Yeast cells: have a nucleus, cytoplasm and membrane.

After fertilisation, an embryo forms through cell division (mitosis) and this contains stem cells
(unspecialised/undifferentiated cells). Certain genes are switched on and cells will begin to
specialise/differentiate, meaning that they take on unique shapes and characteristics to perform particular jobs.

Sperm cells are streamlined, have a tail to swim, the area around the tail is packed with mitochondria to release
the energy for the tail to contract.
Red blood cells have no nucleus so they can carry more oxygen
Root hair cells have a large surface area to absorb more water
Palisade cells are packed with chloroplasts

Substances move in and out of cells by diffusion

Net movement of molecules from a high concentration to a low concentration
Rate of diffusion depends upon
Temperature: higher temperature = more kinetic energy = faster diffusion
Concentration gradient (difference between areas) = steeper = faster
Size of particles: smaller = faster

Oxygen diffuses into cells from the blood because

Inside the cell oxygen is used in respiration and so is always at a low concentration compared to the blood (CO2
moves the opposite way as it is produced in respiration)

Carbon Dioxide diffuses into a leaf as it is used in the leaf for photosynthesis so is lower than the surrounding

Cells: are the basic building blocks of life

Tissues: groups of similar cells with similar structure and function:

Muscle cells muscle tissue contracts
Glandular cells glandular tissue produce and secrete substances like hormones and enzymes
Epithelial cells epithelial tissue covers parts of the body
Palisade cells palisade mesophyll main site of photosynthesis
Epidermal cells epidermal tissue cover the leaf
Xylem and phloem tissue transport water and sugar respectively
Organs: made of different tissues working for a common purpose
Stomach: muscle tissue (churn food and digestive juices), glandular tissue (to produce digestive juices), epithelial
tissue (to cover the inside and outside of the stomach)
Leaf: mesophyll tissue where photosynthesis occurs, xylem and phloem for transport, epidermal tissue to cover
the leaf
What are the main differences between a plant and animal cell?
Animal cell has no chloroplasts, cell wall or permanent vacuole

What are the main differences between an animal and bacterial cell?
Bacterial cell has no nucleus, no mitochondria, bacteria have a cell wall
Bacterial cells have a slime capsule (prevents them drying out), they have plasmids,
that are circular pieces of DNA that usually carry genes for antibiotic resistance, they
have flagella for movement.
What are the main differences between a plant and yeast cell?
Plant cell has a permanent vacuole, chloroplast. Yeast respire aerobically, using oxygen,
but can respire anaerobically too, producing ethanol and CO2 (fermentation)

Tissues: a group of similar cells working together

Muscle tissue: a group of muscle cells. When these contract together they cause
muscle to shorten and allow movement
Glandular tissue: group of cells that secrete substances like hormones and enzymes
Epithelial tissue: group of cells that form a covering for some parts of the body

Organelle C, looks like this close up

Organs: made up of different tissues working together for a common purpose

Tissues found in the stomach, an organ involved in digestion are listed below
Epithelial tissue: covering the outside and more on the inside
Muscular tissue: helps churn the food up with the acid and enzymes
Glandular tissue: secreting, acid to kill bacteria, to create the optimum conditions for the enzymes. It secretes
protease enzymes, and it secretes mucus
Organelle H, looks like this close up
All these tissues have a different job, but work together to ensure digestion of food is effective
Organ system: different organs working together. This division of labour improves

The digestive system has a variety of organs doing different jobs

Organs for releasing digestive juices like

1. Pancreas: releases digestive enzymes to the small intestine
2. Salivary glands: release s enzymes into the mouth
3. Liver: releases bile to neutralise stomach acid and help digest fat
4. Stomach: releases enzymes, acid

Organs for digestion like

Stomach, mouth or small intestine. These all have glands to secrete enzymes, and these
digestive secretions are mixed with the food by muscles or by the teeth

Organs for absorption of soluble products of digestion like..

The small intestine, with its folded wall and microvilli to give it a large surface area
The epithelial cells are thin so the nutrients only have a short distance to diffuse
There is muscle tissue to keep the food moving and to mix it
There are blood vessels to carry away the nutrients and keep a steep concentration
Diffusion: the net movement of molecules from a high concentration to a gradient
low concentration. The large intestine, where water is absorbed
It is faster when the temperature is high and the concentration gradient
is steep (like high oxygen in the alveoli and low oxygen in the blood), the Each organ has a different job, structure and is made up of different tissues, but they work
diffusion distance is short, the molecules are small, the surface area together to ensure effective digestion of food
across which diffusion occurs is large.
Photosynthesis: Carbon Dioxide + water Oxygen + Glucose
6CO2 6H2O 6O2 C6H12O6

Photosynthesis occurs in chloroplasts

Light energy is absorbed by chlorophyll: used to convert carbon dioxide and water in to sugar
Water enters through the root hair cells
Carbon dioxide diffuses in through the stomata
Oxygen is released as a by-product and diffuses out of the leaf

Plants use oxygen for respiration.

In the day Rate of photosynthesis > rate of respiration, so there is a net production in oxygen
At night: there is no photosynthesis so only respiration occurs and oxygen levels decrease

Limiting factors: factors that affect the rate of photosynthesis. The key factors are
Light intensity (energy), Carbon Dioxide (raw material) concentration and Temperature (affects enzymes)
Carbon dioxide levels are so low in the atmosphere (0.04%) it is often a limiting factor
Light and temperature will vary with season, CO2 does not vary as greatly

Greenhouse, polytunnels and hydroponics are ways to grow plants and try to minimise effect of limiting factors.
But raising temp, CO2 and light intensity costs money and so must be balanced against the profit form increased

Uses of glucose
Respiration: to release energy
Cellulose: for cell walls
Starch: insoluble storage sugar
Fats and Oils: energy store
Amino Acids: glucose is combined with nitrates to make amino acid that can be made into proteins

Plants need minerals for growth

Nitrates to make amino acid for proteins lack of nitrate = stunted growth
Magnesium to make chlorophyll lack of magnesium = yellow leaves
How a leaf is adapted for photosynthesis

Waxy layer reduces water loss, water is needed for photosynthesis

Palisade cells contain many chloroplasts and are close to the surface of the leaf to absorb
most light. They have a thin cell wall so gases can diffuse in quicker.

Spongy layer has air spaces so gas diffusion is quick. Spongy cells have chloroplasts to
absorb light

Vascular tissue to bring water and minerals and remove sugar

Guard cells can open and close the stomata to reduce water loss and regulate gas
exchange. Guard cells have chloroplasts to absorb light for photosynthesis
The uses of glucose:
Used in respiration to release energy, used to make starch an insoluble storage sugar,
used to make cellulose for the cell wall, combined with nitrates to make amino acids for
Nitrate Making proteins Stunted growth
proteins, used to make fats and oils.

Magnesium Making chlorophyll Yellow leaves The three limiting factors are..

Carbon dioxide concentration, light intensity and temperature

Plants can only photosynthesis in

the day

Plants respire all the time; this is

how they get energy for making
new thing or absorbing minerals
from the soil

In the day the rate of respiration is

less than photosynthesis so more
oxygen is released than used
2. The graph shows how the rate of photosynthesis is affected by different conditions.

4% CO2 at 25C

Rate of 4% CO2 at 15C


0.03% CO 2 at 25C
0.03% CO 2 at 15C
Light intensity

(a) What patterns can you find from this graph? (5)

(b) How useful could this information be to a grower using glasshouses? Give reasons
for your answer. (2)

9. The graph shows the concentration of carbon dioxide in the air in a greenhouse full of
tomato plants, measured over a period of 24 hours.

of carbon

0 6 12 18 24
mid dawn midday dusk mid
night night
Time in hours

(a) Explain why the concentration of carbon dioxide in the air in the greenhouse
increased between X and Y.(2)

(b) Explain why the concentration of carbon dioxide in the air in the greenhouse
decreased between Y and Z. (2)
5. (a) Balance the following equation for photosynthesis.

............. CO2 + ............. H2O C6HI2O6 + ............. O2 (1)

(b) Name two things necessary for photosynthesis apart from a suitable temperature
range and the availability of water and carbon dioxide. (2)

(a) Plants have leaves which contain guard cells and palisade cells. Explain how each
of these kinds of cell assists photosynthesis.

Guard cells (2)

Palisade cells (2)

(d) Glucose is a product of photosynthesis. Give three uses which green plants make
of glucose. (3)

11. Algae are small green plants. Give three conditions needed by green plants to produce
sugars. (3)

13. The graph shows the mean light intensity at different times of the year in an oak wood.

mean total light


light reaching ground

in wood

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

(a) (i) In which month would you expect the rate of photosynthesis in the oak trees
to be greatest? (1)

(ii) There are plants living on the ground in the wood. In which month would
you expect their rate of growth to be fastest? Explain your answer.. (3)

(b) Name two factors, other than light intensity, that would affect the rate of
photosynthesis in the oak trees. (2)
2. (a) + light = + photosynthesis 5
+ light = + photosynthesis to a limit
limit depends on temp/CO2 levels
+ CO2 = + photosynthesis
+ temp = + photosynthesis
each for 1 mark

(b) need to raise optimum levels 2

when one other raised
to get max/economic yield

9. (a) respiration 1

no photosynthesis because no light 1

(b) photosynthesis rate greater than 1

respiration rate
reject no respiration / photosynthesis only

photosynthesis since light 1

. (a) 666

(b) any two of 2

(presence of) chlorophyll or (amount of) chloroplasts

accept green leaves (or other green parts)

(sufficient) light (intensity)

(light) of a suitable wavelength

(c) guard cells 2

any two of

* control by osmosis
* the movement of gases
accept movement of carbon dioxide or oxygen or water
vapour beware movement of CO2 out
accept a diagram or description

* through the stoma

palisade cells 2

any two of

* near the upper surface

* contain (a great) many or more chloroplasts
* (so) contain the most chlorophyll
(d) any three of 3

* for respiration
* conversion to (insoluble) starch

or to food store or to (other)carbohydrates

* (conversion to) sucrose or to food store or to (other) carbohydrates

or polysaccharides

* (conversion to) lipids or fats or oils

* (conversion to) amino acids or (plant) proteins or auxins or (plant) hormones or

11. carbon dioxide


13. (a) (i) June 1

for 1 mark

(ii) April 3
max. light
photosynthesis makes sugars/substances needed for growth
for 1 mark each

(b) 2 of: 2
carbon dioxide availability
any 2 for 1 mark each
The distribution of organisms is affected by
Temperature: affects enzyme activity
Nutrients: like magnesium and nitrates for plant growth
Light: for photosynthesis
Water: raw material for photosynthesis, needed for chemical reactions,
Oxygen: needed for aerobic respiration, release energy
Carbon Dioxide: raw material for photosynthesis
pH: affects enzyme activity

Sampling the distribution of organisms can be done using

1) Transects:
Use a tape measure to make transect
Place quadrats at regular interval along transect
Record the number of species in each quadrat
Repeat with several transects at regular intervals

2) Random sampling:
Divide the sample area into a grid
Generate random numbers on a calculator and Use random
numbers as co-ordinates (avoid bias)
Place quadrats at coordinates
Count number of species in each quadrat, repeating with a
large number to be representative
Proteins have many uses in organisms
Hormones antibodies structural components like
muscles enzymes
Why sample an area???
To estimate the number of different types of organisms in the habitat

To estimate the amount of each organism living in the habitat (population size)

How do you sample an area?

Randomly: using a quadrat
Using transects when there is an environmental gradient (the habitat changes from one place to the next)
Use a random process to avoid bias
Use a large sample to be representative of the population

Using quadrats

Divide the area into a grid

Generate random number to use as coordinates (avoids bias)

Put the quadrat down and.
Count the number of different species within
The number of a particular species within
Or the area covered by one/each species

Use a large sample to be representative of the area

Creating a transect
Use a tape measure to create the transect

Place quadrats

At regular intervals along the transect

Record the number of different plants/number of each plant

Repeat the transect several times

At random/regular intervals along the habitat

Proteins are polymers of amino acids that are folded into specific shapes

Enzymes have a specific region called an active site

They are biological catalysts: speed up chemical reactions by lowering the activation
They are sensitive to temperature and pH
As temp increases, the rate of reactions increase as the particles gain
Kinetic energy, collide more frequently and forcefully, forming more
enzyme substrate complexes.
Beyond the optimum temperature (temperature where enzyme
works best)
The enzyme denatures, meaning that it active site changes shape and
is no longer complementary to the substrate.

Extreme pH beyond the optimum will also denature the enzyme

Different enzymes work in different conditions; human enzymes
have an optimum at 37 degrees. Enzymes in the stomach (protease)
prefer acidic conditions (hydrochloric acid), and enzymes in the
small intestine prefer alkaline conditions as their optimum.

Digestion is the breakdown of large molecules that cannot be

absorbed into the blood, into small molecules that can be

Digestion of carbohydrates
Amylase is produced in the salivary glands, pancreas and small
intestine. It catalyses the breakdown of starch into simple sugars in
the mouth and small intestine

Digestion of proteins
Protease is produced in the stomach, pancreas and small intestine. Protease catalyses the breakdown of proteins
into amino acids in the small intestine and stomach.

Digestion of lipids
Lipase enzymes are produced by the small intestine and pancreas. They catalyse the breakdown of lipids into fatty
acids and glycerol in the small intestine.
Bile (from the liver which is stored in the gall bladder) aids fat digestion by emulsifying lipids to increase the surface
area for lipase activity

Bile also neutralises stomach acid and creates the alkaline conditions for the enzymes in the small intestine

Enzymes in industry
They are usually sourced from microbes

Used as they are reusable, and have a high turnover rate (rate at which they change substrate to product), so are
effective in small quantities.
Work at low temperatures and pressure so reduce cost of manufacturing processes

Problems: water soluble so difficult to separate form products, activity is affected by temperature and pH, can be
expensive to buy.
Applications (making cheese, yoghurt, beer, wine, genetic engineering)
Biological detergents: proteases and lipases, so wash clothes at lower temperatures and get cleaner clothes.
Proteases to pre-digest baby food
Carbohydrases to convert starch into glucose syrup
Isomerase: converts glucose to a sweeter sugar fructose. So is added in smaller quantities to slimming food making
them less calorific.
Enzyme Facts
They are organic/biological catalysts that speed up chemical
reactions by providing an alternate pathway of lower activation
energy (graph)
They are proteins
Proteins are made up of long chains of amino acids
The chains of amino acids are folded in a specific way to give a unique
Enzymes have a special region called an active site into which the
substrate fits during a reaction
A substrate is the molecule the enzyme reacts with
Enzymes are not destroyed or used up in the reaction
Enzymes have an optimum pH and temperature at which they work
The arte of enzyme catalysed reactions are affected bypH,
temperature, substrate concentration and enzyme concentration

Describing effect of pH
As the pH moves away from its optimum the
rate of the reaction changes
Large changes in the pH will denature the
Describing and explaining effect of temp on
This model shows the lock and key hypothesis enzymes
1. The enzyme has a specific active site that As temperature increases so does enzyme
is complementary to a particular substrate activity up to a point (optimum) beyond
2. The substrate binds to the active site and which the rate of activity decreases
an enzyme substrate complex forms, and Increase in activity because
the reaction occurs Enzyme and substrate have more kinetic
3. The new products no longer complement energy, Collide more frequently, Collide
the active site and are released, the with more energy, More successful enzyme
enzyme is ready to accept the next substrate complexes form. If temperature
substrate molecule gets too high the enzyme denatures, see
diagram opposite explaining this term.
Digestion begins in the mouth. It is the breakdown
of large molecules into smaller ones by enzymes.
These small molecules can be absorbed in to the
blood stream.

Mechanical digestion: is when the teeth grind up

food to increase the surface area for enzymes

Chemical digestion: the action of enzymes

Salivary glands (2) produce and secrete amylase.

This enzyme digests starch to simple sugars

The liver (4) produces bile which is stored in the gall

bladder (3). Bile emulsifies lipids, to increase the
surface area for lipase enzymes, so fat digestion is
faster. Bile neutralises stomach acid and creates The stomach stores food for 2-3 hours and churns it with the
optimum conditions for digestive enzymes in the muscular wall to mix it with digestive juices containing
small intestine HCl: kills bacteria and creates optimum conditions for
protease enzyme
Protease: enzyme called pepsin digests proteins to amino
The pancreas (5) produces enzymes for the small
intestine. Lipase, Protease and carbohydrases like

The large intestine absorbs water and minerals

The small intestine is the site of most digestion. It receives
enzymes form the pancreas and produces enzymes itself.
Lipids are digested by lipase
Lipids fatty acids and glycerol

Proteins are digested by protease

Proteins amino acids

Carbohydrates (starch), digested by carbohydrases (amylase)

Carbohydrates simple sugars
Temperature (C) 0 20 40 60 80 100

Rate of bubbling (per minute) 2 8 40 4 0 0

(i) Briefly describe how the rate of bubbling depends on the temperature. (3)

(ii) What does an enzyme do?.


(iii) Enzymes have many uses. For example they are used in some washing
powders. Give two examples of other uses for which enzymes, or products
containing enzymes, are sold. (2)

3. (a) Starch and protein are foods which have to be digested before they can be
absorbed. For each, state the enzyme involved in the digestion process, where it
occurs in the digestive system and what is formed and absorbed.

Food Enzyme Where digestion occurs What is formed and




Which enzyme is used:

(i) to help to get greasy stains out of clothes?

(ii) in making slimming foods?

(iii) in making baby foods?...... (3)

Explain why enzymes are used in industry. (3)

12. (a) The graph shows how the rate of an enzyme-catalysed reaction changes with



Rate of
reaction in
mg of 2.0
products per
unit time


0 10 20 30 40 50 60
Temperature in C

(i) Explain why, in terms of particles, the rate of most reactions increases as the
temperature is increased. (3)

Q6. A manufacturer of slimming foods is investigating the effectiveness of carbohydrases from

different microorganisms. Iodine solution is a pale golden brown, transparent solution. Starch reacts
with iodine to form a dark blue mixture. Known concentrations of starch are added to iodine solution.
The mixture is placed in a colorimeter which measures the percentage of light passing through the

Graph 1 shows the results.

(a) Explain why less light passes through the mixture when the starch is more concentrated. (1)

(b) The manufacturer adds carbohydrase from each of three different microorganisms, A, B and
C, to starch in flasks at 40 C.

Every minute a sample of the mixture is added to iodine solution and placed in the colorimeter.

Graph 2 shows these results.

(i) When the concentration of starch reaches 2 %, digestion is considered to be sufficient for the next
stage in the manufacture of the slimming food.

How long does this take for the most effective carbohydrase?

Show clearly how you work out your answer. .............................. minutes (2)

(ii) Explain why the manufacturer carried out the investigation at 40 C. (2)

(c) Carbohydrases convert starch into glucose. To complete the manufacture of the slimming food the
glucose should be converted into fructose.

(i) Name the enzyme which would be used to convert glucose into fructose. (1)

(ii) Explain why fructose, rather than glucose, is used in slimming foods. (2)

it/the rate is fastest at 40C

bubbling stops at 80C/between 6080C
the rate is slower at lower temperatures/increases with temp
i)35 (C)

ii)speeds up or alters the rate of 1
(chemical) reactions
do not credit speeds up things
accept speeds up specific (1) reaction (1)

n living things or body or material in 2
or from living things
accept to act as a biological (1) catalyst (1)

(a) amylase mouth or small inetstine sugar or maltose

protease small intestine or stomach amino acids or peptides

b) (i) lipase 1

(ii) isomerase 1

(iii) protease 1

(b) bring about reactions at lower 1


lower pressures 1

less expensive process

12. (a) (i) any three from: 3

particles / they gain energy

particles / they move faster

collide more often or more collisions or more chance of collision

have more energy when they collide or more energetic collisions or

more collisions with activation energy

M6. (a) opaque / less transparent / blue

allow mixture becomes dark / black
ignore thicker

(b) (i) 7 (minutes) or in range 6.7 to 7

award 2 marks for correct answer

if answer is incorrect evidence of selection of

40(% light intensity) either in working or in graph
2 for 1 mark

(ii) any two from:

slower / takes longer at lower temperatures

(40oC is) optimum / best temperature

allow near to 37oC / body
temperature where enzymes work best

enzyme denatured / destroyed / damaged at higher temperatures

allow description of denaturation

(c) (i) isomerase

(ii) fructose is sweeter than glucose

needed in smallerquantities or less is needed

Respiration (occurs in all living organisms, plants and animals)

Aerobic (with oxygen): Glucose + oxygen carbon dioxide + water
Most steps occur in the mitochondria (folded inner membrane to
increase surface area for reaction)
Releases a lot of energy from each glucose molecule used

Energy is used for

Building large molecules from smaller (amino acids into proteins)
Enabling muscle contraction
Maintaining body temperature in mammals and birds
Building sugars and nitrates into amino acids in plants

Anaerobic (without oxygen): Glucose lactic acid

Occurs in the cytoplasm
Releases a little energy from each glucose molecule
Lactic acid: causes muscle cramp/fatigue, inability of the muscle to generate a full force
Anaerobic respiration creates an oxygen debt: oxygen is needed to break down lactic acid into carbon dioxide
and water

Energy and Exercise

In exercise muscles contract more, so need more energy so respiration rate must

To achieve this
1) The heart rate increases:
Delivers more oxygen and more glucose to the muscles for respiration
This also helps to remove more lactic acid, heat and carbon dioxide form the muscles

2) Breathing rate and depth increases

More oxygen is taken in and more carbon dioxide is exhaled.

Muscles store glucose as insoluble glycogen. In exercise, glycogen

levels decrease as it is converted back to glucose and used in
respiration to release energy for muscle contraction.
The mitochondria are organelles in
Cellular respiration: plant and animal cells. It has a folded
A series of enzyme controlled reactions that release energy from organic molecules, like glucose. inner membrane; this gives it a large
Animals store sugar as glycogen in the liver and muscles. This is broken down during exercise to surface area for the chemical
release glucose reactions to take place so it can
There are two types release more energy.
Aerobic: With oxygen
Anaerobic: Without oxygen
Exhaled air has
How aerobic respiration differs to anaerobic. Less oxygen (used in
Aerobic respiration Aerobic uses oxygen respiration)
Most steps take place in the mitochondria (an organelle found in plant and animal cells) Aerobic does not produce lactic acid More CO2 (released in
Aerobic produces carbon dioxide and water respiration)
This releases a lot of energy. The energy is used in many ways
Aerobic respiration releases more energy More water
Is warmer
Aerobic respiration
Glucose comes from the breakdown
Used in many ways
of starch. Starch Digestion begins in
the mouth, with amylase enzymes, Muscle contraction
this produces maltose. Maltose is Building large molecules form
then broken down by maltase smaller ones in animals, like amino
enzymes in the small intestine to acids into proteins, of simple sugars
form glucose, which is soluble, and is into large carbohydrates
absorbed into the blood stream. Building proteins form glucose and
nitrates in plants
This is carried in the Water levels in the body are Keeping a constant body
Carried by red blood cells. Diffuses into the blood at the alveoli. There temperature in mammals and birds.
blood to the lungs maintained as part of
are many alveoli to give a large surface area for rapid diffusion, and
where it diffuses homeostasis, this is the concept
they have thin wall to speed up diffusion. Ventilation and circulation A fit person
where the body keeps a constant Has a low resting heart rate
keeps the concentration gradient steep so diffusion is fast. Red blood into the alveoli and
internal environment During exercise their heart rate does not
cells have no nucleus so they can carry more oxygen is exhaled
increase as much
They recover quickly to rest after exercise

During exercise our heart rate and breathing rate and depth of breathing increase because.
Anaerobic Respiration Our muscles are contracting more, so they require more energy; so more respiration must
take place. We breathe faster and deeper to take in more oxygen and to exhale the excess
carbon dioxide, and our heart beats faster to deliver more oxygen and glucose to the
muscles faster, the fast hear rate also removes lactic acid/carbon dioxide quicker

Anaerobic respiration: this occurs during sustained periods of exercise or short intervals of high intensity. The muscles cannot get sufficient energy from aerobic respiration and so use
anaerobic respiration to release energy without oxygen. Lactic acid is produced and builds up causing muscle fatigue. After exercise the lactic acid is removed by the blood and broken down
by oxygen to carbon dioxide and water. So even after exercise we have a high oxygen demand to break down the lactic acid, this is called the oxygen debt.
1. (i) What is the name of the process which takes place in living cells in your body and
which releases energy from oxygen and glucose? (1)

(ii) Name the two products of the process in part (i).

(c) The bar charts show what happens in an athletes muscles when running in two
races of different distances.

Rate at Rate at
which which
muscles muscles
transfer produce
energy carbon
(average) dioxide

100m 1500m 100m 1500m

race race race race

(i) Compare what happens in the athletes muscles when running in the two
races. (3)

Use the information in the box to explain your answer to (4)

12. In an investigation four groups of athletes were studied. The maximum rate of oxygen
consumption for each athlete was measured and the mean for each group was calculated.
The athletes then ran 10 mile races and the mean of the best times was calculated for
each group. The results are shown in the table below.


(cm per kg per min) (minutes)

A 78.6 48.9

B 67.5 55.1

C 63.0 58.7

D 57.4 64.6

(i) What is the relationship between maximum rate of oxygen consumption and time
for a 10 mile race? (1)

(ii) Suggest an explanation for this relationship. (3)

16. Paula is training for a marathon. When she runs, her heart beats faster than it does when
she is resting. Complete the sentences, using words from the box.

blood breathe carbon dioxide glucose heat nitrogen oxygen respire

When she is running, Paulas muscle activity increases. To do this, her muscle cells .......................... at a
faster rate to give her more energy. Her muscles need to be supplied with ........................................... and
............................ more quickly. Her heart beats faster to increase the flow of................. which carries the


What is the immediate effect of extreme physical activity on the glycogen content of muscles?
Describe how this effect occurs. (why does the glycogen change in the way you suggested
above) (3)

Give three differences between aerobic and anaerobic respiration. (3)

Explain the advantage to the students heart rates increasing during exercise. (4)

The breathing rate and the amount of oxygen used were still higher after exercise, even
though the student sat down to rest. Why were they still higher?

(aerobic) respiration1

carbon dioxide and water (vapour)1

(c) (i) ideas that 2

energy transferred faster in 100m race
carbon dioxide produced faster during 1500m race / more
carbon dioxide produced
for 1 mark each

correct reference to twice / half as fast in either / both cases 1

for a further mark

(ii) respiration during 100m race (mainly) anaerobic 2

respiration during 1500m race (mainly) aerobic
aerobic respiration produced carbon dioxide
anaerobic respiration produced / lactic acid
for 1 mark each
12. (i) the higher the rate of oxygen consumption, the shorter the 1
time taken to complete
for 1 mark

(ii) the faster oxygen is taken into the blood, 3

the faster energy can be released in the muscles,
and the faster the athlete can run
for 1 mark each

16. (a) respire 1

oxygen / glucose
each onceonly 1
glucose / oxygen
blood 1
carbon dioxide / heat
each onceonly 1
heat / carbon dioxide

reduced sharply
Converted to glucose
Which is respired
to release energy

oxygen used in aerobic respiration

more energy from aerobic respiration
carbon dioxide and water are end products of aerobic respiration
lactic acid is end product of anaerobic respiration

when exercising the rate of respiration (in the muscles) is higher

(the increased heart rate delivers)
more oxygen to the (respiring) muscles
more glucose to the (respiring) muscles
and results in faster removal of carbon dioxide and lactic acid and heat

still need to remove extra carbon dioxide

still need to remove heat / to cool
(some) anaerobic respiration (in exercise)
lactic acid made (in exercise)
oxygen needed to break down lactic acid or suitable reference to oxygen debt
lactic acid broken down to CO2 and water or lactic acid changed into glucose

The nucleus contains 23 pairs (46) chromosomes. We inherit 1 of each pair from our parents when sperm and egg
cells nuclei fuse in fertilisation. So are similar but not identical to them. Sexual reproduction produces variation as
offspring inherit different combinations of their parents alleles on the chromosomes.
Chromosomes are made of DNA
Short sections of DNA are genes
Genes determine our characteristics,
They are unique sequences of bases, that code for amino acid sequences which make proteins.
Alleles are alternate forms of genes

Alleles can be
Dominant: allele expressed in the heterozygous form, (shown as a capital letter)
Recessive: allele not expressed in the heterozygous form (shown as a lower case letter)

Phenotype: physical appearance of an organism

Genotype: the allele combination an organism contains

Genotypes can be described as the following

Homozygous = pure breed: same alleles
Homozygous dominant: two dominant alleles (AA)
Homozygous recessive: two recessive alleles (aa)
Heterozygous: 2 different alleles in the genotype (Aa)

Genetic disorders
Cystic fibrosis: caused by a recessive allele
To have condition must be homozygous recessive. Heterozygous people are carriers
A disorder of the cell membranes causing a thicker/sticky/viscous mucus; difficult breathing/trachea blocked;
digestion difficult/glands blocked
Treated with antibiotics, physiotherapy and supplementation of digestive enzymes

Polydactyly: caused by a dominant allele

Results in additional fingers and toes

Cell division
Mitosis: growth, repair replacement, asexual reproduction. Occurs in most body cells
DNA is copied one division 2 daughter cells that are diploid genetically identical to parent cell

Meiosis: gamete formation, sexual reproduction, occur in the testes and ovaries
DNA is copied 2 divisions 4 daughter cells that are haploid genetically unique

Stem cells: unspecialised cells, with ability to differentiate into any other type of cell and divide.
Stem cell sources: embryos, umbilical cord, bone marrow
Uses: treatment of diseases
Stem cells: pros and cons

(A)Stem cells from an embryo can grow into any type of tissue.
(A)Stem cells may be used in medical research or to treat some human diseases.
(A)Large numbers of stem cells can be grown in the laboratory.
(D) Stem cells may grow out of control, to form cancers.
(D) Patients treated with stem cells need to take drugs for the rest of their life to prevent rejection.
(D) Collecting and growing stem cells is expensive.
Embryo screening

(embryos) checked for inherited / genetic disorders / conditions / specific allele

Embryo Screening: pros and cons

Reduce number of people with cystic fibrosis (in population)
Reduce health-care costs
Expensive to have baby with cystic fibrosis
allow decision / emotional preparation example: understand how to care for child better/allows abortion
Allows people to make choices about termination
Help to prepare financially / emotionally etc

Possible damage / risk to embryo / foetus / baby

Allow possible harm / risk to mother
Screening / it is expensive
Have to make ethical / moral / religious decisions / playing God / unethical / immoral / right to life
The DNA replicates
There is one cell division Meiosis
2 daughter cells form The DNA replicates
The daughter cells are genetically identical There are two cell divisions
Each daughter cell has a full set of chromosomes 4 daughter cells form
(diploid) These are genetically
They have half the genetic
information (Haploid cells)

The nucleus controls the cells activities.

It contains 23 pairs of chromosomes (46 in total)
Chromosomes are made up of DNA
A short section of DNA is called a gene
Genes determine our characteristics (eye colour, hair colour)
Alleles are the different forms of a gene (blue eyes, brown eyes)
Some alleles are dominant: always expressed when present
Some alleles are recessive: only expressed when present on both chromosomes

Genetic information is passed on from parents to offspring in the gametes/sex cells.

Males have sex chromosomes.XY
Females have sex chromosomesXX
Diploid: cells that contain a full set of chromosomes
Haploid: cells that contain a half set of chromosomes

DNA determines our proteins because..

DNA is a code, sequence of bases (A, T, C and G)
Every three letters codes for 1 amino acid
The order of the bases determines
The order of amino acids in proteins
1. (a) Complete the sentence.


(b) Explain, as fully as you can, how a person usually inherits cystic fibrosis. (3)

(c) One effect of cystic fibrosis in some patients is that enzymes from the pancreas do
not reach food in the intestine. Doctors now give capsules containing enzymes to
these patients.

(i) Name three digestive enzymes produced by the pancreas. (3)

(ii) The first attempts at giving pancreatic enzymes involved giving a pill
consisting of powdered pancreatic enzymes to the patient. The treatment
failed. When scientists investigated why this happened, they found the
enzymes from the pill in the stomach of the patient, but not in the intestine.

Suggest two possible reasons why the enzymes in the pill did not reach the
small intestine.

3. The diagram shows a family tree in which some individuals have an inherited disorder,
which may cause serious long-term health problems.




Male without disorder Male with disorder

Female without disorder Female with disorder

(a) What proportion of the children of A and B have the disorder? (1)

(b) Explain the evidence from the diagram which shows that the allele for the disorder
is dominant. Use the appropriate letters to identify individuals in your answer.

You may use genetic diagrams in your explanation. There is space for you to draw
a genetic diagram at the top of the facing page. (3)
Explain how DNA controls the structure of proteins. (3)

What are the symptoms of cystic fibrosis? (3)

The black pigment in human skin and eyes is called melanin.

A single gene controls the production of melanin.

A person who is homozygous for the recessive allele of the gene has no melanin and is
said to be albino.

The diagram shows the inheritance of albinism in a family.

affected male

unaffected male

affected female

R S unaffected female

(a) Use a genetic diagram to explain the inheritance of the albino allele by children of
parents P and Q. (3)

(b) R and S decide to have a child.

What is the chance that this child will be an albino? ...............................................

Use a genetic diagram to explain your answer. (3)

1. (a) cell membranes 1

(b) caused by recessive allele 1

both parents carriers / do not have condition 1

receives one recessive allele from each 1

(c) (i) amylase 1

protease 1
lipase 1

(ii) acid destroys enzymes 1

enzymes digested by stomach enzymes 1
3. (a) 1 in 4 / 1/4 / 1: 3 / 25% / 0.25 1
do not accept 3:1 / 1:4 / 2:6

(b) either from C and D

accept synonyms for dominant / recessive eg
Normal / faulty
accept genetic diagram if clearly referring to correct
individuals or genotypes on family tree
allow gene for allele

any three from: 3

C and D have disorder

ignore C & D are carriers

I/J dont have disorder

C and D have dominant and

recessive alleles

recessive alleles from C and D passed to I/J

or I/J have two recessive alleles
NB if allele was recessive then all offspring of C and D
would have the disorder = 3 marks

or from A and B
assume response refers to A+B unless contradicted

A is homozygous recessive / rr, and B is

heterozygous / Rr can be shown in words or symbols
allow any symbol

offspring can be rr or Rr described

allow without key

(c) (i) (embryos) checked for inherited / genetic 1

disorders / conditions
accept diseases for disorders

(ii) any three from: 3

C/D have disorder / have dominant allele

accept disease / condition
accept gene for allele
ignore reference to carriers

chance of embryo / foetus / child having disorder

or may pass on alleles for disorder to their offspring

C/D might want to decide on termination or prepare

for child with disorder
G and H don.t have disorder / both homozygous
recessive / have no dominant alleles (for this disorder)

so offspring (of G and H) cannot / don.t have disorder

order of bases acts as a code; 3

which controls the order;
in which amino acids are assembled into protein;
read in triplet

affects the cell membranes causing

thicker/sticky/viscous mucus;
difficult breathing/trachea blocked;
digestion difficult/glands blocked

19. (a) gametes A or a A or a 1

F1 genotypes correctly derived 1

albino identified 1

A a
a Aa aa
gametes 1
boxes all correct 1
albino (aa) identified 1

(b) 2
/ half / 50% evens/ 1in 2 1
do not credit 1 to 2 or 50/50

gametes A or a a or a or one 1
parent heterozygous, one parent
homozygous recessive

F1 genotypes correctly derived 1


A a
(S) a Aa aa
a Aa aa
gametes correctly derived 1
F1 genotypes correctly derived 1
Speciation and fossils

Fossils are the remains of organisms from many years ago, and are found in rocks. Fossils may be formed in
various ways:
From the hard parts of animals that do not decay easily
From parts of organisms that have not decayed because one or more of the conditions needed for decay
are absent
When parts of the organism are replaced by other materials as they decay
As preserved traces of organisms, eg footprints, burrows and rootlet traces.

traces there were have been mainly destroyed by geological activity.

Fossils provide evidence that species alive today have evolved from simpler organisms
fossil is (remains / impression of) organism that lived a long time ago
fossils show changes over time or older fossils simpler or fossils simpler than present-day species
fossils have similar features to present-day species

Extinction may be caused by:

changes to the environment over geological time
New predators
New diseases
New, more successful, competitors
A single catastrophic event, eg massive volcanic eruptions or collisions with asteroids
Through the cyclical nature of speciation.

Species: organisms that can interbreed and produce fertile offspring

Speciation: development of a new species from an existing species

Explained by..
Isolation of members of a population
By geographical barrier (example???)
Variation in isolated communities
Different selection pressures (examples??? temperature, food, body shape)
Natural selection (certain alleles passed on, certain alleles die out)
Over time population no longer able to produce fertile offspring if they interbreed
in rocks.

Fossils may be formed in various ways:

From the hard parts of animals that do not decay easily
from parts of organisms that have not decayed because one or more of the
conditions needed for decay are absent
As preserved traces of organisms, eg footprints, burrows and rootlet

The fossil record is incomplete!!!

Speciation: the development of a new species from an

existing one.
It occurs due to isolation of members of the species and exposure to
different environmental conditions over many generations

Species: organisms that can interbreed and have fertile

Year 11 quiz
1. What is the job of the cell membrane? 1. What are the problems with using enzymes in industry?
2. What is the job of the nucleus? 2. What is respiration?
3. What is the job of the cytoplasm? 3. Where do most steps of aerobic respiration occur?
4. What is the job of the chloroplast? 4. What does aerobic mean
5. What is the job of the ribosomes? 5. What does anaerobic mean
6. What is the job of the mitochondria? 6. What are the equations for aerobic and anaerobic
7. What is the job of the cell wall? respiration?
8. What is the job of the vacuole? 7. How is energy used in organisms?
9. Define diffusion? 8. What happens to glycogen in exercise?
10. Suggest some factors that affect the rate of diffusion? 9. How does aerobic respiration differ to anaerobic?
11. What is a tissue? 10. What is oxygen debt?
12. What is an organ? 11. What is muscle fatigue?
13. What is the job of the epithelia tissue in the stomach? 12. Why does the heart beat faster during exercise?
14. What is the job of the muscular tissue in the stomach? 13. Why do we breathe heavier during exercise?
15. What is the job of the glandular tissue in the stomach? 14. Name two types of cell divisions
16. What is the job of the epidermal tissue in a leaf? 15. What is an allele?
17. What are the two types of mesophyll tissue? 16. What is a chromosome?
18. How is each mesophyll layer adapted for its job? 17. What is a gene
19. What is the job of the xylem tissue? 18. How many pairs of chromosomes are there in humans?
20. What is the job of the phloem tissue? 19. How many chromosomes do humans have in their cells?
21. What is the word and symbol equation for 20. Where in the cells are chromosomes found?
photosynthesis? 21. What are dominant alleles?
22. How does a plant use glucose? 22. What are recessive alleles?
23. What does a plant need nitrates for 23. What does homozygous mean
24. What does plant need magnesium for 24. What does heterozygous mean
25. Name three limiting factors 25. What does pure breed mean?
26. What is the name of the insoluble sugar store in plants? 26. What type of allele causes cystic fibrosis?
27. What is the name of the insoluble sugar store in muscles? 27. What other term is used for people who are heterozygous
28. Name some factors that affect the distribution of for cystic fibrosis
organisms 28. What type of allele causes polydactyly
29. What are enzymes made from? 29. What is the result of polydactyly
30. Where are enzymes made? 30. What is genotype
31. What other terms can we use to describe enzymes? 31. What is phenotype
32. What region of the enzyme is the site of activity? 32. What are the symptoms of cystic fibrosis
33. How to enzymes work 33. What are the male chromosomes
34. What two key factors are enzymes sensitive too? 34. What are the female chromosomes
35. What does denature mean 35. What did Mendel call chromosomes?
36. Where is amylase produced? 36. Why did people reject Mendels ideas
37. Where does amylase do its digestion? 37. What are stem cells
38. Where is protease produced? 38. Where can stem cells come from
39. Where does protease do its digestion? 39. Why are people for and against stem cells
40. Where is lipase produced? 40. What is embryo screening
41. Where does lipase do its digestion? 41. Why are people for and against embryo screening
42. What is the substrate for amylase? 42. Describe mitosis
43. What is the substrate for lipase? 43. Describe meiosis
44. What is the substrate for protease? 44. Compare meiosis and mitosis
45. Suggest some roles of proteins in the body other than 45. What are gametes
enzymes? 46. Where are gametes made
46. Write an equation for digestion of fats, proteins and starch 47. Why is variation produced by sexual reproduction important
47. What does bile do in digestion (2 things?) 48. Describe how a gene is responsible for the production of a
48. Where is bile produced? protein
49. Where is bile stored? 49. What are fossils
50. What enzyme is used to convert glucose to fructose? 50. Explain how fossils can be made
51. How does fructose differ to glucose? 51. What is extinction
52. Where is fructose used in industry? 52. Suggest some factors that cause extinction
53. What enzymes are used in production of baby food? 53. Explain how speciation develops
54. What enzymes are useful in biological detergents? 54. Define a species
55. Where do many of the enzymes used in industry come 55. Describe complete digestion of fats, carbohydrates and
from? proteins
56. Why are enzymes used in industry?
1. Controls what enters and exits the cell 1. Expensive/affected by temp + pH/water soluble difficult to
2. Contains genetic information/controls cells activities separate form products
3. Site of chemical reactions 2. Release of energy from glucose
4. Photosynthesis (has chlorophyll to absorb light energy) 3. Mitochondria
5. Protein synthesis 4. With O2
6. Respiration 5. Without O2
7. Support the cell 6. ---------
8. Contains cell sap 7. Muscles contraction/build large molecules from smaller/keep
9. Net Movement form high to low concentration body temp steady in birds and mammals/in plants to build sugar
10. Concentration/temperature/surface area/diffusion and nitrates into amino acids
distance/size of molecules 8. Broken down to glucose/use din respiration/release energy
11. A tissue is a group of cells with similar structure and function 9. More energy/need oxygen/no lactic acid
12. Organs are made of different tissues doing common function 10. O2 needed to break down lactic acid CO2 and water
13. Cover the outside and inside 11. Inability of muscle to contract with full force due to lactic acid
14. Churn the food and digestive juices 12. More oxygen and glucose to muscle for increased respiration
15. Secrete digestive juices, acid and protease to release more energy/remove heat/CO2 and Lactic acid
16. Cover the leaf 13. More O2 in more CO2 out
17. Palisade and spongy 14. Mitosis and meiosis
18. Palisade = packed chloroplasts/ spongy = air spaces 15. Alternate form of a gene
19. Carry water and dissolved minerals 16. Threat structure made from DNA
20. Carry sugar 17. Short section DNA/determines characteristics
21. ------ 18. 23
22. Respiration/starch/cellulose/fats/oils/amino acids 19. 46
23. To make amino acids 20. Nucleus
24. Make chlorophyll 21. Allele expressed in heterozygote
25. CO2/Light/Temp 22. Allele not expressed in heterozygote
26. Starch 23. Same allele in genotype
27. Glycogen 24. One of each allele
28. Temp/O2/CO2/light/nutrients/water 25. Homozygous
29. Amino acids, linked as proteins/folded to specific shape 26. Recessive
30. Ribosomes 27. Carriers
31. Biological catalysts 28. Dominant
32. Active site 29. Extra fingers and toes
33. Lower activation energy 30. Genetic constitution of organisms (allele combination)
34. Temp and pH 31. Physical appearance
35. Active site changes shape 32. Damaged cell membrane, thick viscous mucus Difficult to
36. Salivary gland and pancreas breathe, difficult to digest
37. Mouth and small intestine 33. Xy
38. Stomach and pancreas 34. Xx
39. Stomach and small intestine 35. Units of inheritance
40. Pancreas 36. Not a scientist/chromosomes not discovered/different ideas
41. Small intestine 37. Unspecialised cells with potential to form any cell
42. Starch 38. Bone marrow, embryos, umbilical cord
43. Lipids/fats 39. Cure disease, grow tissues and organs/ large numbers
44. Protein grown/may cause cancer/destroy embryos/rejection of
45. Antibodies/hormones/structural components of muscle organs/expensive
46. ----------- 40. Embryos are checked for a particular allele
47. Emulsify fats, neutralise stomach acid 41. Make informed choices, prepare mentally, financially, plan for
48. Liver treatments, may encourage abortion, screen for other things
49. Gall bladder intelligence, gender
50. Isomerase 42. DNA copied, cell divides once, 2 daughter cell genetically
51. Sweeter identical, diploid
52. Slimming foods 43. DNA copied, cell divides twice, 4 haploid cells with genetic
53. Proteases variation
54. Lipases and proteases 44. -------
55. Microbes 45. Sex cell
56. Reactions at lower temps/pressure less expensive 46. Testes/sperm eggs/ovary
process/less likely to produce unwanted by-products 47. More likely for species to survive
48. Order DNA bases = Code for order of amino acids
49. Remains of an organism form a long time ago, show changes in species over time, can be compared to
other organisms and thus look for similarities to present day species

50. from the hard parts of animals that do not decay easily
As preserved traces of organisms, eg footprints, burrows and rootlet trace.

51. Permanent loss of a species form the earth

52. Changes to the environment over geological time/ new predators/ new diseases/ new, more successful,
competitors/ a single catastrophic event, eg massive volcanic eruptions or collisions with asteroids/ through
the cyclical nature of speciation.

53. Isolation/geographical barrier/ variation/different selection pressure in areas/natural selection/ no longer

interbreed after a long time

54. Species = organisms that can interbreed and produce fertile offspring