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Year 12 Pre‐Course Tasks: BIOLOGY
Student Name
GCSE science grade
Mark
/127
Percentage %
This booklet contains 15 GCSE examination questions that become progressively more challenging as you work through the paper. The subject knowledge needed to answer these questions will be built upon during the first weeks of your AS Biology course. It is therefore essential that you attempt all questions and thoroughly revise the topics they cover, mainly cell structure and enzymes, before your first biology lesson in September.
To help you answer these questions use your GCSE Biology notes or the internet to revise. The questions should take you approximately 2 hours to complete.
If you would like something to read relating to biology, there are a few books listed at the end of the questions – these are not compulsory.
Good luck.
See you in September!
St Robert of Newminster
Catholic School and Sixth Form College
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Q1.Figure 1 shows a human cheek cell viewed under a light microscope.
Figure 1
© Ed Reschke/Photolibrary/Getty Images
(a) Label the nucleus and cell membrane on Figure 1. (2)
(b) Cheek cells are a type of body cell.
Body cells grow through cell division.
What is the name of this type of cell division?
Tick one box.
Differentiation
Mitosis
Specialisation
(1)
(c) Ribosomes and mitochondria are not shown in Figure 1.
What type of microscope is needed to see ribosomes and mitochondria?
............................................................................................................................. (1)
(d) What is the advantage of using the type of microscope you named in part (c)?
Tick one box.
Cheaper
Higher magnification
Lower resolution
(1)
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(e) The cheek cell in Figure 2 is magnified 250 times. The width of the cell is shown by the line D to E.
Figure 2
Calculate the width of the cheek cell in micrometres (µm). Complete the following steps.
Measure the width of the cell using a ruler .......................................... mm
Use the equation to work out the real width of the cell in mm:
real size = ............................................ mm
Convert mm to µm ............................................. µm (3)
(f) A red blood cell is 8 µin diameter. A bacterial cell is 40 times smaller. Calculate the diameter of the bacterial cell.
Tick one box.
0.02 µm
0.2 µm
2.0 µm
20.0 µm
(1)
(Total 9 marks)
Q2.The diagram shows how a student transferred some sour milk from a bottle to a Petri dish of nutrient agar.
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List A gives four actions carried out by the student. List B gives five possible effects of these actions.
Draw a straight line from each action in List A to its effect in List B. Draw only one line from each action.
List A – Action List B – Effect
Risk of contamination with bacteria increased
Heating loop in flame
Fewer bacteria will enter
Placing loop on bench to cool
Kills bacteria
Only lifting lid of Petri dish a little
Prevents air entering
Placing Petri dish in incubator at 25°C
Risk of growth of pathogens decreased
(Total 4 marks)
Q3.The diagram below shows the human digestive system.
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(a) (i) What is Organ A?
Draw a ring around the correct answer.
gall bladder liver stomach (1)
(ii) What is Organ B?
Draw a ring around the correct answer.
large intestine pancreas small intestine (1)
(b) Digestive enzymes are made by different organs in the digestive system. Complete the table below putting a tick (✓) or cross (✕) in the boxes. The first row has been done for you.
Organ producing enzyme
salivary glands
stomach pancreas small
intestine
Enzyme
amylase ✓ ✕ ✓ ✓
lipase
protease
(2)
(c) The stomach also makes hydrochloric acid. How does the acid help digestion?
........................................................................................................................
........................................................................................................................ (1)
(d) Draw one line from each digestive enzyme to the correct breakdown product.
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Digestive enzyme Breakdown products
amino acids.
Amylase breaks down starch into……
bases.
Lipase breaks down fats into…
fatty acids and glycerol.
Protease breaks down proteins into…
sugars.
(3)
(Total 8 marks)
Q4.Some students investigated the effect of pH on the digestion of boiled egg white by an enzyme called pepsin. Egg white contains protein.
The students:
• put a glass tube containing boiled egg white into a test tube
• added a solution containing pepsin at pH 7
• set up six more tubes with solutions of pepsin at different pH values
• left the test tubes for 24 hours at room temperature.
The image below shows one of the test tubes, at the start and at the end of the 24 hours.
At start 24 hours later
(a) (i) Name the product of protein digestion.
............................................................................................................... (1)
(ii) What type of enzyme digests protein?
Tick ( ) one box.
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amylase
lipase
protease
(1)
(b) The egg white in each tube was 50 mm long at the start of the investigation. The table below shows the students’ results.
pH Length in mm of boiled egg white after 24 hours
1 38
2 20
3 34
4 45
5 50
6 50
7 50
(i) At which pH did the pepsin work best?
pH .................................. (1)
(ii) The answer you gave in part (b)(i) may not be the exact pH at which pepsin works best. What could the students do to find a more accurate value for this pH?
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(iii) There was no change in the length of the egg white from pH 5 to pH 7.
Explain why.
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(c) Pepsin is made by the stomach.
Name the acid made by the stomach which allows pepsin to work well.
........................................................................................................................ (1)
(Total 8 marks)
Q5. The diagram shows two cells, a bacterial cell and a plant cell.
(a) (i) Both the bacterial cell and the plant cell contain ribosomes.
What is the function of a ribosome?
...............................................................................................................
............................................................................................................... (1)
(ii) The plant cell contains mitochondria but the bacterial cell does not contain mitochondria.
Give one other way in which the plant cell is different from the bacterial cell.
...............................................................................................................
............................................................................................................... (1)
(b) (i) Both cells are drawn the same length, but the magnification of each cell is
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different.
The real length of the bacterial cell is 2 micrometres. Calculate the real length, X, of the plant cell. Give your answer in micrometres.
Show clearly how you work out your answer.
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X = ........................................ micrometres (2)
(ii) Most mitochondria are about 3 micrometres in length. The plant cell contains mitochondria but the bacterial cell does not contain mitochondria.
Use your answer to part (b)(i) and the information in the diagram to suggest why.
...............................................................................................................
............................................................................................................... (1)
(Total 5 marks)
Q6.The diagram below shows a single-celled alga which lives in fresh water.
(a) Which part of the cell labelled above:
(i) traps light for photosynthesis
............................................................................................................... (1)
(ii) is made of cellulose?
............................................................................................................... (1)
(b) In the freshwater environment water enters the algal cell.
(i) What is the name of the process by which water moves into cells?
............................................................................................................... (1
(ii) Give the reason why the algal cell does not burst.
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(c) (i) The alga can photosynthesise. Complete the word equation for photosynthesis.
water + .............................. ............................... + oxygen (2)
(ii) The flagellum helps the cell to move through water. Scientists think that the flagellum and the light-sensitive spot work together to increase photosynthesis.
Suggest how this might happen.
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(d) Multicellular organisms often have complex structures, such as lungs, for gas exchange.
Explain why single-celled organisms, like algae, do not need complex structures for gas exchange.
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(Total 11 marks)
Q7.The image below shows some muscle cells from the wall of the stomach, as seen through a light microscope.
(a) Describe the function of muscle cells in the wall of the stomach.
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........................................................................................................................ (2)
(b) Figure above is highly magnified. The scale bar in Figure above represents 0.1 mm. Use a ruler to measure the length of the scale bar and then calculate the magnification of Figure above.
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Magnification = ............................. times (2)
(c) The muscle cells in Figure above contain many mitochondria. What is the function of mitochondria?
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........................................................................................................................ (2)
(d) The muscle cells also contain many ribosomes. The ribosomes cannot be seen in Figure above.
(i) What is the function of a ribosome?
...............................................................................................................
............................................................................................................... (1)
(ii) Suggest why the ribosomes cannot be seen through a light microscope.
...............................................................................................................
............................................................................................................... (1)
(Total 8 marks)
Q8.(a) The graph shows the effect of pH on the activities of three enzymes, X, Y and Z. These enzymes help to digest food in the human digestive system. Each enzyme is produced by a different part of the digestive system.
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pH
(i) What is the optimum (best) pH for the action of enzyme Z?
.............................. (1)
(ii) The stomach makes a substance that gives the correct pH for enzyme action in the human stomach.
Name this substance. .................................................................................................. (1)
(iii) Which enzyme, X, Y or Z, will work best in the human stomach?
.............................. (1)
(b) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
Different parts of the human digestive system help to break down molecules of fat so that they can be absorbed into the body. Describe how.
To gain full marks you should refer to:
• the enzyme and where the enzyme is produced
• the products of digestion
• any other chemicals involved.
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(Total 9 marks)
Q9.Catalase is an enzyme found in many different tissues in plants and animals.It speeds up the rate of the following reaction.
hydrogen peroxide water + oxygen
Figure 1 shows a 25-day-old broad bean seedling.
Some students investigated whether different parts of bean seedlings contained different amounts of catalase.
The students: • put hydrogen peroxide into five test tubes
• added a different part of a bean seedling to each tube
• recorded the results after half a minute.
If there was catalase in part of the seedling, oxygen gas was given off. When oxygen gas is given off, foam is produced in the tubes.
Figure 2 shows the results.
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The students made the following conclusions: • most parts of a bean seedling contain catalase
• the seed contains a lot of catalase
• stems and roots have quite a lot of catalase
• the leaves have a little bit of catalase
• the seed coat has hardly any catalase.
The students’ teacher said that the students needed to improve their investigation in order to make valid conclusions.
(a) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate. Describe how you would carry out an investigation to compare the amounts of catalase in different parts of bean seedlings.
You should include details of how you would make sure your results give a valid comparison of the amounts of catalase.
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(b) Scientists investigated the effect of pH on the activity of the enzyme catalase in a fungus.
The table below shows the scientists’ results.
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pH
Enzyme activity in arbitrary units
Test 1 Test 2 Test 3 Test 4 Test 5 Mean
3.0 0 0 0 0 0 0
4.0 6 5 8 4 7 6
5.0 38 65 41 42 39
5.5 80 86 82 84 88 84
6.0 100 99 96 103 102 100
6.5 94 92 90 93 91 92
7.0 61 63 61 62 63 62
8.0 22 22 21 24 21 22
(i) Calculate the mean enzyme activity at pH 5.0.
...............................................................................................................
...............................................................................................................
Mean = ......................... arbitrary units (2)
(ii) On the graph paper in Figure 3, draw a graph to show the scientists’ results.
Remember to: • add a label to the vertical axis
• plot the mean values of enzyme activity
• draw a line of best fit.
Figure 3
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(4)
(iii) At what pH does the enzyme work best?
........................................ (1)
(iv) Predict the activity of the enzyme at pH 9.0.
........................................ arbitrary units (1)
(v) Suggest why the enzyme’s activity at pH 3.0 is zero.
...............................................................................................................
............................................................................................................... (1)
(Total 15 marks)
Q10. There are enzymes in biological washing powders. Biological washing powder has to be used at temperatures below 45 °C.
(a) The enzymes in biological washing powders do not work on the stains on clothes at temperatures above 45 °C.
Explain why.
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(b) Some bacteria, called thermophilic bacteria live in hot springs at temperatures of 80 °C.
Scientists have extracted enzymes from these thermophilic bacteria. These enzymes are being trialled in industrial laundries. The laundries expect to increase the amount of clothes they can clean by using enzymes from thermophilic bacteria instead of using the biological washing powders the laundries use now.
(i) The laundries expect to be able to increase the amount of clothes that they can clean each day.
Suggest why.
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(ii) Using washing powders with enzymes from thermophilic bacteria may be more harmful to the environment than using the biological washing powders that laundries use now.
Suggest why.
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(Total 6 marks)
Q11.Fresh milk is a mixture of compounds including lipid, protein and about 5% lactose sugar.
Lactose must be digested by the enzyme lactase, before the products can be absorbed.
Lactase can be added to fresh milk to pre-digest the lactose. This makes ‘lactose-free’ milk, which is suitable for people who do not produce enough lactase of their own.
A student investigated the effect of changing pH and temperature on the digestion of lactose in milk.
The results are shown in Tables 1 and 2.
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Table 1 Effect of pH
Table 2
Effect of temperature
pH Time taken to
digest lactose in minutes
Temperature
in °C
Time taken to digest lactose in
minutes
4.0 20 25 20
5.0 18 30 14
6.0 13 35 11
7.0 7 40 6
8.0 5 45 29
9.0 6 50 No digestion
(a) The label on a carton of lactose-free milk states:
‘Lactase is normally produced in the stomach of mammals.’
The results in Table 1 suggest that this statement is not true.
Explain how.
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(b) Explain, as fully as you can, the results shown in Table 2 .
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(c) Bile is produced in the liver and is released into the small intestine. mBile helps the digestion of lipid in the milk. Describe how.
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(Total 7 marks)
Q12.Figure 1 shows photographs of some animal cells at different stages during the cell cycle.
Figure 1
A © Ed Reschke/Photolibrary/Getty Images. B © Ed Reschke/Oxford Scientific/Getty Images. C © Ed Reschke/Photolibrary/Getty Images
(a) Which photograph in Figure 1 shows a cell that is not going through mitosis? Tick one box.
A
B
C
(1)
(b) Describe what is happening in photograph A.
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(c) A student wanted to find out more about the cell cycle. The student made a slide of an onion root tip. She counted the number of cells in each stage of the cell cycle in one field of view. The table below shows the results.
Stages in the cell cycle
Non-dividing cells Stage 1 Stage 2 Stage 3 Stage 4 Total
Number of cell
s 20 9 4 2 1 36
Each stage of the cell cycle takes a different amount of time. Which stage is the fastest in the cell cycle? Give a reason for your answer.
Stage ..........................................
Reason ...............................................................................................................
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(d) The cell cycle in an onion root tip cell takes 16 hours.Calculate the length of time Stage 2 lasts in a typical cell. Give your answer to 2 significant figures.
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Time in Stage 2 = .................................................. minutes (3)
(e) Bacteria such as Escherichia coli undergo cell division similar to mitosis.
Figure 2 shows a growth curve for E. coli grown in a nutrient broth.
Figure 2
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What type of cell division causes the change in number of E. coli cells at P?
............................................................................................................................. (1)
(f) Suggest why the number of cells levels out at Q.
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(Total 11 marks)
Q13.Diagram 1 shows a cell from the pancreas.
Diagram 2 shows part of the cell seen under an electron microscope.
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Part A is where most of the reactions of aerobic respiration happen.
(a) (i) Name part A.
........................................ (1)
(ii) Complete the equation for aerobic respiration.
glucose + oxygen ......................... + ......................... (+ energy) (2)
(iii) Part A uses oxygen.
Explain how oxygen passes from the blood to part A.
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(b) The pancreas cell makes enzymes.
Enzymes are proteins.
Describe how the ribosomes and part A help the cell to make enzymes.
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(Total 9 marks)
Q14.(a) Mr and Mrs Smith both have a history of cystic fibrosis in their families. Neither of them has cystic fibrosis. Mr and Mrs Smith are concerned that they may have a child with cystic fibrosis.
Use a genetic diagram to show how they could have a child with cystic fibrosis. Use the symbol A for the dominant allele and the symbol a for the recessive allele.
(3)
(b) Mr and Mrs Smith decided to visit a genetic counsellor who discussed embryo screening.
Read the information which they received from the genetic counsellor.
• Five eggs will be removed from Mrs Smith's ovary while she is under an anaesthetic.
• The eggs will be fertilised in a dish using Mr Smith’s sperm cells. • The embryos will be grown in the dish until each embryo has about thirty cells. • One cell will be removed from each embryo and tested for cystic fibrosis. • A suitable embryo will be placed into Mrs Smith’s uterus and she may become
pregnant. • Any unsuitable embryos will be destroyed.
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(i) Suggest why it is helpful to take five eggs from the ovary and not just one egg.
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(ii) Evaluate the use of embryo screening in this case. Remember to give a conclusion to your evaluation.
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(c) In someone who has cystic fibrosis the person’s mucus becomes thick. The diagram shows how, in a healthy person, cells at the lung surface move chloride ions into the mucus surrounding the air passages.
The movement of chloride ions causes water to pass out of the cells into the mucus.
Explain why.
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(Total 11 marks)
Q15.Explain how the human circulatory system is adapted to:
• supply oxygen to the tissues
• remove waste products from tissues.
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Some books you may enjoy: Emily Anthes: Frankenstein's Cat
Bill Bryson: A Short History of Nearly Everything
Ness Carey: Junk DNA
Charles Darwin: The origin of species
