Question 1:-
Lactobacillus is a type of bacterium used to make yoghurt.
The diagram shows a single Lactobacillus bacterium.
(a) (i) What is the function of ribosomes?
A photosynthesis
B protein synthesis
C respiration
D storage of cell sap
(ii) Which row of the table gives the components that are found in all bacteria and in all eukaryotic cells?
(iii) Lactobacillus cells do not burst when placed in distilled water.
Red blood cells burst when placed in distilled water.
Explain why the Lactobacillus cells do not burst but the red blood cells do burst.
(b) Describe how Lactobacillus bacteria produce yoghurt from milk.
▶️Answer/Explanation
Ans : 1(a)(i) The only correct answer is B (protein synthesis)
A is incorrect as chloroplasts perform photosynthesis
C is incorrect as mitochondria perform respiration
D is incorrect as vacuoles store cell sap
1(a)(ii) The only correct answer is B
A is incorrect as animal cells do not have cell walls
C is incorrect as eukaryotic cells have cytoplasm
D is incorrect as animal cells do not have cell walls
1(a)(iii) An explanation that makes reference to three of the following.
• Lactobacillus / they, have cell walls / red blood cells do not have a cell wall / eq (1)
• water enters (cells) / eq (1)
• by osmosis (1)
• (because) water potential inside the cells is low(er) / eq (1)
Ignore refs to water not entering Lactobacillus
Allow from a high concentration (of water) to a low concentration (of water) / from a dilute to a concentrated solution / eq
1(b) A description that makes reference to three of the following.
• respiration / fermentation / ferment (1)
• lactose (1)
• lactic acid / lactate, produced (1)
• (protein) clots / milk thickens / milk coagulates / goes solid / eq (1)
Ignore aerobic / anaerobic
Allow milk becomes acid(ic) / low pH occurs
Allow protein denatures
Question 2:-
The photograph shows some seeds called lentils.
Lentils are a good source of protein and are often eaten as part of a balanced diet.
(a) Describe how lentils are transported from the mouth to the stomach after being eaten.
(b) The recommended daily amount (RDA) of a nutrient is the mass of that nutrient required by an individual each day.
The table shows some nutrients found in lentils.
It also shows the percentage of each RDA for 16-year-old humans provided by 50g of lentils.
(i) Give one component of a balanced diet that is not shown in the table.
(ii) Lentils do not contain large amounts of vitamin C and calcium.
State the long-term effect of a dietary shortage of vitamin C and of calcium.
vitamin C
calcium
(iii) Calculate the mass, in grams, of lentils that a 16-year-old needs to eat, each day, to provide their RDA of protein.
Give your answer to two significant figures.
mass of lentils needed each day = …………………………………………………….. g
(iv) Describe how protein is digested in the human alimentary canal.
▶️Answer/Explanation
Ans : 2 (a) A description that makes reference to two of the following.
• peristalsis (1)
• muscle contraction (1)
• along oesophagus (1)
2 (b)(i) An answer that makes reference to one of the following.
• fibre (1)
• water (1)
• other named vitamin / mineral (1)
e.g. vitamin A / iron Ignore vitamin C and calcium
2(b)(ii) An answer that makes reference to the following.
• (vitamin C) scurvy / skin does not heal / blood vessels are weak / cartilage is weak / wounds do not heal / eq (1)
• (calcium) rickets / weak bones / osteoporosis / eq (1)
Allow vitamin C needed for healthy skin / cartilage / connective tissue / eq
Allow calcium needed for strong teeth / bones / eq
2(b)(iii)• RDA = 230 (g)(2)
One mark for 227.2727 OR 227 OR 2.3 OR other answer to correct decimal places with correct rounding
2(b)(iv) A description that makes reference to three of the following.
• protease / peptidase (1)
• pepsin (in stomach) (1)
• (digestion) in small intestine / duodenum / stomach / (protease) released by pancreas / stomach (1)
• (produces) amino acids / (di)peptides (1)
Allow trypsin (in duodenum / from pancreas)
Ignore absorbed in small intestine
Question 3:-
The diagram shows a forest food web.
(a) (i) How many secondary consumers are there in this food web?
A 1
B 2
C 3
D 4
(ii) Which term describes all the organisms in the food web together with their environment?
A community
B ecosystem
C habitat
D population
(iii) The fox receives 1% of the energy present in the oak tree.
The fox receives 0.04% of the energy present in the grass.
Explain why a higher proportion of the energy reaches the fox from the oak tree than reaches the fox from the grass.
(b) A student uses this method to estimate the total area of the woodland floor that is covered by grass.
• randomly place a 0.25m2 quadrat in one location of the woodland
• estimate the percentage of the quadrat that is covered by grass
• repeat at one other location
• calculate the mean percentage covered by grass for both quadrats
• measure the total area of the woodland floor
• calculate the total area of the woodland covered by grass.
(i) State why the student placed the quadrats randomly at each location.
(ii) Explain how the student could improve their method, to obtain a more reliable estimate of the total area of woodland covered by grass.
(iii) The diagram shows the dimensions of the woodland.
The student finds the mean percentage of the two quadrats covered by grass is 65%.
Use this value to calculate the total area of the woodland floor covered by grass.
total area covered by grass = ……………………………………………………..m2
▶️Answer/Explanation
Ans : 3(a)(i) The only correct answer is C (3)
A is incorrect as there are more than 1 secondary consumers
B is incorrect as there are more than 2 secondary consumers
D is incorrect as there are fewer than 4 secondary consumers
3 (a)(ii) The only correct answer is B (ecosystem)
A is incorrect as the community does not include the environment
C is incorrect as the habitat does not include the organisms
D is incorrect as population is the number of one species
3 (a)(iii) An explanation that makes reference to three of the following.
• shorter food chain to oak tree / one species between fox and oak tree / eq (1)
AND two from (energy lost from)
• excretion / urine / eq (1)
• inedible parts / parts not eaten / eq (1)
• indigestible parts / faeces / egestion / eq (1)
• death / decomposition / decay / some organisms not eaten / eq (1)
• respiration / heat loss / eq (1)
• movement /eq (1)
Allow converse for grass Allow fox is a secondary consumer from oak tree / tertiary consumer from grass / eq
Allow fewer / 3, levels in oak tree food chain / eq Allow only rabbit / squirrel between tree and fox / eq
Do not award two marks for excrete faeces
3 (b)(i) An answer that makes reference to the following.
• avoid bias / make sample representative / more accurate (result) / makes (survey) fair / eq (1)
Allow fair test / valid
Ignore reliable
3(b)(ii) An explanation that makes reference to two of the following.
• grid area / eq (1)
• repeats / more quadrats / eq (1)
• identify anomalies / calculate mean / average / to see if they are similar / eq (1)
Ignore larger quadra
3 (b)(iii) • 2925 (3)
Correct answer gains all three marks
two marks for 4500
If answer incorrect then up to max 2 of:
one mark for 4000 or 50 x 80
one mark for 500 or (20 x 50) / 2
one mark for 0.65 x OR 65/100 x
Question 4:-
Yeast is a fungus that can respire anaerobically.
(a) (i) What substance is the cell wall of a yeast cell made of?
A cellulose
B chitin
C glycogen
D starch
(ii) Which row of the table shows the substances produced by yeast during anaerobic respiration?
(b) A student uses this apparatus to investigate the effect of temperature on anaerobic respiration by yeast.
This is the student’s method.
• place yeast cells and glucose solution into a test tube
• keep the test tube at a temperature of 25°C
• cover the yeast and glucose solution with paraffin oil
• count the number of bubbles produced each minute for 20 minutes
• repeat at a temperature of 37°C
The student draws a graph to show the total number of bubbles that have been produced by the end of each minute for the 20-minute period.
The graph shows the student’s results.
(i) State the function of the paraffin oil.
(ii) Describe a method the student could use to keep the temperature of the yeast and glucose mixture constant.
(iii) Calculate the rate of bubble production from 0 minutes to 8 minutes when the yeast is at 37°C.
rate of bubble production = …………………………………………………….. bubbles per minute
(iv) Explain the change in the total number of bubbles produced from 0 minutesto 20 minutes at 25°C.
(v) Explain the difference in the rate of bubble production between 0 and 10 minutes at 37°C compared with 25°C.
(vi) Describe how the student could modify the experiment to give more accurate results.
▶️Answer/Explanation
Ans : 4 (a)(i) The only correct answer is B (chitin)
A is incorrect as fungal cell walls do not contain cellulose
C is incorrect as fungal cell walls do not contain glycogen
D is incorrect as fungal cell walls do not contain starch
4 (a)(ii) The only correct answer is A (ethanol and carbon dioxide)
B is incorrect as yeast anaerobic respiration also produces carbon dioxide
C is incorrect as yeast anaerobic respiration does not produce lactic acid
D is incorrect as yeast anaerobic respiration does not produce lactic acid
4 (b)(i) An answer that makes reference to the following.
• stops oxygen getting in / prevents aerobic respiration / eq (1)
Ignore ensures anaerobic respiration
4 (b)(ii) A description that makes reference to the following.
• water bath (1)
• (monitor with) thermometer / (use of) thermostat / eq (1)
4 (b)(iii) • 4 (2)
one mark for 32 OR ÷ 8
Correct answer gains both marks
4 (b)(iv) An explanation that makes reference to two of the following.
• increases up to 16 (min) / 17 (min) / 18 (min) and then levels off / slows / (bubble production) stops / eq
• (when bubbles increase / initially) glucose is not limiting / eq (1)
• (levels off because) glucose runs out / is limiting / yeast is poisoned by ethanol / eq (1)
Allow times between 16 and 18 for turning point
Allow constant rate (or respiration) until 16 /18 then (respiration) stops / levels off / slows
Allow glucose is not limiting when bubbles are increasing
Allow substrate for glucose throughout
4 (b)(v) An explanation that makes reference to three of the following.
• faster / more, respiration (1)
• (at 37 ºC) more (kinetic) energy / faster (particle) movement /eq (1)
• more / faster, collisions / more E/S complexes / eq (1)
• at 37ºC glucose runs out (sooner) / glucose starts to limit / eq (1)
Allow 37ºC / it, is (closer to) optimum
4 (b)(vi) A description that makes reference to the following.
• collect volume (of gas) (1)
• using a measuring cylinder / syringe / burette / eq (1)
Question 5:-
The diagram shows the structure of a human heart, with two chambers labelled W and Z and two blood vessels labelled X and Y.
(a) (i) Which row of the table correctly identifies chambers W and Z?
(ii) Give two differences between the composition of the blood in X and Y.
(b) A scientist investigates the effect of exercise on the heart rate of two people.
One person is a trained athlete and the other is an untrained volunteer.
The heart rates of both individuals are measured at rest (0 minutes). Both individuals then exercise for six minutes and then rest for another six minutes.
The table shows the heart rates of the untrained volunteer and the trained athlete at rest, during and after exercise.
(i) The cardiac output is the volume of blood pumped out by the left ventricle in one minute.
The stroke volume is the volume of blood pumped out by the left ventricle in one beat.
The cardiac output of a resting human is 4900cm3 per minute.
Calculate the stroke volume of the trained athlete when at rest when their cardiac output is 4900cm3 per minute.
Use this formula.
cardiac output = stroke volume × heart rate
stroke volume = ……………………………………………………..cm3
(ii) Plot a graph to show the heart rate of the untrained volunteer and the trained athlete when resting and during exercise from 0 minutes (when at rest) to 12 minutes.
Use a ruler to join the points with straight lines.
(iii) Explain why the trained athlete can run faster than the untrained volunteer.
Use the information in the table to support your answer.
▶️Answer/Explanation
Ans : 5 (a)(i) The only correct answer is C
A is incorrect as W is not the left atrium
B is incorrect as W is not a ventricle
D is incorrect as W is not a ventricle
5 (a)(ii) A description that makes reference to the following.
• X / pulmonary artery, has lower oxygen / is deoxygenated / eq (1)
• X / pulmonary artery has higher carbon dioxide / eq (1)
Allow Y / aorta, has higher oxygen / is oxygenated
Allow Y / aorta, has lower carbon dioxide
5(b)(i) • 89 (2)
Allow any number of correct decimal places e.g. 89.0909, 89.1 Allow 90
One mark for 55 OR One mark for 75, 75.4, 75.38 etc.
Correct answer gains both marks
5 (b)(ii) An answer that makes reference to the following.
S – linear scales for both axes and at least half grid (1)
L – ruled, straight lines (1)
A – both axes fully labelled (1)
P – correct plots (1)
K – key / eq (1)
time must be on x axis
Minimum label: heart rate /bpm and time / min
Allow plots if non-linear scales Plots +/- half square
Bar chart: S, A, P, K (max 4) One data set plotted: S, L, A
5 (b)(iii) An explanation that makes reference to four of the following.
• (trained athlete) has lower heart rate / heart rate returns to normal quicker / eq (1)
• (trained athlete) has larger heart / larger stroke volume / pumps more blood / eq (1)
• more / faster transport of, oxygen / glucose pumped / more removal of carbon dioxide / heat / eq (1)
• (more) (aerobic) respiration / ATP production / energy / eq (1)
• (more) muscle contraction (1)
• less anaerobic respiration / lactic acid / less oxygen debt / eq (1)
Allow converse for untrained
Allow stronger heart
Allow untrained has to pump faster to move same amount of blood / eq
Allow untrained has to pump faster to move same amount of oxygen / eq
Question 6:-
Variegated leaves have areas that are green and areas that are white.
A student uses this method to investigate the effect of light on photosynthesis in a variegated leaf.
• place a plant in the dark for 24 hours
• wrap a strip of black paper across a leaf
• shine light on the plant for 24 hours
• remove the black paper
• use iodine solution to test the leaf for starch
The diagram shows the apparatus the student uses.
(a) Complete the balanced chemical symbol equation for photosynthesis.
………………………….. + 6H2O → ………………………….. + …………………………..
(b) (i) State why the plant was placed in the dark for 24 hours.
(ii) Diagram 1 shows the position of the black paper on the leaf.
Complete diagram 2 to show where the variegated leaf would appear black after testing with iodine solution.
(c) The student observes that the leaves on different ivy plants seem to be different sizes depending on the amount of sunlight the plants receive.
Design an investigation to test whether the amount of sunlight received by ivy plants affects the size of their leaves.
Include experimental details in your answer and write in full sentences.
▶️Answer/Explanation
Ans : 6 (a) An answer that makes reference to the following.
6CO2 + 6H2O → C6H12O6 + 6O2 (2) one mark if correct equation but incorrectly balanced
6(b)(i) An answer that makes reference to the following.
• destarch the leaves / remove starch eq (1)
Allow so no starch present (in leaves) / so starch is used up / starch respired
6(b)(ii) An answer that makes reference to the following.
• both green areas shaded and area with no green with no shading / eq (1)
• no shading in strip under paper / eq (1)
Allow labelled areas if not shaded (black / orange / starch / no starch)
No mp2 if rest of leaf is blank
6 (c) An answer that makes reference to six of the following.
• C – (plant ivy in) shaded and unshaded area / different exposure to light / eq (1)
• O – same species / type / age / starting size of leaf / same plant / eq (1)
• R – repeat with multiple leaves / repeat / eq (1)
• M1 – measure length / width / height / surface area / eq (of leaves) (1)
• M2 – grow ivy for same stated time (1)
• S1 – temperature / pests / humidity / plant density / carbon dioxide / weather / time of year / wind / eq (1)
• S2 – same water / minerals / soil / nutrients / fertiliser / pH / eq (1)
Allow different light intensities / distances of lamp
Allow groups
Ignore size of leaves
Allow measure size with a ruler / in mm / eq
Allow volume Minimum time of one day
Question 7:-
The diagram shows the human female reproductive system.
(a) (i) Where does fertilisation normally occur?
A
B
C
D
(ii) State how oestrogen and progesterone affect structure C during the menstrual cycle.
oestrogen
progesterone
(b) In vitro fertilisation (IVF) is used to help some people have children.
Eggs are mixed with sperm in a laboratory.
Embryos are then transferred into a uterus.
(i) Describe how an embryo forms after the eggs and sperm have been mixed together.
(ii) If more than one embryo is transferred to a uterus, IVF can result in multiple births, such as twins or triplets. Pregnancies that produce more than one baby can be a health risk.
In the United Kingdom, since 2007, the recommendations for the number of embryos transferred are
• a person under 40 should have only one embryo placed into their uterus
• a person over 40 may have two embryos placed into their uterus
The graph shows the percentage of IVF treatments that led to multiple births from 1993 to 2019.
The table shows the success rates for IVF in the United Kingdom in 2019 for people of different age groups.
Discuss the effects of limiting the number of embryos transferred.
Use the information in the table and the graph to support your answer.
▶️Answer/Explanation
Ans : 7 (a) (i) The only correct answer is A
B is incorrect as fertilisation does not occur in the ovary
C is incorrect as fertilisation does not occur in the uterus
D is incorrect as fertilisation does not occur in the vagina
7(a)(ii) A description that makes reference to the following.
• (oestrogen) repairs / thickens lining / thickens wall / eq (1)
• (progesterone) retains / maintains lining / vascularises endometrium / prevents menstruation / eq (1)
Allow builds up lining
Allow fall in progesterone causes lining to shed / causes menstruation
Allow increase blood flow in lining
7(b)(i) A description that makes reference to the following.
• fusion of nuclei / fusion of egg and sperm / zygote (forms) / eq (1)
• mitosis / cell division / (to form an embryo) / eq (1)
Reject meiosis
7 (b) (ii) An answer that makes reference to five of the following.
• number of (multiple births) has decreased / eq (1)
• constant / steady /eq, decrease, (in multiple births) until 2007 / 2008 / 2009 / before recommendations / eq (1)
• (steep) decrease / since 2007 / 2008 / 2009 / since recommendations / eq (1)
• (so) less risk to health / multiple births increase health risks / eq (1)
• (repeated IVF) is expensive / stressful / eq (1)
• IVF success rate / fertility decreases with age / eq (1)
• (older women have lower success rate) so better to use more than one embryo / eq (1)
• no information on sample sizes / only one country / only UK data / eq (1)
• reliable as data is for a long period of time / eq (1)
• (could be affected by) other health issues / diet / genetics / sperm / eq (1)
Allow age references for any ages of >=37 for older women
MP3 also gets MP1
Allow recommendations have made it safer / multiple births are dangerous
Allow older women have low(er) success rate / young(er) women have high success rate
Allow restricting number of embryos for younger women has less effect on success / eq
Allow cannot be generalised / needs to be researched in other countries / eq
Allow no information about health issues / eq
Question 8:-
The diagram shows the carbon cycle.
(a) (i) Which letter in the diagram represents respiration?
A T
B X
C Y
D Z
(ii) Give the name of the process labelled W.
(b) Carbon dioxide, methane, and nitrous oxide are three greenhouse gases.
The table shows a comparison of these greenhouse gases.
The Global Warming Potential (GWP) is the ratio of the heat absorbed by a greenhouse gas in the atmosphere relative to the heat absorbed by the same mass of carbon dioxide gas.
(i) Name one other greenhouse gas.
(ii) Evaluate the information in the table to identify which of these gases is likely to contribute most to global warming.
▶️Answer/Explanation
Ans : 8(a)(i) The only correct answer is C (Y)
A is incorrect as T is combustion
B is incorrect as X is consumption
D is incorrect as Z is death
8 (a)(ii) • photosynthesis (1)
8 (b) (i) • CFCs / water (vapour) / eq (1)
Allow fluorinated gases e.g. hydrofluorocarbons (HFC), perfluorocarbons (PFC), sulphur hexafluoride
8 (b)(ii) An answer that makes reference to five of the following.
• carbon dioxide (poses the greatest risk) (1)
• carbon dioxide is released in high(est) amounts / eq (1)
• carbon dioxide is produced by many human activities / fossil fuel use / eq (1)
• carbon dioxide stays for long(est) time / eq (1)
• carbon dioxide has low(est) global warming potential / GWP / eq (1)
• methane has a high(er) GWP than carbon dioxide / has middle GWP BUT low(er) amount / second highest amount, released / more released than nitrous oxide / eq (1)
• methane has a high(er) GWP than carbon dioxide / has middle GWP BUT methane does not last long / stays least time / eq (1)
• nitrous oxide has high(est) GWP BUT has low(est) percentage released / eq (1)
• nitrous oxide has high(est) GWP BUT stays less time than carbon dioxide / stays for a medium amount of time / eq (1)
Allow traps / absorbs heat for GWP
If just quoting numbers, they need to be qualified e.g. ONLY 1 (GWP)
Allow cement / vehicles / deforestation / eq
Allow highest GWP BUT stays longer than methane
Question 9:-
Scientists have developed transgenic crop plants that are resistant to herbicides (weedkillers).
(a) (i) State what is meant by the term transgenic
(ii) Suggest why growing herbicide-resistant crop plants is beneficial to farmers.
(b) The photograph shows a weed called Palmer amaranth that is often found in fields growing soybeans.
Palmer amaranth is a weed that has become resistant to many different herbicides.
In some populations of Palmer amaranth plants, a recessive allele (r) makes the plants resistant to herbicide. A dominant allele (R) makes the plants not resistant to herbicide
(i) Give the possible genotypes of Palmer amaranth plants that are not resistant to herbicides.
(ii) A Palmer amaranth plant that is resistant to herbicides is crossed with a Palmer amaranth plant that is heterozygous for herbicide resistance.
Draw a genetic diagram to show the genotypes of the parents, the gametes they produce, and the genotypes and the phenotypes of the offspring.
(iii) Give the probability of the cross in (b)(ii) producing a plant that is resistant to herbicide.
(iv) Explain how Palmer amaranth plants have evolved to become resistant to herbicides in areas where herbicides are used frequently.
(v) In plants such as Palmer amaranth, where the allele for herbicide resistance is recessive, no non-resistant weeds occur after five years of using herbicides.
In other plants, where the allele for herbicide-resistance is dominant, some non-resistant weeds occur after five years of using herbicides.
Explain this difference in the number of non-resistant weeds after five years of using herbicides.
▶️Answer/Explanation
Ans : 9(a)(i) An answer that makes reference to the following.
• (transfer of) genes / alleles / DNA between different species (1)
Allow (organism) with gene / allele / DNA from different species
Ignore genetic modification alone
Ignore organism
9 (a)(ii) An answer that makes reference to two of the following.
• (herbicides) kills / removes, weeds but not crops / eq (1)
• less competition / eq (1)
• so increased yield / more (crop) growth / eq (1)
• no need to remove weeds by hand / eq (1)
Allow (herbicide) only affects / kills, weeds / unwanted plants
9 (b) (i) • RR, Rr, (rR) (1)
Reject if rr included
Allow other letters but not two different letters
Allow ‘homozygous dominant and heterozygous’
9 (b)(ii) An answer that makes reference to the following.
• parents as Rr and rr (1)
• gametes as R or r and r (or r) (1)
• genotypes and stated phenotypes of Rr and rr AND non-resistant and resistant (1)
Allow other letters but not two different letters
ECF for one mark only for gametes
Allow all marks from Punnett square
9 (b)(iii) • 0.5 / 1⁄2 / 50 % (1)
Allow 2/4
9 (b)(iv) An explanation that makes reference to four of the following.
• mutation (produces resistance) / eq (1)
• (produces) variation (1)
• (weeds with gene) survive / eq (1)
• reproduce / pollinate / eq (1)
• pass on the allele / gene / mutation / eq (1)
Allow converse Allow correct ref to selection pressure / selective advantage
Allow pass on allele to next generation for mp4 and mp5
9 (b)(v) An explanation that makes reference to two of the following.
• dominant alleles always expressed / expressed in heterozygotes OR recessive alleles only expressed when homozygous / not expressed in heterozygotes / eq (1)
• if resistance is recessive, only homozygous (recessive) plants survive / no heterozygous plants survive / eq (1)
• if resistance is dominant, heterozygous plants survive / eq (1)
• (when resistance is dominant) if two heterozygotes breed, non-resistant weeds produced / some homozygous recessive plants produced / eq (1)
Allow recessive alleles are not always shown (in phenotype)
Allow no plants with dominant alleles survive
Allow some plants carrying recessive alleles will survive / carriers survive
Allow carriers for heterozygotes Allow both parents can pass on a recessive allele
Question 10:-
The diagram shows the structure of a human eye.
(a) (i) Give the name of structure Z.
(ii) Describe how structures X and Y control the shape of a lens when focusing on a near object.
(b) A cataract occurs when the lens becomes cloudy.
Severe cataracts are the main cause of blindness around the world.
(i) Explain why people with cataracts are unable to see clearly
(ii) Exposure to ultraviolet light is thought to be a risk factor for the development of cataracts.
The table shows the results of a 25-year investigation into the effect of different mean hours of sunlight on agricultural workers in one south Asian country.
Comment on the results of the investigation.
▶️Answer/Explanation
Ans : 10 (a)(i) • iris (1)
10 (a)(ii) A description that makes reference to three of the following.
• X / ciliary muscle, contracts (1)
• Y / suspensory ligaments go slack / loosen / eq (1)
• lens becomes thicker / more spherical / more convex / eq (1)
• so (lens) refracts light more / bends light more / eq (1)
Ignore relax Ignore suspensory muscle
Allow fatter / more rounded / bulges
10 (b)(i) A description that makes reference to two of the following.
• less light can pass through / refraction affected / eq (1)
• to retina / fovea / rods cones / photoreceptors (1)
• so fewer impulses (to brain) (1)
Allow cannot focus well / bend light
Allow stops light getting into eye
10 (b)(ii) An answer that makes reference to four of the following.
• numbers increase as exposure to sunlight increases / eq (1)
• groups sizes are different / eq (1)
• credit calculation of proportions / percentages (1)
• the proportion / percentage of cases fluctuates / does not change (much) between 7 and 10 (hrs) / eq (1)
• proportion / percentage, rises after 10 (hrs) / 11 (hrs) / 12 (hrs) (1)
• the large number of people makes it reliable OR (less reliable as) only one country / no information on location / climate / eq (1)
• age / sex / health status / genetics / diet / clothing / sunglasses / could affect the results / eq (1)
Allow more sunlight increases chance of cataracts
Allow percentage of cases increases
Allow number of people vary / increase
Allow no / little effect between 7 – 10 (hrs) / 10 (hrs) is lower than 7 / 8 / 9 (hrs)
Allow (proportion of) cases only increases after 10 / 11 (hrs)
Allow reliable / valid as it is a long survey / lasts 25 years
Allow other countries / regions should be investigated
Allow other correct, relevant factors