References only, not question text. Open Official paper ↗ where Cambridge publishes the paper,
or see the official Cambridge past-papers page; for other papers, ask your
school. “Paper 42” means Paper 4, variant 2.
Practice questions
Original questions written by HomiLabs in the style of the exam, with answers and mark schemes. They are not
Cambridge past paper questions and have not been reviewed by Cambridge. Try each one before opening the answer.
Q1Cell structure & organelles · Core · Paper 2 style · 1 mark
(a)Which structure is found in both plant cells and animal cells but NOT in bacterial cells?[1]
Show answer
(a) C mitochondrion
Bacteria have a cell membrane, a cell wall and ribosomes, but no mitochondria. Plant and animal cells both have mitochondria. Cell wall is wrong because animal cells lack one.
Q2Cell structure & organelles · Core · Paper 4 style · 4 marks
(a)Name the cell structure that matches each description.(i) the site of aerobic respiration(ii) the site of protein synthesis(iii) controls the movement of substances into and out of the cell(iv) contains the chromosomes[4]
Show answer
(a) (i) mitochondrion (ii) ribosome (iii) cell membrane (iv) nucleus
B1 each. Do not accept cell wall for (iii).
Q3Cell structure & organelles · Core · Paper 4 style · 3 marks
(a)Complete the sentences about plant cells using suitable words.The cell wall is made of ______ and stops the cell bursting. The large permanent vacuole contains ______. Chloroplasts absorb ______ energy for photosynthesis.[3]
Show answer
(a) cellulose; cell sap; light
B1 each.
Q4Cell structure & organelles · Standard · Paper 2 style · 1 mark
(a)Which features are present in a bacterial cell?1 cell wall2 plasmids3 nucleus4 ribosomes[1]
Show answer
(a) A 1, 2 and 4
Bacteria have a cell wall, plasmids, ribosomes and circular DNA that is not enclosed in a nucleus. Any option including 3 is wrong; 1 and 4 only omits plasmids.
Q5Cell structure & organelles · Standard · Paper 4 style · 5 marks
(a)State three structural differences between a palisade mesophyll cell and a liver cell.[3]
(b)Liver cells contain many mitochondria. Explain why.[2]
Show answer
(a) palisade cell has a cellulose cell wall, chloroplasts and a large permanent vacuole; liver cell has none of these
1 mark each for any three: cell wall (cellulose) present / absent; chloroplasts present / absent; large permanent vacuole (with cell sap) present / absent or only small vacuoles; regular shape / irregular shape.
(b) liver cells have a high rate of metabolism, so they need a lot of energy released by aerobic respiration in mitochondria
B1 mitochondria are the site of aerobic respiration; B1 high metabolic rate / many energy-requiring reactions (e.g. protein synthesis, active transport) so much energy must be released. Do not credit 'produce energy'.
Q6Cell structure & organelles · Standard · Paper 4 style · 5 marks
(a)State two structures that are found in both a bacterial cell and a plant cell.[2]
(b)Name one structure found in a bacterial cell that is not found in a plant cell.[1]
(c)Describe how the main genetic material of a bacterial cell differs from that of a plant cell.[2]
Show answer
(a) any two of: cell wall, cell membrane, cytoplasm, ribosomes
1 mark each for any two. (Not nucleus, not chloroplast, not mitochondrion.)
(b) plasmid
B1.
(c) bacterial DNA is a single circular chromosome / loop free in the cytoplasm, not enclosed in a nucleus
B1 circular DNA; B1 not in a nucleus / no nuclear membrane.
Q7Cell structure & organelles · Standard · Paper 5 style · 6 marks
(a)A student peels a thin layer of epidermis from the inside of an onion bulb, places it on a slide in a drop of iodine solution and adds a coverslip. State why iodine solution is added.[1]
(b)Name two structures the student would see in the onion cells with a light microscope.[2]
(c)The student notices that the onion cells have no chloroplasts. Explain why.[2]
(d)State why the coverslip should be lowered slowly at an angle.[1]
Show answer
(a) to stain the cells / make the nucleus and cell outline visible
B1.
(b) any two of: cell wall, nucleus, cytoplasm, vacuole
1 mark each.
(c) the bulb grows underground / receives no light, so the cells do not photosynthesise and do not need chloroplasts
B1 no light reaches these cells; B1 chloroplasts are for photosynthesis, which they do not carry out.
(d) to avoid trapping air bubbles
B1.
Q8Cell structure & organelles · Challenge · Paper 4 style · 5 marks
(a)Cells in the pancreas make and secrete large quantities of digestive enzymes. Electron micrographs of these cells show very many ribosomes and many mitochondria.Explain how each of these features helps the cells to carry out their function.[5]
Show answer
(a) enzymes are proteins; ribosomes are the site of protein synthesis, so many ribosomes allow enzymes to be made quickly in large amounts; mitochondria are the site of aerobic respiration, releasing the energy needed for protein synthesis and for secreting the enzymes
1 mark each for any five: enzymes are proteins; ribosomes are the site of protein synthesis; many ribosomes = enzymes made quickly / in large quantities; mitochondria are the site of aerobic respiration; respiration releases energy; energy needed to join amino acids / for protein synthesis; energy needed for secretion of the enzymes out of the cell. Do not credit 'mitochondria produce energy'.
Q9Cell structure & organelles · Challenge · Paper 4 style · 6 marks
(a)The table shows the mean number of mitochondria in four types of human cell.cell type | mean number of mitochondria per cellheart muscle cell | 5000liver cell | 2000skin cell (outer layer) | 300mature red blood cell | 0Calculate how many times more mitochondria a heart muscle cell has than a skin cell. Give your answer to two significant figures.[2]
(b)Explain the difference in the number of mitochondria between heart muscle cells and skin cells.[3]
(c)Suggest why a mature red blood cell can still release some energy even though it has no mitochondria.[1]
Show answer
(a) 17 times
M1 5000 ÷ 300; A1 17 (2 s.f.).
(b) heart muscle contracts continuously, needs much energy from aerobic respiration in mitochondria; skin cells are less active and need less energy
B1 mitochondria are where aerobic respiration releases energy; B1 heart muscle contracts continuously / never rests; B1 so heart cells need much more energy than skin cells (skin cells have low metabolic activity).
(c) it respires anaerobically (in the cytoplasm)
B1.
Q10Magnification & size (units) · Core · Paper 2 style · 1 mark
(a)[1]
Show answer
(a) B ×500
Magnification = image size ÷ actual size = 20 ÷ 0.04 = 500 (both in mm). ×50 comes from misplacing the decimal point.
Q11Magnification & size (units) · Core · Paper 6 style · 3 marks
(a)A student draws a mango leaf from a photograph. On the drawing, the length of the leaf blade (line PQ, from leaf tip to the base of the blade) is 96 mm. The actual length of the leaf blade is 38 mm.Calculate the magnification of the drawing. Give your answer to two significant figures. Show your working.[3]
Show answer
(a) ×2.5
M1 magnification = length of drawing ÷ actual length; M1 96 ÷ 38 (= 2.526…); A1 ×2.5 (2 s.f., no units).
Q12Magnification & size (units) · Core · Paper 4 style · 3 marks
(a)Write down the equation that links magnification, image size and actual size.[1]
(b)Convert 0.25 mm into micrometres (µm).[1]
(c)Convert 1800 µm into millimetres.[1]
Show answer
(a) magnification = image size ÷ actual size
B1 (any correct rearrangement accepted).
(b) 250 µm
B1 0.25 × 1000 = 250 µm.
(c) 1.8 mm
B1 1800 ÷ 1000 = 1.8 mm.
Q13Magnification & size (units) · Core · Paper 6 style · 2 marks
(a)A photograph of a whole water-lily leaf has a line drawn across its widest part. On the photograph the line is 82 mm long. The actual width of the leaf is 164 mm.Calculate the magnification of the photograph.[2]
Show answer
(a) ×0.5
M1 82 ÷ 164; A1 ×0.5 (accept ×0.50).
Q14Magnification & size (units) · Standard · Paper 2 style · 1 mark
(a)In an electron micrograph a chloroplast is 30 mm long. The magnification is ×6000. What is the actual length of the chloroplast?[1]
Show answer
(a) B 5 µm
Convert the image to µm: 30 mm = 30 000 µm. Actual = 30 000 ÷ 6000 = 5 µm. 0.5 µm comes from using 3000 µm per 30 mm.
Q15Magnification & size (units) · Standard · Paper 2 style · 1 mark
(a)[1]
Show answer
(a) B 0.0075 mm
1 mm = 1000 µm, so 7.5 µm = 7.5 ÷ 1000 = 0.0075 mm. 0.075 mm results from dividing by 100.
Q16Magnification & size (units) · Standard · Paper 6 style · 4 marks
(a)A photograph shows a transverse section of an okra (bhindi) pod at a magnification of ×1.7. The line XY drawn across the widest part of the image of the section is 68 mm long.Calculate the actual width of the okra pod in mm. Show your working.[3]
(b)State why line XY should be measured in millimetres rather than centimetres.[1]
Show answer
(a) 40 mm
M1 actual size = image size ÷ magnification; M1 68 ÷ 1.7; A1 40 mm.
(b) mm gives a more precise reading / fewer decimal places / ruler graduated in mm
B1 idea that measuring to the nearest mm is more precise (cm leads to rounding errors).
Q17Magnification & size (units) · Standard · Paper 4 style · 4 marks
(a)A photomicrograph of human cheek cells shows one cell with an image diameter of 45 mm. The actual diameter of the cell is 60 µm.Calculate the magnification of the photomicrograph. Show your working.[2]
(b)The nucleus of the same cell is 6 mm across in the photomicrograph. Calculate the actual diameter of the nucleus in µm.[2]
Show answer
(a) ×750
M1 convert 45 mm to 45 000 µm (or 60 µm to 0.06 mm) and divide; A1 ×750.
(b) 8 µm
M1 6000 µm ÷ 750 (ecf from (a)); A1 8 µm.
Q18Magnification & size (units) · Standard · Paper 6 style · 3 marks
(a)A student views a thin strip of onion epidermis under a microscope. The diameter of the circular field of view is 2.0 mm. Along one diameter, 8 cells fit end to end exactly.Calculate the mean length of one cell in µm.[2]
(b)Suggest one reason why this method gives only an estimate of cell length.[1]
Show answer
(a) 250 µm
M1 2.0 ÷ 8 = 0.25 mm; A1 × 1000 = 250 µm.
(b) cells are not all the same length / cells may not fit exactly / cells may not lie exactly along the diameter
B1 any one valid idea.
Q19Magnification & size (units) · Standard · Paper 6 style · 3 marks
(a)A drawing of a neem leaflet is 152 mm long. The actual leaflet is 190 mm long.Calculate the magnification of the drawing. Give your answer to two significant figures.[2]
(b)State what a magnification less than 1 tells you about the drawing.[1]
Show answer
(a) ×0.80
M1 152 ÷ 190; A1 ×0.80 (2 s.f.).
(b) the drawing is smaller than the real leaflet
B1.
Q20Magnification & size (units) · Standard · Paper 4 style · 3 marks
(a)The sizes of four structures are:mitochondrion 1.5 µmnucleus of a liver cell 0.008 mmbacterium 0.003 mmred blood cell 7 µmConvert all the sizes to µm.[2]
(b)List the four structures in order of size, starting with the smallest.[1]
B2 both conversions (0.008 mm = 8 µm, 0.003 mm = 3 µm) correct; B1 one correct.
(b) mitochondrion, bacterium, red blood cell, nucleus
B1 (ecf from (a)).
Q21Magnification & size (units) · Standard · Paper 6 style · 3 marks
(a)A student draws a pigeon feather. Line AB on the drawing, from the tip of the feather to the end of the shaft, is 118 mm. The drawing has a magnification of ×3.5.Calculate the actual length of the feather. Give your answer in mm to two significant figures.[3]
Show answer
(a) 34 mm
M1 actual = image ÷ magnification; M1 118 ÷ 3.5 (= 33.7…); A1 34 mm.
Q22Magnification & size (units) · Challenge · Paper 2 style · 1 mark
(a)On a photomicrograph of root tip cells, a scale bar 25 mm long is labelled 10 µm. What is the magnification of the photomicrograph?[1]
Show answer
(a) C ×2500
Scale bar image = 25 mm = 25 000 µm; actual = 10 µm. Magnification = 25 000 ÷ 10 = 2500. ×250 comes from converting 25 mm to 2500 µm.
Q23Magnification & size (units) · Challenge · Paper 6 style · 5 marks
(a)A photograph of a green chilli has a magnification of ×0.8. On the photograph the chilli is 56 mm long, measured from the tip to the point where the stalk joins.Calculate the actual length of the chilli in mm.[2]
(b)A student makes a large drawing of the chilli from the photograph. The same length on the drawing is 140 mm.Calculate the magnification of the student's drawing compared with the real chilli. Give your answer to two significant figures.[2]
(c)Explain why the answer to (b) is not 140 ÷ 56.[1]
Show answer
(a) 70 mm
M1 56 ÷ 0.8; A1 70 mm.
(b) ×2.0
M1 140 ÷ 70 (use of the actual length from (a), allow ecf); A1 ×2.0.
(c) 56 mm is the size of the photograph image, not the actual size; the photograph is itself magnified (×0.8)
B1 magnification must compare the drawing with the actual object, not with another image.
Q24Magnification & size (units) · Challenge · Paper 4 style · 4 marks
(a)A rod-shaped bacterium is 2.5 µm long. It is drawn in a textbook at a magnification of ×12 000. Calculate the length of the drawing in mm.[2]
(b)A yeast cell drawn at the same magnification is 96 mm long. How many times longer is the yeast cell than the bacterium?[2]
Show answer
(a) 30 mm
M1 image = actual × magnification = 2.5 × 12 000 = 30 000 µm; A1 30 mm (÷ 1000).
(b) 3.2 times
M1 96 ÷ 30 (or actual 8 µm ÷ 2.5 µm); A1 3.2.
Q25Magnification & size (units) · Challenge · Paper 4 style · 4 marks
(a)A pollen grain from a cotton flower has an image diameter of 36 mm in a micrograph taken at ×800. Calculate its actual diameter in µm.[2]
(b)A pollen grain from a second species has an actual diameter of 40 µm. Calculate the diameter of its image, in mm, if photographed at the same magnification.[2]
Show answer
(a) 45 µm
M1 36 000 µm ÷ 800; A1 45 µm.
(b) 32 mm
M1 40 × 800 = 32 000 µm; A1 32 mm.
Q26Magnification & size (units) · Challenge · Paper 6 style · 4 marks
(a)A student traces the outline of a lotus leaf on centimetre-square grid paper. Inside the outline there are 42 complete squares and 18 squares that are partly covered. The student counts each part-covered square as half a square.Estimate the area of the leaf in cm².[2]
(b)Convert your answer to (a) into mm².[1]
(c)Suggest how the estimate of leaf area could be made more accurate.[1]
Show answer
(a) 51 cm²
M1 42 + 18 ÷ 2; A1 51 cm².
(b) 5100 mm²
B1 1 cm² = 100 mm²; 51 × 100 = 5100 mm².
(c) use grid paper with smaller squares (e.g. mm squares)
B1.
Q27Specialised cells & levels of organisation · Core · Paper 2 style · 1 mark
(a)Which sequence shows the levels of organisation from the smallest to the largest?[1]
Show answer
(a) B cell → tissue → organ → organ system
Similar cells form a tissue; tissues form an organ; organs working together form an organ system. Option A swaps tissue and organ.
Q28Specialised cells & levels of organisation · Core · Paper 4 style · 3 marks
(a)Red blood cells have a biconcave disc shape. State how this helps the cell carry out its function.[1]
(b)State two other features of red blood cells that help them transport oxygen.[2]
Show answer
(a) large surface area (to volume ratio) for fast diffusion of oxygen
B1.
(b) contain haemoglobin; no nucleus (more room for haemoglobin); small and flexible to pass through capillaries
1 mark each for any two.
Q29Specialised cells & levels of organisation · Standard · Paper 4 style · 4 marks
(a)For each specialised cell, state one feature and explain how it helps the cell carry out its function.(i) root hair cell(ii) ciliated cell lining the trachea(iii) palisade mesophyll cell(iv) sperm cell[4]
Show answer
(a) (i) long extension – large surface area for water and ion uptake; (ii) cilia – beat to move mucus up and out of the airway; (iii) many chloroplasts – absorb light for photosynthesis; (iv) flagellum / tail – swims to the egg (or many mitochondria – energy for swimming; enzymes in acrosome – digest jelly coat)
1 mark each for feature linked to function.
Q30Specialised cells & levels of organisation · Challenge · Paper 4 style · 5 marks
(a)Classify each of these as a cell, a tissue, an organ or an organ system:xylem; leaf; digestive system; neurone; heart[3]
(b)Explain why the stomach is described as an organ.[2]
Show answer
(a) xylem – tissue; leaf – organ; digestive system – organ system; neurone – cell; heart – organ
All five correct 3 marks; four correct 2 marks; two or three correct 1 mark.
(b) it is made of several different tissues (e.g. muscle, glandular / epithelial tissue) working together to perform a specific function (digestion)
B1 group of different tissues; B1 working together for a specific function.
Similar questions
Questions that test the same subtopic in different years, grouped so you can work on one skill at a time.
References only: find each question in its paper (official link where available, otherwise through your school).
