▶️ Answer/Explanation
(a)(i) C (oak tree)
A is not the answer as beetle is not the producer
B is not the answer as deer is not the producer
D is not the answer as tick is not the producer
(a)(ii)
oak tree → caterpillar → mouse → tick
Allow 1 mark for correct order. No credit for pyramids.
(a)(iii) D (mouse)
A is not correct as the ant is not at two levels
B is not correct as the blue jay is not at two levels
C is not correct as the caterpillar is not at two levels
(b)(i)
Measurement of line = \(10.4 \text{ cm} = 104 \text{ mm}\)
Magnification = \(\frac{\text{image size}}{\text{actual size}} = \frac{104}{3.5}\)
Magnification = \(29.7\) (range \(29.0 – 30.0\) accepted)
Allow 1 mark for correct measurement of line (10.3-10.5 cm or 103-105 mm) with units.
(b)(ii)
An explanation makes reference to four of the following points (substance + matching function):
• Glucose (1) — for energy / respiration (1)
• Iron (1) — for haemoglobin / red blood cells (1)
• Amino acids (1) — for protein (synthesis) / growth (1)
• Fatty acids / lipids (1) — for energy / insulation (1)
• Water (1) — for keeping body hydrated / transport / solvent (1)
• Vitamin C (1) — for prevents scurvy (1)
Allow named vitamin or mineral for one mark each. Function must match substance.
(b)(iii)
An answer that makes reference to two of the following:
• Tick picks up / bites / sucks up / absorbs blood from infected animal / animal with disease (1)
• Bacteria / virus / pathogen is present in the blood (1)
• Tick then feeds on / bites a new / uninfected animal (1)
• Pathogen is transferred to the new host (1)
Allow ‘transfer’ if reference to biting is included.
▶️ Answer/Explanation
(a)(i) B (Q)
A is not the answer as P is not the style
C is not the answer as S is not the style
D is not the answer as T is not the style
(a)(ii) D (U)
A is not the answer as P does not release pollen
B is not the answer as R does not release pollen
C is not the answer as T does not release pollen
(a)(iii) A (P)
B is not correct as pollen grains do not germinate on R
C is not correct as pollen grains do not germinate on S
D is not correct as pollen grains do not germinate on U
(b) A description that makes reference to the following:
• P feathery / large surface area / outside flower / exposed / eq (1)
• R absent / smaller / not coloured / green / eq (1)
• T longer / hinged / outside flower / exposed / eq (1)
(c)(i) • runners / bulbs / corms / tubers / rhizomes / eq (1)
(c)(ii) • cuttings / grafting / layering / tissue culture / micropropagation / eq (1)
Note: Reject ‘cloning’.
(d) An answer that makes reference to the following:
Allow two / three in one numbered line
• no gametes produced in asexual / no meiosis in asexual / gametes produced in sexual / meiosis in sexual / one parent cell (1)
• no fusion or fertilisation in asexual / present in sexual (1)
• offspring are clones / show no genetic variation in asexual / genetic variation in sexual / eq (1)
• asexual faster / shorter time / sexual slower / longer time / eq (1)
Note: Only mitosis in asexual. Ignore reference to number of parents. ‘Sexual involves fusion of gametes’ scores marking point 1 and marking point 2.
(e) An explanation makes reference to three of the following:
• selective breeding / artificial selection (1)
• cross red (flower) / unscented (flower) with white (flower) / scented (flower) / eq (1)
• select / breed / offspring with red and scent / eq (1)
• repeat / for many generations eq (1)
Note: Ignore reference to GM as it is the farmer. ‘Cross varieties / the plants’ is acceptable. Ignore ‘desired characteristics’ alone.
▶️ Answer/Explanation
Completed Passage:
Yoghurt is made by heating milk to a high temperature.
This heating process is known as pasteurisation or sterilisation.
This ensures that bacteria present in the liquid are killed.
The liquid is then cooled to between \(40^\circ C\) and \(46^\circ C\).
A type of bacteria called Lactobacillus (or Streptococcus) is then added.
These bacteria use a sugar called lactose for
anaerobic respiration.
The pH of the yoghurt decreases because this respiration produces a substance called
lactic acid (or lactate).
Topic Mapping:
• 6(a) Food production (Micro-organisms) – 6.7, 6.8: The question directly assesses knowledge of yoghurt production using bacteria (Lactobacillus) and the conditions in a fermenter (heating, cooling).
• 2(f) Respiration – 2.36, 2.38: The question involves the type of respiration (anaerobic) and its product (lactic acid).
• 1(b) Variety of living organisms (Bacteria) – 1.3: Requires naming a specific bacterium used in food production.
▶️ Answer/Explanation
(a) \( C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O \)
(b)(i) An explanation that makes reference to two of the following:
• The bubble would not move / \( CO_2 \) also moves / shifts the bubble (1)
• Carbon dioxide is produced/released (1)
• Only oxygen consumption is measured (1)
(b)(ii) • Use a water bath (1)
(c)(i) \( 22 + 25 + 24 = 71 \)
\( 71 \div 3 = 23.7 \) (or 24) mm (2)
(c)(ii) An explanation that makes reference to three of the following:
• Increases (kinetic) energy of molecules / molecules move faster (1)
• Collide more frequently / form more enzyme-substrate complexes (1)
• Respiration (rate) increases (1)
• More oxygen consumed / oxygen used faster (1)
• Reference to/nearer to optimum temperature for enzymes (1)
▶️ Answer/Explanation
(a)(i) C (1, 2 and 4 only)
A is not correct as water vapour is a greenhouse gas
B is not correct as oxygen is not a greenhouse gas and water vapour is a greenhouse gas
D is not correct as oxygen is not a greenhouse gas
(1 mark)
(a)(ii) An explanation that makes reference to the following:
• IR / long wave radiation is absorbed / traps IR / long wave radiation / traps heat / prevents heat escaping (1)
• (so) increases (global) temperature / earth warms / global warming (1)
(2 marks)
(b)(i)
Calculation:
Readings from the graph (in million tonnes, approximately):
Agriculture ≈ 50, Energy ≈ 110, Business ≈ 118, Transport ≈ 175.
Total = \(50 + 110 + 118 + 175 = 453\).
Percentage from energy = \(\left(\frac{110}{453}\right) \times 100 \approx 24.3\%\) (Allow range: 23.9% – 24.9%).
(3 marks for correct answer with working; 1 mark for correct readings even if unlabelled; 1 mark for dividing 110 by their total if not correct answer)
(b)(ii)
An answer that makes reference to five of the following points (1 mark each):
1. Overall emissions fall / less mass from 1990 to 2020.
2. Energy production had the highest emissions in 1990 and showed the largest fall.
3. The fall in energy emissions is due to a shift to renewable sources (wind, solar) and less use of coal/gas power stations (burning fewer fossil fuels).
4. Transport emissions increased initially, then fell from around 2009/2010.
5. The initial rise in transport was due to more cars/vehicles; the later fall is linked to more electric/hybrid cars and less commuting.
6. Agriculture emissions dropped.
7. This drop may be due to less cattle farming, reducing methane release.
8. Business emissions changed little / dropped slightly.
(5 marks total)
▶️ Answer/Explanation
(a)(i) B (oxygen)
A is not the answer as carbon dioxide is not released
C is not the answer as methane is not released
D is not the answer as nitrogen is not released
(a)(ii) A (chloroplast)
B mitochondrion is not the site of photosynthesis
C nucleus is not the site of photosynthesis
D ribosome is not the site of photosynthesis
(a)(iii) • temperature / carbon dioxide concentration / pH / background light / same bulb/ lamp / time period / eq (1)
(b)(i) Line graph plotting criteria (from mark scheme):
• scale linear and plot half grid on y (1)
• lines straight and through points (1)
[Note: A full graph is expected here. The mark scheme awards marks for correct scaling, plotting, and straight line connections.]
(b)(ii) An explanation that refers to three of the following:
• as distance increases rate falls / fewer bubbles / eq (1)
• as light intensity reduces / less light energy / light becomes limiting factor (1)
• slower rate of / less photosynthesis (1)
• less oxygen released / fewer oxygen bubbles released (1)
▶️ Answer/Explanation
(a) An answer that refers to three of the following:
- red cell has no nucleus / white cell has nucleus (1)
- red cell is a biconcave disc / white cell is not biconcave / has irregular shape (1)
- red cell is smaller / white cell is larger (1)
- red cell contains haemoglobin / white cell does not contain haemoglobin (1)
(Award 1 mark for each correct, contrasting difference, up to 3 marks.)
(b)(i) Calculation method (marking points):
• 4.3 × 5.20 × \(10^{12}\) (1)
• = 22.36 × \(10^{12}\) (1)
• = \(2.236 \times 10^{13}\) or \(2.24 \times 10^{13}\) (1 for correct standard form)
Answer: \(2.2 \times 10^{13}\) (allow \(2.24 \times 10^{13}\))
(Award full marks for correct process and final answer in standard form.)
(b)(ii) Calculation method (marking points):
• Difference = 151 – 148 = 3 (1)
• Percentage = \( \left( \frac{3}{148} \right) \times 100 \) = 2.03% (1)
Answer: 2.03% (allow 2.03, 2.0, 2.027)
(b)(iii) An answer that makes reference to five of the following points (1 mark each):
- The study involves large numbers of people / provides reliable results.
- However, there are fewer people in the study at higher altitudes than at sea level.
- There are more women than men in the sample at all altitudes.
- No information is given on age, health, or body mass of the subjects.
- Haemoglobin (Hb) mass increases from sea level (0 m) to 1890 m altitude.
- This is because more red blood cells are produced at higher altitude.
- This adaptation occurs due to lower partial pressure / availability of oxygen at altitude.
- The increase enables sufficient oxygen transport / uptake for aerobic respiration.
- Hb shows little change / a slight reduction from 1890 m to 2270 m.
- This may be because the increase in altitude is smaller between these two points.
- The number of red cells drops slightly from 1890 m to 2270 m.
- Men have more Hb and more red cells than women at every altitude.
(Award up to 5 marks for a coherent discussion that links data to biological knowledge.)
▶️ Answer/Explanation
(a) An allele that is only expressed in the homozygote / only shown in phenotype if two copies are present / not expressed in the heterozygote / not expressed if a dominant allele is present. (1 mark)
(b)(i)
A: Ff (heterozygous) (1)
B: Ff (heterozygous) (1)
C: ff (homozygous recessive) (1)
(Total 3 marks)
(b)(ii) A genetic diagram showing:
• Parental genotypes: Ff and Ff (1)
• Gametes: F and f from each parent (1)
• Offspring genotypes and phenotypes: FF (unaffected), Ff (unaffected), Ff (unaffected), ff (affected) OR correct phenotype ratio (1)
(Total 3 marks)
(c)(i) An explanation that refers to three of the following:
• Pancreas produces/releases amylase/proteases/lipases. (1)
• No/less digestion of starch to maltose. (1)
• No/less digestion of proteins to amino acids. (1)
• No/less digestion of lipids to fatty acids and glycerol. (1)
• Less absorption of smaller/soluble molecules (e.g., amino acids, glucose, fatty acids). (1)
(Total 3 marks)
(c)(ii) An explanation that refers to two of the following:
• Reduces likelihood of pregnancy / less likely to conceive. (1)
• Sperm/semen cannot enter the fallopian tube/oviduct. (1)
• Fertilisation less likely / no fusion of gametes. (1)
(Total 2 marks)
▶️ Answer/Explanation
(a)(i) An answer that makes reference to two of the following:
• sunlight / light / eq (1)
• volume / mass of solution / eq (1)
• number of plants / number of leaves / size of leaves / size of plant / health of leaves (at start) / eq (1)
• same species / use duckweed / eq (1)
• time / duration / eq (1)
• all jars covered / eq (1)
(a)(ii) An explanation that makes reference to two of the following:
• it (complete solution) (contains all minerals) so produces normal growth / ideal growth / eq (1)
• distilled water contains no minerals / plant would be lacking all minerals / would not grow normally / eq (1)
• so any difference in growth due to missing one mineral / eq (1)
(a)(iii) An explanation that makes reference to two of the following:
• photosynthesis / eq (1)
• to produce glucose (for respiration) / eq (1)
• for growth / to allow normal growth / eq (1)
(a)(iv) • mineral that is missing / absent from solution / minerals present / composition of solution / solution / eq (1)
(b)(i) • (quantitative / number of leaves) uses number / is measured / counted / and (qualitative / size of leaf) is a type / category / uses words / observed / subjective / opinion / eq (1)
(b)(ii) An answer that makes reference to 6 of the following:
1. complete / no minerals lacking / A have most leaves / largest leaves / eq (1)
2. complete / no minerals lacking / A have dark green / greenest leaves / eq (1)
3. minus nitrate / B have few / least / smaller / smallest leaves / less green / yellow / eq (1)
4. nitrate required for amino acid / protein / chlorophyll / chloroplasts / nitrate required for growth / eq (1)
5. minus magnesium / C have few / smaller / less green / yellow / eq (1)
6. magnesium required for chlorophyll / chloroplasts / photosynthesis / eq (1)
7. minus iron / D have few / smaller leaves / less green / least green / yellow / eq (1)
8. iron required for chlorophyll / chloroplasts / photosynthesis / eq (1)
9. Not repeated / not reliable / few plants used / eq (1)
▶️ Answer/Explanation
Answer that makes reference to six of the following points:
O: Use crop plants of the same species / same variety / same age / same initial size / from the same batch / genetic clone / eq. (1)
R: Repeat each concentration / have replicates / repeat the whole investigation / eq. (1)
M1: Measure the yield / mass / kg / amount / number of seeds / number of fruits / size of fruits / biomass / eq. (1) (Not yield alone, not height)
M2: After a stated suitable time / e.g., after the growing season / after flowering / after a set number of weeks / eq. (1)
S1: Control / keep constant: temperature / (sun)light intensity / light wavelength / photoperiod (day length) / same season / eq. (1)
S2: Control / keep constant: same soil type / same volume of water / same watering regime / same humidity / same fertiliser / same mineral ions / same pH / eq. (1)
Core Design Aspect: Use at least three different concentrations of \( CO_2 \) / e.g., high, medium, low, zero / a range of concentrations. (Implied in question, credit for a valid method to vary/measure \( CO_2 \) concentration)
Total: 6 marks
Example full-sentence answer structure:
Use a large number of genetically identical crop plants (e.g., tomato plants) of the same age and initial size. Grow them in separate, identical glasshouse compartments. In each compartment, maintain a different, known concentration of carbon dioxide (e.g., 0.04%, 0.10%, 0.20%). For each \( CO_2 \) concentration, use multiple plants as replicates. Keep all other conditions that affect growth and yield constant: use the same light intensity, temperature, watering regime, soil type, and fertiliser application for all plants. Allow the plants to grow for a full growing season (e.g., 12 weeks). Then, measure the yield by harvesting and weighing the total mass of fruits (or seeds) produced by the plants in each \( CO_2 \) concentration group. The \( CO_2 \) concentration that produces the greatest mass of fruit is the concentration needed for maximum yield.