AQA GCSE Biology Biology Paper 2 (Higher), June 2022: Question 6

13 marks · Standard Demand difficulty · Short Answer

Identify processes in the water cycle and plant water transport, calculate the comparative energy efficiency of grass and a cow in a food chain, and evaluate rearing livestock indoors.

Practise this question

Question

Question text

06 Energy flows through an ecosystem and materials are recycled.

Figure 6 shows the water cycle.

Figure 6

06.1 Name process X.

[1 mark]

06.2 Name the process by which water is absorbed into plant roots.

[1 mark]

06.3 Give two uses of water in plants.

[2 marks]

Figure 7 shows the flow of energy through a food chain.

The numbers are in kilojoules/m2/year.

Figure 7

06.4 The cow is more efficient than the grass at converting energy.

The energy conversion efficiency of the cow is 4.098%.

Calculate how many times more efficient the cow is at converting energy than

the grass.

The equation for energy conversion efficiency is:

energy used for growth

energy conversion efficiency = × 100

energy input

Give your answer to 3 significant figures.

[5 marks]

Number of times (3 significant figures) =

06.5 It is more energy-efficient to rear cows indoors than to rear cows outdoors.

Give two reasons why.

[2 marks]

06.6 Suggest two possible disadvantages of rearing cows indoors.

[2 marks]

*23* 1

Mark scheme

Show the mark scheme

Question 6

AO /

Question Answers Extra information Mark

Spec. Ref.

06.1 evaporation allow vaporisation 1 AO1

4.7.2.2

AO /

Spec. Ref.

06.2 osmosis allow diffusion 1 AO1

ignore absorption 4.7.2.2

4.2.3.2

AO /

Spec. Ref.

06.3 any two from: 2 AO1

4.7

• photosynthesis 4.7.2.2

• support allow turgor 4.1.1.2

allow to fill vacuole 4.2.3.2

allow opening of stomata 4.4.1.1

allow to prevent wilting 4.4.2.3

• (solvent for) transport allow (as a) solvent

translocation

for the transpiration stream

allow (as a) medium for

chemical reactions

allow hydrolysis / digestion /

breakdown of stored food

allow cooling

allow making cytoplasm

AO /

Spec. Ref.

substitution

06.4 AO2

21 800 1 4.7.2.1

× 100

1 700 000 4.7.4.3

1.282(3529) 1

allow 1.28 or 1.3

comparative efficiency 1

4.098 allow an incorrectly calculated

1.282 value for efficiency correctly

substituted

3.196 … 1

significant figures

3.20 do not accept 3.2 1

do not accept if a unit is given

AO /

Spec. Ref.

06.5 less energy lost as heat allow less heat lost 1 AO1

allow less energy lost keeping 4.7.4.3

warm 4.7.5.2

or less energy for maintaining

body temperature

less energy lost in movement ignore less movement 1

ignore less energy lost

unqualified

ignore controlling diet

do not accept energy used for

respiration

do not accept energy produced

/ made / created

AO /

Spec. Ref.

06.6 any two from: 2 AO3

4.7.5.1

• increased spread of disease allow diseases spread (more) 4.7.5.2

or easily

increased use of drugs

/ antibiotics (to

reduce disease)

• more antibiotics in meat / milk

• (extra) cost of heating / allow (extra) energy used for

lighting / food / drugs heating / lighting

ignore (extra) cost unqualified

• aggressive behaviour

(causing harm)

‘emotional’ stress reduces

productivity

ignore cruelty / unethical

ignore need to clean out barns /

sheds

ignore need to maintain / build

barns

Total Question 6 13

How to answer it

Water Cycle, Trophic Efficiency & Intensive Farming Study Guide

📌 What This Question Tests

This 13-mark question assesses core ecology and plant physiology concepts across Topic 7 (Ecology) and Topic 4 (Bioenergetics):

Material cycling: Identification of key physical processes in the water cycle (evaporation).
Transport in plants: Water uptake by root hair cells via osmosis and functional uses of water.
Energy transfer calculations: Multi-step quantitative calculation comparing trophic efficiency using diagrammatic energy flow data.
Food production & intensive farming: Biological rationale for indoor livestock rearing and associated ethical/environmental disadvantages.

Question 06.1

Water Cycle: Process X

Identifying processes in material cycling (1 Mark)

✅ Correct Answer

Evaporation (also accept vaporisation)

🧠 Exam Technique

Trace the arrow carefully: arrow X points directly from a liquid body of water (lake/puddle) up into atmospheric clouds. Liquid turning into water vapour is evaporation.

❌ Common Errors

Confusing evaporation with transpiration (transpiration is water loss from the leaves of plants, shown by the tree).
Confusing evaporation with condensation (condensation is water vapour cooling to form liquid droplets in clouds).

Mark scheme: 1 mark for evaporation / vaporisation [AO1, Spec Ref 4.7.2.2].

Question 06.2

Water Absorption in Roots

Cell transport mechanisms (1 Mark)

✅ Correct Answer

Osmosis (allow diffusion; ignore 'absorption')

💡 Key Knowledge

Water moves from a dilute solution in the soil to a concentrated solution inside the root hair cells down a water potential gradient across a partially permeable membrane via osmosis.

Mark scheme: 1 mark for osmosis [AO1, Spec Ref 4.7.2.2 & 4.2.3.2].

Question 06.3

Uses of Water in Plants

Physiological roles of water (2 Marks)

✅ Correct Answers (Choose Any Two)

Photosynthesis (as a reactant)
Support / turgor (keeps cells firm, fills vacuole, prevents wilting)
Transport (transpiration stream, transport of dissolved minerals/sucrose)
Cooling the plant (via transpiration evaporation)
Solvent / medium for chemical reactions

🧠 Exam Technique

Give precise biological functions rather than vague claims like "to survive" or "to grow". Always refer to specific biological mechanisms: photosynthesis, cell turgidity/support, or transport of minerals.

Mark scheme: 2 marks total (1 mark per distinct biological use) [AO1, Spec Ref 4.1.1.2, 4.2.3.2, 4.4.1.1, 4.4.2.3, 4.7.2.2].

Question 06.4

Efficiency Comparison Calculation

Multi-step trophic level calculation & significant figures (5 Marks)

📐 Step-by-Step Calculation

Given: Cow energy conversion efficiency = 4.098%

Equation: Efficiency = (Energy used for growth ÷ Energy input) × 100

Step 1: Extract correct values for grass
Energy used for growth (grass) = 21 800 kJ/m²/year
Energy input (sunlight) = 1 700 000 kJ/m²/year
Step 2: Calculate energy efficiency of grass
(21 800 ÷ 1 700 000) × 100 = 1.28235... %
(Award 1 mark for substitution, 1 mark for 1.282%)
Step 3: Compare cow efficiency to grass efficiency
Ratio = Cow efficiency ÷ Grass efficiency
4.098 ÷ 1.28235... = 3.1957...
(Award 1 mark for dividing 4.098 by grass efficiency, 1 mark for quotient 3.196...)
Step 4: Round to 3 significant figures
3.1957... rounds to 3.20
(Award 1 mark for correct rounding to 3 sig figs)

❌ Calculation Traps & Common Errors

Trailing zeros matter: Writing 3.2 instead of 3.20 loses the final mark. 3.2 is 2 significant figures!
Adding units: Do not write "%" or "times" as a unit. It is a pure ratio.
Selecting the wrong energy input: Using food eaten ( 3050 ) instead of sunlight ( 1 700 000 ) for the producer level.

🧠 Exam Technique: Error Carried Forward (ecf)

Even if you make an arithmetic slip in Step 2, you can still gain marks for Step 3, 4, and 5 provided you divide 4.098 by your calculated efficiency and round your answer correctly to 3 significant figures.

Mark Breakdown (5 marks):
• Mark 1: Correct substitution (21 800 ÷ 1 700 000) × 100
• Mark 2: Calculated grass efficiency = 1.282...% (or 1.28 / 1.3)
• Mark 3: Comparative efficiency calculation 4.098 ÷ 1.282...
• Mark 4: Value = 3.196...
• Mark 5: Final answer rounded to 3 sig figs: 3.20

Question 06.5

Energy Efficiency of Indoor Rearing

Limiting energy loss in livestock (2 Marks)

✅ Correct Reasons (Both Required)

Less energy lost as heat: Heated/sheltered indoor environments reduce the energy needed to maintain body temperature.
Less energy lost in movement: Restricted space means less muscle contraction and less aerobic respiration for locomotion.

❌ Common Errors & Disallowed Phrasing

"Less movement" on its own is rejected – you must say less energy lost in movement.
"Energy is created / produced" – scientifically incorrect (violates conservation of energy).
"Less energy used for respiration" without qualifying that respiration provides energy for movement or heat maintenance.

Mark scheme: 1 mark for less energy lost as heat; 1 mark for less energy lost in movement [AO1, Spec Ref 4.7.4.3 & 4.7.5.2].

Question 06.6

Disadvantages of Indoor Rearing

Ethical, economic, and health implications (2 Marks)

✅ Correct Disadvantages (Any Two)

Disease spread: Higher stocking density leads to faster, easier spread of infectious pathogens.
Antibiotic issues: Overuse of antibiotics leads to antibiotic-resistant bacterial strains, or antibiotic residues in milk/meat.
Extra financial/energy costs: Higher costs associated with artificial heating, lighting, and ventilation.
Animal welfare & behavioural stress: Increased aggressive behaviour, injury, or emotional stress reducing productivity.

❌ What the Examiner Ignores

Vague assertions like "it is cruel" or "it is unethical" without explaining biological/welfare consequence.
Unqualified "it costs more" (must specify cost of heating/lighting/feed).
Cleaning out barns or maintenance chores.

Mark scheme: 2 marks total (1 mark per valid disadvantage) [AO3, Spec Ref 4.7.5.1 & 4.7.5.2].

Topics

Biology · B1: Cell Biology · B2: Organisation · B7: Ecology

Question and mark scheme from the AQA GCSE Biology examination, Biology Paper 2 (Higher), June 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.