AQA GCSE Combined Science: Trilogy Biology Paper 2 (Foundation), 2021: Question 3

13 marks · Low Demand difficulty · Short Answer

Analyze food chains, biotic factors, adaptations, and the process of evolution using a bird population example.

Practise this question

Question

A multi-part exam question about bird evolution. It includes a photo of birds at a feeder and a line graph (Figure 3) showing mean beak length in mm from 1982 to 2007. The graph shows a steady increase from approximately 13.54 mm to 13.62 mm. The questions ask for a food chain involving nuts, birds, and cats; identification of biotic factors; reading a value from the graph for the year 2000; identifying the type of adaptation; and completing a cloze text about the process of natural selection using terms like variation, mutation, and reproduction.
Question text

03 Figure 2 shows one species of bird on a bird feeder.

Figure 2

The birds use their beaks to reach nuts inside the bird feeder.

Cats sometimes eat the birds.

03.1 Give the food chain for the birds, cats and nuts.

[2 marks]

03.2 Which organism in the food chain you gave in Question 03.1 is the

primary consumer?

[1 mark]

03.3 Cats are one biotic factor that affects the size of the bird population.

Which two of the following are biotic factors?

[2 marks]

Tick ( ) two boxes.

Food

Pathogens

Sunlight

Temperature

Water 12

Figure 3 shows the mean beak length of this species of bird from 1982 to 2007.

Figure 3

03.4 What was the mean beak length in 2000?

[1 mark]

Mean beak length = mm

03.5 What type of adaptation is beak length?

[1 mark]

Tick ( ) one box.

Behavioural

Chemical

Structural 13

Figure 3 shows evidence of evolution in this species of bird.

03.6 Scientists have concluded that beak length in this species of bird is increasing.

Complete the sentences about the evolution of this species of bird.

Choose answers from the box.

[4 marks]

excretion generation mutation

reproduction respiration variation

The difference in beak length in the bird population

is called .

A change in a gene affects the beak length.

Change in a gene is called .

The birds with the longest beaks get more food.

Getting more food improves a bird’s chances of

survival and .

This process of evolution takes place over more

than one 14 .

03.7 Birds of this species:

• live for about 3 years

• produce up to 24 eggs every year.

Why is evolution easier to study in birds than in humans?

[1 mark]

Tick ( ) one box.

Birds breed less frequently than humans.

Birds have a shorter life cycle than humans.

Birds have fewer offspring than humans.

03.8 Bacteria also provide evidence for evolution.

Which statement describes evidence for evolution?

[1 mark]

Tick ( ) one box.

Bacteria can become resistant to antibiotics.

Decomposition can be caused by bacteria.

Some bacteria are pathogens.

Mark scheme

Show the mark scheme The mark scheme table for questions 03.1 to 03.8. It lists the correct food chain as nut(s) to bird(s) to cat(s) with arrows. It identifies the bird as the primary consumer and food and pathogens as biotic factors. The mean beak length for 2000 is 13.60 mm. The adaptation is structural. The evolution sequence is variation, mutation, reproduction, and generation. It notes birds have a shorter life cycle and bacteria becoming resistant to antibiotics as evidence for evolution.

AO /

Question Answers Extra information Mark

Spec. Ref.

03.1 nut(s) → bird(s) → cat(s) allow 1 mark for organisms in 2 AO2

correct order (left to right) but 4.7.2.1

arrows incorrect or missing

allow 2 marks for

cat(s) ← bird(s) ← nut(s)

do not accept

cat(s)bird(s) nut(s)

do not accept

cat(s) →bird(s) →nut(s)

03.2 answer must be consistent with if no answer to question 03.1 1 AO2

food chain given in question allow bird(s) 4.7.2.1

03.1

03.3 food 1 AO1

4.7.1.3

pathogens 1

03.4 13.60 (mm) allow 13.6 (mm) 1 AO2

4.6.2.2

03.5 structural 1 AO2

4.7.1.4

03.6 must be in this order AO2

variation 1 4.6.2.2

mutation 1

reproduction 1

generation 1

03.7 birds have a shorter life cycle 1 AO3

than humans 4.6.3.1

4.6.3.4

03.8 bacteria can become resistant to 1 AO1

antibiotics 4.6.3.1

4.6.3.4

Total 13

How to answer it

Ecology, Adaptations, and Evolution

What this question tests

This question assesses your ability to construct food chains, identify biotic factors, interpret data from graphs, and explain the mechanism of natural selection using key scientific terminology.

Part 03.1 & 03.2

Food Chains and Consumers

Correct Answers

  • 03.1: nuts → bird(s) → cat(s)
  • 03.2: bird(s)

Exam Technique

In a food chain, the arrow represents the flow of energy. It must point from the organism being eaten to the organism doing the eating (into the mouth!).

Common Errors

Students often lose marks by pointing arrows the wrong way or using simple lines without arrowheads. Also, ensure you identify the Primary Consumer as the first animal in the chain (the herbivore).

Part 03.3

Biotic Factors

Identifying living influences on a population

Key Knowledge

Biotic factors are living factors that affect an ecosystem. Examples include:

  • Availability of food
  • New pathogens (diseases)
  • New predators
  • Competition between species

Correct Answers

  • Food
  • Pathogens

Abiotic vs Biotic

If it's non-living (like temperature, sunlight, or water), it is Abiotic. Don't mix these up!

Part 03.4 & 03.5

Data and Adaptations

03.4 Graph Reading

  1. Find "2000" on the x-axis (Year).
  2. Move vertically up to the line of best fit.
  3. Move horizontally to the y-axis (Mean beak length).
  4. Answer: 13.60 mm (13.6 is also accepted).

03.5 Types of Adaptation

  • Structural: Physical features (e.g., beak shape, fur color).
  • Behavioural: The way an organism acts (e.g., migration).
  • Functional: Internal processes (e.g., producing venom).

Beak length is a physical feature, so it is Structural.

Part 03.6

The Process of Evolution

Natural Selection Cloze Activity

Correct Sequence

The difference in beak length in the bird population is called variation.

A change in a gene affects the beak length. Change in a gene is called mutation.

The birds with the longest beaks get more food. Getting more food improves a bird's chances of survival and reproduction.

This process of evolution takes place over more than one generation.

Examiner Insight

Top-level responses correctly identify that mutation is the source of variation. Evolution is not something that happens to one individual bird; it is a change in the inherited characteristics of a population over multiple generations.

Part 03.7 & 03.8

Evidence for Evolution

03.7 Life Cycles

Evolution is easier to study in organisms with shorter life cycles (like birds or bacteria) because they produce many generations in a short amount of time, allowing us to see changes faster than in humans.

03.8 Bacterial Evidence

The fact that bacteria can become resistant to antibiotics is modern-day proof of evolution by natural selection happening right now.

Final Answers

  • 03.7: Birds have a shorter life cycle than humans.
  • 03.8: Bacteria can become resistant to antibiotics.

Topics

Biology · B6: Inheritance, Variation and Evolution · B7: Ecology

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Biology Paper 2 (Foundation), 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.