AQA GCSE Biology Biology Paper 1 (Foundation), November 2021: Question 2

14 marks · Low Demand difficulty · Short Answer

Answer questions on viral pathogens, vaccines, and the effect of tobacco mosaic virus (TMV) on photosynthesis and plant growth, including completing a bar chart.

Practise this question

Question

Question 2 consists of nine sub-questions: 02.1 asks what name is given to disease-causing microorganisms with options pathogens, predators, and prokaryotes. 02.2 asks how viruses cause symptoms. Figure 4 shows diagrams comparing a virus (protein coat and genetic material) to an animal cell (cell membrane, cytoplasm, nucleus). 02.3 asks why viruses are not classed as cells. 02.4 asks what a vaccine contains. 02.5 shows three sketches of antibody concentration against time following two vaccinations to choose from. 02.6 asks which part of a plant shows discolouration from TMV. Table 1 gives the rate of photosynthesis for plants with different levels of TMV infection: None (15), Mild (13), Medium (7), and High (3). 02.7 asks to complete a bar chart on a grid in Figure 5 using Table 1. 02.8 asks for a conclusion from the data. 02.9 asks to explain why high TMV infection reduces plant growth.
Question text

02 Viruses cause disease.

02.1 What name is given to microorganisms that cause disease?

[1 mark]

Tick ( ) one box.

Pathogens

Predators

Prokaryotes

02.2 How do viruses cause the symptoms of disease?

[1 mark]

Tick ( ) one box.

Viruses engulf white blood cells, destroying them.

Viruses produce antibodies that damage tissues.

Viruses reproduce inside cells, damaging them.7

Figure 4 shows a virus and an animal cell.

Figure 4

*0062.*3 Suggest one reason why viruses are not classed as cells.

[1 mark]

A vaccine can protect humans from a viral disease.

02.4 What does the vaccine contain?

[1 mark]

Tick ( ) one box.

A toxic form of a virus

A weakened form of a virus

An active form of a virus 8

In some cases, a first vaccination needs to be followed by a second vaccination some

time later.

02.5 Which graph shows how the concentration of antibodies in a person’s blood changes

after the first and second vaccinations?

[1 mark]

Tick ( ) one box.

Tobacco mosaic virus (TMV) causes disease in plants.

TMV affects the rate of photosynthesis in plants.

02.6 Which part of a plant shows discolouration caused by TMV?

[1 mark]

Tick ( ) one box.

Flower

*08* Leaf

Root 10

Table 1 shows the rate of photosynthesis in four different tobacco plants.

Table 1

Level of TMV infection Rate of photosynthesis

Tobacco plant

in plant in arbitrary units

A None 15

B Mild 13

C Medium 7

D High 3

02.7 Complete Figure 5.

You should:

• label the y-axis

• add the correct scale to the y-axis

• plot the data from Table 1

• label each bar.

[5 marks]

Figure 5

02.8 What conclusion can be made from the data in Table 1?

[1 mark]

02.9 Explain why a high level of TMV infection reduces growth in a plant.

[2 marks]

Mark scheme

Show the mark scheme Mark scheme for Question 2 with total 14 marks: 02.1 requires 'pathogens' (1 mark). 02.2 requires 'viruses reproduce inside cells, damaging them' (1 mark). 02.3 accepts lack of cell membrane, cytoplasm, nucleus, mitochondria, or ribosomes (1 mark). 02.4 requires 'a weakened form of a virus' (1 mark). 02.5 requires selecting the first graph showing a secondary immune response with a higher and steeper curve (1 mark). 02.6 requires 'leaf' (1 mark). 02.7 allocates 5 marks for y-axis label ('rate of photosynthesis in arbitrary units'), correct scale, plotting bars correctly within half a small square tolerance, and labelling each bar. 02.8 gives 1 mark for stating that as infection increases, rate of photosynthesis decreases. 02.9 awards 2 marks for 'less chlorophyll' and 'so less glucose / starch / protein made'.

AO /

Question Answers Extra information Mark

Spec. Ref.

02.1 pathogens 1 AO1

4.3.1.1

02.2 viruses reproduce inside cells, 1 AO1

damaging them 4.3.1.1

02.3 any one from: 1 AO2

• they do not have a cell do not accept they do not have 4.1.1.2

membrane a cell wall

• they do not have cytoplasm

• they do not have a nucleus

• they do not have

mitochondria (like most

eukaryotic cells)

• they do not have ribosomes

do not accept they do not have

chloroplasts / chlorophyll

ignore they are not living / alive

ignore they can only replicate

inside cells

ignore virus has a protein coat

02.4 a weakened form of a virus 1 AO1

4.3.1.7

02.5 1 AO2

4.3.1.7

02.6 leaf 1 AO1

4.3.1.2

02.7 y-axis labelled rate of 1 AO2

photosynthesis in arbitrary units 4.4.1.1

correct scale 1

all bars plotted correctly allow a tolerance of ± ½ small 2

square

allow 2 correct bars for 1 mark

allow bars touching

allow any width of bars

all bars correctly labelled ignore letters 1

02.8 as the level of infection (with allow as TMV increases, 1 AO3

TMV) increases, (the rate of) photosynthesis decreases 4.4.1.1

photosynthesis decreases

allow (the rate of)

photosynthesis decreases as

the level of infection (with TMV)

increases

allow as infection gets worse,

photosynthesis decreases

allow TMV reduces

photosynthesis

02.9 less chlorophyll allow fewer chloroplasts 1 AO2

allow less light absorbed 4.4.1.1

ignore less photosynthesis 4.4.1.3

4.3.1.2

(so) less glucose / starch / 1

protein made

Total 14

How to answer it

Viruses, Immunity & Plant Disease (TMV)

📋 What this question tests

This question assesses core recall, data skills, and biological explanations from the Infection and Response and Bioenergetics topics:

  • Recall: Definition of pathogens, how viruses damage host cells, viral structure vs animal cells, and contents of vaccines.
  • Data analysis & Graph interpretation: Identifying secondary immune response curves and drawing a complete 5-mark bar chart.
  • Application & Reasoning: Explaining how Tobacco Mosaic Virus (TMV) reduces leaf chlorophyll, decreases photosynthesis, and limits plant growth.

Question 02.1 & 02.2: Pathogen Definitions & Viral Action

1 Mark each • AO1 Recall

✅ Correct Selections

  • 02.1: Tick box 1: Pathogens
  • 02.2: Tick box 3: Viruses reproduce inside cells, damaging them.

💡 Key Knowledge

  • A pathogen is a microorganism that causes infectious disease (bacteria, viruses, protists, fungi).
  • Viruses cannot reproduce on their own; they hijack host cell machinery to replicate until the cell bursts and is destroyed.

❌ Common Errors

  • Confusing pathogens with prokaryotes: Prokaryotes are organisms without a nucleus (e.g., bacteria). Many bacteria are harmless or beneficial.
  • Confusing viral damage with toxins: Bacteria typically produce toxins that make us feel ill; viruses cause symptoms by cell damage/lysis.

Question 02.3: Viral Structure vs Animal Cells

1 Mark • AO2 Application

✅ Accepted Answers (Give any ONE)

  • They do not have a cell membrane.
  • They do not have cytoplasm.
  • They do not have a nucleus.
  • They do not have mitochondria (or ribosomes).

🧠 Exam Technique: Use Figure 4 Directly

Figure 4 directly labels three cell features on the animal cell: cell membrane, cytoplasm, and nucleus. Simply state that the virus lacks any one of these three labelled parts!

❌ Mark Scheme Traps

  • DO NOT ACCEPT: "They do not have a cell wall" (animal cells don't have cell walls either!).
  • DO NOT ACCEPT: "They do not have chloroplasts" (irrelevant for animal cell comparison).
  • IGNORED: "They are not alive" or "They have a protein coat" (the question asks why they are not classed as cells).

Question 02.4 & 02.5: Vaccination & The Secondary Response

1 Mark each • AO1 & AO2

✅ Correct Selections

  • 02.4: Tick box 2: A weakened form of a virus
  • 02.5: Tick box 1 (Top graph: small first peak followed by a steep, much higher secondary peak).

💡 Secondary Immune Response

The first vaccine creates memory cells. When a booster (second vaccine) is injected, memory white blood cells produce antibodies faster, in greater quantity, and for a longer duration.

🧠 How to Spot the Correct Graph

Look at the arrow for the second injection:

  • Graph 1 clearly shows a faster surge to a much higher concentration.
  • Graph 2 is just a straight line (impossible biologically).
  • Graph 3 drops down to zero after the second dose (completely wrong).

Question 02.6 & 02.7: Tobacco Mosaic Virus & Bar Chart

6 Marks Total (02.6: 1 Mark • 02.7: 5 Marks) • AO1 & AO2

✅ 02.6 Answer

Tick box 2: Leaf (TMV produces a characteristic 'mosaic' pattern of discolouration on plant leaves).

📐 Step-by-Step Guide to the 5-Mark Graph (02.7)

  1. Y-axis label [1 mark]: Copy the header exactly:
    Rate of photosynthesis in arbitrary units
  2. Scale [1 mark]: Linear scale starting at 0, going up in regular increments (e.g. 2, 4, 6, 8, 10, 12, 14, 16) that use more than half the grid.
  3. Plotting bars [2 marks]:
    • Plant B (Mild) = 13
    • Plant C (Medium) = 7
    • Plant D (High) = 3
    • (Tolerance is ± 0.5 of a small square. 2 correct bars gives 1 mark; all 3 correct gives 2 marks).
  4. Bar labels [1 mark]: Label underneath each bar: Mild, Medium, High (or B, C, D).

❌ Costly Graph Mistakes

  • Missing the units: Writing only "Rate of photosynthesis" without "in arbitrary units" loses the label mark.
  • Unequal scales: Skipping numbers or writing numbers unevenly along the axis grid lines.
  • Messy bars: Not using a ruler or varying bar widths wildly. Leaving gaps is fine, but bars must be clearly distinguished.

Question 02.8 & 02.9: Analyzing TMV Effects on Plant Growth

02.8: 1 Mark (AO3) • 02.9: 2 Marks (AO2)

✅ 02.8 Conclusion (1 Mark)

Answer: As the level of TMV infection increases, the rate of photosynthesis decreases.

Examiner note: Always state both variables: "As [Variable X] increases, [Variable Y] decreases."

✅ 02.9 Explanation of Reduced Growth (2 Marks)

  • Mark 1 (Cause): Less chlorophyll (or fewer chloroplasts / less light absorbed).
  • Mark 2 (Effect): Less glucose (or starch/protein/cellulose) is produced for growth.

🧠 The "TMV to Growth" Cause-and-Effect Chain

Mosaic discolouration on leaf ➜ Less chlorophyll ➜ Less light absorbed ➜ Less photosynthesis ➜ Less glucose made ➜ Reduced plant growth

Tip: The question stem already says "photosynthesis is reduced". Repeating "less photosynthesis" alone will not get credit! You must explain why (chlorophyll) and how that stops growth (glucose).

Topics

Biology · B1: Cell Biology · B3: Infection and Response · B4: Bioenergetics

Question and mark scheme from the AQA GCSE Biology examination, Biology Paper 1 (Foundation), November 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.