AQA GCSE Biology Biology Paper 1 (Foundation), November 2021: Question 7

13 marks · Standard Demand difficulty · Extended Answer

Identify microscope parts and cell preparation equipment, compare red blood cell and plant cell structures, and explain the effect of osmosis on both cell types.

Practise this question

Question

An exam question spanning several parts based on microscopy and cell structure. Figure 14 shows hands mounting a cover slip onto a glass slide with a liquid specimen. Question 07.1 asks for two pieces of laboratory equipment used to prepare the cells. Figure 15 shows a standard light microscope with Part A pointing to the eyepiece lens and Part B pointing to the focus adjustment knob. Sub-questions 07.2 to 07.4 ask for the name of Part A, the function of Part B, and a reason no cells were visible. Question 07.5 asks students to compare the structure of a red blood cell with a plant cell in a 6-mark extended response. Question 07.6 describes placing both cells into water, where the red blood cell bursts but the plant cell does not, asking candidates to explain why.
Question text

07 A student prepared some animal cells to view using a microscope.

Figure 14 shows the student preparing the cells.

Figure 14

07.1 Name two pieces of laboratory equipment the student could have used to prepare

cells to view using a microscope.

[2 marks]

Figure 15 shows the student’s light microscope.

Figure 15

07.2 Name part A.

[1 mark]

07.3 What is the function of part B?

[1 mark]

07.4 The student tried to look at the cells using the microscope.

Suggest one reason why the student could not see any cells when looking through

part A.

[1 mark]

07.5 Red blood cells are specialised animal cells.

Compare the structure of a red blood cell with the structure of a plant cell.

[6 marks]

07.6 When placed into a beaker of water:

• a red blood cell bursts

• a plant cell does not burst.

Explain why the red blood cell bursts but the plant cell does not burst.

[2 marks]

Mark scheme

Show the mark scheme Mark scheme table for question 07: 07.1 awards 2 marks for any two of slide, cover slip, dye/stain, mounted needle, pipette, scalpel, or forceps; 07.2 awards 1 mark for eyepiece / lens; 07.3 awards 1 mark for focusing the image or cells; 07.4 awards 1 mark for reasons such as no cells in view, slide not aligned, objective lens not in place, or microscope unfocused; 07.5 provides a level of response mark scheme for 6 marks comparing differences (nucleus, cell wall, haemoglobin, chloroplasts, vacuole, size) and similarities (cytoplasm, cell membrane); 07.6 awards 2 marks for water entering by osmosis and the plant cell possessing a cell wall which prevents it bursting.

AO /

Question Answers Extra information Mark

Spec. Ref.

07.1 any two from: 2 AO1

• (microscope) slide 4.1.1.5

• cover slip RPA1

• dye / stain allow named dye / stain

ignore water

• (mounted) needle

• pipette / dropper

• scalpel ignore knife

• forceps / tweezers

allow swab (to collect cells)

07.2 eyepiece / lens do not accept objective lens 1 AO1

4.1.1.5

RPA1

07.3 to focus (the image / cells) allow to make the cells / image 1 AO1

clear(er) 4.1.1.5

RPA1

allow to improve resolution (of

the image)

ignore to move the stage up /

down

do not accept reference to

magnification

07.4 any one from: 1 AO3

• no cells in the field of view 4.1.1.5

• slide not in the correct RPA1

position

• mirror not in correct position allow light / microscope not

switched on / plugged in

• (objective) lens not clicked

into place

or

(objective) lens dirty

• (student is) looking at a

(large) air bubble

• (the microscope is) not

focussed

allow student did not stain the

cells

allow idea of magnification not

being high enough

07.5 Level 2: Scientifically relevant features are identified; the way(s) in 4‒6 AO2

which they are similar/different is made clear and (where

appropriate) the magnitude of the similarity/difference is noted.

Level 1: Relevant features are identified and differences noted. 1‒3 AO1

No relevant content 0

Indicative Content 4.1.1.2

4.2.2.3

Differences:

• red blood cell has no nucleus or plant cell has a nucleus

• red blood cell has no cell wall or plant cell has a cell wall

• red blood cell is a biconcave disc or there are many different

shapes of plant cell

• red blood cell contains haemoglobin or plant cells do not contain

haemoglobin

• red blood cells do not contain chlorophyll or plant cells (may)

contain chlorophyll

• red blood cell has no chloroplasts or plant cell has chloroplasts

• red blood cell has no (permanent) vacuole or plant cell has

(permanent) vacuole

• red blood cells are (much) smaller than plant cells

Similarities:

both have:

• cytoplasm

• cell membrane

• pigments (although they are different)

ignore references to mitochondria and ribosomes

for Level 2, consideration of both red blood cells and plant cells is

required.

07.6 water enters (the cells) by allow water enters and the cell 1 AO2

osmosis / diffusion starts to swell

ignore explanations of osmosis

plant cell has a cell wall (which allow red blood cell has no cell 1 AO1

prevents it from bursting) wall (so it swells and bursts)

4.1.3.2

4.1.1.2

Total 13

How to answer it

Microscopy, Cell Structure & Osmosis in Blood Cells

📌 What this question tests

This 13-mark question assesses fundamental laboratory practical skills (Required Practical 1: Microscopy), parts of a light microscope and troubleshooting, an extended comparison of specialised animal cells vs plant cells, and the biological explanation of osmosis in plant and animal cells.

Question 07.1: Equipment for Slide Preparation

Name two pieces of laboratory equipment used to prepare cells to view using a microscope [2 marks]

✅ Acceptable Answers (Any Two)

  • (Microscope) slide
  • Cover slip
  • Dye / stain (e.g. methylene blue, iodine)
  • Pipette / dropper
  • (Mounted) needle
  • Forceps / tweezers
  • Scalpel
  • Swab (to collect cheek cells)

❌ Common Errors & What Gets Ignored

  • Water is ignored (it is not a piece of laboratory equipment).
  • Writing "knife" instead of scalpel is not credited.
  • Naming parts of the microscope itself (e.g. stage, lens) — the question asks for equipment used to prepare the cells.
Award 1 mark for each correct named piece of equipment up to a maximum of 2.

Questions 07.2 & 07.3: Microscope Anatomy & Function

07.2: Name part A [1 mark]  |  07.3: Function of part B [1 mark]

✅ Correct Answers

  • Part A: Eyepiece / eyepiece lens
  • Part B function: To focus (the image / cells) or make the image clearer / improve resolution.

🧠 Exam Technique: Focus vs Magnification

  • Part B is the focusing knob (coarse/fine adjustment knob). Its job is strictly focusing.
  • Never say Part B is for "zooming in" or "magnifying" — magnification is controlled by switching objective lenses!
  • Merely stating "to move the stage up and down" is an action, not a biological function; the mark requires mentioning focusing or clarity of the image.
07.2: 1 mark for eyepiece. Do NOT accept objective lens.
07.3: 1 mark for focusing. Do NOT accept references to magnification.

Question 07.4: Troubleshooting Under the Microscope

Suggest one reason why the student could not see any cells [1 mark]

✅ Acceptable Reasons (Any One)

  • No cells in the field of view
  • Slide is not in the correct position / not over the light hole
  • Mirror not aligned / light not turned on / not plugged in
  • Objective lens not clicked into place
  • Objective lens is dirty
  • Looking at an air bubble instead of cells
  • Microscope is not focused
  • Cells were not stained (so are transparent/invisible)
  • Magnification is not high enough

🧠 How to Think Like an Examiner

Imagine setting up a microscope in class. What physical things can go wrong?

  • Light path blocked: lamp off, mirror tilted away, lens not clicked in.
  • Positioning: slide off-centre, cell sample missed.
  • Image quality: unfocused or unstained specimen.
1 mark for any one scientifically valid troubleshooting reason.

Question 07.5: Comparing Red Blood Cells with Plant Cells

Compare the structure of a red blood cell with the structure of a plant cell [6 marks]

🧠 How Level 2 (5–6 marks) is Achieved

A "compare" question demands both similarities and differences. To reach the top mark band (Level 2, 5–6 marks), you must discuss features of both cell types clearly and explicitly compare them.

💡 Structural Differences (Red Blood Cell vs Plant Cell)

Feature Red Blood Cell (RBC) Plant Cell (e.g. Palisade)
Nucleus No nucleus (mature RBC) Has a nucleus
Cell Wall No cell wall Has a cellulose cell wall
Vacuole No permanent vacuole Has a large permanent vacuole
Chloroplasts None Present (in photosynthetic plant cells)
Pigment Contains haemoglobin May contain chlorophyll
Shape Biconcave disc shape Regular / rectangular shape
Size Much smaller (~7–8 µm) Much larger (~20–100 µm)

✅ Structural Similarities (Both Have)

  • Both have a cell membrane
  • Both have cytoplasm
  • Both contain pigments (haemoglobin vs chlorophyll)

⚠️ Examiner Note on Organelles

Mature mammalian red blood cells lack mitochondria and ribosomes. The mark scheme explicitly notes to ignore references to mitochondria and ribosomes.

Marking Criteria:
Level 2 (4–6 marks): Scientifically relevant structural features identified; comparisons (similarities and differences) between both red blood cells and plant cells are clearly made.
Level 1 (1–3 marks): Relevant features are listed, but mainly differences or only one cell type described without clear direct comparison.

Question 07.6: Osmosis and Cell Lysis

Explain why the red blood cell bursts but the plant cell does not burst in water [2 marks]

✅ Model Answer (2 Marks)

Mark 1: Water enters both cells by osmosis (down a water potential / concentration gradient).

Mark 2: The plant cell has a rigid cell wall made of cellulose which withstands internal pressure and prevents it from bursting (it becomes turgid), whereas the red blood cell has no cell wall.

❌ Common Errors

  • Forgetting to name the process: simply stating "water goes inside" misses Mark 1 unless osmosis or diffusion is credited.
  • Attributing the strength to the cell membrane rather than the cell wall. Membranes are fragile and burst easily!
  • Wasting time giving long definitions of osmosis (e.g. "partially permeable membrane from dilute to concentrated solution") — the mark scheme explicitly states: ignore explanations of osmosis. Just state water enters by osmosis.
Mark 1: Water enters (the cells) by osmosis / diffusion.
Mark 2: Plant cell has a cell wall which prevents it from bursting (or red blood cell lacks a cell wall).

Topics

Biology · Required Practicals · B1: Cell Biology · Required Practicals

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.