10 free IGCSE Biology Organisation of the Organism questions written in the style of Cambridge Biology papers: 3 multiple-choice and 7 structured, each with its answer and mark scheme. 4 of them are A* challenge questions, built to catch the mistakes strong students still make.
This topic covers Cell structure, Cell size & magnification. Work through the questions below, then generate a full Organisation of the Organism paper with a fresh set every time.
Generate a full Organisation of the Organism paper →Which row matches the cell structure with its function?
| ribosome | mitochondrion | cell wall | |
|---|---|---|---|
| A | protein synthesis | aerobic respiration | controls what enters the cell |
| B | protein synthesis | aerobic respiration | prevents the cell bursting |
| C | protein synthesis | photosynthesis | controls what enters the cell |
| D | aerobic respiration | protein synthesis | prevents the cell bursting |
Answer: B
A drawing of a cell is 36 mm long. The magnification of the drawing is ×600.
What is the actual length of the cell?
Answer: C
A cell is 23 µm long. In a drawing, its image is 27 mm long. What is the magnification?
Answer: A
A student measures a cell with a microscope.
Convert 0.08 mm into micrometres.
The image of a 80 µm cell is 40 mm long. Calculate the magnification.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 80 µm 80 µm B1 | 1 |
| (b) | ×500 40 mm = 40 000 µm C1 40 000 ÷ 80 = ×500 A1 | 2 |
Different cell structures have different functions.
State the function of the mitochondria.
State the function of the ribosomes.
State the function of the cell wall.
Explain why muscle cells contain many mitochondria.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | aerobic respiration site of aerobic respiration (releases energy) B1 | 1 |
| (b) | protein synthesis protein synthesis B1 | 1 |
| (c) | support/prevents bursting gives support and stops the cell bursting B1 | 1 |
| (d) | need much energy muscle cells need a lot of energy for contraction B1 mitochondria release energy by aerobic respiration B1 | 2 |
Plant and animal cells have structural similarities and differences.
Name three structures found in both plant and animal cells.
Name three structures found in plant cells but not animal cells.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | nucleus, cytoplasm, cell membrane, mitochondria, ribosomes Any 3 of: any three of: nucleus; cytoplasm; cell membrane; mitochondria; ribosomes B3 | 3 |
| (b) | cell wall, chloroplasts, permanent vacuole cell wall B1 chloroplasts B1 large permanent vacuole B1 | 3 |
A student draws a cell. The length of the cell in the drawing is 24 mm. The magnification of the drawing is ×400.
Write the formula linking magnification, image size and actual size.
Calculate the actual length of the cell in µm.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | M = image ÷ actual magnification = image size ÷ actual size B1 | 1 |
| (b) | 60 µm actual = 24 ÷ 400 = 0.06 mm C1 × 1000 C1 60 µm A1 | 3 |
A student prepares a slide of onion epidermis cells.
Describe how to prepare the slide.
Explain why iodine solution is added.
Explain why onion cells have no chloroplasts.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | peel epidermis, water/iodine, coverslip at angle peel a thin layer of epidermis B1 place on a slide with a drop of water/iodine B1 lower a coverslip at an angle to avoid air bubbles B1 | 3 |
| (b) | stains nucleus/starch to make visible to stain the cells so structures (nucleus) are visible B1 | 1 |
| (c) | underground, no light the bulb grows underground with no light, so no photosynthesis B1 | 1 |
A cheek cell has an actual diameter of 25 µm. It is viewed with a microscope at a magnification of ×100.
Calculate the diameter of the image in mm.
State why micrometres are used to measure cells.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 2.5 mm image = actual × magnification = 2500 µm C1 2.5 mm A1 | 2 |
| (b) | cells are very small Any 1 of: cells are very small; micrometres give convenient numbers B1 | 1 |
This question is about specialised cells.
Define the term tissue.
Explain how a red blood cell is adapted for transporting oxygen.
Explain how ciliated cells in the trachea protect the lungs.
A red blood cell measures 30 mm in a photograph taken at a magnification of × 400. Calculate its actual diameter in micrometres.
Explain how a palisade mesophyll cell is adapted to its function.
Explain why a muscle cell contains many more mitochondria than a skin cell.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | group of cells with similar structures working together for a shared function a group of cells with similar structures, working together to perform a shared function B1 | 1 |
| (b) | biconcave, large surface area; no nucleus, more haemoglobin; small and flexible to pass through capillaries biconcave shape gives a large surface area B1 no nucleus so more space for haemoglobin B1 small and flexible to squeeze through capillaries B1 | 3 |
| (c) | cilia beat; move mucus with trapped pathogens away from lungs cilia beat / move rhythmically B1 sweeping mucus containing trapped dust and pathogens up and away from the lungs B1 | 2 |
| (d) | 75.0 µm actual size = image size / magnification = 30/400 M1 = 0.0750 mm M1 75.0 µm A1 | 3 |
| (e) | many chloroplasts for photosynthesis; column shape packed near upper surface many chloroplasts to absorb light for photosynthesis B1 tall shape and closely packed near the upper surface B1 | 2 |
| (f) | muscle needs lots of energy for contraction; mitochondria site of aerobic respiration muscle cells need more energy for contraction B1 mitochondria are the site of aerobic respiration, releasing energy B1 | 2 |
In the 0610 syllabus, Organisation of the Organism covers Cell structure, Cell size & magnification.
This page has 10 Organisation of the Organism questions with answers. For more, the free generator on mentorriyaz.in builds a new Organisation of the Organism paper with a full mark scheme each time you click.
Riyaz Shaikh has mentored IGCSE, IB and A Level students for 15+ years, one-on-one, online and in Mumbai. The hardest questions on this site are the ones he uses to find a student's weak points.
Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in