Cell Structure and Organisation: Practice Questions

These are original questions written for Marlbridge, in the style and at the standard of the examination. They are not reproduced past-paper questions — examination boards hold copyright in their own papers. Use these alongside the official past papers available free from your board.

Related: Cell Structure and Organisation revision notes

---

Section A

1. State the function of the cell membrane, nucleus, mitochondrion and ribosome. [4]

2. Name three structures found in a plant cell but not an animal cell, and give the function of each. [6]

Section B

3. A root hair cell is adapted for absorbing water and mineral ions.

(a) Describe two adaptations and explain how each helps. [4] (b) Explain why root hair cells contain many mitochondria. [2]

4. Red blood cells, ciliated cells and palisade mesophyll cells are all specialised.

(a) For each, state one adaptation and the function it serves. [6] (b) Define the terms tissue, organ and organ system, giving an example of each. [6]

5. A cell is 0.05 mm long and is drawn 40 mm long.

(a) Calculate the magnification. [2] (b) Express the actual length in micrometres. [1]

6. A student compares a bacterial cell with a typical plant cell.

(a) State two structural differences between them. [2] (b) Explain where the genetic material is found in a bacterial cell. [2]

7. Xylem vessels transport water up a plant.

(a) Describe two structural features of a xylem vessel. [2] (b) Explain how each feature helps the vessel carry out its function. [2]

---

Answers

1. Cell membrane — controls what enters and leaves the cell; partially permeable [1]. Nucleus — contains DNA, controls cell activities [1]. Mitochondrion — site of aerobic respiration, releasing energy as ATP [1]. Ribosome — site of protein synthesis [1].

2. Cell wall of cellulose — provides support and prevents bursting [1] [1]. Chloroplast — contains chlorophyll, absorbs light for photosynthesis [1] [1]. Permanent vacuole containing cell sap — keeps the cell turgid, storing water and solutes [1] [1].

3. (a) A long, narrow extension [1] giving a large surface area for absorption [1]. A thin cell wall and membrane [1] shortening the diffusion distance [1]. (Also accept: no chloroplasts, so more space; thin layer of cytoplasm.) (b) Mineral ions are taken up by active transport against a concentration gradient [1], which needs ATP released by aerobic respiration in the mitochondria [1].

4. (a) Red blood cell — biconcave and lacks a nucleus [1], giving a large surface area and more room for haemoglobin to carry oxygen [1]. Ciliated cell — has cilia that beat [1], moving mucus and trapped particles away from the lungs [1]. Palisade mesophyll cell — packed with chloroplasts at the top of the leaf [1], maximising light absorption for photosynthesis [1]. (b) Tissue — a group of similar cells working together, e.g. muscle tissue [1] [1]. Organ — several tissues working together for a function, e.g. the heart [1] [1]. Organ system — several organs working together, e.g. the circulatory system [1] [1].

5. (a) Magnification = image ÷ actual = 40 ÷ 0.05 [1] = ×800 [1]. (b) 0.05 mm × 1000 = 50 µm [1].

6. (a) A bacterial cell has no nucleus [1] and its cell wall is not made of cellulose (unlike a plant cell wall) [1]. (Also accept: bacteria lack chloroplasts, mitochondria and a permanent vacuole.) (b) The genetic material is free in the cytoplasm as a circular loop of DNA [1], often with additional small circles called plasmids [1] — the cell has no nucleus to contain it.

7. (a) A xylem vessel is hollow (the end walls between cells have broken down) [1] and is made of dead cells with walls thickened and strengthened by lignin [1]. (b) Being hollow allows an uninterrupted column of water to pass straight through with no cross-walls to block the flow [1]. Being dead and lignified means the vessel needs no cytoplasm (leaving the whole tube free for water) and the rigid, waterproof walls provide support and withstand the pressure changes of water movement [1].

---

Where marks are usually lost

• Saying the membrane is “fully permeable”.
• Giving an adaptation without saying what it achieves.
• Mixing up image and actual size in the magnification formula.
• Forgetting the units when converting mm to µm.
• Saying bacteria “have no DNA” — they have no nucleus, but the DNA itself is still present, free in the cytoplasm.
• Describing xylem as a living tissue — the vessel cells are dead at maturity, which is essential to how they function.
• Confusing xylem (water transport, one direction, up from the roots) with phloem (transports sugars, both directions).

Cells to know by their adaptation

Cell	Key adaptation	What it achieves
Root hair cell	Long, thin extension	Large surface area for water/ion uptake
Xylem vessel	Hollow, dead, lignified	Uninterrupted water column; support
Red blood cell	Biconcave, no nucleus	More space and surface area for oxygen transport
Palisade mesophyll cell	Many chloroplasts, top of leaf	Maximum light absorption
Ciliated cell	Cilia that beat	Moves mucus and trapped particles

This table is worth memorising as a set — exam questions on this topic almost always ask for the adaptation and the reason it helps, and the two must be paired correctly to score both marks. For the full explanation of cell structure across animal, plant and bacterial cells, see the Cell Structure and Organisation revision notes and the linked study guide.