O Level / IGCSE Biology chapter 1: Cells MCQs with answers
By Team Megalecture · Updated 4 Nov 2026
20 exam-style questions on Cells, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
1. A mitochondrion is 3 µm long. A student draws it at a magnification of ×20 000. How long is the drawing, in mm?
A
600 mm
B
6 mm
C
0.06 mm
D
60 mm
Show answer
Answer: D. Drawing length = actual length × magnification = 3 µm × 20 000 = 60 000 µm, and 60 000 µm ÷ 1000 = 60 mm.
2. Which three structures are present in a palisade mesophyll cell but absent from a human liver cell?
A
cell wall, chloroplasts and a large sap vacuole
B
chloroplasts, a sap vacuole and a cell membrane
C
cell wall, chloroplasts and a well-defined nucleus
D
cell wall, ribosomes and a large sap vacuole
Show answer
Answer: A. Only plant cells have a cellulose cell wall, chloroplasts and a large permanent sap vacuole. Both cell types have a nucleus, cytoplasm, membrane, mitochondria and ribosomes.
3. A plant cell and an animal cell are placed in distilled water. The animal cell bursts but the plant cell does not. Which part of the plant cell explains this?
A
the chloroplasts, which use up the extra water in photosynthesis
B
the mitochondria, which use energy to pump the water back out
C
the cellulose cell wall, which resists the pressure of the water entering
D
the cell membrane, which is thicker and stops water crossing it
Show answer
Answer: C. The strong cellulose cell wall is fully permeable but resists the pressure of the water that enters, so the cell becomes turgid instead of bursting. An animal cell has no wall to resist this pressure.
4. A cell taken from the root of a plant is compared with a palisade cell from a leaf. Which structure does the palisade cell have that the root cell lacks?
A
a cellulose cell wall
B
chloroplasts
C
ribosomes
D
a large sap vacuole
Show answer
Answer: B. A root cell has a cell wall, nucleus and sap vacuole, but it lives underground with no light, so it has no chloroplasts. A palisade cell in the leaf has many.
5. Which statement describes the genetic material of a bacterial cell?
A
a single circular DNA molecule in the cytoplasm, with small plasmids
B
several linear chromosomes enclosed within a double nuclear membrane, with no plasmids
C
many separate linear chromosomes free in the cytoplasm
D
plasmids only, held inside a small nucleus
Show answer
Answer: A. A bacterial cell has no nucleus. Its main DNA is one circular molecule lying free in the cytoplasm, and it often also has small circles of DNA called plasmids.
6. How is the long, thin extension of a root hair cell related to its function?
A
it anchors the plant firmly in the soil so that it is not blown over
B
it holds extra chloroplasts so that more photosynthesis can take place
C
it increases the surface area for absorbing water and mineral ions
D
it stores starch so that the root has a supply of energy for the winter
Show answer
Answer: C. The long, thin extension of a root hair cell greatly increases its surface area, so more water and mineral ions can be absorbed. Root hair cells have no chloroplasts in the soil.
7. A mature human red blood cell has no nucleus. What is the advantage of this?
A
it can make more of its own proteins, so the cell lasts longer
B
there is more room for haemoglobin, so more oxygen can be carried to the tissues
C
it can divide more quickly, so damaged cells are replaced faster
D
it can engulf pathogens more easily, so the blood is protected
Show answer
Answer: B. With no nucleus there is more space for haemoglobin, which carries oxygen. Red blood cells cannot divide or make proteins, and engulfing pathogens is done by white blood cells.
8. In which structure of an animal cell does aerobic respiration take place?
A
mitochondrion
B
ribosome
C
nucleus
D
cell membrane
Show answer
Answer: A. Mitochondria are the site of aerobic respiration, which releases energy from glucose. Ribosomes make proteins.
9. A drawing of a cell is 60 mm long. The magnification of the drawing is ×400. What is the actual length of the cell?
A
0.15 µm
B
150 µm
C
24 000 µm
D
15 µm
Show answer
Answer: B. Actual size = image size ÷ magnification = 60 mm ÷ 400 = 0.15 mm, and 0.15 mm × 1000 = 150 µm.
10. A student places a thin layer of onion epidermis on a slide and adds a drop of iodine solution before looking at it under the microscope. Why is the iodine added?
A
to make the cells swell so that they look bigger
B
to stain the structures so that they show up clearly
C
to test the cells for the presence of glucose
D
to kill the cells so that they stop moving
Show answer
Answer: B. Cell structures are almost colourless, so a stain such as iodine or methylene blue is added to make the nucleus and other parts visible. Iodine tests for starch, not glucose, and it does not enlarge cells.
20, each with the answer and a short explanation, across 2 topics: Cell structure and function, Specialised cells, tissues and organs. Every chapter test draws ten of them, so you can take it many times.
Is the O Level / IGCSE Biology chapter 1 test free?
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
How is the chapter test marked?
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
