A-Level Biology Topic 1: Cell Structure MCQs – 30 Practice Questions with Answers (Cambridge 9700)

Practice for Cambridge International AS and A Level Biology 9700, Topic 1, covering microscopes, measurements, organelles, prokaryotic cells and viruses, with a short explanation after every question.

Microscopes and Measurement

Q1. What is meant by magnification?

  • (A) How much larger an image appears than the real specimen
  • (B) How much detail can be seen in the image at that magnification
  • (C) How bright an image appears
  • (D) How much colour an image shows
Show Answer

Answer: A – Magnification is the factor by which an image is enlarged compared with the actual size of the specimen.

Q2. What is meant by resolution?

  • (A) The size of the microscope lens
  • (D) The depth of field in a slide
  • (C) The total enlargement of a specimen
  • (B) The ability to distinguish two separate points as distinct
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Answer: D – Resolution is the ability to see two close points as separate, which is different from simply enlarging an image.

Q3. An image of a cell is 20 mm long and its actual length is 0.02 mm. What is the magnification?

  • (A) ×100
  • (C) ×10
  • (B) ×1000
  • (D) ×400
Show Answer

Answer: C – Magnification equals image size divided by actual size, so 20 divided by 0.02 gives 1000.

Q4. How many micrometres are there in 1 mm?

  • (A) 10
  • (B) 100
  • (C) 1000
  • (D) 1000000
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Answer: C – One millimetre contains 1000 micrometres, so lengths must be converted to the same unit before calculating magnification.

Q5. How many nanometres are there in 1 micrometre?

  • (A) 10
  • (B) 100
  • (C) 1000
  • (D) 10000
Show Answer

Answer: C – One micrometre equals 1000 nanometres, a conversion often needed when working from electron micrographs.

Q6. What is an eyepiece graticule used for?

  • (A) Staining cell walls
  • (D) Preserving prepared slides
  • (C) Focusing the condenser
  • (B) Measuring specimens seen through a microscope
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Answer: D – An eyepiece graticule is a scale in the eyepiece that allows the size of a specimen to be measured in graticule units.

Q7. Why must an eyepiece graticule be calibrated before use?

  • (A) Its divisions represent different lengths at different magnifications
  • (B) Its divisions gradually change colour over time when the microscope is used
  • (C) It only works with stained material
  • (D) It loses divisions when heated
Show Answer

Answer: A – The real length of one graticule division depends on the magnification, so calibration against a stage micrometer is needed for each objective.

Q8. Which instrument is used to calibrate an eyepiece graticule?

  • (B) A stage micrometer scale
  • (A) A coverslip
  • (C) A cavity slide
  • (D) A haemocytometer grid
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Answer: A – A stage micrometer has a scale of known length, so it can be used to find the value of one eyepiece graticule division.

Q9. Why does an electron microscope give higher resolution than a light microscope?

  • (A) It uses a shorter wavelength than light
  • (B) It uses larger lenses that magnify the specimen much more
  • (C) It uses brighter illumination
  • (D) It uses thicker specimens
Show Answer

Answer: A – Electrons have a much shorter wavelength than visible light, so an electron microscope can resolve finer detail.

Q10. A student draws a cell from a photomicrograph. Which practice gives the most useful drawing?

  • (A) Shading the whole cell dark
  • (D) Drawing only the nucleus
  • (C) Adding colours not seen in the image
  • (B) Drawing clear outlines with correct proportions and a scale
Show Answer

Answer: D – A good biological drawing shows clear outlines, realistic proportions and a stated magnification or scale bar.

Organelles and Eukaryotic Cells

Q11. Which organelle is the site of most ATP production in a eukaryotic cell?

  • (A) The Golgi body
  • (D) The ribosome
  • (C) The lysosome
  • (B) The mitochondrion
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Answer: D – Mitochondria carry out aerobic respiration, producing ATP for energy-requiring processes in the cell.

Q12. What is the function of the nucleolus?

  • (A) It produces ribosomal RNA and assembles ribosome subunits
  • (B) It stores starch grains
  • (C) It breaks down worn organelles and stores the products for later use
  • (D) It controls movement of cilia
Show Answer

Answer: A – The nucleolus, inside the nucleus, is where ribosomal RNA is made and ribosome subunits are assembled.

Q13. Which structure separates the nucleus from the cytoplasm?

  • (A) The tonoplast
  • (D) The plasmodesma
  • (C) The cell wall
  • (B) The nuclear envelope
Show Answer

Answer: D – The nuclear envelope is a double membrane surrounding the nucleus, with pores that control movement in and out.

Q14. Rough endoplasmic reticulum differs from smooth endoplasmic reticulum because it has what on its surface?

  • (A) Chlorophyll pigments
  • (B) Ribosomes
  • (C) Lysosomes
  • (D) Centrioles
Show Answer

Answer: B – Rough endoplasmic reticulum carries ribosomes on its surface and is involved in protein synthesis and transport.

Q15. What is a main function of smooth endoplasmic reticulum?

  • (A) Making ribosomal RNA for new ribosomes in the cytoplasm
  • (B) Producing ATP
  • (C) Synthesising lipids and steroids
  • (D) Digesting bacteria
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Answer: C – Smooth endoplasmic reticulum lacks ribosomes and is involved in lipid and steroid synthesis.


Q16. What is the main role of the Golgi body?

  • (A) Modifying, packaging and secreting proteins
  • (B) Carrying out photosynthesis using light energy in the cell
  • (C) Producing ribosomes
  • (D) Storing genetic information
Show Answer

Answer: A – The Golgi body modifies proteins received from the endoplasmic reticulum, packages them and prepares them for secretion.

Q17. Which organelle contains hydrolytic enzymes that digest worn-out cell material?

  • (A) The vacuole
  • (D) The centriole
  • (C) The chloroplast
  • (B) The lysosome
Show Answer

Answer: D – Lysosomes contain hydrolytic enzymes that break down ingested material and worn-out organelles.

Q18. Which ribosomes are found in mitochondria and chloroplasts?

  • (A) 80S ribosomes only
  • (B) 70S ribosomes
  • (C) 60S ribosomes only
  • (D) 90S ribosomes
Show Answer

Answer: B – Mitochondria and chloroplasts contain smaller 70S ribosomes, while the cytoplasm of eukaryotic cells contains 80S ribosomes.

Q19. What do mitochondria and chloroplasts both contain in addition to their own ribosomes?

  • (A) A large central vacuole
  • (D) A protein capsid
  • (C) A peptidoglycan wall
  • (B) Small circular DNA
Show Answer

Answer: D – Both mitochondria and chloroplasts contain small circular DNA, which supports their ability to make some of their own proteins.

Q20. Which pair of structures is found in a typical plant cell but not in a typical animal cell?

  • (A) Nucleus and mitochondria
  • (B) Chloroplasts and a large permanent vacuole
  • (C) Ribosomes and Golgi body
  • (D) Cell surface membrane and lysosomes, both found in animal cells
Show Answer

Answer: B – Plant cells typically have chloroplasts and a large permanent vacuole bounded by the tonoplast, which animal cells lack.

Prokaryotic Cells and Viruses

Q21. What is the typical diameter range of a bacterial cell given in the syllabus?

  • (A) 10–50 micrometres
  • (B) 1–5 micrometres
  • (C) 50–100 micrometres
  • (D) 0.1–0.5 micrometres
Show Answer

Answer: B – A typical bacterial cell is generally 1–5 micrometres in diameter, much smaller than most eukaryotic cells.

Q22. Which material forms the wall of a typical bacterial cell?

  • (A) Cellulose, as in plant cell walls
  • (B) Chitin
  • (C) Peptidoglycan
  • (D) Collagen
Show Answer

Answer: C – Bacterial cell walls are made of peptidoglycan, unlike plant cell walls, which are mainly cellulose.

Q23. What form does the genetic material of a typical bacterium take?

  • (A) Linear DNA in a nucleus
  • (B) Circular DNA free in the cytoplasm
  • (C) RNA in a capsid
  • (D) DNA wrapped in histones inside a membrane-bound nucleus
Show Answer

Answer: B – Bacteria have circular DNA that lies free in the cytoplasm, since they have no membrane-bound nucleus.

Q24. Which feature distinguishes a prokaryotic cell from a eukaryotic cell?

  • (A) It has a cell surface membrane surrounding the cytoplasm
  • (B) It has ribosomes
  • (C) It lacks organelles surrounded by double membranes
  • (D) It carries out respiration
Show Answer

Answer: C – Prokaryotic cells lack membrane-bound organelles such as mitochondria and chloroplasts, which are surrounded by double membranes.

Q25. Which ribosomes are found in a bacterial cell?

  • (A) 80S ribosomes
  • (B) 70S ribosomes
  • (C) 40S ribosomes
  • (D) No ribosomes
Show Answer

Answer: B – Bacterial cells contain 70S ribosomes, smaller than the 80S ribosomes in eukaryotic cytoplasm.

Q26. What are plasmodesmata?

  • (A) Channels through plant cell walls linking neighbouring cells
  • (B) Pores in the nuclear envelope
  • (C) Folds in the inner mitochondrial membrane that increase its surface area
  • (D) Tubes that move water in roots
Show Answer

Answer: A – Plasmodesmata are narrow channels through plant cell walls that connect the cytoplasm of adjacent cells.

Q27. What is the function of microvilli on some animal cells?

  • (A) They move the cell through fluid by beating in a coordinated way
  • (B) They increase surface area for absorption
  • (C) They produce ATP
  • (D) They form the cell wall
Show Answer

Answer: B – Microvilli are small folds of the cell surface membrane that greatly increase the surface area available for absorption.

Q28. Which statement about viruses is correct?

  • (A) All viruses are made of cells
  • (B) All viruses have a nucleic acid core and a protein capsid
  • (C) All viruses contain both DNA and RNA in the same particle
  • (D) All viruses have a peptidoglycan wall
Show Answer

Answer: B – Viruses are non-cellular structures with a nucleic acid core, either DNA or RNA, surrounded by a protein capsid.

Q29. Some viruses have an outer envelope. What is this envelope made of?

  • (A) Cellulose
  • (B) Peptidoglycan
  • (C) Phospholipids
  • (D) Chitin
Show Answer

Answer: C – Some viruses possess an outer envelope made of phospholipids, derived from the host cell membrane.

Q30. Why do viruses raise the question of whether cells are the basic unit of life?

  • (A) Viruses are non-cellular yet can reproduce inside host cells
  • (B) Viruses have no genetic material and cannot reproduce in any way
  • (C) Viruses are larger than bacteria
  • (D) Viruses carry out photosynthesis
Show Answer

Answer: A – Viruses are not cells, yet they can replicate using a host cell, which challenges a simple definition of life based on cells alone.

Work through any questions you missed again, then revise those areas before moving on to the next topic.