Cell – Structure and Functions – MCQs with Answers and Explanations
CBSE Class 8 Science — Chapter 8: Cell — Structure and Functions
50 Multiple Choice Questions (MCQs) — Topic-wise • NCERT-aligned • Board-exam standard
Class: 8
Subject: Science
Chapter: Cell — Structure & Functions
CBSE Board Examinations (Study order):
- Study NCERT diagrams and organelle functions thoroughly.
- Practice transport processes, compare plant vs animal cells, and do microscopy exercises.
- Use topic-wise MCQs for quick revision and self-assessment.
Topic 1 — Basics & Cell Theory (Q1–Q8)
- Q1. Who first used the term 'cell' after observing cork under a microscope?Answer: BExplanation: Robert Hooke coined the term 'cell' in 1665 when observing cork tissue under a microscope.
- Q2. Which statement is NOT part of the cell theory?Answer: DExplanation: Modern cell theory rejects spontaneous generation; cells arise from other cells.
- Q3. Which of these is an example of a unicellular organism?Answer: BExplanation: Amoeba is a single-celled organism performing all life functions within one cell.
- Q4. Eukaryotic cells differ from prokaryotic cells because they:Answer: BExplanation: Eukaryotic cells (plants, animals) contain membrane-bound organelles like nucleus, mitochondria.
- Q5. Cytoplasm in a cell is:Answer: BExplanation: Cytoplasm is a gel-like fluid that holds organelles and is the site for many metabolic reactions.
- Q6. Which organelle contains genetic material in a eukaryotic cell?Answer: CExplanation: The nucleus houses DNA which carries hereditary information and controls cell activities.
- Q7. Which of the following is NOT an organelle?Answer: BExplanation: Cytoskeleton is a network of fibres (cell structure), not a membrane-bound organelle like others listed.
- Q8. Which process is mainly carried out in mitochondria?Answer: CExplanation: Mitochondria are the site of cellular respiration, producing ATP from food molecules.
Topic 2 — Cell Membrane & Transport (Q9–Q18)
- Q9. The cell membrane is mainly made up of:Answer: BExplanation: The phospholipid bilayer with embedded proteins forms the selectively permeable cell membrane.
- Q10. Selective permeability refers to the membrane's ability to:Answer: CExplanation: Selective permeability enables cells to control internal composition by regulating transport.
- Q11. Which of these moves by diffusion across membranes?Answer: AExplanation: Small nonpolar molecules like oxygen diffuse through membranes; large molecules require transporters.
- Q12. Osmosis is the movement of:Answer: BExplanation: Osmosis is water movement across a semi-permeable membrane toward higher solute concentration.
- Q13. Active transport differs from passive transport because it:Answer: CExplanation: Active transport uses ATP to pump ions or molecules against their concentration gradients (e.g., Na⁺/K⁺ pump).
- Q14. Which example illustrates diffusion in organisms?Answer: BExplanation: Oxygen diffuses from high concentration in alveoli to lower concentration in blood across respiratory membranes.
- Q15. Plasmolysis occurs when plant cells are placed in:Answer: CExplanation: In hypertonic solutions water leaves the cell, the membrane pulls away from the cell wall causing plasmolysis.
- Q16. Which cell adaptation increases absorption in roots?Answer: BExplanation: Root hairs increase surface area for water and mineral absorption through diffusion and active transport.
- Q17. Which transport uses vesicles to move large particles into the cell?Answer: BExplanation: Endocytosis engulfs large particles or fluids into vesicles; exocytosis exports materials out of the cell.
- Q18. Which molecule would most likely require a carrier protein to cross the membrane?Answer: CExplanation: Large polar molecules like glucose require facilitated diffusion via transport proteins.
Topic 3 — Nucleus, DNA & Cell Division (Q19–Q26)
- Q19. DNA is made up of units called:Answer: CExplanation: Nucleotides (sugar, phosphate, base) are the building blocks of DNA and RNA.
- Q20. Chromosomes are most visible during which phase of cell division?Answer: BExplanation: Chromosomes condense and are clearly visible during prophase and metaphase of mitosis.
- Q21. Binary fission is a method of reproduction in:Answer: CExplanation: Bacteria reproduce by binary fission, a simple division of the cell into two.
- Q22. Which structure directs all activities of a eukaryotic cell?Answer: BExplanation: The nucleus contains DNA and manages cell functions by controlling protein synthesis.
- Q23. Mitosis results in the formation of:Answer: BExplanation: Mitosis produces two genetically identical daughter cells for growth and repair.
- Q24. Which process copies DNA into mRNA?Answer: BExplanation: Transcription is the process where genetic information in DNA is copied to messenger RNA.
- Q25. Which organelle assembles amino acids into proteins?Answer: BExplanation: Ribosomes translate mRNA into polypeptide chains (proteins).
- Q26. A mutation in a gene may cause:Answer: BExplanation: Mutations can alter the amino acid sequence of proteins, changing their function; effects vary from neutral to harmful or rarely beneficial.
Topic 4 — Major Organelles & Functions (Q27–Q36)
- Q27. Which organelle is responsible for packaging and shipping proteins?Answer: BExplanation: Golgi apparatus modifies, sorts and packages proteins into vesicles for transport.
- Q28. Rough endoplasmic reticulum is distinct because it:Answer: BExplanation: Ribosomes on rough ER synthesise proteins destined for secretion or membrane insertion.
- Q29. Lysosomes help the cell by:Answer: BExplanation: Lysosomes contain enzymes that break down macromolecules and recycle cellular components.
- Q30. Which statement about vacuoles is correct?Answer: BExplanation: Plant vacuoles store water and solutes and maintain turgidity; animal vacuoles are smaller if present.
- Q31. Which organelle contains chlorophyll?Answer: BExplanation: Chloroplasts contain chlorophyll to capture light energy for photosynthesis.
- Q32. Which organelle would you expect to be abundant in secretory cells (e.g., pancreas)?Answer: AExplanation: Secretory cells synthesise proteins on rough ER and process them in Golgi for secretion.
- Q33. Which structures are directly involved in protein synthesis?Answer: BExplanation: Ribosomes assemble amino acids; those on rough ER synthesise proteins for export or membranes.
- Q34. Which organelle plays a role in detoxification of drugs in liver cells?Answer: BExplanation: Smooth ER is involved in lipid synthesis and detoxification of harmful substances in liver cells.
- Q35. Which of the following is TRUE about lysosomes?Answer: BExplanation: Lysosomes digest cellular waste using hydrolytic enzymes.
- Q36. Which organelle is essential for aerobic respiration?Answer: BExplanation: Mitochondria oxidise substrates to produce ATP using oxygen—key to aerobic respiration.
Topic 5 — Photosynthesis & Cellular Respiration (Q37–Q42)
- Q37. Photosynthesis primarily occurs in which plant cell organelle?Answer: BExplanation: Chloroplasts contain chlorophyll and the thylakoid membranes where light-dependent reactions occur.
- Q38. Which gas is released during photosynthesis?Answer: BExplanation: Oxygen is a by-product of splitting water during the light reactions of photosynthesis.
- Q39. Cellular respiration produces energy mainly in the form of:Answer: BExplanation: ATP (adenosine triphosphate) is the energy currency produced by respiration in mitochondria.
- Q40. Where does the light-independent (Calvin cycle) stage of photosynthesis occur?Answer: AExplanation: The Calvin cycle takes place in the stroma of the chloroplast where CO₂ is fixed into sugars.
- Q41. Which molecule is the immediate source of energy for cellular activities?Answer: BExplanation: ATP releases energy when its phosphate bonds are broken to fuel cellular processes.
- Q42. Anaerobic respiration in muscle cells leads to the production of:Answer: BExplanation: In low oxygen conditions, muscle cells undergo anaerobic respiration producing lactic acid and less ATP.
Topic 6 — Specialised Cells, Tissues & Adaptations (Q43–Q47)
- Q43. Root hair cells are adapted for absorption because they:Answer: BExplanation: Root hairs increase the surface area to enhance water and mineral uptake from soil.
- Q44. Which tissue conducts water in plants?Answer: BExplanation: Xylem vessels transport water and minerals from roots to shoots by transpiration pull.
- Q45. Nerve cells are specialised to:Answer: BExplanation: Nerve cells (neurons) have long processes to carry impulses and communicate between body parts.
- Q46. Guard cells control the opening of stomata by changing their:Answer: BExplanation: When guard cells become turgid they curve and open the stomatal pore; loss of turgor closes it.
- Q47. Which blood cells transport oxygen in humans?Answer: CExplanation: Red blood cells contain haemoglobin which binds and transports oxygen to tissues.
Topic 7 — Microscopy, Observation & Practical Tips (Q48–Q50)
- Q48. Which microscope is most commonly used in school laboratories to view cells?Answer: BExplanation: Compound light microscopes use lenses and visible light; suitable for viewing cell structures like nucleus, cell wall.
- Q49. Which stain is commonly used in school to observe cell structures like nucleus in onion peel?Answer: AExplanation: Iodine stains starch and helps visualise cell structures like nucleus in plant cells.
- Q50. When preparing a slide, you should avoid which of the following mistakes?Answer: CExplanation: Thick specimens block light and prevent clear observation; thin mounting is essential for microscopy.
These MCQs and explanations are strictly aligned with NCERT content for CBSE Class 8 Chapter 8 and crafted to aid conceptual clarity and exam preparation.