CBSE Class 9 Science – Chapter Wise Study Materials

History & Microscope (Q1–Q6)

1. Who coined the term "cell" and in which year?
Robert Hooke, 1665.
2. Who observed living microorganisms with simple microscopes?
Anton van Leeuwenhoek.
3. What is total magnification of a microscope with 40× objective and 10× eyepiece?
400× (40 × 10).
4. Which adjustment knob is used for coarse focusing first?
Coarse adjustment knob.
5. Give one precaution while preparing a temporary mount.
Avoid air bubbles under the cover slip.
6. What unit is commonly used to measure cell size?
Micrometre (µm).

7. State one main point of modern cell theory.
All living organisms are made of one or more cells.
8. What does "cell is the basic unit of life" mean?
Cells are the smallest units that can perform all life processes.
9. What does "cells arise from pre-existing cells" imply?
New cells form by division of existing cells.
10. Define prokaryote in one line.
A cell without a true nucleus or membrane-bound organelles.
11. Define eukaryote in one line.
A cell with a membrane-bound nucleus and organelles.
12. Give typical size range of bacterial cells.
About 1–5 µm.

13. What is the function of the nucleus?
Stores genetic material and controls cell activities.
14. What is cytoplasm?
Jelly-like fluid where organelles are suspended.
15. What is plasma membrane?
Selective barrier controlling substance entry/exit.
16. Name the site of protein synthesis.
Ribosomes.
17. Where are ribosomes found?
Free in cytoplasm or on rough ER.
18. What is chromatin?
DNA-protein complex in the nucleus (forms chromosomes).

19. Function of rough endoplasmic reticulum (RER)?
Protein synthesis and transport (has ribosomes).
20. Function of smooth ER?
Lipid synthesis and detoxification (no ribosomes).
21. Role of Golgi apparatus?
Modifies, sorts and packages proteins/lipids for secretion.
22. What are vesicles?
Membrane-bound carriers that transport substances in the cell.
23. Where are secretory proteins packaged?
In Golgi-apparatus-derived secretory vesicles.
24. Name an organelle involved in intracellular digestion.
Lysosome.

25. Why are mitochondria called 'powerhouse'?
They generate ATP via cellular respiration.
26. Which organelle contains chlorophyll?
Chloroplast.
27. Where does photosynthesis occur?
In chloroplasts (thylakoids and stroma).
28. Name one difference between mitochondria and chloroplasts.
Mitochondria are in all eukaryotes; chloroplasts only in plants/algae and perform photosynthesis.
29. Do mitochondria have their own DNA?
Yes — they contain small circular DNA.
30. Give a simple function of vacuoles in plant cells.
Storage of water, nutrients and maintaining turgor pressure.

31. What material mainly makes up plant cell walls?
Cellulose.
32. Do animal cells have cell walls?
No — animal cells have extracellular matrix instead.
33. Function of lysosomes in one line?
Contain enzymes to digest cellular waste and foreign materials.
34. What is autophagy?
Self-digestion of damaged organelles by lysosomes.
35. Role of extracellular matrix (ECM)?
Provides structural support and signalling outside animal cells.
36. Name a structural protein in ECM.
Collagen.

37. Define diffusion in one line.
Movement of particles from higher to lower concentration.
38. What is osmosis?
Diffusion of water across a selectively permeable membrane.
39. Give an example of active transport.
Sodium–potassium pump moving ions against gradient (requires ATP).
40. What happens to a plant cell in hypotonic solution?
It becomes turgid (swollen) due to water intake.
41. What is plasmolysis?
Shrinking of cell membrane away from cell wall in hypertonic solution.

42. Name the type of cell division that produces identical daughter cells.
Mitosis.
43. Give one biological purpose of mitosis.
Growth or tissue repair.
44. Name one specialised plant cell and its function.
Root hair cell — increases surface area for water absorption.
45. Name one specialised animal cell and its function.
Red blood cell — transports oxygen (in mammals, lacks nucleus).
46. Why do nerve cells have long axons?
To transmit impulses over long distances quickly.

47. Which stain is commonly used to view nuclei in onion cells?
Methylene blue (or acetocarmine/iodine for plant cells).
48. In a labeled plant cell diagram, where should chloroplasts be placed?
In the cytoplasm, especially near cell periphery where light reaches.
49. What information must you write under a microscope diagram in exams?
Name of specimen, magnification, and labels of major parts.
50. Give one quick tip to remember organelle functions.
Use mnemonics (e.g., "Mighty Mitochondria make ATP" or "Golgi packages goods").