1. The limit of resolution of the unaided human eye is:
(a) 0.01 mm
(b) 0.1 mm
(c) 1 mm
(d) 10 mm
2. Robert Hooke first observed cells in 1665 while examining a thin slice of:
(a) onion peel
(b) cork
(c) cheek cells
(d) bacteria
3. Which of the following is a selectively permeable membrane?
(a) Cell wall
(b) Plasma membrane
(c) Nuclear membrane
(d) Both (b) and (c)
4. In the potato experiment with plain water and concentrated salt solution, the movement of water across the cell membrane is an example of:
(a) diffusion
(b) osmosis
(c) active transport
(d) endocytosis
5. Prokaryotic cells differ from eukaryotic cells because they lack:
(a) cell membrane
(b) cytoplasm
(c) membrane-bound nucleus and organelles
(d) ribosomes
6. The fluid-mosaic model describes the structure of:
(a) cell wall
(b) plasma membrane
(c) nuclear membrane
(d) mitochondrial membrane
7. Which organelle is called the “powerhouse of the cell”?
(a) Ribosome
(b) Golgi apparatus
(c) Mitochondrion
(d) Lysosome
8. Chloroplasts are a type of:
(a) leucoplast
(b) chromoplast
(c) plastid
(d) vacuole
9. Assertion (A): Plant cells do not shrink in size when placed in a hypertonic solution.
Reason (R): The rigid cell wall maintains the shape of plant cells even when the cell membrane shrinks away from it.
Options:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
10. Assertion (A): Mitochondria and plastids contain their own DNA and ribosomes.
Reason (R): These organelles can synthesise some of their own proteins independently.
Options:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
11. Define the term “cell” as the basic structural and functional unit of life. Give one example each of a unicellular and a multicellular organism.
12. Differentiate between prokaryotic and eukaryotic cells on the basis of (i) presence of membrane-bound nucleus and (ii) membrane-bound organelles.
13. What is osmosis? How is it different from simple diffusion?
14. Name the two types of endoplasmic reticulum. State one function of each.
15. What is the role of the cell wall in plant cells? Why do animal cells lack a cell wall?
16. State the three postulates of the Cell Theory as proposed by Schleiden, Schwann and Virchow.
17. Describe the structure of the plasma membrane with reference to the fluid-mosaic model. How does its selectively permeable nature help the cell?
18. Draw a neat labelled diagram of a typical plant cell as seen under an electron microscope. Label any four organelles.
19. Explain the structure and function of the nucleus in a eukaryotic cell. What is the difference between chromatin and chromosomes?
20. What are plastids? Differentiate between chloroplasts, chromoplasts and leucoplasts on the basis of pigments and function.
21. Describe the process of mitosis and state its significance in the growth and repair of organisms.
22. Describe the structure and function of mitochondria with the help of a labelled diagram. Why are they called the “powerhouses of the cell”? (Diagram description required)
23. Explain the structure and functions of the following cell organelles: (i) Golgi apparatus, (ii) Lysosomes, (iii) Ribosomes. How do these organelles work together in a cell?
24. Compare and contrast mitosis and meiosis. Explain how errors in these processes can lead to tumours or genetic disorders.
Scientists studied hot springs in Puga Valley, Ladakh, where thermophilic bacteria live at nearly boiling temperatures. Calcium carbonate deposits around these springs may have protected early organic molecules and helped form the first protective membrane—the cell membrane.
25. (i) What does the presence of thermophilic bacteria tell us about the possible origin of life? (1)
(ii) How is the cell membrane described as a “universal feature of a cell”? (1)
(iii) What property of the cell membrane allows some substances to pass while blocking others? (1)
(iv) Relate the formation of the first membrane to the definition of a cell. (1)
An experiment was performed with two equal-sized potato pieces. One was placed in plain water (Beaker A) and the other in 20% salt solution (Beaker B). After one hour, the piece in Beaker A swelled while the piece in Beaker B shrank.
26. (i) Name the process responsible for the observed change in size. (1)
(ii) Why did the potato piece in plain water gain weight? (1)
(iii) Why did the potato piece in salt solution lose weight? (1)
(iv) What would happen if the same experiment were performed with cheek cells instead of potato pieces? Give reason. (1)
1. (b)
2. (b)
3. (b)
4. (b)
5. (c)
6. (b)
7. (c)
8. (c)
9. (a)
10. (a)
11. Cell = basic structural & functional unit of life (1 mark); unicellular e.g. bacteria/yeast (½ mark); multicellular e.g. human/plant (½ mark).
12. Prokaryotic: no membrane-bound nucleus (1 mark); no membrane-bound organelles (1 mark). Eukaryotic: well-defined membrane-bound nucleus and organelles (implied contrast).
13. Osmosis = diffusion of water across selectively permeable membrane (1 mark); diffusion = net movement of particles from higher to lower concentration without membrane requirement (1 mark).
14. RER – ribosomes attached, protein synthesis (1 mark); SER – no ribosomes, lipid/hormone synthesis (1 mark).
15. Cell wall provides rigidity, protection and maintains shape (1 mark); animal cells lack it because they need flexibility for movement (1 mark).
16. All living organisms made of one or more cells; cell = basic unit of structure & function; all cells arise from pre-existing cells (1 mark each).
17. Lipid bilayer + proteins (fluid-mosaic) (1 mark); selectively permeable nature controls entry/exit of substances (1 mark); maintains internal environment (1 mark).
18. Correct diagram of plant cell with any four labels (cell wall, cell membrane, nucleus, chloroplast, mitochondria, vacuole, etc.) – 3 marks (diagram + labels).
19. Double membrane with pores, nucleolus, chromatin/chromosomes (1 mark); controls cellular activities & inheritance (1 mark); chromatin = thread-like in non-dividing cell, chromosomes = rod-shaped during division (1 mark).
20. Plastids = double-membrane organelles in plant cells (1 mark); chloroplast – chlorophyll (photosynthesis); chromoplast – other pigments (colour); leucoplast – no pigment (storage) (2 marks).
21. Mitosis = division producing two identical daughter cells (1 mark); maintains chromosome number (1 mark); significance – growth, repair, asexual reproduction (1 mark).
22. Double membrane, cristae, own DNA & ribosomes (2 marks); site of cellular respiration & ATP production (2 marks); labelled diagram description (outer/inner membrane, cristae, matrix) (1 mark).
23. Golgi – modifies, sorts, packages proteins/lipids (1½ marks); Lysosome – digestive enzymes, waste breakdown (1½ marks); Ribosome – protein synthesis (1 mark); coordination shown (1 mark).
24. Mitosis – one division, two identical diploid cells (1½ marks); Meiosis – two divisions, four haploid gametes with variation (1½ marks); errors → tumours (mitosis) or genetic disorders (meiosis) (2 marks).
25. (i) Life possibly originated in hot water pools similar to early Earth (1).
(ii) Present in all living cells (1).
(iii) Selectively permeable nature (1).
(iv) Membrane defines cell boundary and individuality (1).
26. (i) Osmosis (1).
(ii) Hypotonic solution – water enters potato cells (1).
(iii) Hypertonic solution – water leaves potato cells (1).
(iv) Cheek cells would shrink (no cell wall) (1).
All questions are answerable from the NCERT chapter text. Reviewed by GFIS faculty.