Q30. Which cell component contains the hereditary material, DNA?
[SSC MTS (2022 cycle), 3 May 2023, Shift 1]
(a) Cell wall
(b) Nucleus
(c) Cell membrane
(d) Cytoplasm
Answer: (b) Nucleus
Explanation: In eukaryotic cells, most hereditary DNA is enclosed within the nucleus and arranged into chromosomes. The nuclear envelope separates it from the cytoplasm. Mitochondria also contain a small DNA genome, but the nucleus houses the majority of genetic material.
Q29. Match the organelles and functions:
(i) Mitochondria,
(ii) Ribosomes,
(iii) Nucleus,
(iv) Lysosomes;
(a) Protein synthesis,
(b) Cell regulation,
(c) Intracellular digestion,
(d) Energy generation.
[SSC CGL Tier I, 5 December 2022, Shift 3]
(a) i–c, ii–a, iii–d, iv–b
(b) i–b, ii–a, iii–c, iv–d
(c) i–a, ii–b, iii–c, iv–d
(d) i–d, ii–a, iii–b, iv–c
Answer: (d) i–d, ii–a, iii–b, iv–c
Explanation: Mitochondria produce much of the cell’s ATP, ribosomes build proteins, the nucleus regulates gene expression and cell functions, and lysosomes digest cellular material. This gives the correspondence i–d, ii–a, iii–b and iv–c.
Q28. Identify the option that does NOT represent a prokaryotic cell.
[SSC CGL Tier I, 3 December 2022, Shift 3]
(a) Mycoplasma
(b) Blue-green alga
(c) Sperm
(d) Pleuropneumonia-like organism
Answer: (c) Sperm
Explanation: Sperm is a specialized animal reproductive cell and is eukaryotic. Mycoplasma and pleuropneumonia-like organisms are bacteria; blue-green algae are cyanobacteria. Prokaryotes lack a membrane-enclosed nucleus, while sperm carry chromosomes in a true nucleus.
Q27. What happens when an animal cell is surrounded by a medium having a lower concentration of water?
[UPSC NDA (II), General Ability Test, 4 September 2022]
(a) The cell loses water
(b) There is no net water movement
(c) The cell gains water
(d) The cell swells
Answer: (a) The cell loses water
Explanation: Water moves by osmosis across the plasma membrane from higher water potential toward lower water potential. A concentrated external medium draws water out of an animal cell, causing shrinkage. A dilute external medium would instead tend to produce swelling.
Q26. A cell cannot synthesize lipids. Which organelle may be defective?
[UPSC NDA (I), General Ability Test, 10 April 2022]
(a) Smooth endoplasmic reticulum
(b) Golgi bodies
(c) Lysosomes
(d) Mitochondria
Answer: (a) Smooth endoplasmic reticulum
Explanation: Smooth endoplasmic reticulum is a major location for synthesis of phospholipids, cholesterol and other lipids. It also contributes to detoxification and calcium handling in specialized cells. Ribosome-studded rough ER is more directly involved in protein synthesis.
Q25. Which statements about the breakdown of glucose are true?
(i) In cytoplasm, glucose breaks down into four-carbon pyruvate.
(ii) Without oxygen, pyruvate may form lactic acid.
(iii) Without oxygen, pyruvate may form carbon dioxide and ethanol.
[CGPSC State Service Preliminary Examination (2021 cycle), 13 February 2022]
(a) (i), (ii) and (iii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) Only (iii)
Answer: (c) (ii) and (iii)
Explanation: Glycolysis occurs in cytoplasm and yields three-carbon pyruvate, making statement (i) incorrect. Without oxygen, muscle cells can produce lactic acid, while yeast ferments pyruvate into ethanol and carbon dioxide. Thus both statements (ii) and (iii) are correct.
Q24. The study of cells is called ________.
[RRB NTPC CBT I, 8 February 2021, Shift 2]
(a) Serology
(b) Etiology
(c) Cytology
(d) Cytoplasm
Answer: (c) Cytology
Explanation: Cytology is the scientific study of cells, including their structure, activity and abnormalities. Modern cell biology also examines molecular mechanisms within cells. Serology concerns serum-related investigations, etiology concerns causes, and cytoplasm is cellular material rather than a field of study.
Q23. Which organelle keeps the cell clean by digesting foreign material and worn-out organelles?
[RRB NTPC CBT I, 26 July 2021, Shift 1]
(a) Mitochondria
(b) Endoplasmic reticulum
(c) Golgi apparatus
(d) Lysosome
Answer: (d) Lysosome
Explanation: Lysosomes fuse with compartments containing unwanted material and break the contents down using digestive enzymes. This disposal and recycling function maintains cellular health. The Golgi apparatus helps generate lysosomes but is primarily concerned with modification, sorting and packaging.
Q22. The smallest unit of life capable of independent existence is:
[RRB NTPC CBT I, 7 January 2021, Shift 2]
(a) Protoplasm
(b) Cytoplasm
(c) Cell
(d) Vacuoles
Answer: (c) Cell
Explanation: An individual cell can carry out fundamental processes such as metabolism, responsiveness and reproduction. Cytoplasm and vacuoles are components of a cell rather than independent living units. Unicellular organisms demonstrate how one complete cell can function as an organism.
Q21. Osmosis is the movement of water molecules from:
[UPSC CDS (I), General Knowledge 2021]
(a) Higher to lower water concentration through a cell wall
(b) Lower to higher water concentration through a fully permeable membrane
(c) Higher to lower water concentration through a fully permeable membrane
(d) Higher to lower water concentration through a semipermeable membrane
Answer: (d) Higher to lower water concentration through a semipermeable membrane
Explanation: Osmosis is passive movement of water across a selectively permeable membrane from higher water potential to lower water potential. Unlike a freely permeable wall, such a membrane restricts some solutes. The process explains cell swelling, shrinkage and plant turgor.
