Q50. Which of the following cell organelles does NOT have its own DNA?
[RRB Group D, 14 December 2025, Shift 2]
(a) Nucleus
(b) Plastids
(c) Mitochondria
(d) Lysosomes
Answer: (d) Lysosomes
Explanation: Lysosomes are membrane-bound digestive compartments containing hydrolytic enzymes but no independent genome. Mitochondria and plastids retain small DNA molecules and limited protein-synthesis machinery. The nucleus holds most of a eukaryotic cell’s DNA, organized into chromosomes.
Q49. Which cell organelle contains digestive enzymes and keeps the cell clean by digesting foreign material and worn-out organelles?
[RRB Group D, 12 December 2025, Shift 2]
(a) Chloroplast
(b) Ribosome
(c) Lysosome
(d) Chromoplast
Answer: (c) Lysosome
Explanation: Lysosomes contain digestive hydrolases, operating in an acidic interior. They break down engulfed microbes and recycle damaged components through intracellular digestion and autophagy. Chloroplasts support photosynthesis, whereas ribosomes assemble proteins and chromoplasts store pigment in certain plant tissues.
Q48. What is the role of lysosomes in a cell?
[RRB Group D, 1 December 2025, Shift 1]
(a) To store proteins
(b) To produce ATP
(c) To transport products
(d) To digest foreign material
Answer: (d) To digest foreign material
Explanation: Lysosomal enzymes degrade foreign particles, waste and cellular material inside membrane-enclosed compartments. Their contents include proteases, lipases and nucleases. Cellular ATP is principally generated through respiration, while trafficking and storage involve other structures, so digestion is the defining choice.
Q47. Select the incorrect statement regarding mitochondria.
[RPSC Senior Teacher Grade II (Science), Paper II, 9 September 2025]
(a) The mitochondrial matrix contains circular DNA
(b) Inner and outer mitochondrial membranes have different enzyme complements
(c) The inner membrane forms folds called cristae
(d) The mitochondrial matrix possesses 80S ribosomes
Answer: (d) The mitochondrial matrix possesses 80S ribosomes
Explanation: Mitochondria have their own translation machinery. In school-level classifications, their ribosomes are described as prokaryote-like, rather than the 80S ribosomes typical of eukaryotic cytoplasm. Cristae increase inner-membrane surface area, while mitochondrial DNA is present in the matrix.
Q46. Which one of the following organelles can be seen in a prokaryotic cell?
[UPSC CDS (II), General Knowledge 2025]
(a) Mitochondria
(b) Definitive nucleus
(c) Ribosomes
(d) Golgi bodies
Answer: (c) Ribosomes
Explanation: Both prokaryotes and eukaryotes require ribosomes to translate messenger RNA into proteins. Typical bacteria have 70S ribosomes and lack a membrane-bound nucleus, mitochondria and Golgi bodies. Ribosomes are therefore an important exception to the absence of complex organelles.
Q45. Why does the rough endoplasmic reticulum appear rough under a microscope?
[UPSC CDS (I), General Knowledge 2025]
(a) Ribosomes are present on its surface
(b) Ribosomes are absent from its surface
(c) Lysosomes are present on its surface
(d) Mitochondria are present on its surface
Answer: (a) Ribosomes are present on its surface
Explanation: Attached ribosomes create the granular appearance of rough endoplasmic reticulum. These ribosomes synthesize proteins destined for secretion, membranes or certain organelles. Smooth endoplasmic reticulum lacks surface ribosomes and contributes to lipid synthesis and detoxification.
Q44. What is the structural and functional unit of life?
[70th BPSC Preliminary Examination, 13 December 2024]
(a) Cell
(b) Organ
(c) Tissue
(d) Organism
Answer: (a) Cell
Explanation: The cell is the smallest structural unit that carries out the essential processes of life. In multicellular organisms, related cells build tissues, tissues form organs and organs form systems. Unicellular organisms perform all life functions within one cell.
Q43. Which of the following statements is NOT true?
[UPPSC PCS Preliminary Examination 2024, GS Paper I]
(a) The nucleus does not play a role in cellular reproduction
(b) Chromosomes carry hereditary information
(c) Chromosomes consist of DNA and proteins
(d) A functional segment of DNA is called a gene
Answer: (a) The nucleus does not play a role in cellular reproduction
Explanation: The nucleus is crucial for reproduction of eukaryotic cells because its chromosomes replicate and are distributed during cell division. Chromosomes consist of DNA associated with proteins, and genes are functional DNA sequences involved in the expression of inherited traits.
Q42. Match the cell structures with their functions:
(i) Cell membrane,
(ii) Smooth ER,
(iii) Golgi apparatus,
(iv) Ribosomes;
(a) Protein synthesis,
(b) Glycolipids/glycoproteins formation,
(c) Lipid synthesis,
(d) Molecular transport.
[SSC MTS, 5 November 2024, Shift 3]
(a) i–d, ii–c, iii–b, iv–a
(b) i–c, ii–d, iii–b, iv–a
(c) i–a, ii–c, iii–d, iv–b
(d) i–c, ii–d, iii–a, iv–b
Answer: (a) i–d, ii–c, iii–b, iv–a
Explanation: The plasma membrane regulates molecular entry and exit. Smooth ER synthesizes many lipids; the Golgi apparatus modifies and processes glycoproteins and glycolipids; ribosomes translate RNA into proteins. Matching these specialized roles yields i–d, ii–c, iii–b and iv–a.
Q41. Who first postulated that cells are generated from pre-existing cells?
[SSC MTS, 17 October 2024, Shift 1]
(a) Jennifer Doudna
(b) Rudolf Virchow
(c) William Harvey
(d) Carl Linnaeus
Answer: (b) Rudolf Virchow
Explanation: Rudolf Virchow popularized the principle Omnis cellula e cellula, meaning every cell arises from an existing cell. This extended earlier cell-theory work by Schleiden and Schwann and rejected the idea that new living cells appear spontaneously from nonliving matter.
