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Cell - Structure and Function PYQs – Biology, SSC & Railway

133 Cell - Structure and Function (Biology) questions asked in recent SSC and Railway exams, newest first, with exam, date & shift, answers and solutions.

📚 133 questionsSSC 23 · Railway 110
12
RRB Group D 2025-26 – 25 August 2026 Shift 2 · Prokaryotic and eukaryotic cells

Q1. What do scientists examine to determine whether an organism is a eukaryote or prokaryote?

  1. (a) General feeding behavior and diet
  2. (b) Ecological role within the environment
  3. (c) Cell structure and presence of nucleus
  4. (d) Method of reproduction and offspring
Answer & solution

Answer: (c) Cell structure and presence of nucleus

Correct Answer:
Correct Answer: Option 3 – Cell structure and presence of nucleus
Explanation:
The fundamental distinction between eukaryotic and prokaryotic organisms lies in theircell structure, specifically whether they possess amembrane-bound (true) nucleusand other membrane-bound organelles. Eukaryotes have a well-defined nucleus and organelles (e.g., mitochondria), while prokaryotes lack a true nucleus (their genetic material lies free in the cytoplasm as a nucleoid).
RRB Group D 2025-26 – 25 August 2026 Shift 3 · Plant cell and animal cell

Q2. A botanist observes two cell types under a microscope. The first type has thick cell walls and large vacuoles, while the second type lacks cell walls and has small vacuoles. What can be inferred?

  1. (a) The first sample is plant tissue, and the second is animal tissue.
  2. (b) Both samples are plant tissues.
  3. (c) Both samples are animal tissues.
  4. (d) The first sample is animal tissue, and the second is plant tissue.
Answer & solution

Answer: (a) The first sample is plant tissue, and the second is animal tissue.

Correct Answer:
Correct Answer: Option 1 – The first sample is plant tissue, and the second is animal tissue.
Explanation:
Plant cells have a rigid cell wall (made of cellulose) and typically a large central vacuole, matching the first description. Animal cells lack a cell wall and have small or no prominent vacuoles, matching the second description.
Important Facts:
• Cell wall is a defining structural feature distinguishing plant cells from animal cells.
• The large central vacuole in plant cells helps maintain turgor pressure and stores water/nutrients.
RRB Group D 2025-26 – 21 August 2026 Shift 2 · Prokaryotic and eukaryotic cells

Q3. A scientist discovers a single-celled eukaryotic organism. Which key feature distinguishes it from Monera in the five kingdom system?

  1. (a) Autotrophic mode of nutrition
  2. (b) Presence of a membrane-bound nucleus
  3. (c) Multicellular organization
  4. (d) Cell wall made of chitin
Answer & solution

Answer: (b) Presence of a membrane-bound nucleus

Correct Answer:
Correct Answer: Option 2 – Presence of a membrane-bound nucleus
Explanation:
In the five kingdom classification, Monera consists of prokaryotes lacking a true, membrane-bound nucleus. Any single-celled organism possessing a well-defined nucleus enclosed by a nuclear membrane is eukaryotic, distinguishing it from Monera.
RRB Group D 2025-26 – 21 August 2026 Shift 3 · Cytoskeleton, cell death and cancer cells

Q4. Name the process of selective cell destruction that helps in the formation of separate fingers during embryonic development.

  1. (a) Meiosis
  2. (b) Programmed cell death
  3. (c) Plasmolysis
  4. (d) Mitosis
Answer & solution

Answer: (b) Programmed cell death

Correct Answer:
Correct Answer: Option 2 – Programmed cell death
Explanation:
Programmed cell death (apoptosis)selectively destroys the cells present between developing digits (fingers/toes), separating them during embryonic development.
Important Facts:
• Apoptosis is a normal, genetically controlled process essential for development, distinct from accidental cell death (necrosis).
• Meiosis and mitosis are cell division processes, not cell destruction.
RRB Group D 2025-26 – 20 August 2026 Shift 1 · Cytoskeleton, cell death and cancer cells

Q5. A eukaryotic cell that performs its functions and undergoes programmed cell death when no longer required is best described as a __________.

  1. (a) Bacterial cell
  2. (b) Malignant cell
  3. (c) Tumour cell
  4. (d) Normal cell
Answer & solution

Answer: (d) Normal cell

Correct Answer:
Correct Answer: Option 4 – Normal cell
Explanation:
Anormal cellperforms its designated functions and undergoesprogrammed cell death (apoptosis)when it is old, damaged, or no longer needed, maintaining tissue homeostasis. In contrast, cancerous/tumour/malignant cells divide uncontrollably and typically evade apoptosis.
Important Facts:
• Apoptosis is a regulated, energy-dependent process of cell self-destruction.
• Failure of apoptosis is a hallmark of cancerous (malignant/tumour) cells.
RRB Group D 2025-26 – 20 August 2026 Shift 1 · Endoplasmic reticulum and ribosomes

Q6. Which organelle is physically continuous with the nuclear envelope?

  1. (a) Golgi Body
  2. (b) Endoplasmic Reticulum
  3. (c) Lysosome
  4. (d) Mitochondria
Answer & solution

Answer: (b) Endoplasmic Reticulum

Correct Answer:
Correct Answer: Option 2 – Endoplasmic Reticulum
Explanation:
TheEndoplasmic Reticulum (ER)is a network of membranous tubules and sacs that is physically continuous with the outer membrane of thenuclear envelope, allowing direct communication between the nucleus and the cytoplasm.
Important Facts:
• Rough ER has ribosomes attached and is involved in protein synthesis.
• Smooth ER is involved in lipid synthesis and detoxification.
• Golgi body, lysosomes, and mitochondria are distinct, separate organelles not directly continuous with the nuclear envelope.
RRB Group D 2025-26 – 20 August 2026 Shift 2 · Plastids

Q7. Complete the analogy.Mitochondria : Energy Release :: Chloroplast : ______________.

  1. (a) Genetic Transfer
  2. (b) Cell Digestion
  3. (c) Food Synthesis
  4. (d) Waste Removal
Answer & solution

Answer: (c) Food Synthesis

Correct Answer:
Correct Answer: Option 3 – Food Synthesis
Explanation:
Mitochondria are the 'powerhouse of the cell', releasing energy via respiration. Chloroplasts are the site of photosynthesis, i.e., food (glucose) synthesis using sunlight, water, and CO₂.
Important Facts:
• Chloroplasts are found only in plant cells and some protists, containing chlorophyll.
RRB Group D 2025-26 – 20 August 2026 Shift 2 · Nucleus and chromosomes

Q8. Which structure in an animal cell acts as the control centre and contains the genetic material?

  1. (a) Vacuole
  2. (b) Ribosome
  3. (c) Nucleus
  4. (d) Endoplasmic reticulum
Answer & solution

Answer: (c) Nucleus

Correct Answer:
Correct Answer: Option 3 – Nucleus
Explanation:
The nucleus contains the cell's genetic material (DNA/chromosomes) and controls and coordinates all cellular activities, making it the 'control centre' of the cell.
Important Facts:
• Ribosomes are the site of protein synthesis; the vacuole stores substances; the endoplasmic reticulum aids in transport and synthesis of proteins/lipids.
RRB Group D 2025-26 – 20 August 2026 Shift 3 · Cell division - mitosis and meiosis

Q9. Complete the analogy.Mitosis : 2 Daughter Cells :: Meiosis : ________

  1. (a) 4 Daughter Cells
  2. (b) 1 Daughter Cell
  3. (c) 8 Daughter Cells
  4. (d) 3 Daughter Cells
Answer & solution

Answer: (a) 4 Daughter Cells

Correct Answer:
Option 1 – 4 Daughter Cells
Explanation:
Mitosis produces 2 genetically identical daughter cells, while meiosis (a reduction division occurring in two stages) produces4 daughter cells, each with half the chromosome number of the parent cell.
RRB Group D 2025-26 – 19 August 2026 Shift 2 · Discovery of cell and cell theory

Q10. Which material did Robert Hooke use to first discover "cells"?

  1. (a) Leaf surface
  2. (b) Cork slice
  3. (c) Onion peel
  4. (d) Human cheek
Answer & solution

Answer: (b) Cork slice

Correct Answer:
Correct Answer: Option 2 – Cork slice
Explanation:
In 1665, Robert Hooke examined a thin slice ofcorkunder a primitive compound microscope and observed small box-like compartments, which he named 'cells' (resembling the small rooms/cells of a monastery).
Important Facts:
• Hooke published his observations in the book 'Micrographia' (1665).
• The cork cells he saw were actually dead cell walls, not living cells.
RRB Group D 2025-26 – 19 August 2026 Shift 3 · Prokaryotic and eukaryotic cells

Q11. Identify the CORRECTLY matched cell–structure pair.

  1. (a) Eukaryotic Cell – Membrane-bound Endoplasmic Reticulum
  2. (b) Bacteria Cell – Well-defined Nucleus
  3. (c) Prokaryotic Cell – Mitochondria
  4. (d) Animal Cell – Cell Wall
Answer & solution

Answer: (a) Eukaryotic Cell – Membrane-bound Endoplasmic Reticulum

Correct Answer:
Option 1 – Eukaryotic Cell – Membrane-bound Endoplasmic Reticulum
Explanation:
Onlyeukaryotic cellspossess membrane-bound organelles, including the endoplasmic reticulum, mitochondria, Golgi apparatus, and a well-defined (membrane-bound) nucleus. Bacteria are prokaryotic and lack a well-defined nucleus and membrane-bound organelles like mitochondria. Animal cells lack a cell wall (only plant cells, fungi and bacteria have cell walls).
Important Facts:
• Prokaryotic cells (e.g., bacteria) lack a nuclear membrane and membrane-bound organelles.
• Plant cells (not animal cells) have a rigid cell wall made of cellulose.
Correct Answer: Option 1 – Eukaryotic Cell – Membrane-bound Endoplasmic Reticulum
RRB Group D 2025-26 – 18 August 2026 Shift 1 · Cytoskeleton, cell death and cancer cells

Q12. Which of the following cell structures is mainly responsible for providing support and maintaining the shape of eukaryotic cells?

  1. (a) Cell Sap
  2. (b) DNA
  3. (c) Nucleoid
  4. (d) Cytoskeleton
Answer & solution

Answer: (d) Cytoskeleton

Cytoskeleton and cell shape
Thecytoskeletonis a network of protein filaments (microfilaments, intermediate filaments, and microtubules) that extends throughout the cytoplasm of eukaryotic cells.
It provides mechanical support, maintains and determines cell shape, and enables organelle movement and cell motility. Cell sap is the fluid content of the vacuole, DNA carries genetic information, and a nucleoid is the DNA-containing region in prokaryotic cells — none of these provide structural support.
Correct Answer: Cytoskeleton
RRB Group D 2025-26 – 18 August 2026 Shift 1 · Mitochondria

Q13. Complete the analogy.Ribosomes : Protein Synthesis :: Mitochondria : __________.

  1. (a) DNA Replication
  2. (b) Energy Production
  3. (c) Cell Division
  4. (d) Waste Removal
Answer & solution

Answer: (b) Energy Production

Analogy: cell organelles and their functions
Ribosomes are the site of protein synthesis. Similarly, mitochondria are the 'powerhouse of the cell', responsible for aerobic respiration and generating ATP (energy production).
Correct Answer: Energy Production
RRB Group D 2025-26 – 18 August 2026 Shift 3 · Nucleus and chromosomes

Q14. When a cell prepares to divide, the chromatin material organizes itself into __________.

  1. (a) Proteins
  2. (b) Lysosomes
  3. (c) Chromosomes
  4. (d) Nuclear pores
Answer & solution

Answer: (c) Chromosomes

Concept: Cell Division
In a non-dividing cell, the genetic material exists as a loosely coiled, thread-like mass called chromatin. As the cell prepares to divide (during prophase), the chromatin condenses and organizes into distinct, tightly coiled structures calledchromosomes, which can then be equally distributed to daughter cells.
Correct Answer: Chromosomes
RRB Group D 2025-26 – 17 August 2026 Shift 3 · Mitochondria

Q15. Apart from the nucleus and plastids, which of the following organelle contains its own DNA?

  1. (a) Mitochondrion
  2. (b) Golgi Apparatus
  3. (c) Ribosome
  4. (d) Lysosome
Answer & solution

Answer: (a) Mitochondrion

Organelle with its Own DNA
Apart from the nucleus and plastids (chloroplasts), themitochondrionis the other organelle that contains its own DNA (and ribosomes), supporting the endosymbiotic theory.
• Golgi apparatus, ribosomes, and lysosomes do not contain their own DNA.
Correct Answer: Mitochondrion
RRB Group D 2025-26 – 14 August 2026 Shift 2 · Prokaryotic and eukaryotic cells

Q16. In a bacterial cell, the genetic material is found without a surrounding membrane in a region called the __________.

  1. (a) Nucleoid
  2. (b) Vacuole
  3. (c) Nucleolus
  4. (d) Cytoplasm
Answer & solution

Answer: (a) Nucleoid

Answer: Option 1 – Nucleoid.
• In bacteria (prokaryotes), the genetic material lies free (no membrane) in a region called thenucleoid.
RRB Group D 2025-26 – 14 August 2026 Shift 2 · Cell membrane and cell wall

Q17. If a researcher finds that a plant cell is neither swelling nor shrinking in a specific solution, they can conclude the solution is ____.

  1. (a) Pure water
  2. (b) Concentrated
  3. (c) Hypotonic
  4. (d) Isotonic
Answer & solution

Answer: (d) Isotonic

Answer: Option 4 – Isotonic.
• If the cell neither swells nor shrinks, the solution's concentration equals the cell's ⇒isotonic.
RRB Group D 2025-26 – 14 August 2026 Shift 3 · Cell membrane and cell wall

Q18. Complete the analogy.Hypotonic solution : Cell Swells :: Hypertonic solution : _______.

  1. (a) Cell becomes rigid
  2. (b) Cell Shrinks
  3. (c) Cell Divides
  4. (d) Cell stays same
Answer & solution

Answer: (b) Cell Shrinks

Answer: Option 2 – Cell Shrinks.
• In a hypertonic solution water leaves the cell, so thecell shrinks(plasmolysis).
RRB Group D 2025-26 – 9 August 2026 Shift 2 · Mitochondria

Q19. Which organelle is primarily responsible for aerobic respiration in animal cells?

  1. (a) Ribosome
  2. (b) Mitochondria
  3. (c) Endoplasmic reticulum
  4. (d) Nucleus
Answer & solution

Answer: (b) Mitochondria

Answer: Option 2 — Mitochondria
Aerobic respiration occurs in themitochondria→ Option 2.
RRB Group D 2025-26 – 6 August 2026 Shift 3 · Plant cell and animal cell

Q20. Complete the Analogy.Plant : Rigid Cell Wall :: Animal : __________

  1. (a) Photosynthetic tissues
  2. (b) Fixed position
  3. (c) Cellular flexibility
  4. (d) Lignified support
Answer & solution

Answer: (c) Cellular flexibility

Answer: Option 3 — Cellular flexibility
Plants have a rigid cell wall; animal cells lack it, givingcellular flexibility→ Option 3.
RRB NTPC UG CBT-1 2025-26 – 20 June 2026 Shift 1 · Biomolecules and enzymes

Q21. DNA and RNA are polymers made of long chains of ______.

  1. (a) Fatty acids
  2. (b) Nucleotides
  3. (c) Monosaccharides
  4. (d) Amino acids
Answer & solution

Answer: (b) Nucleotides

Topic: Biomolecules - Nucleic Acids
DNA (Deoxyribonucleic Acid)andRNA (Ribonucleic Acid)are nucleic acids.
Both arepolymers of nucleotides.
Each nucleotide consists of:
• A nitrogenous base
• A pentose sugar (ribose/deoxyribose)
• A phosphate group
Note: Proteins are polymers of amino acids, carbohydrates are polymers of monosaccharides, and lipids contain fatty acids.
Answer: Option 2 → Nucleotides
RRB NTPC UG CBT-1 2025-26 – 17 June 2026 Shift 3 · Cell membrane and cell wall

Q22. The process by which water moves from the soil (high water concentration) into root cells (low water concentration) through a semi-permeable membrane is called ____.

  1. (a) Active Transport
  2. (b) Diffusion
  3. (c) Osmosis
  4. (d) Plasmolysis
Answer & solution

Answer: (c) Osmosis

Water Movement in Plants
Process: Water moves from high concentration (soil) to low concentration (root cells)
Through: Semi-permeable membrane (cell membrane)
Definition: Osmosis→ Movement of water molecules from higher water concentration to lower water concentration through a semi-permeable membrane
Other processes:
• Active Transport → Against concentration gradient (needs energy)
• Diffusion → Movement of any substance (not specific to water)
• Plasmolysis → Shrinking of cell due to water loss
Answer: Option 3 → Osmosis
RRB NTPC UG CBT-1 2025-26 – 13 June 2026 Shift 2 · Cell division - mitosis and meiosis

Q23. Which of the following is the specialized kind of cell division that reduces the chromosome number by half, resulting in the production of haploid daughter cells?

  1. (a) Meiosis
  2. (b) Mitosis
  3. (c) Fertilization
  4. (d) Translocation
Answer & solution

Answer: (a) Meiosis

Topic:Cell Division - Meiosis
Meiosisis a specialized type of cell division that occurs in reproductive cells (gametes).
Key characteristics:
• Reduces chromosome number by half (diploid → haploid)
• Produces 4 daughter cells from one parent cell
• Occurs in two stages: Meiosis I and Meiosis II
Mitosismaintains chromosome number (produces identical diploid cells).
Fertilizationis fusion of gametes (restores diploid number).
Translocationis chromosomal rearrangement, not division.
Answer: Option 1 → Meiosis
SSC GD 2026 – 25 May 2026 Shift 1 · Cell membrane and cell wall

Q24. What is the primary function of the plant cell wall?

  1. (a) Provides structural rigidity to plants
  2. (b) Assists in cell division
  3. (c) Food synthesis
  4. (d) Performs photosynthesis in plants
Answer & solution

Answer: (a) Provides structural rigidity to plants

Correct Answer: Provides structural rigidity to plants — Option (a)
The primary function of the plant cell wall is to provide structural rigidity (firmness/strength) to plant cells and the overall plant. About the Plant Cell Wall: Composition: Primarily made of Cellulose (a polysaccharide) — long chains of glucose molecules; Also contains hemicellulose, pectin, and in some cells, lignin (in wood cells); Structure: Present OUTSIDE the cell membrane (plasma membrane); Plants, fungi, and bacteria have cell walls; Animal cells do NOT have cell walls; Primary functions: Structural support and rigidity: Gives shape, strength, and firmness to plant cells and the plant body; Prevents excessive water intake (prevents cell bursting when water enters by osmosis); Protection: Protects against mechanical damage, pathogens, and osmotic stress; Cell shape maintenance: Maintains the characteristic shape of the cell; Allows plants to grow tall and upright without a skeleton; Types of cell walls: Primary cell wall: Thin, flexible, present in young/growing cells; Secondary cell wall: Thick, rigid, deposited inside the primary wall in mature cells (contains lignin in wood cells); Middle lamella: Cementing layer between adjacent cells (pectin); Turgor pressure: The plant cell wall allows buildup of turgor pressure (internal water pressure that keeps plants firm/turgid); without cell walls, excess water would burst animal-like cells.
Option (b) Assists in cell division — Incorrect: Cell division in plants is carried out by the cell plate (formed by the Golgi apparatus during cytokinesis) and the mitotic spindle — NOT by the cell wall; the cell wall provides structural support, not assistance in cell division.
Option (c) Food synthesis — Incorrect: Food synthesis (photosynthesis) is carried out by Chloroplasts (which contain chlorophyll) in the cytoplasm of plant cells — NOT by the cell wall; the cell wall is a structural component, not a site of food synthesis.
Option (d) Performs photosynthesis in plants — Incorrect: Photosynthesis is performed by Chloroplasts (organelles containing chlorophyll pigment) — NOT by the cell wall; the cell wall is made of cellulose and provides structural support; it plays no role in photosynthesis.
RRB NTPC UG CBT-1 2025-26 – 9 May 2026 Shift 3 · Cell membrane and cell wall

Q25. Why are lipids important in the cell membrane structure of living organisms?

  1. (a) They store genetic information.
  2. (b) They provide instructions for protein synthesis.
  3. (c) They catalyze biochemical reactions.
  4. (d) They form a barrier that controls what enters and leaves the cell.
Answer & solution

Answer: (d) They form a barrier that controls what enters and leaves the cell.

Cell Membrane Structure
Lipids (phospholipids) form thebilayer structureof cell membrane.
This bilayer creates aselectively permeable barrier.
Controls entry/exit of substances (water, ions, nutrients).
Maintains cell integrity and homeostasis.
Answer: Option 4 → They form a barrier that controls what enters and leaves the cell.
SSC GD 2026 – 30 April 2026 Shift 2 · Mitochondria

Q26. By how many membranes is a mitochondrion covered?

  1. (a) One
  2. (b) Two
  3. (c) Three
  4. (d) Four
Answer & solution

Answer: (b) Two

Correct Answer: Two — Option (b)
A mitochondrion is a double-membrane-bound organelle with two membranes:
1. Outer membrane — smooth and permeable to small molecules and ions.
2. Inner membrane — highly folded into cristae, the site of ATP synthesis (oxidative phosphorylation).
The space between the two membranes is the intermembrane space, and the innermost compartment is the matrix.
Option (a) One — Incorrect: Mitochondria have two membranes, not one.
Option (c) Three — Incorrect: There is no third membrane in a mitochondrion.
Option (d) Four — Incorrect: Mitochondria are bounded by exactly two membranes.
SSC GD 2026 – 29 April 2026 Shift 1 · Golgi apparatus, lysosomes and vacuoles

Q27. Which of the following is the primary function of lysosomes in a cell?

  1. (a) Energy production
  2. (b) Waste disposal
  3. (c) Protein synthesis
  4. (d) Lipid storage
Answer & solution

Answer: (b) Waste disposal

Correct Answer: Waste disposal — Option (b)
Lysosomes are membrane-bound organelles found in animal cells whose primary function is waste disposal — the breakdown and digestion of cellular waste, old or damaged organelles, and foreign materials. Key facts about lysosomes: They contain powerful hydrolytic (digestive) enzymes (over 50 types) such as proteases, lipases, nucleases, and glycosidases; These enzymes work optimally at an acidic pH (around 4.5-5.0) maintained within the lysosome by proton pumps; Lysosomes perform autophagy — breaking down old, damaged, or excess cellular organelles and molecules; They perform phagocytosis — digesting pathogens, bacteria, and foreign particles engulfed by white blood cells; They are often called 'garbage disposal bags' or 'suicide bags' of the cell (the term 'suicide bag' was coined by Christian de Duve, who discovered lysosomes and received the Nobel Prize in Physiology or Medicine in 1974); Lysosomal dysfunction leads to lysosomal storage diseases.
Option (a) Energy production — Incorrect: Energy production is the primary function of mitochondria (called the 'powerhouse of the cell'), which produce ATP through cellular respiration; lysosomes do not produce energy.
Option (c) Protein synthesis — Incorrect: Protein synthesis is the primary function of ribosomes (in the cytoplasm) and the rough endoplasmic reticulum; lysosomes contain enzymes that BREAK DOWN proteins rather than synthesize them.
Option (d) Lipid storage — Incorrect: Lipid storage is associated with lipid droplets (fat bodies) in cells; the primary function of lysosomes is waste disposal through enzymatic digestion, not lipid storage.
SSC GD 2026 – 29 April 2026 Shift 3 · Plastids

Q28. What is the primary function of chloroplast?

  1. (a) Storage of starch
  2. (b) Protein synthesis
  3. (c) Energy production like mitochondria
  4. (d) Photosynthesis
Answer & solution

Answer: (d) Photosynthesis

Correct Answer: Photosynthesis — Option (d)
The primary function of chloroplasts is photosynthesis — the process by which plants, algae, and some bacteria convert light energy into chemical energy (food). The photosynthesis equation: 6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ (glucose) + 6O₂. Structure of chloroplasts supporting photosynthesis: Thylakoids: Flattened membrane sacs containing chlorophyll and other photosynthetic pigments; the light-dependent reactions occur here; Grana: Stacks of thylakoids; Stroma: The fluid-filled space surrounding the thylakoids where the Calvin cycle (light-independent reactions/dark reactions) occur; Outer and inner membranes: Regulate material transport. Two stages of photosynthesis: Light reactions (occur in thylakoids): Light energy is converted to ATP and NADPH; Calvin cycle/Dark reactions (occur in stroma): CO₂ is fixed into organic molecules (glucose) using ATP and NADPH. Chloroplasts contain chlorophyll (which gives plants their green color) that absorbs sunlight to drive photosynthesis.
Option (a) Storage of starch — Incorrect: While chloroplasts can temporarily store starch (made during photosynthesis) as starch grains, this is a secondary function; the PRIMARY function of chloroplasts is photosynthesis (converting light energy to chemical energy).
Option (b) Protein synthesis — Incorrect: Ribosomes in the chloroplast (70S ribosomes) do synthesize some proteins, but protein synthesis is not the PRIMARY function of chloroplasts; the primary function is photosynthesis.
Option (c) Energy production like mitochondria — Incorrect: Mitochondria produce energy (ATP) through cellular respiration (oxidizing glucose); chloroplasts CAPTURE light energy and STORE it as glucose through photosynthesis — they are not analogous to mitochondria in function.
RRB NTPC GL CBT-1 2025-26 – 24 March 2026 Shift 1 · Biomolecules and enzymes

Q29. Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA) belong to which class of biomolecules?

  1. (a) Carbohydrate
  2. (b) Lipid
  3. (c) Protein
  4. (d) Nucleic acids
Answer & solution

Answer: (d) Nucleic acids

Topic:Biomolecules Classification
DNA (Deoxyribonucleic Acid)andRNA (Ribonucleic Acid)are polymers of nucleotides.
They belong to the class ofNucleic Acids, which are responsible for storage and transmission of genetic information.
Other biomolecule classes: Carbohydrates (sugars), Lipids (fats), Proteins (amino acid polymers).
Answer: Option 4 → Nucleic acids
RRB NTPC GL CBT-1 2025-26 – 22 March 2026 Shift 2 · Cell division - mitosis and meiosis

Q30. What is the function of the anaphase-telophase transition in mitosis?

  1. (a) Synthesis of new DNA strands
  2. (b) Condensation of chromosomes
  3. (c) Separation of chromatids and reformation of the nuclear envelope
  4. (d) Initiation of DNA replication
Answer & solution

Answer: (c) Separation of chromatids and reformation of the nuclear envelope

Topic: Mitosis - Anaphase to Telophase Transition
Anaphase:Sister chromatids separate and move to opposite poles.
Telophase:Nuclear envelope reforms around each set of chromosomes.
Key Events:Chromatid separation completes, nuclei re-form, chromosomes decondense.
Answer: Option 3 → Separation of chromatids and reformation of the nuclear envelope
RRB NTPC GL CBT-1 2025-26 – 17 March 2026 Shift 2 · Cytoskeleton, cell death and cancer cells

Q31. Which cell organelle is responsible for maintaining cell shape and providing structural support?

  1. (a) Peroxisome
  2. (b) Nucleus
  3. (c) Golgi apparatus
  4. (d) Cytoskeleton
Answer & solution

Answer: (d) Cytoskeleton

Cell Organelle: Structural Support
Cytoskeletonis a network of protein filaments.
Functions:
• Maintains cell shape and rigidity
• Provides mechanical support to cell
• Helps in cell movement and division
Components: Microfilaments, Microtubules, Intermediate filaments
Answer: Option 4 → Cytoskeleton
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 3 · Prokaryotic and eukaryotic cells

Q32. Choose a term to complete the analogy.
Prokaryotic cell : Small and simple :: Eukaryotic cell : _______

  1. (a) Smaller and simple
  2. (b) Larger and complex
  3. (c) Irregular and simple
  4. (d) Same size and complexity
Answer & solution

Answer: (b) Larger and complex

The question compares the characteristics of prokaryotic and eukaryotic cells.
Prokaryotic cells are generally small and simple in structure.
Eukaryotic cells are usually larger and more complex due to organelles and a defined nucleus.
Hence, the analogy is: Prokaryotic cell : Small and simple : : Eukaryotic cell : Larger and complex.
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 1 · Mitochondria

Q33. The deeply folded inner membrane of mitochondria helps to increase the __________ for ATP generation.

  1. (a) Surface area
  2. (b) Cell wall thickness
  3. (c) Volume
  4. (d) Colour
Answer & solution

Answer: (a) Surface area

The inner membrane of mitochondria is highly folded into structures called cristae.
These folds increase the surface area available inside the mitochondria.
More surface area allows for more space where ATP generation can occur using enzymes and proteins.
Thus, the increased surface area facilitates efficient ATP production during cellular respiration.
Therefore, the correct answer is surface area.
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 2 · Golgi apparatus, lysosomes and vacuoles

Q34. The principal role of the large central vacuole in mature plant cells is to:

  1. (a) Synthesize proteins for export.
  2. (b) Carry out cellular respiration to produce energy.
  3. (c) Control cell division and heredity.
  4. (d) Store cell sap and help maintain turgor pressure.
Answer & solution

Answer: (d) Store cell sap and help maintain turgor pressure.

The large central vacuole in mature plant cells primarily stores cell sap.
It helps maintain turgor pressure, which keeps the cell rigid and supports the plant structure.
Other options are functions of different organelles: Proteins are synthesised by ribosomes,
cellular respiration occurs in mitochondria,
and cell division control is done by the nucleus.
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 3 · Endoplasmic reticulum and ribosomes

Q35. The rough endoplasmic reticulum is associated with:

  1. (a) Enzyme breakdown
  2. (b) DNA replication
  3. (c) Lipid synthesis
  4. (d) Protein synthesis
Answer & solution

Answer: (d) Protein synthesis

The rough endoplasmic reticulum (RER) is studded with ribosomes on its surface.
Ribosomes are the sites of protein synthesis.
Therefore, the rough ER is primarily involved in protein synthesis and processing.
Options 1, 2, and 3 are functions associated with other organelles.
Hence, the correct answer is protein synthesis.
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 2 · Cell membrane and cell wall

Q36. Two beakers contain sugar solution of different concentrations. A semipermeable membrane separates them. After some time, the level of solution in one beaker rises while in the other, it falls. Which property of solutions does this experiment best demonstrate, and why?

  1. (a) Sedimentation – because sugar crystals settle at the bottom due to gravity
  2. (b) Diffusion – because sugar molecules move freely across the membrane until equilibrium is reached
  3. (c) Osmosis – because solvent molecules move from the dilute solution to the concentrated solution through the semipermeable membrane
  4. (d) Evaporation – because water molecules escape from the surface of the solution causing a level difference
Answer & solution

Answer: (c) Osmosis – because solvent molecules move from the dilute solution to the concentrated solution through the semipermeable membrane

This experiment shows osmosis.
Explanation:
A semipermeable membrane allows only solvent (usually water) molecules to pass through, not sugar molecules.
Solvent moves from the dilute solution (less sugar) to the concentrated solution (more sugar).
This causes the level in one beaker to rise and the other to fall.
Thus, the movement of solvent due to concentration difference across a semipermeable membrane is osmosis.
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 1 · Cell membrane and cell wall

Q37. What causes only the animal cell to burst when both plant and animal cells are placed in pure water?

  1. (a) Plant cells have a rigid cell wall.
  2. (b) Plant cells can actively pump out water.
  3. (c) Animal cells have a thicker membrane.
  4. (d) Osmosis occurs only in animal cells.
Answer & solution

Answer: (a) Plant cells have a rigid cell wall.

Plant cells have a rigid cell wall that provides structural support.
This cell wall prevents plant cells from bursting when water enters by osmosis.
Animal cells lack this rigid cell wall; they have a flexible cell membrane only.
When animal cells are placed in pure water, water enters rapidly by osmosis, causing them to swell and burst.
Hence, only animal cells burst due to the absence of a cell wall.
RRB Technician Grade III 2025-26 – 10 March 2026 Shift 2 · Cell membrane and cell wall

Q38. Which part of a plant cell helps it stay intact and prevents bursting in a hypotonic environment?

  1. (a) Cell wall made of cellulose
  2. (b) Cell membrane
  3. (c) Vacuole
  4. (d) Cytoplasm
Answer & solution

Answer: (a) Cell wall made of cellulose

Correct option is 1.
The cell wall made of cellulose provides structural support to plant cells.
It prevents the cell from bursting when water enters in a hypotonic environment.
The cell membrane alone cannot prevent bursting, but the rigid cell wall ensures cell integrity.
Hence, the cell wall helps plant cells stay intact in hypotonic conditions.
RRB Technician Grade III 2025-26 – 9 March 2026 Shift 3 · Golgi apparatus, lysosomes and vacuoles

Q39. Lysosomes are also known as:

  1. (a) Control centers
  2. (b) Energy powerhouses
  3. (c) Suicidal bags of the cell
  4. (d) Protein factories
Answer & solution

Answer: (c) Suicidal bags of the cell

Lysosomes are membrane-bound organelles inside cells.
They contain digestive enzymes that break down waste materials and cellular debris.
Because they digest unwanted materials and can trigger cell destruction, they are called 'suicidal bags of the cell.'
Other options do not describe lysosomes correctly:
Control centres are the nucleus.
Energy powerhouses refer to mitochondria.
Protein factories are ribosomes.
Thus, the correct answer is option 3.
RRB Technician Grade III 2025-26 – 9 March 2026 Shift 1 · Plastids

Q40. Plastids, which are found only in plant cells, help in:

  1. (a) photosynthesis and storage
  2. (b) transport
  3. (c) excretion
  4. (d) respiration
Answer & solution

Answer: (a) photosynthesis and storage

Plastids are organelles found only in plant cells.
They are involved mainly in photosynthesis and storage of food.
Chloroplasts (a type of plastid) carry out photosynthesis.
Other plastids store starch or pigments.
Therefore, plastids help in photosynthesis and storage.
RRB Technician Grade III 2025-26 – 9 March 2026 Shift 3 · Golgi apparatus, lysosomes and vacuoles

Q41. Which of the following describes a key function of lysosomal enzymes?

  1. (a) Transporting molecules across the membrane
  2. (b) Storing genetic material
  3. (c) Breaking down proteins, lipids, and carbohydrates
  4. (d) Creating new proteins for the cell
Answer & solution

Answer: (c) Breaking down proteins, lipids, and carbohydrates

Lysosomal enzymes are responsible for breaking down various biomolecules.
They digest proteins, lipids, carbohydrates, and other cellular waste substances.
This helps in recycling cell components and clearing waste.
Other options describe functions of different cell parts.
Hence, the correct function is breaking down proteins, lipids, and carbohydrates.
RRB Technician Grade III 2025-26 – 9 March 2026 Shift 1 · Endoplasmic reticulum and ribosomes

Q42. Which of the following distinguishes the Rough Endoplasmic Reticulum from the Smooth Endoplasmic Reticulum?

  1. (a) SER synthesizes proteins only.
  2. (b) RER stores lipids.
  3. (c) SER is rich in ribosomes.
  4. (d) RER has ribosomes.
Answer & solution

Answer: (d) RER has ribosomes.

The Rough Endoplasmic Reticulum (RER) is characterised by the presence of ribosomes on its surface.
These ribosomes give it a 'rough' appearance under a microscope.
The Smooth Endoplasmic Reticulum (SER) does not have ribosomes and is involved in lipid synthesis and detoxification.
Hence, the key distinction is that RER has ribosomes attached.
Correct option is 4 as it states 'RER has ribosomes'.
This clearly distinguishes RER from SER.
RRB Technician Grade III 2025-26 – 9 March 2026 Shift 2 · Golgi apparatus, lysosomes and vacuoles

Q43. Which of the following is a function of the Golgi apparatus?

  1. (a) Packaging and secretion of materials
  2. (b) Photosynthesis
  3. (c) Protein synthesis
  4. (d) ATP production
Answer & solution

Answer: (a) Packaging and secretion of materials

The Golgi apparatus processes and packages proteins and lipids that are synthesised in the cell.
It is responsible for modifying, sorting and packaging these materials into vesicles for secretion or use within the cell.
Photosynthesis happens in chloroplasts, not Golgi apparatus.
Protein synthesis occurs in ribosomes.
ATP production happens in mitochondria.
Hence, the correct function of the Golgi apparatus is packaging and secretion of materials.
RRB Technician Grade III 2025-26 – 9 March 2026 Shift 2 · Plant cell and animal cell

Q44. Which structure is present in plant cells but absent in animal cells?

  1. (a) Endoplasmic reticulum
  2. (b) Cytoplasm
  3. (c) Cell wall
  4. (d) Mitochondria
Answer & solution

Answer: (c) Cell wall

Correct option is 3: Cell wall.
Plant cells have a rigid cell wall made of cellulose that surrounds the cell membrane.
Animal cells do not have a cell wall; they only have a cell membrane.
Endoplasmic reticulum, cytoplasm, and mitochondria are present in both plant and animal cells.
Hence, cell wall is the structure present in plant cells but absent in animal cells.
This is a fundamental difference between plant and animal cells.
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 1 · Prokaryotic and eukaryotic cells

Q45. Choose a term to pair the analogy.
Nucleus : Eukaryotic Cell :: Nucleoid : _______

  1. (a) Animal Cell
  2. (b) Prokaryotic Cell
  3. (c) Plant Cell
  4. (d) Multicellular Organism
Answer & solution

Answer: (b) Prokaryotic Cell

The nucleus is the central organelle present in a eukaryotic cell.
The nucleoid is the central region of a prokaryotic cell where DNA is found.
Hence, the correct analogy is: Nucleus : Eukaryotic Cell as Nucleoid : Prokaryotic Cell.
Final answer: Option 2
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 2 · Cell membrane and cell wall

Q46. The principal function of the plasma membrane is to:

  1. (a) Regulate movement of substances across the cell.
  2. (b) Serve as the site of ATP synthesis.
  3. (c) Provide rigid support and prevent cell swelling.
  4. (d) Store the cell’s genetic material.
Answer & solution

Answer: (a) Regulate movement of substances across the cell.

Correct Option: 1
The plasma membrane controls the entry and exit of substances in the cell.
It acts as a selective barrier, maintaining the internal environment.
Option 2 is incorrect because ATP synthesis mainly occurs in mitochondria.
Option 3 is wrong as rigid support is provided by the cell wall (in plants).
Option 4 is incorrect since genetic material is stored in the nucleus.
Hence, the main function is to regulate movement of substances.
Answer complete: Option 1
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 1 · Cell membrane and cell wall

Q47. What is the primary function of the cell wall in plant cells?

  1. (a) Control cellular respiration
  2. (b) Control cell division
  3. (c) Provide rigidity and protection
  4. (d) Transport nutrients
Answer & solution

Answer: (c) Provide rigidity and protection

The primary function of the cell wall in plant cells is to provide rigidity and protection.
It supports the plant cell by maintaining its shape and preventing excessive water intake.
Other options like controlling cellular respiration, cell division or nutrient transport are not functions of the cell wall.
Hence, the correct option is 3.
Final answer: Option 3
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 2 · Mitochondria

Q48. What unique feature allows mitochondria to produce some of their own proteins?

  1. (a) They produce ATP.
  2. (b) Their outer membrane is porous.
  3. (c) They contain their own DNA and ribosomes.
  4. (d) They have two membranes.
Answer & solution

Answer: (c) They contain their own DNA and ribosomes.

Mitochondria can produce some of their own proteins because they contain their own DNA.
They also have their own ribosomes to synthesise proteins.
This means they can independently carry out protein synthesis for some proteins needed within the mitochondria.
Other options describe general features of mitochondria but do not explain protein production capability.
Therefore, the unique feature is having their own DNA and ribosomes.
Final answer: Option 3
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 3 · Plant cell and animal cell

Q49. When observing onion peel and cheek cells under a microscope, which part appears lightly stained and contains many organelles?

  1. (a) Cell wall only
  2. (b) Cell membrane only
  3. (c) Cytoplasm
  4. (d) Nucleus
Answer & solution

Answer: (c) Cytoplasm

Correct option: 3
When observing onion peel and cheek cells, the cytoplasm appears lightly stained.
The cytoplasm contains many organelles such as mitochondria, ribosomes, and endoplasmic reticulum.
The nucleus is usually more darkly stained, and cell wall or membrane are thinner layers, not densely packed with organelles.
Hence, the lightly stained part with many organelles is the cytoplasm.
Answer is Option 3
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 3 · Mitochondria

Q50. Which organelle is known as the 'powerhouse of the cell' because it performs aerobic respiration?

  1. (a) Ribosome
  2. (b) Lysosome
  3. (c) Nucleus
  4. (d) Mitochondria
Answer & solution

Answer: (d) Mitochondria

The organelle called the 'powerhouse of the cell' is the mitochondria.
It performs aerobic respiration, producing energy in the form of ATP.
Therefore, the correct answer is mitochondria.
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 3 · Plant cell and animal cell

Q51. Why do cells in a multicellular organism exhibit a wide range of shapes and sizes?

  1. (a) Their structure is adapted to perform specific functions.
  2. (b) Each cell type contains a different genome in the same organism.
  3. (c) Cell shape is random and unrelated to function.
  4. (d) Variation in cell shape and size occurs without any functional significance.
Answer & solution

Answer: (a) Their structure is adapted to perform specific functions.

Cells in multicellular organisms have different shapes and sizes because their structures are specially adapted to perform specific functions.
Different functions require different cell forms, such as nerve cells being long to transmit impulses and red blood cells being biconcave to carry oxygen efficiently.
This adaptation helps the organism function effectively as a whole.
Option 1 is correct because it directly explains the reason for the diversity in cell shape and size.
Final answer: Option 1
RRB JE CBT-1 2025-26 – 25 February 2026 Shift 3 · Cell membrane and cell wall

Q52. The fluid content inside the plasma membrane is named:

  1. (a) Chromosomes
  2. (b) Genes
  3. (c) Cytoplasm
  4. (d) Chromatin
Answer & solution

Answer: (c) Cytoplasm

The fluid content inside the plasma membrane is called cytoplasm.
It contains the cell organelles and the cytosol (fluid part).
Chromosomes and chromatin are related to the genetic material inside the nucleus.
Genes are segments of DNA, not fluid content.
Therefore, the correct answer is cytoplasm.
RRB JE CBT-1 2025-26 – 20 February 2026 Shift 2 · Plastids

Q53. Chloroplast is present in which of the following parts of a cell?

  1. (a) Cytoplasm
  2. (b) Peroxisome
  3. (c) Endoplasmic reticulum
  4. (d) Nucleoplasm
Answer & solution

Answer: (a) Cytoplasm

Chloroplast is an organelle where photosynthesis occurs.
It contains chlorophyll, giving plants their green colour .
Chloroplasts are found within the cytoplasm of plant cells.
They are not found in peroxisomes, endoplasmic reticulum, or nucleoplasm.
Hence, the correct location is the cytoplasm.
Final answer: Option 1
RRB JE CBT-1 2025-26 – 20 February 2026 Shift 1 · Nucleus and chromosomes

Q54. Where is perinuclear space present?

  1. (a) Inside of the nucleus
  2. (b) Between two layers of the nuclear envelope
  3. (c) Outside the nucleus
  4. (d) Within the nucleolus
Answer & solution

Answer: (b) Between two layers of the nuclear envelope

Perinuclear space is the region between the two membranes of the nuclear envelope.
The nuclear envelope has an inner and an outer membrane, with perinuclear space between them.
It is not inside the nucleus or outside the nucleus, but specifically between the two layers.
Hence, the correct location is between the two layers of the nuclear envelope.
Final answer: Option 2
RRB JE CBT-1 2025-26 – 20 February 2026 Shift 2 · Golgi apparatus, lysosomes and vacuoles

Q55. Which of the following is an example of membrane bound little structures present in a cell?

  1. (a) Cytoplasm
  2. (b) Ribosome
  3. (c) Lysosome
  4. (d) Nucleoplasm
Answer & solution

Answer: (c) Lysosome

Correct option is 3: Lysosome.
Lysosomes are membrane-bound organelles containing digestive enzymes.
They help in breaking down waste materials and cellular debris.
Other options explanation:
1. Cytoplasm is the jelly-like substance in a cell, not membrane-bound.
2. Ribosomes are not membrane-bound; they are complexes of RNA and protein.
4. Nucleoplasm is the substance within the nucleus but not a separate organelle.
Thus, lysosome is the best example of a membrane-bound small structure in a cell.
Answer closed.
RRB JE CBT-1 2025-26 – 20 February 2026 Shift 2 · Plant cell and animal cell

Q56. Which of the following is NOT correctly matched, with regard to plant and animal cells?

  1. (a) Plastids - Present in plant cells
  2. (b) Cell wall - Present in animal cells
  3. (c) Vacuoles - Very large and present in plant cells
  4. (d) Plastids - Absent in animal cells
Answer & solution

Answer: (b) Cell wall - Present in animal cells

Option 2 is incorrect because the cell wall is found in plant cells, not animal cells.
Animal cells do not have a cell wall; they only have a flexible cell membrane.
Plastids are present in plant cells and absent in animal cells, so options 1 and 4 are correct.
Vacuoles are very large in plant cells, serving as storage, which makes option 3 correct.
Therefore, cell wall present in animal cells is a wrong match.
Final answer: Option 2
RRB JE CBT-1 2025-26 – 20 February 2026 Shift 1 · Plant cell and animal cell

Q57. Which of the following is present only in plant cell?

  1. (a) Cell wall
  2. (b) Vacuoles
  3. (c) Nucleus
  4. (d) Endoplasmic reticulum
Answer & solution

Answer: (a) Cell wall

Option 1: Cell wall is found only in plant cells.
Vacuoles, nucleus and endoplasmic reticulum are present in both plant and animal cells.
The cell wall provides structural support and protection to plant cells only.
Hence, cell wall is unique to plant cells among the given options.
Final answer: Option 1
RRB JE CBT-1 2025-26 – 20 February 2026 Shift 2 · Prokaryotic and eukaryotic cells

Q58. Which statement is INCORRECT regarding prokaryotic organism?

  1. (a) Membrane-bound organelles are absent
  2. (b) Nuclear region is defined
  3. (c) Primitive form of organism
  4. (d) Single chromosome is present
Answer & solution

Answer: (b) Nuclear region is defined

Correct option: 2
Prokaryotic organisms do not have a defined nuclear membrane; their nuclear region is called the nucleoid and is not membrane-bound.
Other statements are correct: Membrane-bound organelles are absent in prokaryotes.
They are considered primitive forms of organisms compared to eukaryotes.
Most prokaryotes have a single circular chromosome.
Hence, option 2 is incorrect as nuclear region is not well defined.
Final answer: Option 2
RRB JE CBT-1 2025-26 – 19 February 2026 Shift 3 · Golgi apparatus, lysosomes and vacuoles

Q59. A large central vacuole is a characteristic feature of which of the following cells?

  1. (a) Bacterial cells
  2. (b) Animal cells
  3. (c) Protozoan cells
  4. (d) Plant cells
Answer & solution

Answer: (d) Plant cells

Correct option is 4.
A large central vacuole is a distinct characteristic of plant cells.
It stores water, nutrients and waste products.
This vacuole helps maintain turgor pressure in plant cells.
Other cells, like animal, bacterial, or protozoan cells typically do not have a large central vacuole.
Therefore, the feature is unique and diagnostic to plant cells.
Final answer: Option 4
RRB JE CBT-1 2025-26 – 19 February 2026 Shift 2 · Plastids

Q60. In which of the following organisms are chromoplasts present?

  1. (a) Rose
  2. (b) Hydra
  3. (c) Amoeba
  4. (d) Star fish
Answer & solution

Answer: (a) Rose

Chromoplasts are plastids that contain pigments responsible for colours other than green in plants.
They are commonly found in fruits and flowers where they provide red, orange, or yellow colours.
Rose, being a flowering plant, contains chromoplasts in its petals, giving them colour.
Hydra, Amoeba, and Star fish are animals and do not contain chromoplasts, which are plant cell organelles.
Final answer: Option 1
RRB JE CBT-1 2025-26 – 19 February 2026 Shift 1 · Endoplasmic reticulum and ribosomes

Q61. Ribosomes are attached to the surface of the rough endoplasmic reticulum. What is the primary function of the rough endoplasmic reticulum?

  1. (a) Protein synthesis and transport
  2. (b) Energy production and cellular respiration
  3. (c) Lipid synthesis
  4. (d) DNA replication and transcription
Answer & solution

Answer: (a) Protein synthesis and transport

Ribosomes are attached to the rough endoplasmic reticulum (RER).
RER is primarily involved in protein synthesis.
These proteins are then transported to various parts of the cell.
Other options are incorrect as:
- Energy production is by mitochondria.
- Lipid synthesis is mainly by smooth ER.
- DNA replication and transcription occur in the nucleus.
RRB JE CBT-1 2025-26 – 19 February 2026 Shift 3 · Nucleus and chromosomes

Q62. The nucleus contains chromosomes, which appear as rod-shaped structures only when the cell is about to divide. These chromosomes are composed of _____.

  1. (a) Glucose and enzymes
  2. (b) RNA and lipids
  3. (c) Amino acids and carbohydrates
  4. (d) DNA and proteins
Answer & solution

Answer: (d) DNA and proteins

Chromosomes are structures found in the nucleus of a cell.
They are visible as rod-shaped bodies only during cell division.
Chromosomes are made up of DNA and proteins.
DNA carries genetic information.
Proteins, mainly histones, help package and organise the DNA.
Hence, the correct composition of chromosomes is DNA and proteins.
Final answer: Option 4
RRB JE CBT-1 2025-26 – 19 February 2026 Shift 1 · Endoplasmic reticulum and ribosomes

Q63. Which cell organelle is responsible for the manufacture of lipids in the cell?

  1. (a) Smooth Endoplasmic Reticulum
  2. (b) Golgi Apparatus
  3. (c) Rough Endoplasmic Reticulum
  4. (d) Mitochondria
Answer & solution

Answer: (a) Smooth Endoplasmic Reticulum

The Smooth Endoplasmic Reticulum (Smooth ER) is responsible for lipid synthesis in cells.
Smooth ER lacks ribosomes, unlike Rough ER, which is involved in protein synthesis.
Hence, the organelle responsible for manufacturing lipids is the Smooth Endoplasmic Reticulum.
Final answer: Option 1
SSC MTS 2025 – 18 February 2026 Shift 2 · Endoplasmic reticulum and ribosomes

Q64. Which of the following organelle is the site for protein manufacture?

  1. (a) Lysosomes
  2. (b) Nuclear envelope
  3. (c) Plasma membrane
  4. (d) Ribosomes
Answer & solution

Answer: (d) Ribosomes

The correct answer is option 4.
Ribosomes are the cellular organelles responsible for protein synthesis (translation). They read the messenger RNA (mRNA) sequence and assemble the corresponding chain of amino acids to form proteins. Ribosomes can be free in the cytoplasm or attached to the rough endoplasmic reticulum.
Option 1 is incorrect: Lysosomes are the cell's digestive organelles; they contain hydrolytic enzymes that break down waste materials and cellular debris — they do not manufacture proteins.
Option 2 is incorrect: The nuclear envelope is the double membrane surrounding the nucleus; its function is to regulate movement of molecules between the nucleus and the cytoplasm.
Option 3 is incorrect: The plasma membrane is the outer boundary of the cell and controls transport of substances into and out of the cell; it is not involved in protein synthesis.
SSC MTS 2025 – 17 February 2026 Shift 3 · Nucleus and chromosomes

Q65. What feature of the nuclear membrane allows materials to move between the nucleus and the cytoplasm?

  1. (a) Ribosomes
  2. (b) Pores
  3. (c) Vesicles
  4. (d) Lysosomes
Answer & solution

Answer: (b) Pores

Nuclear pores are specialized protein-lined channels in the nuclear membrane (nuclear envelope) that allow selective transport of materials (RNA, proteins, etc.) between the nucleus and the cytoplasm. Ribosomes are sites of protein synthesis; Vesicles transport materials within and out of the cell; Lysosomes are digestive organelles — none of these are features of the nuclear membrane.
SSC MTS 2025 – 16 February 2026 Shift 2 · Endoplasmic reticulum and ribosomes

Q66. Rough Endoplasmic Reticulum looks rough under a microscope because it has particles called ____ attached to its surface.

  1. (a) plastid
  2. (b) chromosomes
  3. (c) ribosomes
  4. (d) cytoplasm
Answer & solution

Answer: (c) ribosomes

The Rough Endoplasmic Reticulum (RER) appears rough or granular under a microscope because of the numerous ribosomes attached to its outer surface. These ribosomes are involved in the synthesis of proteins that are destined for secretion, incorporation into cell membranes, or packaging in lysosomes.
Why other options are incorrect:
- Plastid: Organelles found in plant cells (e.g., chloroplasts); they are not found on the surface of the RER.
- Chromosomes: Found in the nucleus; they do not attach to the endoplasmic reticulum.
- Cytoplasm: The fluid matrix of the cell; it is not a particle that attaches to the RER surface.
Delhi Police Constable (Exe) 2025-26 – 6 January 2026 Shift 1 · Cell membrane and cell wall

Q67. Which structure in plant cells forms cytoplasmic channels, allowing communication and transport between adjacent cells?

  1. (a) Plasmodesmata
  2. (b) Tight junctions
  3. (c) Gap junctions
  4. (d) Desmosomes
Answer & solution

Answer: (a) Plasmodesmata

The correct answer is (a) Plasmodesmata.
Plasmodesmata are microscopic channels that traverse the cell walls of plant cells, connecting the cytoplasm of adjacent cells and allowing direct communication, water movement, and transport of small molecules between them. They form a continuous network called the symplast in plants.
(b) Tight junctions: Found in animal cells (especially epithelial cells); they seal adjacent cells together to prevent leakage of molecules; not found in plant cells.
(c) Gap junctions: Found in animal cells; allow direct electrical and chemical communication between adjacent animal cells; the plant equivalent is plasmodesmata.
(d) Desmosomes: Found in animal cells (especially skin and heart muscle); provide mechanical adhesion between adjacent cells; not the communication channels in plant cells.
Delhi Police Constable (Exe) 2025-26 – 6 January 2026 Shift 3 · Mitochondria

Q68. Some organelles generate energy for the cell. Which organelle is commonly called the "powerhouse of the cell"?

  1. (a) Nucleus
  2. (b) Mitochondria
  3. (c) Ribosome
  4. (d) Lysosome
Answer & solution

Answer: (b) Mitochondria

The correct answer is (b) Mitochondria.
Mitochondria are called the 'powerhouse of the cell' because they generate most of the cell's supply of ATP (adenosine triphosphate) through the process of cellular respiration (oxidative phosphorylation). They have a double-membrane structure with an inner folded membrane called cristae. Mitochondria have their own DNA and are thought to have evolved from ancient bacteria (endosymbiotic theory).
(a) Nucleus: The control center of the cell containing genetic material (DNA); directs cell activities but does not generate energy.
(c) Ribosome: The site of protein synthesis; translates mRNA into protein; does not generate ATP energy.
(d) Lysosome: Contains digestive enzymes; responsible for breaking down waste materials and cellular debris (autophagocytosis); does not generate energy.
Delhi Police Constable (Exe) 2025-26 – 24 December 2025 Shift 2 · Prokaryotic and eukaryotic cells

Q69. Which of the following is a major structural difference between prokaryotic and eukaryotic cells?

  1. (a) Presence of DNA
  2. (b) Presence of mitochondria
  3. (c) Presence of ribosomes
  4. (d) Presence of plasma membrane
Answer & solution

Answer: (b) Presence of mitochondria

The correct answer is Presence of mitochondria (Option 2).
Mitochondria are membrane-bound organelles found only in eukaryotic cells (animal, plant, fungal cells) and are absent in prokaryotic cells (bacteria and archaea). Mitochondria are responsible for cellular respiration and energy production (ATP). This represents a major structural difference between the two cell types.
Option 1 - Presence of DNA: Both prokaryotic and eukaryotic cells contain DNA, so this is NOT a distinguishing difference.
Option 3 - Presence of ribosomes: Both prokaryotic and eukaryotic cells have ribosomes (though different in size: 70S in prokaryotes, 80S in eukaryotes), so ribosomes alone do not distinguish them.
Option 4 - Presence of plasma membrane: Both prokaryotic and eukaryotic cells have a plasma membrane surrounding them, so this is NOT a structural difference.
Delhi Police Constable (Exe) 2025-26 – 23 December 2025 Shift 3 · Mitochondria

Q70. What is the function of the mitochondria in a cell?

  1. (a) Protein synthesis
  2. (b) DNA replication
  3. (c) Energy production
  4. (d) Waste removal
Answer & solution

Answer: (c) Energy production

The correct answer is Energy production (Option 3).
Mitochondria are known as the 'powerhouses of the cell.' They produce energy in the form of ATP (adenosine triphosphate) through a process called cellular respiration, using oxygen and nutrients.
Option 1 - Protein synthesis: Protein synthesis is carried out by ribosomes, not mitochondria.
Option 2 - DNA replication: DNA replication occurs in the nucleus of the cell.
Option 4 - Waste removal: Waste removal and cellular digestion are functions of lysosomes.
Delhi Police Constable (Exe) 2025-26 – 22 December 2025 Shift 3 · Prokaryotic and eukaryotic cells

Q71. Which of the following components is NOT common to both prokaryotic and eukaryotic cells?

  1. (a) Plasma membrane
  2. (b) Cytoplasm
  3. (c) Nucleus
  4. (d) Ribosomes
Answer & solution

Answer: (c) Nucleus

The correct answer is Nucleus (Option 3).
The nucleus is NOT present in prokaryotic cells. Prokaryotes (like bacteria) lack a membrane-bound nucleus; their genetic material is located in the nucleoid region. The nucleus is exclusive to eukaryotic cells.
Option 1 - Plasma membrane: Present in both prokaryotic (bacteria) and eukaryotic cells as the outer boundary.
Option 2 - Cytoplasm: Present in both types of cells as the fluid medium containing organelles and molecules.
Option 4 - Ribosomes: Present in both prokaryotic (70S) and eukaryotic cells (80S cytoplasmic ribosomes), though they differ in size.
SSC CPO Paper-1 2025 – 10 December 2025 Shift 1 · Cell membrane and cell wall

Q72. Which of the following biomolecules is most abundant in plant cell walls?

  1. (a) Cellulose
  2. (b) Pectin
  3. (c) Lignin
  4. (d) Hemicellulose
Answer & solution

Answer: (a) Cellulose

Correct Answer: Cellulose
Cellulose is the most abundant organic polymer on Earth and the primary structural component of plant cell walls. It accounts for about 40–50% of the cell wall's dry weight. Cellulose is made of glucose units linked by β-1,4 glycosidic bonds, forming rigid microfibrils.
Option 2 (Pectin): Incorrect. Pectin is present in the middle lamella and primary cell wall in smaller quantities.
Option 3 (Lignin): Incorrect. Lignin is present in secondary cell walls of woody plants but is less abundant than cellulose.
Option 4 (Hemicellulose): Incorrect. Hemicellulose is present but in smaller quantities than cellulose.
SSC Stenographer 2025 – 8 December 2025 Shift 3 · Cell division - mitosis and meiosis

Q73. Which of the following statements about the G0 (G zero phase) phase of the cell cycle is most accurate?

  1. (a) DNA synthesis occurs rapidly in cells present in the G0 phase.
  2. (b) It is the phase where cell division is initiated in cancerous cells.
  3. (c) It is a temporary quiescent stage where cells exit the cell cycle.
  4. (d) Cells in G0 actively prepare for DNA replication.
Answer & solution

Answer: (c) It is a temporary quiescent stage where cells exit the cell cycle.

The G0 phase is also known as the resting or quiescent stage. In this stage, cells exit the active cell cycle after mitosis and do not proceed to DNA synthesis (S phase). Some cells enter G0 temporarily, such as liver cells which can re-enter the cycle when required, while others enter it permanently, such as neurons and cardiac muscle cells. Hence, statement 3 is the most accurate. Statement 1 and 4 are wrong because DNA synthesis does not occur in G0, it happens in the S phase. Statement 2 is also incorrect because cancer cells bypass G0 and divide uncontrollably, but G0 itself is not the stage of division initiation.
SSC Stenographer 2025 – 6 December 2025 Shift 1 · Golgi apparatus, lysosomes and vacuoles

Q74. Which of the following is not a correct statement regarding vacuoles?

  1. (a) In some plant cells, the central vacuole can take up most of the cell’s volume
  2. (b) Vacuoles serve as storage sacs for both solids and liquids
  3. (c) Vacuoles are generally larger in animal cells than in plant cells
  4. (d) Animal cells usually contain smaller vacuoles compared to plant cells
Answer & solution

Answer: (c) Vacuoles are generally larger in animal cells than in plant cells

The correct answer is “Vacuoles are generally larger in animal cells than in plant cells.” This is incorrect because in reality, plant cells generally have a single large central vacuole that occupies up to 80–90% of the cell’s volume, playing a major role in maintaining turgor pressure, storing nutrients, and waste management. In contrast, animal cells contain multiple small vacuoles , which are much smaller in size and perform functions like storage and transport. Hence, vacuoles are larger in plant cells, not in animal cells.
SSC Stenographer 2025 – 6 December 2025 Shift 2 · Cell membrane and cell wall

Q75. Which of the following pairs is correctly matched?

  1. (a) Cell wall – Composed mainly of protein
  2. (b) Plasma membrane – Located outside the cell wall
  3. (c) Cellulose – Provides structural strength to plant cells
  4. (d) Plasmolysis – Gain of water by plant cell
Answer & solution

Answer: (c) Cellulose – Provides structural strength to plant cells

The correct answer is Cellulose – Provides structural strength to plant cells . Plant cell walls are mainly made up of cellulose, which is a polysaccharide. Cellulose microfibrils form a rigid framework that provides mechanical strength and support to plant cells, allowing them to maintain their shape and resist osmotic pressure. The other options are incorrect: (1) Cell wall is not mainly protein, it is mainly cellulose; (2) Plasma membrane is located inside the cell wall, not outside; (4) Plasmolysis refers to the loss of water from a plant cell in a hypertonic solution, not the gain of water. Thus, only option (3) is correctly matched.
SSC Stenographer 2025 – 6 December 2025 Shift 2 · Prokaryotic and eukaryotic cells

Q76. The cell uses internal compartmentalization to manage its complexity.
Which of the following best reflects this idea?

  1. (a) All cellular functions occur in the same space without any separation.
  2. (b) Organelles in eukaryotic cells float freely without any specific role.
  3. (c) Eukaryotic cells have membrane-bound organelles that separate different functions.
  4. (d) Prokaryotic cells use multiple membranes to isolate cell activities.
Answer & solution

Answer: (c) Eukaryotic cells have membrane-bound organelles that separate different functions.

The correct answer is Eukaryotic cells have membrane-bound organelles that separate different functions . Internal compartmentalization is a key feature of eukaryotic cells , where organelles such as the nucleus, mitochondria, endoplasmic reticulum, and Golgi apparatus are surrounded by membranes. This allows specific biochemical processes to occur in isolated environments, improving efficiency and reducing interference between different activities. For example, DNA replication occurs inside the nucleus, while energy production happens in mitochondria. This division of labor enables eukaryotic cells to manage their complexity, grow larger, and perform highly specialized functions compared to prokaryotic cells, which lack such compartmentalization.
SSC CGL Tier-1 2025 – 19 September 2025 Shift 1 · Biomolecules and enzymes

Q77. Read the below statements about enzymes and choose the correct option:
1. Enzymes increase the activation energy of a reaction.
2. Enzymes are specific to substrates due to active site configuration.
3. Enzyme activity is affected by pH and temperature.
Which of the above statements arecorrect?

  1. (a) Only 1 and 2 are correct
  2. (b) Only 2 and 3 are correct
  3. (c) Only 1 and 3 are correct
  4. (d) 1, 2 and 3 all are correct
Answer & solution

Answer: (b) Only 2 and 3 are correct

Statement 1 is wrong — enzymes lower (not increase) activation energy.
Statement 2 is correct — active site shape gives substrate specificity.
Statement 3 is correct — pH and temperature strongly influence enzyme activity.
Hence only 2 and 3 are correct.
SSC CGL Tier-1 2025 – 15 September 2025 Shift 1 · Cell membrane and cell wall

Q78. Which of these biomolecules is an essential component of the plasma membrane?

  1. (a) Cellulose
  2. (b) Phospholipids
  3. (c) DNA
  4. (d) Glycogen
Answer & solution

Answer: (b) Phospholipids

The plasma membrane is composed primarily of a phospholipid bilayer with embedded proteins (fluid mosaic model).
Cellulose forms plant cell walls, DNA is genetic material, and glycogen is a storage carbohydrate.
SSC CGL Tier-1 2025 – 13 September 2025 Shift 2 · Golgi apparatus, lysosomes and vacuoles

Q79. What is the primary function of the Golgi apparatus?

  1. (a) ATP production
  2. (b) Protein modification
  3. (c) Lipid synthesis
  4. (d) DNA replication
Answer & solution

Answer: (b) Protein modification

• Cell Biology - Golgi apparatus:
• The Golgi apparatus (also called Golgi body or Golgi complex) is the cell's post office/packaging center.
• Primary function: Protein modification, sorting, and packaging — modifies proteins received from endoplasmic reticulum
• ATP production: done by mitochondria
• Lipid synthesis: primarily done by smooth ER
• DNA replication: occurs in the nucleus
• Answer: Protein modification
SSC CGL Tier-1 2025 – 12 September 2025 Shift 2 · Golgi apparatus, lysosomes and vacuoles

Q80. The function of lysosomes in cells is:

  1. (a) Protein synthesis
  2. (b) Intracellular digestion
  3. (c) Energy production
  4. (d) Genetic information storage
Answer & solution

Answer: (b) Intracellular digestion

Lysosomes are membrane-bound organelles that contain hydrolytic enzymes capable of digesting macromolecules and worn-out cell parts inside the cell — i.e., intracellular digestion. They are often called the 'suicide bags' of the cell.
Protein synthesis is performed by ribosomes.
Energy production happens in mitochondria.
Genetic information storage is the role of the nucleus (DNA).
Hence the correct option is Intracellular digestion.
RRB NTPC UG CBT-1 2024-25 – 8 September 2025 Shift 2 · Biomolecules and enzymes

Q81. Which macromolecule is primarily responsible for energy storage in plants?

  1. (a) Starch
  2. (b) Nucleic acids
  3. (c) Proteins
  4. (d) Vitamins
Answer & solution

Answer: (a) Starch

RRB NTPC UG CBT-1 2024-25 – 28 August 2025 Shift 1 · Plastids

Q82. Which organelle is responsible for photosynthesis in plants?

  1. (a) Mitochondria
  2. (b) Chloroplast
  3. (c) Leucoplast
  4. (d) Chromoplast
Answer & solution

Answer: (b) Chloroplast

RRB NTPC UG CBT-1 2024-25 – 21 August 2025 Shift 1 · Biomolecules and enzymes

Q83. Which of the following elements is NOT generally found in proteins?

  1. (a) Nitrogen
  2. (b) Hydrogen
  3. (c) Phosphorus
  4. (d) Carbon
Answer & solution

Answer: (c) Phosphorus

RRB NTPC UG CBT-1 2024-25 – 13 August 2025 Shift 2 · Biomolecules and enzymes

Q84. Which biomolecules are responsible for catalysing biochemical reactions?

  1. (a) Polysaccharides
  2. (b) Enzymes
  3. (c) Nucleotides
  4. (d) Phospholipids
Answer & solution

Answer: (b) Enzymes

SSC Selection Post 2025 (Phase XIII) – 26 July 2025 Shift 2 · Golgi apparatus, lysosomes and vacuoles

Q85. What is the function of the lysosomes in animal cells?

  1. (a) Transport proteins within the cell
  2. (b) Break down waste materials and cellular debris
  3. (c) Produce ATP through cellular respiration
  4. (d) Synthesize lipids
Answer & solution

Answer: (b) Break down waste materials and cellular debris

Correct Answer: Option 2 – Break down waste materials and cellular debris
Lysosomes are membrane-bound organelles found in animal cells containing digestive enzymes (hydrolases) that break down waste materials, cellular debris, foreign particles (bacteria), worn-out organelles (autophagy), and macromolecules (proteins, lipids, carbohydrates, nucleic acids). They are called the 'suicide bags' of the cell (term coined by Christian de Duve) because if their membrane ruptures, the released enzymes can digest the cell itself.
Option 1 (Transport proteins): Proteins are transported via the endoplasmic reticulum and Golgi apparatus; not lysosomes.
Option 3 (Produce ATP): ATP is produced by mitochondria through cellular respiration; lysosomes have no role in ATP synthesis.
Option 4 (Synthesize lipids): Lipid synthesis occurs in the smooth endoplasmic reticulum; not lysosomes.
SSC Selection Post 2025 (Phase XIII) – 25 July 2025 Shift 2 · Endoplasmic reticulum and ribosomes

Q86. What is the role of the ribosome in a cell?

  1. (a) Energy production
  2. (b) Protein synthesis
  3. (c) Cell division
  4. (d) Transport of substances
Answer & solution

Answer: (b) Protein synthesis

Correct Answer: Option 2 – Protein synthesis
Ribosomes are cellular organelles (composed of rRNA and proteins) that serve as the site of protein synthesis. They translate the genetic information from mRNA (messenger RNA) into a specific sequence of amino acids, forming polypeptide chains (proteins). Ribosomes can be free in the cytoplasm or attached to the rough endoplasmic reticulum. They are present in all living cells — both prokaryotes and eukaryotes.
Option 1 (Energy production): Energy (ATP) is produced by mitochondria through cellular respiration; not ribosomes.
Option 3 (Cell division): Cell division involves the nucleus, centrioles, and spindle fibers; ribosomes have no direct role.
Option 4 (Transport of substances): Transport of substances is carried out by the cell membrane, vesicles, and endoplasmic reticulum; not ribosomes.
RRB NTPC GL CBT-1 2024-25 – 24 June 2025 Shift 3 · Cytoskeleton, cell death and cancer cells

Q87. Which cytoskeletal protein is the major component of neurofilaments that helps maintain the caliber and integrity of large axons?

  1. (a) Keratin protein
  2. (b) Neurofilament protein
  3. (c) Tubulin protein
  4. (d) Actin protein
Answer & solution

Answer: (b) Neurofilament protein

RRB NTPC GL CBT-1 2024-25 – 14 June 2025 Shift 2 · Biomolecules and enzymes

Q88. Enzyme cofactors such as NAD⁺ function mainly by:

  1. (a) acting as a permanent structural component of the enzyme
  2. (b) providing a binding site for competitive inhibitors
  3. (c) lowering the activation energy by stabilising the transition state
  4. (d) increasing the overall concentration of the enzyme
Answer & solution

Answer: (c) lowering the activation energy by stabilising the transition state

RRB NTPC GL CBT-1 2024-25 – 12 June 2025 Shift 1 · Biomolecules and enzymes

Q89. The Michaelis-Menten constant (Km) of an enzyme is defined as:

  1. (a) The maximum reaction rate (Vmax)
  2. (b) The enzyme concentration required for half-maximal catalysis
  3. (c) The substrate concentration at which the reaction rate is half of Vmax
  4. (d) The inhibitor concentration that reduces enzyme activity by 50%
Answer & solution

Answer: (c) The substrate concentration at which the reaction rate is half of Vmax

RRB NTPC GL CBT-1 2024-25 – 10 June 2025 Shift 3 · Biomolecules and enzymes

Q90. According to the induced-fit model of enzyme action, substrate binding __________.

  1. (a) inhibits the enzyme by permanently altering its structure
  2. (b) induces a conformational change that optimises the active site for catalysis
  3. (c) occurs without any change to the enzyme’s active site
  4. (d) leads to immediate release of the substrate without transformation
Answer & solution

Answer: (b) induces a conformational change that optimises the active site for catalysis

RRB NTPC GL CBT-1 2024-25 – 6 June 2025 Shift 2 · Cell membrane and cell wall

Q91. Which kitchen process is an example of osmosis?

  1. (a) Flushing food items with nitrogen
  2. (b) Grinding spices together
  3. (c) Placing raw mango in a concentrated salt solution
  4. (d) Boiling pasta in milk
Answer & solution

Answer: (c) Placing raw mango in a concentrated salt solution

RRB Technician Grade III 2024-25 – 30 December 2024 Shift 1 · Mitochondria

Q92. Which organelle is the powerhouse of the cell?

  1. (a) Plastids
  2. (b) Endoplasmic reticulum
  3. (c) Mitochondria
  4. (d) Golgi apparatus
Answer & solution

Answer: (c) Mitochondria

Correct Answer: Option 3 — Mitochondria
Mitochondria are called the powerhouse of the cell. They carry out aerobic respiration, breaking down glucose in the presence of oxygen and releasing energy that is stored as ATP (adenosine triphosphate) — the energy currency of the cell. This ATP is spent on every activity: muscle contraction, protein synthesis and nerve conduction.
A mitochondrion has a double membrane; the outer membrane is smooth while the inner membrane is deeply folded into cristae, which greatly increase the surface area available for ATP-producing reactions. Mitochondria possess their own DNA and ribosomes and can make some of their own proteins, so they are called semi-autonomous organelles.
❌ Why the other options are incorrect
✗ Plastids — present only in plant cells; chloroplasts (with chlorophyll) carry out photosynthesis, chromoplasts give colour and leucoplasts store food.
✗ Endoplasmic reticulum — a network of membranes; RER (with ribosomes) makes proteins while SER makes lipids and detoxifies poisons.
✗ Golgi apparatus — the packaging and dispatching centre of the cell; it modifies, stores and sends out materials and forms lysosomes.
📌 SSC & Railway Exam Facts
• Mitochondria were discovered by Altmann (1890) and named by Benda.
• The lysosome is the suicidal bag of the cell, discovered by Christian de Duve.
• The ribosome is the protein factory; the Golgi body was discovered by Camillo Golgi.
• Mitochondrial DNA is inherited maternally (from the mother).
• The chloroplast is called the kitchen of the cell and the mitochondrion the powerhouse.
RRB Technician Grade III 2024-25 – 30 December 2024 Shift 2 · Cell membrane and cell wall

Q93. What will happen when a plant cell is put in a medium having higher water concentration than the cell?

  1. (a) It will burst
  2. (b) It will not show any change
  3. (c) It will likely shrink
  4. (d) It will likely swell
Answer & solution

Answer: (d) It will likely swell

Correct Answer: Option 4 — It will likely swell
A medium with a higher water concentration (i.e. lower solute concentration) than the cell sap is a hypotonic solution. Water then moves into the cell by osmosis — the movement of water molecules from a region of higher water concentration to lower water concentration through a selectively permeable membrane (the plasma membrane).
As water enters, the vacuole fills up and pushes the cytoplasm against the cell wall, so the cell swells and becomes turgid. The outward push of the cell contents is the turgor pressure, which keeps herbaceous stems and leaves firm and erect. The plant cell does not burst, because the tough cellulose cell wall resists further expansion — this is exactly why a plant cell behaves differently from an animal cell in the same medium.
❌ Why the other options are incorrect
✗ It will burst — only an animal cell (e.g. an RBC) bursts in a hypotonic medium; the plant cell's rigid cell wall prevents bursting.
✗ It will not show any change — no change occurs only in an isotonic medium, where water enters and leaves at equal rates.
✗ It will likely shrink — shrinking (plasmolysis) happens in a hypertonic medium, where water leaves the cell.
📌 SSC & Railway Exam Facts
• Osmosis is the diffusion of water through a semi-permeable membrane; diffusion is the movement of any particles from high to low concentration.
• Plasmolysis — shrinkage of the protoplasm away from the cell wall in a hypertonic solution.
• A turgid cell gives plants mechanical support; wilting occurs when turgor is lost.
• Raisins swell in plain water (endosmosis) and shrink in strong sugar solution (exosmosis).
• Roots absorb water from the soil by osmosis through the root hairs.
RRB Technician Grade III 2024-25 – 30 December 2024 Shift 2 · Plastids

Q94. In which organelle of the plant cells does photosynthesis take place?

  1. (a) Chloroplast
  2. (b) Nucleus
  3. (c) Ribosome
  4. (d) Mitochondria
Answer & solution

Answer: (a) Chloroplast

Correct Answer: Option 1 — Chloroplast
Photosynthesis is the process by which green plants make their own food, converting carbon dioxide and water into carbohydrates using sunlight, and releasing oxygen. It takes place in the chloroplast, a green plastid found in the cells of leaves and other green parts.
The chloroplast is a double-membrane organelle. Its inner space, the stroma, holds stacks of flattened sacs called grana (thylakoids) that carry the green pigment chlorophyll. Chlorophyll traps light energy; the light reaction in the grana splits water and makes ATP and NADPH, while the dark reaction in the stroma fixes CO₂ into sugar. Because chloroplasts hold their own DNA and ribosomes, they are called semi-autonomous organelles and are known as the kitchen of the cell.
❌ Why the other options are incorrect
✗ Nucleus — the control centre of the cell; it stores the DNA (chromatin) and directs cell division and inheritance.
✗ Ribosome — the site of protein synthesis; it has no membrane and no pigment.
✗ Mitochondria — the powerhouse of the cell, where respiration releases energy as ATP; this is the reverse of photosynthesis.
📌 SSC & Railway Exam Facts
• Equation — 6CO₂ + 6H₂O → (light, chlorophyll) → C₆H₁₂O₆ + 6O₂.
• Plastids are of three kinds — chloroplast (green), chromoplast (coloured), leucoplast (colourless, stores starch/oil/protein).
• Chlorophyll contains magnesium (Mg); haemoglobin contains iron (Fe).
• Gas exchange for photosynthesis occurs through stomata, guarded by guard cells.
• Mitochondria and chloroplast are the only two organelles with their own DNA.
RRB Technician Grade III 2024-25 – 30 December 2024 Shift 2 · Discovery of cell and cell theory

Q95. Which of the following is NOT a unicellular organism?

  1. (a) Paramecium
  2. (b) Chlamydomonas
  3. (c) Bacteria
  4. (d) Fungi
Answer & solution

Answer: (d) Fungi

Correct Answer: Option 4 — Fungi
A unicellular organism is made of a single cell that performs all the life functions — nutrition, respiration, excretion, growth and reproduction — by itself. A multicellular organism is built of many cells that show division of labour, each group of cells forming a tissue specialised for one job.
Most fungi, such as Rhizopus, Mucor, Penicillium, Aspergillus and mushrooms, are multicellular. Their body is a network of thread-like hyphae collectively called the mycelium, so the group as a whole is treated as multicellular. (Yeast is the well-known exception — a unicellular fungus.) Fungi are eukaryotic, have a chitin cell wall and are heterotrophic, feeding as saprophytes or parasites.
❌ Why the other options are incorrect
✗ Paramecium — a unicellular protozoan with a slipper shape and cilia for locomotion; it has a definite shape and two nuclei.
✗ Chlamydomonas — a unicellular green alga with a cup-shaped chloroplast and two flagella.
✗ Bacteria — unicellular prokaryotes with no true nucleus and no membrane-bound organelles.
📌 SSC & Railway Exam Facts
• Unicellular examples — Amoeba, Paramecium, Euglena, Chlamydomonas, bacteria, yeast.
• Fungi are studied under Mycology; Bacteriology is the study of bacteria.
• Fungal cell wall is made of chitin; plant cell wall of cellulose.
• Penicillin, the first antibiotic, was obtained by Alexander Fleming from the fungus Penicillium notatum.
• Lichen = symbiotic association of a fungus + alga; Mycorrhiza = fungus + plant roots.
RRB Technician Grade III 2024-25 – 30 December 2024 Shift 3 · Prokaryotic and eukaryotic cells

Q96. Select the correct statement related to the characteristics of prokaryotic cell.

  1. (a) It has a single chromosome.
  2. (b) Membrane bound cell organelles are present.
  3. (c) Nuclear region is well defined and surrounded by nuclear membrane.
  4. (d) It has more than one chromosome.
Answer & solution

Answer: (a) It has a single chromosome.

Correct Answer: Option 1 — It has a single chromosome.
A prokaryotic cell is a primitive cell that lacks a true nucleus. Its genetic material — a single, circular chromosome of naked DNA — lies free in the cytoplasm in a region called the nucleoid, which has no nuclear membrane around it. Bacteria and blue-green algae (cyanobacteria) are the standard examples.
Prokaryotic cells also lack membrane-bound organelles such as mitochondria, plastids, Golgi apparatus, endoplasmic reticulum and lysosomes; the only organelle present is the ribosome (70S). Respiration takes place on infoldings of the plasma membrane called mesosomes. In contrast, eukaryotic cells (plants, animals, fungi, protists) have a well-defined nucleus with a nuclear membrane and more than one chromosome.
❌ Why the other options are incorrect
✗ Membrane bound cell organelles are present. — false; membrane-bound organelles are a defining feature of eukaryotic cells only.
✗ Nuclear region is well defined and surrounded by nuclear membrane. — false; in prokaryotes the nuclear region is an undefined nucleoid with no nuclear membrane.
✗ It has more than one chromosome. — false; multiple chromosomes occur in eukaryotes; a prokaryote carries only one.
📌 SSC & Railway Exam Facts
• Prokaryote size is about 1–10 µm; eukaryote about 5–100 µm.
• Prokaryotic ribosome is 70S; eukaryotic (cytoplasmic) is 80S.
• Prokaryotes divide by binary fission, not by mitosis or meiosis.
• Extra small circular DNA in bacteria is the plasmid, widely used in genetic engineering.
• Human somatic cells have 46 chromosomes (23 pairs); E. coli has a single circular chromosome.
RRB Technician Grade III 2024-25 – 30 December 2024 Shift 3 · Biomolecules and enzymes

Q97. Which of the following is/are called biological catalysts?

  1. (a) Mucus
  2. (b) Hydrochloric acid
  3. (c) Digestive juices
  4. (d) Enzymes
Answer & solution

Answer: (d) Enzymes

Correct Answer: Option 4 — Enzymes
Enzymes are protein molecules made by living cells that speed up biochemical reactions without being used up or changed themselves — exactly what a catalyst does. Because they are produced by living organisms, they are called biological catalysts or biocatalysts.
Each enzyme is highly specific: it acts on one substrate only, which is explained by the lock-and-key model. Enzymes also work only within a narrow range of temperature and pH — pepsin needs an acidic medium in the stomach, while trypsin needs an alkaline medium in the small intestine. In digestion, amylase breaks starch into sugar, pepsin and trypsin break protein into amino acids, and lipase breaks fat into fatty acids and glycerol.
❌ Why the other options are incorrect
✗ Mucus — a slimy secretion that protects and lubricates the stomach lining against HCl; it has no catalytic action.
✗ Hydrochloric acid — it makes the stomach acidic, kills germs and activates pepsinogen into pepsin, but it is an acid, not an enzyme.
✗ Digestive juices — these are mixtures (saliva, gastric juice, pancreatic juice, bile); the catalysts are the enzymes contained in them, not the juices themselves.
📌 SSC & Railway Exam Facts
• Almost all enzymes are proteins; ribozymes are the RNA exception.
• Enzymes are denatured (destroyed) by high temperature, which is why fever affects digestion.
• Ptyalin (salivary amylase) acts at pH ≈ 6.8 in the mouth; pepsin at pH ≈ 2.
• Bile contains no enzyme; it only emulsifies fat and provides an alkaline medium.
• The term enzyme was coined by Wilhelm Kühne; the first enzyme crystallised was urease (J. B. Sumner).
RRB Technician Grade III 2024-25 – 30 December 2024 Shift 3 · Mitochondria

Q98. ATP is broken down giving rise to a fixed amount of energy that can drive the endothermic reactions taking place in which cell organelle of a cell?

  1. (a) Mitochondria
  2. (b) Ribosome
  3. (c) Chloroplast
  4. (d) Lysosome
Answer & solution

Answer: (a) Mitochondria

Correct Answer: Option 1 — Mitochondria
Mitochondria are the powerhouses of the cell. They release the energy needed for all life activities in the form of ATP (Adenosine Tri Phosphate) — the energy currency of the cell. During aerobic respiration inside the mitochondria, glucose is oxidised and the energy released is used to join ADP + inorganic phosphate → ATP.
Whenever the cell needs energy, the terminal phosphate bond of ATP is broken by water, releasing about 30.5 kJ/mol. This fixed packet of energy then drives the endothermic (energy-absorbing) reactions of the cell, such as the making of new proteins and the contraction of muscles. A mitochondrion has a double membrane, the inner one deeply folded into cristae to increase surface area, and it possesses its own DNA and ribosomes.
❌ Why the other options are incorrect
✗ Ribosome — the site of protein synthesis; it consumes ATP but does not produce it and is not a membrane-bound organelle.
✗ Chloroplast — the organelle of photosynthesis in plant cells; it traps light energy, and is absent in animal cells.
✗ Lysosome — the suicidal bag of the cell containing digestive enzymes that break down worn-out organelles and foreign material.
📌 SSC & Railway Exam Facts
• ATP is called the energy currency of the cell; the term mitochondria was given by Carl Benda.
• Inner folds of the mitochondrion are cristae; the fluid inside is the matrix.
• Aerobic respiration yields 38 ATP per glucose molecule; anaerobic yields only 2 ATP.
• Mitochondria and chloroplast are semi-autonomous — they have their own DNA and ribosomes.
• Organelle tags — Golgi apparatus: packaging and dispatch; ER: transport; lysosome: suicidal bag; ribosome: protein factory.
RRB Technician Grade III 2024-25 – 30 December 2024 Shift 3 · Golgi apparatus, lysosomes and vacuoles

Q99. Most mature plant cells have a ______ that helps to maintain the turgidity of the cell and store important substances including wastes.

  1. (a) small ribosome
  2. (b) leucoplasts
  3. (c) chromoplasts
  4. (d) large central vacuole
Answer & solution

Answer: (d) large central vacuole

Correct Answer: Option 4 — large central vacuole
In a mature plant cell a single large central vacuole may occupy 50–90 % of the cell volume. It is bounded by a membrane called the tonoplast and is filled with cell sap — a solution of water, sugars, amino acids, mineral salts, pigments and waste products.
The vacuole performs two key jobs stated in the question. By taking in water it presses the cytoplasm outward against the cell wall, creating turgor pressure, which keeps the cell turgid and gives rigidity and support to non-woody stems and leaves. It also acts as the cell's storehouse and dustbin, holding useful substances and isolating toxic wastes that the plant cannot excrete. Animal cells, by contrast, have only small, temporary vacuoles.
❌ Why the other options are incorrect
✗ small ribosome — the site of protein synthesis; it is a tiny non-membranous granule and stores nothing.
✗ leucoplasts — colourless plastids that store starch, oils and proteins; they are storage granules, not the turgidity-maintaining organelle.
✗ chromoplasts — coloured plastids (other than green) that give flowers and fruits their red, orange and yellow colours to attract pollinators.
📌 SSC & Railway Exam Facts
• The vacuole membrane is the tonoplast; the fluid inside is cell sap.
• Amoeba has a food vacuole and a contractile vacuole for osmoregulation.
• Loss of turgor causes wilting; regaining water restores firmness.
• Plastids — chloroplast (green, photosynthesis), chromoplast (coloured), leucoplast (colourless, storage).
• Features unique to plant cells — cell wall, plastids and a large central vacuole.
RRB Technician Grade III 2024-25 – 30 December 2024 Shift 3 · Cell membrane and cell wall

Q100. Which of the following unicellular organism change their shape?

  1. (a) Yeast
  2. (b) Paramoecium
  3. (c) Amoeba
  4. (d) Bacteria
Answer & solution

Answer: (c) Amoeba

Correct Answer: Option 3 — Amoeba
Amoeba is a unicellular, freshwater protozoan that has no fixed shape. Its outer boundary is only a flexible plasma membrane — there is no rigid cell wall — so the cell can push out finger-like projections of cytoplasm called pseudopodia ("false feet") in any direction. As the pseudopodia are formed and withdrawn, the shape of Amoeba keeps changing continuously.
The pseudopodia serve two purposes: locomotion (amoeboid movement) and ingestion of food, which they surround and enclose in a food vacuole — a process called phagocytosis. In our own body, white blood cells (WBCs) move and engulf germs in the same amoeboid way.
❌ Why the other options are incorrect
✗ Yeast — a unicellular fungus with a rigid cell wall; it keeps a definite oval shape and reproduces by budding.
✗ Paramoecium — a unicellular protozoan with a definite slipper-like shape maintained by a firm pellicle; it swims using cilia.
✗ Bacteria — they have a tough cell wall and hold fixed shapes — cocci (round), bacilli (rod), spirilla (spiral), vibrio (comma).
📌 SSC & Railway Exam Facts
• Amoeba shows holozoic nutrition and reproduces by binary fission in any plane.
• Its contractile vacuole removes excess water — it performs osmoregulation.
• Amoebic dysentery (amoebiasis) is caused by Entamoeba histolytica.
• Cell shape is maintained by the cell wall in plants, fungi and bacteria; animal cells have none.
• The cell was discovered by Robert Hooke (1665); Leeuwenhoek first saw free-living cells.
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