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Plant Physiology and Morphology PYQs – Biology, SSC & Railway

76 Plant Physiology and Morphology (Biology) questions asked in recent SSC and Railway exams, newest first, with exam, date & shift, answers and solutions.

📚 76 questionsSSC 20 · Railway 56
RRB Group D 2025-26 – 25 August 2026 Shift 1 · Transport in plants (xylem, phloem)

Q1. Transport of water in plants occurs through ___________.

  1. (a) Xylem
  2. (b) Vacuole
  3. (c) Phloem
  4. (d) Cambium
Answer & solution

Answer: (a) Xylem

Correct Answer:
Correct Answer: Option 1 – Xylem
Explanation:
Xylemis the vascular tissue responsible for transporting water and dissolved minerals from the roots upward to the stem and leaves. It consists of tracheids and vessels that form continuous conducting channels.
Important Facts:
• Phloem transports food (prepared by photosynthesis) from leaves to other parts of the plant.
• Water movement in xylem occurs due to transpiration pull, root pressure, and capillary action.
• Cambium is the meristematic tissue that produces new xylem and phloem.
RRB Group D 2025-26 – 25 August 2026 Shift 1 · Photosynthesis - process and factors

Q2. Which of the following processes in plants are responsible for fulfilling the energy and carbon requirements?

  1. (a) Respiration
  2. (b) Translocation
  3. (c) Photosynthesis
  4. (d) Transpiration
Answer & solution

Answer: (c) Photosynthesis

Correct Answer:
Correct Answer: Option 3 – Photosynthesis
Explanation:
Photosynthesisis the process by which green plants use sunlight, water, and carbon dioxide to synthesize glucose (food), fulfilling both theirenergyrequirements (glucose is later broken down via respiration to release energy) and theircarbonrequirements (carbon is incorporated into organic compounds like carbohydrates).
Important Facts:
• Respiration releases energy from food but does not fix carbon — it releases CO2.
• Translocation moves food (from photosynthesis) via phloem; transpiration is loss of water vapor.
• The overall photosynthesis equation: 6CO2 + 6H2O → C6H12O6 + 6O2 (using light energy).
RRB Group D 2025-26 – 25 August 2026 Shift 3 · Photosynthesis - process and factors

Q3. In a desert plant, carbon dioxide is taken in at night and stored as an intermediate, which is later used during the day for carbohydrate synthesis. What advantage does this adaptation provide to the plant in its environment?

  1. (a) It eliminates the need for chlorophyll
  2. (b) It allows carbohydrate synthesis only at night
  3. (c) It increases the rate of photosynthesis during the day
  4. (d) It reduces water loss by stomatal opening to cooler night hours
Answer & solution

Answer: (d) It reduces water loss by stomatal opening to cooler night hours

Correct Answer:
Correct Answer: Option 4 – It reduces water loss by stomatal opening to cooler night hours
Explanation:
This describes CAM (Crassulacean Acid Metabolism) photosynthesis, common in desert plants like cacti. Stomata open at night (when temperatures are cooler and humidity higher) to take in CO2 and store it as an organic acid; during the hot day, stomata stay closed (minimizing water loss through transpiration) while the stored CO2 is used for carbohydrate synthesis using light energy.
Important Facts:
• This adaptation conserves water in arid, hot environments where daytime stomatal opening would cause excessive water loss.
• Chlorophyll and light-dependent reactions are still required during the day; the adaptation does not eliminate the need for chlorophyll.
RRB Group D 2025-26 – 21 August 2026 Shift 1 · Photosynthesis - process and factors

Q4. Which pigment is responsible for absorbing light during photosynthesis?

  1. (a) Carotene
  2. (b) Chlorophyll
  3. (c) Anthocyanin
  4. (d) Keratin
Answer & solution

Answer: (b) Chlorophyll

Explanation:
Chlorophyll is the green pigment present in chloroplasts that absorbs light energy (mainly red and blue wavelengths) required to drive the light reactions of photosynthesis.
Correct Answer: Option 2 – Chlorophyll
RRB Group D 2025-26 – 19 August 2026 Shift 1 · Photosynthesis - process and factors

Q5. A desert plant absorbs carbon dioxide at night and uses it during the day for photosynthesis. Which property of photosynthesis does this illustrate?

  1. (a) Carbon dioxide is not required for photosynthesis in desert plants
  2. (b) Photosynthesis can involve intermediate compounds stored for later use
  3. (c) Water is unnecessary for photosynthesis in desert plants
  4. (d) Photosynthesis occurs only at night in desert plants
Answer & solution

Answer: (b) Photosynthesis can involve intermediate compounds stored for later use

Correct Answer:
Correct Answer: Option 2 – Photosynthesis can involve intermediate compounds stored for later use
Explanation:
This describesCAM (Crassulacean Acid Metabolism)photosynthesis, found in many desert plants. These plants open their stomata atnightto absorb CO₂ (minimizing water loss in daytime heat) andstore it as an intermediate organic acid, which is then usedduring the dayfor the light-dependent photosynthetic reactions when stomata remain closed.
Important Facts:
• CAM plants include cacti, pineapple, and other succulents adapted to arid conditions.
• This adaptation conserves water by avoiding daytime stomatal opening.
• CO₂ and water are both still essential for photosynthesis in these plants.
RRB Group D 2025-26 – 18 August 2026 Shift 1 · Transport in plants (xylem, phloem)

Q6. Why do plants need a specialized transportation system for water and minerals?

  1. (a) Because diffusion alone is insufficient for large distances in tall plants
  2. (b) Because diffusion does not occur in plants
  3. (c) Because plants have high energy needs like animals
  4. (d) Because plants move and need rapid transport throughout the body
Answer & solution

Answer: (a) Because diffusion alone is insufficient for large distances in tall plants

Need for a transport system in plants
Diffusion is a slow process that is effective only over very short distances. Tall plants need to move water and minerals from roots to leaves over long distances, which diffusion alone cannot achieve fast enough.
Hence plants have a specialized vascular system (xylem and phloem) for efficient long-distance transport.
Correct Answer: Because diffusion alone is insufficient for large distances in tall plants
RRB Group D 2025-26 – 18 August 2026 Shift 2 · Transport in plants (xylem, phloem)

Q7. Water moves from the soil into the root hair cells mainly due to which of the following processes?

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

Answer: (b) Osmosis

Water Uptake by Root Hairs
Root hair cells have a higher solute concentration (lower water potential) than the surrounding soil water. Water moves from the region of higher water concentration (soil) to lower water concentration (root hair cell sap) through a semi-permeable membrane.
This movement of water across a semi-permeable membrane is calledosmosis.
Correct Answer: Osmosis
RRB Group D 2025-26 – 17 August 2026 Shift 2 · Transport in plants (xylem, phloem)

Q8. Among the following, which is transported in xylem?

  1. (a) Water and minerals
  2. (b) Glucose
  3. (c) Amino acids
  4. (d) Proteins
Answer & solution

Answer: (a) Water and minerals

Xylem Transport
Xylem is a vascular tissue in plants that conductswater and dissolved mineralsabsorbed by roots upward to the stem and leaves. It also provides mechanical strength to the plant.
• Glucose (food made by photosynthesis) and amino acids/proteins are transported through phloem, not xylem.
• Xylem transport is unidirectional (upward), driven mainly by transpiration pull.
Correct Answer: Water and minerals
RRB Group D 2025-26 – 17 August 2026 Shift 2 · Plant parts - root, stem and leaf modifications

Q9. How do root hair help plants in the process of absorbing water and minerals from the soil?

  1. (a) They provide mechanical support.
  2. (b) They transport food to leaves.
  3. (c) They synthesize food.
  4. (d) They increase the surface area of absorption.
Answer & solution

Answer: (d) They increase the surface area of absorption.

Function of Root Hairs
Root hairs are thin, tubular extensions of epidermal cells near the root tip. They greatlyincrease the surface areaof the root in contact with soil, enhancing absorption of water and dissolved minerals through osmosis and diffusion.
• Root hairs do not provide significant mechanical support (that is the role of thicker roots/stems).
• They do not transport food to leaves (that is phloem's role) nor synthesize food (roots lack chlorophyll).
Correct Answer: They increase the surface area of absorption.
RRB Group D 2025-26 – 14 August 2026 Shift 1 · Transport in plants (xylem, phloem)

Q10. What is the primary reason water moves into the phloem tissue after sucrose is actively loaded into it in plants?

  1. (a) Pressure equalizes between phloem and xylem tissues
  2. (b) The increase in osmotic pressure draws water into the phloem
  3. (c) Increased ATP usage raises the temperature in the phloem
  4. (d) Water moves to phloem due to root pressure buildup
Answer & solution

Answer: (b) The increase in osmotic pressure draws water into the phloem

Answer: Option 2 – The increase in osmotic pressure draws water into the phloem.
• Loading sucrose raises the phloem'sosmotic pressure, so water enters by osmosis (pressure-flow).
RRB Group D 2025-26 – 14 August 2026 Shift 3 · Transport in plants (xylem, phloem)

Q11. Complete the analogy.Dye in water : Diffusion :: Roots absorbing water : ___________.

  1. (a) Filtration
  2. (b) Photosynthesis
  3. (c) Osmosis
  4. (d) Evaporation
Answer & solution

Answer: (c) Osmosis

Answer: Option 3 – Osmosis.
• Roots absorb water byosmosis(water moving across a semipermeable membrane).
RRB Group D 2025-26 – 13 August 2026 Shift 2 · Transport in plants (xylem, phloem)

Q12. Why are xylem and phloem described as independently organised conducting tubes in plants?

  1. (a) They transport different substances separately.
  2. (b) They share a single pathway for all transport needs
  3. (c) They perform identical functions in tandem
  4. (d) They act as one type of tissue in all plants
Answer & solution

Answer: (a) They transport different substances separately.

Answer: Option 1 – They transport different substances separately.
• Xylem carries water/minerals and phloem carries food –separate transport systems.
RRB Group D 2025-26 – 11 August 2026 Shift 1 · Photosynthesis - process and factors

Q13. What is the primary function of stomata in plant leaves during photosynthesis?

  1. (a) Prevent entry of CO₂
  2. (b) Allow gaseous exchange
  3. (c) Absorption of Oxygen
  4. (d) Maintain constant leaf temperature
Answer & solution

Answer: (b) Allow gaseous exchange

Answer: Option 2 – Allow gaseous exchange.
•Stomataallow exchange of gases (CO₂ in, O₂ out) and transpiration during photosynthesis.
RRB Group D 2025-26 – 10 August 2026 Shift 1 · Transport in plants (xylem, phloem)

Q14. Which process would be directly affected if a plant's phloem were blocked during spring?

  1. (a) Water transport from roots to leaves would decrease
  2. (b) Leaves would be unable to perform gas exchange
  3. (c) Roots would not absorb sufficient nutrients from soil
  4. (d) Buds would fail to receive sugars needed for growth
Answer & solution

Answer: (d) Buds would fail to receive sugars needed for growth

Answer: Option 4 — Buds would fail to receive sugars needed for growth
Phloem transports sugars; if blocked,buds don't get sugarsfor spring growth → Option 4.
RRB Group D 2025-26 – 10 August 2026 Shift 2 · Photosynthesis - process and factors

Q15. In plants, carbohydrates produced during photosynthesis are stored in which form?

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

Answer: (a) Starch

Answer: Option 1 – Starch.
• In plants, the carbohydrate made in photosynthesis is stored asstarch. (In animals the storage form is glycogen.)
RRB Group D 2025-26 – 10 August 2026 Shift 3 · Transport in plants (xylem, phloem)

Q16. Which part of the plant vascular tissue is mainly responsible for transporting amino acids and soluble products of photosynthesis?

  1. (a) Cortex
  2. (b) Epidermis
  3. (c) Xylem
  4. (d) Phloem
Answer & solution

Answer: (d) Phloem

Answer: Option 4 – Phloem.
•Phloemtransports food (sugars/amino acids made in photosynthesis) from leaves to the rest of the plant (translocation). Xylem carries water.
RRB Group D 2025-26 – 9 August 2026 Shift 1 · Transport in plants (xylem, phloem)

Q17. What is the primary mechanism by which sucrose moves into phloem tissue in plants?

  1. (a) Facilitated diffusion via carrier proteins
  2. (b) Active transport with energy from ATP
  3. (c) Simple diffusion along the gradient
  4. (d) Osmosis through a semi-permeable membrane
Answer & solution

Answer: (b) Active transport with energy from ATP

Answer: Option 2 — Active transport with energy from ATP
Sucrose is loaded into phloem byactive transport (using ATP)→ Option 2.
RRB Group D 2025-26 – 9 August 2026 Shift 2 · Photosynthesis - process and factors

Q18. Marine organisms like phytoplankton use dissolved CO₂ in ocean water for the process of __________.

  1. (a) Photosynthesis
  2. (b) Combustion
  3. (c) Respiration
  4. (d) Decomposition
Answer & solution

Answer: (a) Photosynthesis

Answer: Option 1 — Photosynthesis
Phytoplankton use dissolved CO₂ forphotosynthesis→ Option 1.
RRB Group D 2025-26 – 5 August 2026 Shift 1 · Plant parts - root, stem and leaf modifications

Q19. Which part of a plant mainly absorbs water and minerals from the soil?

  1. (a) Stems
  2. (b) Roots
  3. (c) Leaves
  4. (d) Flowers
Answer & solution

Answer: (b) Roots

Answer: Option 2 — Roots
Rootsabsorb water and minerals from the soil → Option 2.
RRB Group D 2025-26 – 5 August 2026 Shift 3 · Transport in plants (xylem, phloem)

Q20. What is the main force that pulls water upward through the xylem in tall trees?

  1. (a) Root pressure
  2. (b) Transpiration pull
  3. (c) Capillary action
  4. (d) Diffusion
Answer & solution

Answer: (b) Transpiration pull

Answer: Option 2 — Transpiration pull
Water rises in tall trees mainly due totranspiration pull→ Option 2.
RRB Group D 2025-26 – 4 August 2026 Shift 3 · Photosynthesis - process and factors

Q21. Since plants prepare their own food using sunlight, they do not require a digestive organ like a stomach. Instead, they possess tissues specialized for ____.

  1. (a) Digestion
  2. (b) Photosynthesis
  3. (c) Thinking
  4. (d) Running
Answer & solution

Answer: (b) Photosynthesis

Answer: Option 2 — Photosynthesis
Plants have tissues specialised forphotosynthesis(to make their own food) → Option 2.
RRB Group D 2025-26 – 4 August 2026 Shift 3 · Transport in plants (xylem, phloem)

Q22. Complete the analogy.Xylem : Water Transport :: Phloem : ______.

  1. (a) Protection from Microbes
  2. (b) Mechanical Strength
  3. (c) Food Transport
  4. (d) Gas Exchange
Answer & solution

Answer: (c) Food Transport

Answer: Option 3 — Food Transport
Xylem → water transport;Phloem → food transport→ Option 3.
RRB Group D 2025-26 – 3 August 2026 Shift 3 · Photosynthesis - process and factors

Q23. What does the splitting of water molecules during photosynthesis produce?

  1. (a) Nitrogen and oxygen
  2. (b) Nitrogen and carbon
  3. (c) Oxygen and carbon
  4. (d) Hydrogen and oxygen
Answer & solution

Answer: (d) Hydrogen and oxygen

Answer: Option 4 — Hydrogen and oxygen
In photosynthesis, thephotolysis (splitting) of waterproduceshydrogen (used to reduce CO₂) and oxygen (released)→ Option 4.
RRB NTPC UG CBT-1 2025-26 – 16 June 2026 Shift 2 · Photosynthesis - process and factors

Q24. Which pigment is responsible for the green color of plants?

  1. (a) Carotene
  2. (b) Anthocyanin
  3. (c) Chlorophyll
  4. (d) Xanthophyll
Answer & solution

Answer: (c) Chlorophyll

Topic:Plant Pigments
Chlorophyllis the primary pigment in plants.
Located in chloroplasts, absorbs light for photosynthesis.
Absorbs red and blue light, reflects green light.
Other pigments: Carotene (orange), Anthocyanin (red/purple), Xanthophyll (yellow).
Answer: Option 3 → Chlorophyll
SSC GD 2026 – 25 May 2026 Shift 3 · Mineral nutrition in plants

Q25. In living organisms, nitrogen is a component of which of the following?
I. Protein
II. Chlorophyll

  1. (a) Only I
  2. (b) Only II
  3. (c) Both I and II
  4. (d) Neither I nor II
Answer & solution

Answer: (c) Both I and II

Correct Answer: Both I and II — Option (c)
Nitrogen is a component of both Protein (I) and Chlorophyll (II) in living organisms. Statement I Analysis — Nitrogen in Protein (CORRECT): Proteins are made of amino acids; Each amino acid contains: a carbon atom, a hydrogen atom, a carboxyl group (-COOH), an amino group (-NH2 — contains NITROGEN), and a side chain (R group); The amino group (-NH2) in every amino acid contains nitrogen; Therefore, ALL proteins contain nitrogen ✓ ; Proteins make up about 16% nitrogen by weight; Other nitrogen-containing biomolecules: Nucleic acids (DNA, RNA) — in nitrogenous bases; ATP (adenosine triphosphate); Vitamins (B1, B3, B12) — contain nitrogen; Chlorophyll ✓ ; Statement II Analysis — Nitrogen in Chlorophyll (CORRECT): Chlorophyll is the green pigment in plants responsible for photosynthesis; Chemical formula of Chlorophyll a: C55H72O5N4Mg; The porphyrin ring structure of chlorophyll contains 4 nitrogen atoms; These 4 nitrogen atoms form the pyrrole rings that coordinate with the central magnesium (Mg) atom; Therefore, chlorophyll CONTAINS nitrogen ✓ ; This is why adequate nitrogen supply (from fertilizers) is crucial for plant growth — nitrogen is needed for both proteins AND chlorophyll production.
Option (a) Only I — Incorrect: Nitrogen is a component of BOTH protein AND chlorophyll; chlorophyll (C55H72O5N4Mg) contains 4 nitrogen atoms in its porphyrin ring structure; 'Only I' is an incomplete answer.
Option (b) Only II — Incorrect: Nitrogen is a component of BOTH chlorophyll AND protein; all amino acids (building blocks of proteins) contain the amino group (-NH2) which contains nitrogen; 'Only II' is an incomplete answer. The candidate selected this incorrect option.
Option (d) Neither I nor II — Incorrect: Nitrogen is DEFINITELY a component of both proteins (amino group -NH2 in amino acids) and chlorophyll (porphyrin ring with 4 nitrogen atoms); 'Neither I nor II' is completely incorrect.
SSC GD 2026 – 19 May 2026 Shift 3 · Photosynthesis - process and factors

Q26. What causes the green colour of leaves?

  1. (a) Guard cells
  2. (b) Xylem
  3. (c) Phloem
  4. (d) Chlorophyll
Answer & solution

Answer: (d) Chlorophyll

Correct Answer: Chlorophyll — Option (d)
The green colour of leaves is caused by chlorophyll, the primary photosynthetic pigment found in chloroplasts. Chlorophyll is a green pigment that absorbs light energy primarily in the red (wavelength ~670 nm) and blue (wavelength ~430 nm) regions of the visible spectrum, while reflecting green light (~500-565 nm) — which is why leaves appear green to our eyes. There are two main types of chlorophyll: Chlorophyll a (blue-green) and Chlorophyll b (yellow-green). Chlorophyll uses absorbed light energy to power the process of photosynthesis, converting CO2 and water into glucose and oxygen. In autumn, chlorophyll breaks down as days shorten, revealing underlying yellow and orange pigments (carotenoids).
Option (a) Guard cells — Incorrect: Guard cells are kidney-shaped cells surrounding stomata that regulate gas exchange and water loss through transpiration; they do not cause the green colour of leaves.
Option (b) Xylem — Incorrect: Xylem is the vascular tissue responsible for water and mineral transport in plants; it does not impart green colour to leaves — that function belongs to chlorophyll.
Option (c) Phloem — Incorrect: Phloem is the vascular tissue that transports food (sugars) produced during photosynthesis to other parts of the plant; it does not cause the green colour of leaves.
SSC GD 2026 – 19 May 2026 Shift 3 · Photosynthesis - process and factors

Q27. Which part of a plant is called the 'food factory'?

  1. (a) Flower
  2. (b) Stem
  3. (c) Root
  4. (d) Leaf
Answer & solution

Answer: (d) Leaf

Correct Answer: Leaf — Option (d)
The leaf is called the 'food factory' of the plant because it is the primary site of photosynthesis — the biological process by which plants manufacture their own food. Leaves contain chlorophyll in chloroplasts, which absorbs sunlight. Using this light energy, carbon dioxide (absorbed through stomata) and water (transported from roots via xylem) are converted into glucose (food/energy) and oxygen. The equation is: 6CO2 + 6H2O + light energy → C6H12O6 (glucose) + 6O2. Leaves are specially adapted for photosynthesis: they have a broad, flat surface to maximize light absorption, a thin structure for CO2 diffusion, and numerous stomata for gas exchange. The manufactured glucose is then transported to other parts of the plant via phloem.
Option (a) Flower — Incorrect: The flower is the reproductive organ of the plant, responsible for pollination and seed production; it is not the primary site of food (glucose) manufacturing.
Option (b) Stem — Incorrect: The stem provides structural support and serves as a conduit for water, minerals, and food transport; while some stems can photosynthesize (e.g., cactus stems), the primary 'food factory' is the leaf.
Option (c) Root — Incorrect: Roots absorb water and minerals from the soil and anchor the plant; they do not perform photosynthesis (as they are underground and have no chlorophyll) and are not called the food factory.
RRB NTPC GL CBT-1 2025-26 – 25 March 2026 Shift 1 · Plant secretions and defence (latex, resins)

Q28. Many plants secrete a sticky milky fluid and use it for their defence mechanism. This fluid is known as ___________________.

  1. (a) enzyme
  2. (b) plant hormone
  3. (c) latex
  4. (d) cell sap
Answer & solution

Answer: (c) latex

Topic: Plant Defence Mechanism
Many plants secrete asticky milky fluidas a defence mechanism.
This fluid is calledLatex.
Examples: Rubber tree, Papaya, Euphorbia, Poppy.
Function: Protects against herbivores and insects.
Answer: Option 3 → latex
RRB NTPC GL CBT-1 2025-26 – 25 March 2026 Shift 2 · Photosynthesis - process and factors

Q29. What is the primary pigment responsible for photosynthesis in plants?

  1. (a) Anthocyanin
  2. (b) Carotenoid
  3. (c) Xanthophyll
  4. (d) Chlorophyll
Answer & solution

Answer: (d) Chlorophyll

Topic:Photosynthesis Pigments
Chlorophyllis the primary pigment for photosynthesis.
It absorbs light energy (mainly blue and red wavelengths).
Located in chloroplasts, converts light to chemical energy.
Other pigments are accessory (carotenoid, xanthophyll).
Anthocyanin gives red/purple color, not for photosynthesis.
Answer: Option 4 → Chlorophyll
RRB NTPC GL CBT-1 2025-26 – 25 March 2026 Shift 3 · Photosynthesis - process and factors

Q30. What is the process by which plants make their food using sunlight?

  1. (a) Transpiration
  2. (b) Photosynthesis
  3. (c) Respiration
  4. (d) Fermentation
Answer & solution

Answer: (b) Photosynthesis

Topic:Plant Nutrition
Plants prepare food using sunlight, water, and CO₂.
This process occurs in chloroplasts containing chlorophyll.
Photosynthesisconverts light energy into chemical energy (glucose).
Other options:
Transpiration → water loss from leaves
Respiration → breakdown of glucose for energy
Fermentation → anaerobic glucose breakdown
Answer: Option 2 → Photosynthesis
RRB NTPC GL CBT-1 2025-26 – 25 March 2026 Shift 3 · Photosynthesis - process and factors

Q31. Choose the correct statement regarding the process of photosynthesis in plants.

  1. (a) It occurs in the mitochondria of plant cells.
  2. (b) It involves the breakdown of glucose to produce energy.
  3. (c) It primarily takes place during the night to conserve water.
  4. (d) It converts light energy into chemical energy.
Answer & solution

Answer: (d) It converts light energy into chemical energy.

Topic: Photosynthesis
Key Facts:
1. Occurs inchloroplasts(not mitochondria)
2. Convertslight energy → chemical energy (glucose)
3. Takes place duringdaytime(requires sunlight)
4. Process: 6CO₂ + 6H₂O + Light → C₆H₁₂O₆ + 6O₂
Option 2 describesrespiration(opposite process)
Answer: Option 4 → It converts light energy into chemical energy.
RRB NTPC GL CBT-1 2025-26 – 24 March 2026 Shift 1 · Photosynthesis - process and factors

Q32. In the light-independent or dark phase of photosynthesis, apart from CO ₂ , which of the following components act as essential starting materials?

  1. (a) CO ₂ and H ₂ O
  2. (b) CO ₂ and glucose
  3. (c) Hydrolase and H ₂ O
  4. (d) ATP and NADPH
Answer & solution

Answer: (d) ATP and NADPH

Photosynthesis has two stages:
Light Reaction (Light-dependent)
Produces ATP and NADPH using light energy
Dark Reaction (Light-independent/Calvin Cycle)
Uses CO₂ + ATP + NADPH to synthesize glucose
Does not require direct light
Essential starting materials for dark phase:
CO₂ (from atmosphere) +ATP and NADPH(from light reaction)
Answer: Option 4 → ATP AND NADPH
RRB NTPC GL CBT-1 2025-26 – 24 March 2026 Shift 3 · Photosynthesis - process and factors

Q33. The process of fixing inorganic CO₂ into an organic form (sugar) is carried out in which of the following phases during photosynthesis?

  1. (a) Calvin-Benson cycle
  2. (b) Kreb’s cycle
  3. (c) Glycolysis
  4. (d) Light-dependent phase
Answer & solution

Answer: (a) Calvin-Benson cycle

Topic:Photosynthesis - Carbon Fixation
Calvin-Benson Cycle (Dark Reaction/Light-Independent)
- Occurs in stroma of chloroplast
- Fixes atmospheric CO₂ into organic compounds
- Converts CO₂ → 3-PGA → G3P → Glucose
- Does not require direct light (uses ATP & NADPH from light reaction)
Other Options:
Kreb's cycle → Cellular respiration (mitochondria)
Glycolysis → Glucose breakdown (cytoplasm)
Light-dependent phase → Produces ATP & NADPH only
Answer: Option 1 → Calvin-Benson cycle
RRB NTPC GL CBT-1 2025-26 – 24 March 2026 Shift 3 · Photosynthesis - process and factors

Q34. The primary "food" or energy source produced by the plant during photosynthesis is a type of:

  1. (a) Vitamin
  2. (b) Mineral
  3. (c) Protein
  4. (d) Carbohydrate
Answer & solution

Answer: (d) Carbohydrate

Topic:Photosynthesis - Primary Product
During photosynthesis, plants convert CO₂ and H₂O into glucose using sunlight.
Glucose (C₆H₁₂O₆) is a simple sugar, which is acarbohydrate.
This glucose serves as the primary energy source for the plant.
Answer: Option 4 → Carbohydrate
RRB NTPC GL CBT-1 2025-26 – 19 March 2026 Shift 2 · Plant parts - root, stem and leaf modifications

Q35. The modified petiole of Acacia species that resembles a leaf blade is termed as __________________.

  1. (a) phyllode
  2. (b) bracts
  3. (c) spine
  4. (d) tendril
Answer & solution

Answer: (a) phyllode

Topic: Modified Plant Parts - Petiole
Phyllode:A flattened petiole that takes on the function and appearance of a leaf blade.
Found inAcacia species(Australian Acacia).
Function: Performs photosynthesis like normal leaves while reducing water loss.
Other options: Bracts (modified leaves), Spine (modified stem/leaf for protection), Tendril (modified stem/leaf for climbing).
Answer: Option 1 → phyllode
RRB NTPC GL CBT-1 2025-26 – 18 March 2026 Shift 1 · Transport in plants (xylem, phloem)

Q36. Which plant tissue is responsible for transporting water from the roots to the leaves?

  1. (a) Phloem
  2. (b) Cortex
  3. (c) Epidermis
  4. (d) Xylem
Answer & solution

Answer: (d) Xylem

Plant Transport System
Xylem:Transports water and minerals from roots to leaves (upward).
Phloem:Transports food from leaves to other parts (downward).
Cortex:Storage tissue in roots and stems.
Epidermis:Protective outer layer of plant.
Answer: Option 4 → Xylem
RRB NTPC GL CBT-1 2025-26 – 18 March 2026 Shift 2 · Photosynthesis - process and factors

Q37. What is the green pigment found in plants that is essential for capturing light energy during photosynthesis?

  1. (a) Chlorophyll
  2. (b) Insulin
  3. (c) Hemoglobin
  4. (d) Glucose
Answer & solution

Answer: (a) Chlorophyll

Chlorophyllis the green pigment in plants.
Located in chloroplasts of plant cells.
Absorbs light energy (mainly blue and red wavelengths).
Essential for converting light energy into chemical energy.
Other options: Insulin (hormone), Hemoglobin (blood protein), Glucose (sugar product).
Answer: Option 1 → Chlorophyll
RRB NTPC GL CBT-1 2025-26 – 18 March 2026 Shift 2 · Plant parts - root, stem and leaf modifications

Q38. The stem that undergoes modification, becomes flattened and carries chlorophyll to bear the responsibility of photosynthesis instead of leaf, is termed as ______________.

  1. (a) stolon
  2. (b) cladode
  3. (c) thorn
  4. (d) rhizome
Answer & solution

Answer: (b) cladode

Cladode= Flattened green stem that performs photosynthesis
Key features:
• Stem modification (not leaf)
• Contains chlorophyll
• Takes over leaf function
• Example: Asparagus, Ruscus
Other options:
Stolon = Runner stem (strawberry)
Thorn = Sharp pointed stem (lemon)
Rhizome = Underground stem (ginger)
Answer: Option 2 → cladode
RRB NTPC GL CBT-1 2025-26 – 16 March 2026 Shift 2 · Mineral nutrition in plants

Q39. Which ions help chlorophyll to absorb light?

  1. (a) C
  2. (b) Na
  3. (c) Ca
  4. (d) Mg
Answer & solution

Answer: (d) Mg

Chlorophyll is the green pigment in plants responsible for absorbing light for photosynthesis.
Magnesium (Mg) is the central atom in the chlorophyll molecule.
• Mg²⁺ ion is at the core of the porphyrin ring structure.
• It enables the chlorophyll to capture light energy (especially in red & blue regions).
• Mg deficiency → yellowing of leaves (chlorosis).
Other ions and their roles:
• Ca → Cell wall formation, signal transduction.
• Na → Osmotic balance (in some plants).
• C → Backbone of all organic molecules.
Answer: Option 4 → Mg
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 1 · Mineral nutrition in plants

Q40. Plants get macro-nutrients mainly from the ________, and micro-nutrients in small quantities from the ________.

  1. (a) sunlight ; minerals
  2. (b) air ; water
  3. (c) soil ; soil
  4. (d) water ; sand
Answer & solution

Answer: (c) soil ; soil

Plants absorb macro-nutrients mainly from the soil, which provides nitrogen, phosphorus, potassium and other essential elements required in large amounts.
Micro-nutrients are also taken up from the soil but in much smaller quantities, these include elements like iron, manganese, zinc, etc.
Hence, both macro- and micro-nutrients come from the soil in different quantities.
Final answer: Option 3
RRB Technician Grade III 2025-26 – 6 March 2026 Shift 1 · Photosynthesis - process and factors

Q41. Which of the following correctly explains the adaptation of desert plants in photosynthesis?

  1. (a) Carbon dioxide uptake occurs at night and carbohydrates are synthesized during the day.
  2. (b) Oxygen is absorbed at night while carbon dioxide is released during the day.
  3. (c) Photosynthesis is restricted to night-time only to minimise water loss.
  4. (d) Light energy is captured at night and converted into starch for daytime use.
Answer & solution

Answer: (a) Carbon dioxide uptake occurs at night and carbohydrates are synthesized during the day.

Option 1 is correct.
Desert plants typically use CAM photosynthesis to conserve water.
They absorb carbon dioxide at night when evaporation rates are low.
During the day, they close stomata to reduce water loss.
Carbohydrates are synthesised using the stored CO2 in daylight.
This adaptation helps survival in dry, hot desert climates.
Hence, carbon dioxide uptake at night and carbohydrate synthesis during the day explains desert plant photosynthesis adaptation.
Final answer: Option 1
RRB JE CBT-1 2025-26 – 25 February 2026 Shift 3 · Transport in plants (xylem, phloem)

Q42. Which of the following tissues ensures that food made in the leaves is delivered to all plant parts?

  1. (a) Mesophyll
  2. (b) Epidermis
  3. (c) Xylem
  4. (d) Phloem
Answer & solution

Answer: (d) Phloem

Option 4 is correct.
Phloem is the tissue responsible for transporting the food prepared in the leaves to other parts of the plant.
It transports organic nutrients, especially sucrose, from leaves to stems, roots, and storage organs.
Xylem, in contrast, transports water and minerals from roots to leaves.
Hence, phloem ensures delivery of food to all plant parts.
Answer closed.
RRB JE CBT-1 2025-26 – 20 February 2026 Shift 1 · Photosynthesis - process and factors

Q43. Why is potassium hydroxide used in the bell-jar experiment involving photosynthesis?

  1. (a) To absorb carbon dioxide
  2. (b) To remove water
  3. (c) To supply oxygen
  4. (d) To provide sunlight
Answer & solution

Answer: (a) To absorb carbon dioxide

Potassium hydroxide (KOH) absorbs carbon dioxide (CO2).
In the bell-jar experiment on photosynthesis, CO2 must be removed to prove that plants release oxygen.
KOH helps absorb CO2, ensuring the environment inside the jar is CO2-free.
This shows that oxygen released comes from water splitting, not CO2.
Therefore, KOH is used to absorb CO2 in this experiment.
Final answer: Option 1
RRB JE CBT-1 2025-26 – 19 February 2026 Shift 1 · Transport in plants (xylem, phloem)

Q44. Which structural feature primarily enables upward movement of water against gravity in plants?

  1. (a) Lignified xylem vessels forming continuous columns
  2. (b) Thin-walled sieve tubes with companion cells
  3. (c) Large intercellular spaces in spongy mesophyll
  4. (d) Actively dividing meristematic tissues
Answer & solution

Answer: (a) Lignified xylem vessels forming continuous columns

Correct option: 1
Upward movement of water in plants occurs mainly through xylem vessels.
These vessels are lignified, giving them strength and preventing collapse under tension.
They form continuous columns from roots to leaves, aiding water transport against gravity.
This continuity and lignification help in creating capillary action and cohesion-tension, essential for water ascent.
Other options (sieve tubes, intercellular spaces, meristematic tissues) are not involved in primary water transport upwards.
Hence, lignified xylem vessels forming continuous columns enable upward water movement in plants.
This is the main structural feature responsible for water transport against gravity in plants.
Final answer: Option 1
SSC MTS 2025 – 18 February 2026 Shift 1 · Photosynthesis - process and factors

Q45. What is the waste product of photosynthesis in plants?

  1. (a) Nitrogen
  2. (b) Oxygen
  3. (c) Ammonia
  4. (d) Chlorine
Answer & solution

Answer: (b) Oxygen

Oxygen is the waste product (byproduct) of photosynthesis in plants. During photosynthesis, plants use sunlight, water, and carbon dioxide to produce glucose and release oxygen. The equation is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Nitrogen, Ammonia, and Chlorine are not produced during photosynthesis.
SSC MTS 2025 – 18 February 2026 Shift 2 · Photosynthesis - process and factors

Q46. What is the first step in the process of photosynthesis?

  1. (a) Absorption of light energy by chlorophyll
  2. (b) Conversion of light energy to chemical energy
  3. (c) Reduction of carbon dioxide to carbohydrates
  4. (d) Splitting of water molecules into hydrogen and oxygen
Answer & solution

Answer: (a) Absorption of light energy by chlorophyll

The correct answer is option 1.
The first step in photosynthesis is the absorption of light energy by the green pigment chlorophyll present in the chloroplasts. This absorbed energy initiates the light-dependent reactions in the thylakoid membranes.
Option 2 is incorrect: Conversion of light energy to chemical energy is the next step that follows absorption; it cannot occur without light being captured first.
Option 3 is incorrect: Reduction of carbon dioxide to carbohydrates (glucose) occurs in the Calvin cycle (dark/light-independent reactions), a later stage of photosynthesis.
Option 4 is incorrect: Photolysis (splitting of water) also occurs in the light reactions, but it is triggered after the initial absorption of light by chlorophyll.
SSC MTS 2025 – 16 February 2026 Shift 1 · Mineral nutrition in plants

Q47. Which of the following is an example of micronutrient needed by the crops from the soil?

  1. (a) Nitrogen
  2. (b) Iron
  3. (c) Magnesium
  4. (d) Sulphur
Answer & solution

Answer: (b) Iron

Iron (Fe) is a micronutrient required by crops in very small (trace) quantities. It is essential for chlorophyll synthesis and enzyme activity in plants. Micronutrients include: Iron, Manganese, Zinc, Copper, Boron, Molybdenum, and Chlorine.
Why other options are incorrect:
- Nitrogen (N): A primary macronutrient required in large quantities for leaf and shoot growth.
- Magnesium (Mg): A secondary macronutrient (not a micronutrient), essential for chlorophyll production and enzyme activation.
- Sulphur (S): A secondary macronutrient needed for protein synthesis and enzyme function; not a micronutrient.
SSC MTS 2025 – 11 February 2026 Shift 2 · Transpiration

Q48. What controls the opening and closing of stomata?

  1. (a) Root cell
  2. (b) Guard cell
  3. (c) Stem cell
  4. (d) Midrib
Answer & solution

Answer: (b) Guard cell

The correct answer is Guard cell (Option 2). Stomata are tiny pores on the leaf surface used for gas exchange and transpiration. Each stoma is flanked by two guard cells that regulate opening and closing through changes in turgor pressure. When guard cells absorb water, they swell and open the stomata; when they lose water, they shrink and close the stomata. Option 1 (Root cell) is involved in absorption, not stomatal control. Option 3 (Stem cell) is an undifferentiated cell. Option 4 (Midrib) is the central vein of a leaf.
SSC MTS 2025 – 6 February 2026 Shift 2 · Transpiration

Q49. How do plants primarily get rid of excess water?

  1. (a) By transpiration
  2. (b) By shedding their roots
  3. (c) By secreting through the stems
  4. (d) By storing water in fruits
Answer & solution

Answer: (a) By transpiration

Correct Answer: 1 (By transpiration)
Plants primarily get rid of excess water through the process of Transpiration. In transpiration, water is released as water vapour through tiny pores called stomata (mainly on leaves), as well as through the cuticle and lenticels. This process helps in maintaining water balance in the plant.
Option 2 (By shedding their roots) is incorrect - plants do not shed roots to release excess water.
Option 3 (By secreting through the stems) is incorrect - stems are not the primary site of water release.
Option 4 (By storing water in fruits) is incorrect - fruits store water as part of their development but this is not how plants eliminate excess water.
SSC MTS 2025 – 5 February 2026 Shift 1 · Plant parts - root, stem and leaf modifications

Q50. Some plants like the pea plant climb up other plants or fences by means of _____.

  1. (a) Thorn
  2. (b) Root hair
  3. (c) Tendrils
  4. (d) Cell sap
Answer & solution

Answer: (c) Tendrils

Correct Answer: Tendrils
Tendrils are slender, thread-like modified stems or leaves that help climbing plants (like pea, cucumber, grapes) to attach and climb. When they touch a support, they coil around it, helping the plant climb upward toward sunlight.
Why other options are wrong:
Thorn - A modified stem for protection (e.g., roses), not for climbing.
Root hair - Unicellular extensions of root cells for water absorption.
Cell sap - The liquid content inside vacuoles; not a structural organ.
Delhi Police Constable (Exe) 2025-26 – 22 December 2025 Shift 1 · Photosynthesis - process and factors

Q51. Which gas is absorbed by plants during photosynthesis?

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

Answer: (c) Carbon dioxide

During photosynthesis, plants absorb Carbon dioxide (CO2) from the atmosphere through their stomata and use it — along with water and sunlight — to produce glucose and oxygen. The equation is: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2. Option 3 is correct.
Option 1 is wrong: Oxygen is released by plants during photosynthesis as a byproduct — it is not absorbed. Plants do absorb oxygen during cellular respiration (a separate process), but not during photosynthesis.
Option 2 is wrong: Nitrogen is absorbed by plants from the soil (through roots) as nitrates/ammonia, not from the atmosphere during photosynthesis; nitrogen gas cannot be directly used by most plants.
Option 4 is wrong: Hydrogen gas is not absorbed by plants during photosynthesis; hydrogen is obtained from the splitting of water molecules (photolysis) within the plant cells during photosynthesis.
SSC CPO Paper-1 2025 – 11 December 2025 Shift 2 · Special plants (insectivorous, parasitic)

Q52. Which of the following pairs of (Plants-type) is correctly matched?

  1. (a) Nepenthes – Parasitic plant
  2. (b) Cuscuta – Insectivorous plant
  3. (c) Opuntia – Xerophytic plant
  4. (d) Utricularia – Epiphytic plant
Answer & solution

Answer: (c) Opuntia – Xerophytic plant

Correct Answer: Opuntia – Xerophytic plant (Option 3)
Opuntia (cactus/prickly pear) is a Xerophyte — a plant adapted to survive in extremely dry conditions (deserts). It stores water in its thick, succulent stem, has reduced leaves (spines), and a thick waxy cuticle to minimize water loss. This pair is correctly matched.
Nepenthes is an Insectivorous (carnivorous) plant, NOT a parasitic plant. It traps insects in pitcher-shaped leaves.
Cuscuta (Amarbel/dodder) is a Parasitic plant — it wraps around host plants and draws nutrients from them. It is NOT insectivorous.
Utricularia (bladderwort) is an Insectivorous (carnivorous) aquatic plant — NOT an epiphyte. Epiphytes grow on other plants for support (like orchids) but do not absorb nutrients from them.
SSC CHSL Tier-1 2025 – 28 November 2025 Shift 3 · Transport in plants (xylem, phloem)

Q53. What becomes the major driving force in the movement of water in the xylem during the day?

  1. (a) Transpiration pull
  2. (b) Root pressure
  3. (c) Active transport
  4. (d) Osmosis
Answer & solution

Answer: (a) Transpiration pull

Transpiration pull is the major driving force for the movement of water in the xylem during the day. When leaves lose water through transpiration (evaporation from stomata), it creates a negative pressure (tension) that pulls water upward through the xylem from roots to leaves. This is the most significant mechanism especially during daytime.
Root pressure is effective during the night when transpiration is low.
Active transport requires energy (ATP) and is not the primary mechanism in xylem transport.
Osmosis occurs in cell-to-cell water movement, not specifically in xylem transport.
SSC CHSL Tier-1 2025 – 27 November 2025 Shift 2 · Photosynthesis - process and factors

Q54. When do desert plants typically take up carbon dioxide?
I. During the day
II. During the night

  1. (a) Only I
  2. (b) Only II
  3. (c) Both I and II
  4. (d) Neither I nor II
Answer & solution

Answer: (b) Only II

Desert plants follow Crassulacean Acid Metabolism (CAM), a water-conserving adaptation. They open their stomata only during the night to absorb CO2, as temperatures are lower and humidity is higher, minimising water loss.
During the day, stomata remain closed due to extreme heat and low humidity, so CO2 is NOT absorbed during daytime.
Statement I is incorrect; Statement II is correct. Hence, the answer is Only II.
SSC CHSL Tier-1 2025 – 27 November 2025 Shift 2 · Transport in plants (xylem, phloem)

Q55. What is the transport of soluble products of photosynthesis in a plant known as?

  1. (a) Transpiration
  2. (b) Translocation
  3. (c) Evaporation
  4. (d) Diffusion
Answer & solution

Answer: (b) Translocation

Correct Answer: Translocation (Option 2)
The transport of soluble products of photosynthesis (mainly sucrose) in a plant is called Translocation. This process occurs through the phloem tissue of the plant and carries photosynthates from leaves (source) to other parts of the plant such as roots, fruits, and growing regions (sink).
Why others are wrong:
Option 1 - Transpiration: This is the process of water loss from plant surfaces through stomata, not the transport of photosynthetic products.
Option 3 - Evaporation: This is a physical process of water turning into vapour, not a biological transport process in plants.
Option 4 - Diffusion: This is the movement of molecules from high to low concentration and involves simple ions and gases, not the bulk transport of photosynthates.
SSC CHSL Tier-1 2025 – 13 November 2025 Shift 3 · Transport in plants (xylem, phloem)

Q56. Which of the following statements is correct regarding phloem of a plant?
I. The translocation in phloem is achieved by utilizing energy.
II. Material are transferred into phloem tissue using energy from ATP.

  1. (a) Only I
  2. (b) Only II
  3. (c) Both I and II
  4. (d) Neither I nor II
Answer & solution

Answer: (c) Both I and II

Both statements are correct. Statement I: Translocation in phloem (transport of sugars/food) is an active process that requires energy. Statement II: The loading of materials into phloem cells (companion cells and sieve tubes) is an active process that uses ATP energy. According to the pressure-flow hypothesis, the active loading of sucrose at the source requires ATP. Hence, Both I and II are correct.
SSC CGL Tier-1 2025 – 17 September 2025 Shift 3 · Transpiration

Q57. Read the below statements about transpiration:
1. Transpiration is highest in dry and windy conditions.
2. It helps in the ascent of sap through cohesion-tension.
3. Transpiration always results in wilting.
Which of the above statements arecorrect?

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

Answer: (a) Only 1 and 2 are correct

Statement 1 is correct — transpiration increases with dryness and wind speed.
Statement 2 is correct — transpiration drives the ascent of sap through the cohesion-tension theory.
Statement 3 is incorrect — wilting occurs only when transpiration exceeds water absorption, not always.
Hence only 1 and 2 are correct.
SSC CGL Tier-1 2025 – 16 September 2025 Shift 1 · Mineral nutrition in plants

Q58. Which of the following pairs of type of nutrient – nutrient is correctly matched?

  1. (a) Micronutrient – Calcium
  2. (b) Macronutrient – Zinc
  3. (c) Micronutrient – Boron
  4. (d) Macronutrient – Iron
Answer & solution

Answer: (c) Micronutrient – Boron

Macronutrients (needed in large amounts): N, P, K, Ca, Mg, S.
Micronutrients (needed in trace): Fe, Mn, Zn, Cu, B, Mo, Cl.
Calcium and Iron are wrongly placed; Zinc is a micronutrient, not macro.
Boron is correctly classified as a micronutrient.
RRB NTPC UG CBT-1 2024-25 – 1 September 2025 Shift 2 · Plant growth and movements

Q59. Which of the following is an example of plasticity in plants?

  1. (a) Phototropism
  2. (b) Heterophylly
  3. (c) Vernalisation
  4. (d) Photoperiodism
Answer & solution

Answer: (b) Heterophylly

SSC Selection Post 2025 (Phase XIII) – 29 August 2025 Shift 3 · Photosynthesis - process and factors

Q60. Which plant part carries out the process of photosynthesis?

  1. (a) Root
  2. (b) Stem
  3. (c) Flower
  4. (d) Leaf
Answer & solution

Answer: (d) Leaf

Correct Answer: Option 4 – Leaf
Photosynthesis primarily occurs in the leaves of plants. Leaves contain chloroplasts — organelles with chlorophyll (green pigment) that absorbs sunlight. The process: 6CO₂ + 6H₂O + Light energy → C₆H₁₂O₆ (glucose) + 6O₂. Leaves are specially adapted for photosynthesis with: flat, broad surface (maximizing light absorption), thin structure (facilitating CO₂ diffusion), stomata (gas exchange pores), and a network of veins (supplying water and removing sugars). Some stems (green stems) and unripe fruits also photosynthesize but at much lower rates.
Option 1 (Root): Roots absorb water and minerals from soil and anchor the plant. They are usually underground and lack chlorophyll — cannot photosynthesize.
Option 2 (Stem): The stem primarily transports water, minerals, and sugars between roots and leaves (through xylem and phloem). Green stems can photosynthesize slightly, but the leaf is the primary site.
Option 3 (Flower): Flowers are reproductive organs (petals, stamens, pistil). They are generally not the primary site of photosynthesis.
RRB NTPC UG CBT-1 2024-25 – 22 August 2025 Shift 2 · Photosynthesis - process and factors

Q61. Which of the following processes is absent in C₄ plants?

  1. (a) Transpiration
  2. (b) Photorespiration
  3. (c) Photosynthesis
  4. (d) Respiration
Answer & solution

Answer: (b) Photorespiration

RRB NTPC UG CBT-1 2024-25 – 20 August 2025 Shift 1 · Photosynthesis - process and factors

Q62. Which of the following is the most abundant protein in the biosphere?

  1. (a) GLUT-4
  2. (b) Collagen
  3. (c) RuBisCO
  4. (d) Myosin
Answer & solution

Answer: (c) RuBisCO

RRB NTPC UG CBT-1 2024-25 – 18 August 2025 Shift 1 · Photosynthesis - process and factors

Q63. Which of the following pigments is present in vegetables like spinach, giving it the characteristic green colour?

  1. (a) Xanthophyll
  2. (b) Lutein
  3. (c) Chlorophyll
  4. (d) Anthocyanin
Answer & solution

Answer: (c) Chlorophyll

SSC Selection Post 2025 (Phase XIII) – 1 August 2025 Shift 3 · Transport in plants (xylem, phloem)

Q64. What is the primary function of the xylem tissue in plants?

  1. (a) To transport products of photosynthesis from leaves to other parts of the plant
  2. (b) To transport water and minerals obtained from the soil
  3. (c) To provide energy to the plant
  4. (d) To synthesize glucose
Answer & solution

Answer: (b) To transport water and minerals obtained from the soil

Correct Answer: Option 2 – To transport water and minerals obtained from the soil
Xylem is a complex plant tissue that transports water and dissolved minerals (inorganic nutrients) from the roots upward to the leaves and other plant parts through a process called transpiration pull.
Option 1 (Transport photosynthesis products): This is the function of phloem, which transports sugars and organic compounds from leaves to other parts.
Option 3 (Provide energy): Xylem does not provide energy; energy is released through cellular respiration in mitochondria.
Option 4 (Synthesize glucose): Glucose is synthesized in chloroplasts during photosynthesis; not a function of xylem.
SSC Selection Post 2025 (Phase XIII) – 29 July 2025 Shift 2 · Transpiration

Q65. What is the term used for the process of water evaporation through plant leaves?

  1. (a) Respiration
  2. (b) Transpiration
  3. (c) Photosynthesis
  4. (d) Fermentation
Answer & solution

Answer: (b) Transpiration

The correct answer is clearly Option B –Transpiration.Transpiration is the process by which water is absorbed by plant roots, transported through the plant, and released as water vapour through stomata (pores) on leaves and other aerial parts .
RRB Technician Grade III 2024-25 – 30 December 2024 Shift 1 · Transport in plants (xylem, phloem)

Q66. Which of the following statements is/are INCORRECT?
(i) The transport of insoluble product of photosynthesis is known as translocation.
(ii) Respiration is the evaporative loss of water through stomata.
(iii) Photosynthesis is the process by which autotrophs take in substances from outside and in the absence of sunlight convert them into stored forms of energy.

  1. (a) Only (i)
  2. (b) Only (ii) and (iii)
  3. (c) (i), (ii) and (iii)
  4. (d) Only (i) and (ii)
Answer & solution

Answer: (c) (i), (ii) and (iii)

Correct Answer: Option 3 — (i), (ii) and (iii)
All three statements are incorrect.
(i) Translocation is the transport of the soluble products of photosynthesis — chiefly sucrose — through the phloem; the statement wrongly calls the product "insoluble".
(ii) The evaporative loss of water through stomata is transpiration, not respiration. Respiration is the breakdown of food to release energy (ATP), giving out CO₂.
(iii) Photosynthesis takes place in the presence of sunlight, never in its absence. Green plants use chlorophyll to trap sunlight and convert CO₂ and water into glucose, storing the energy in the form of food.
❌ Why the other options are incorrect
✗ Only (i) — wrong; statements (ii) and (iii) are also factually incorrect, so the answer cannot be limited to (i).
✗ Only (ii) and (iii) — wrong; it treats statement (i) as correct, but the word "insoluble" makes (i) false as well.
✗ Only (i) and (ii) — wrong; it leaves out (iii), which wrongly places photosynthesis in the absence of sunlight.
📌 SSC & Railway Exam Facts
• Photosynthesis equation — 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ in the presence of sunlight and chlorophyll.
• Xylem carries water and minerals upward; phloem carries food in both directions (translocation).
• Translocation in the phloem needs ATP and is explained by the pressure-flow (Munch) hypothesis.
• Transpiration creates the transpiration pull that lifts water in tall trees; it is called a necessary evil.
• Stomata are opened and closed by guard cells, and most gas exchange in a leaf occurs through them.
RRB Technician Grade III 2024-25 – 29 December 2024 Shift 1 · Transport in plants (xylem, phloem)

Q67. Besides products of photosynthesis, which of the following substances are transported by the phloem in plants?

  1. (a) Both amino acids and sucrose
  2. (b) Only Water
  3. (c) Only Amino acids
  4. (d) Only Sucrose
Answer & solution

Answer: (a) Both amino acids and sucrose

Correct Answer: Option 1 — Both amino acids and sucrose
The phloem is the food-conducting vascular tissue of plants. The movement of soluble food through it is called translocation, and it is carried out by sieve tubes with the help of companion cells.
Phloem transports sucrose, the main soluble product of photosynthesis, from the source (leaf) to the sink (root, fruit, seed, growing bud). Along with it, the phloem also carries amino acids and other substances such as hormones. Unlike the xylem, translocation in phloem is bidirectional (both upward and downward) and needs energy from ATP — sugar is loaded into the sieve tube using ATP, water then enters by osmosis, and the resulting pressure pushes the sap along.
❌ Why the other options are incorrect
✗ Only Water — pure water and dissolved minerals are conducted by the xylem, and that movement is unidirectional (root to leaf).
✗ Only Amino acids — amino acids are carried, but so is sucrose; restricting it to amino acids alone is incomplete.
✗ Only Sucrose — sucrose is carried, but the phloem also moves amino acids and other organic substances.
📌 SSC & Railway Exam Facts
• Xylem — water and minerals, upward, uses transpiration pull, made of dead cells (tracheids, vessels).
• Phloem — food, both ways, uses ATP energy, made mostly of living cells (sieve tubes, companion cells, phloem parenchyma, phloem fibres).
• The pressure-flow (mass-flow) hypothesis of translocation was given by Ernst Münch (1930).
• Sucrose is the chief transported sugar; starch is the chief stored form.
• Removing a ring of bark (girdling) stops phloem transport and proves that food moves through the bark.
RRB Technician Grade III 2024-25 – 29 December 2024 Shift 1 · Photosynthesis - process and factors

Q68. What is the process by which autotrophs take in substance from outside and in the presence of sunlight, convert them into stored forms of energy?

  1. (a) Movement
  2. (b) Digestion
  3. (c) Circulation
  4. (d) Photosynthesis
Answer & solution

Answer: (d) Photosynthesis

Correct Answer: Option 4 — Photosynthesis
Photosynthesis is the process by which autotrophs (green plants, algae, cyanobacteria) take in simple inorganic substances — carbon dioxide from the air and water from the soil — and, using sunlight trapped by chlorophyll, convert them into carbohydrates (glucose), a stored form of chemical energy. Oxygen is released as a by-product.
6CO₂ + 12H₂O → (sunlight / chlorophyll) → C₆H₁₂O₆ + 6O₂ + 6H₂O
The main events are: absorption of light energy by chlorophyll, conversion of light energy to chemical energy and splitting of water (photolysis) into hydrogen and oxygen, and reduction of CO₂ to carbohydrates. Extra glucose is stored as starch in the plant and as glycogen in animals that eat the plant.
❌ Why the other options are incorrect
✗ Movement — a general sign of life (locomotion in animals, tropic and nastic movements in plants); it does not make food.
✗ Digestion — the breakdown of complex food into simpler absorbable forms by enzymes; it is a heterotrophic process that releases energy rather than storing it.
✗ Circulation — the transport of blood, gases, food and wastes within the body; it distributes materials but does not synthesise them.
📌 SSC & Railway Exam Facts
• Chlorophyll is the green pigment in the chloroplast; the chloroplast is called the kitchen of the cell.
• Chlorophyll contains magnesium (Mg); haemoglobin contains iron (Fe).
• Photosynthesis occurs in two phases — the light reaction in the grana and the dark reaction (Calvin cycle) in the stroma.
• Gaseous exchange in leaves takes place through tiny pores called stomata, guarded by guard cells.
• Van Helmont, Joseph Priestley and Julius von Sachs performed the classic experiments on photosynthesis; the word was coined by Charles Barnes.
RRB Technician Grade III 2024-25 – 28 December 2024 Shift 2 · Transpiration

Q69. ________ is the process through which plants lose water in the form of water vapour.

  1. (a) Transportation
  2. (b) Transcription
  3. (c) Transpiration
  4. (d) Imbibition
Answer & solution

Answer: (c) Transpiration

Correct Answer: Option 3 — Transpiration
Transpiration is the loss of water from the aerial parts of a plant — mainly the leaves — in the form of water vapour. It takes place chiefly through tiny pores called stomata, whose opening and closing is controlled by two bean-shaped guard cells.
Transpiration is not mere waste. It creates a transpiration pull, a suction force that draws a continuous column of water upward through the xylem from the roots to the topmost leaves — this is the main force for ascent of sap in tall trees. It also helps in the absorption and upward movement of minerals and in cooling the plant on hot days.
❌ Why the other options are incorrect
✗ Transportation — the general movement of water, food and minerals within the plant through xylem and phloem; it is not the loss of water as vapour.
✗ Transcription — a molecular process in which mRNA is synthesised from DNA; it has nothing to do with water loss.
✗ Imbibition — the absorption of water by solid colloids such as dry seeds or wood, causing them to swell; it is the opposite of losing water.
📌 SSC & Railway Exam Facts
• Loss of water as liquid droplets from leaf margins is guttation, not transpiration.
• Transpiration pull was explained by the cohesion–tension theory of Dixon and Joly.
• Translocation is the transport of prepared food through phloem, and it requires energy (ATP).
• Stomata mostly open in the day and close at night; in desert plants (CAM), the reverse happens.
• Transpiration is often called a necessary evil of plants.
RRB Technician Grade III 2024-25 – 28 December 2024 Shift 2 · Photosynthesis - process and factors

Q70. In the process of photosynthesis, what happens to the carbohydrates (glucose) that are produced?

  1. (a) First, carbohydrates are utilised for energy production and the rest are stored in the form of starch.
  2. (b) All the carbohydrates are immediately used as energy.
  3. (c) Carbohydrates are stored in the form of glycogen.
  4. (d) All the carbohydrates are stored in the form of a starch.
Answer & solution

Answer: (a) First, carbohydrates are utilised for energy production and the rest are stored in the form of starch.

Correct Answer: Option 1 — First, carbohydrates are utilised for energy production and the rest are stored in the form of starch.
In photosynthesis, green plants use sunlight, chlorophyll, carbon dioxide and water to make glucose and release oxygen. The reaction is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in the presence of sunlight and chlorophyll).
As NCERT states, the carbohydrate produced is used to provide energy to the plant, and the carbohydrates which are not used immediately are stored in the form of starch. Starch acts as the plant's internal energy reserve, drawn upon whenever needed. This is exactly why the iodine test, which turns starch blue-black, is used to show that photosynthesis has taken place in a leaf.
❌ Why the other options are incorrect
✗ All the carbohydrates are immediately used as energy — wrong; a plant makes far more glucose than it needs at that moment, and the surplus is stored.
✗ Carbohydrates are stored in the form of glycogen — wrong; glycogen is the storage carbohydrate of animals and fungi, stored in the liver and muscles, not of plants.
✗ All the carbohydrates are stored in the form of a starch — wrong; part of the glucose is used up at once for the plant's own respiration and growth.
📌 SSC & Railway Exam Facts
• Photosynthesis occurs in the chloroplast; chlorophyll is the green pigment that traps sunlight.
• Its two phases: the light reaction (in grana) and the dark reaction / Calvin cycle (in stroma).
• The oxygen released in photosynthesis comes from water, not from CO₂.
• Storage carbohydrate: starch in plants, glycogen in animals, cellulose builds the plant cell wall.
• Chlorophyll contains magnesium (Mg); haemoglobin contains iron (Fe).
RRB Technician Grade III 2024-25 – 26 December 2024 Shift 3 · Transpiration

Q71. When water enters into the guard cells, the guard cells ______ and the stomatal pore ______.

  1. (a) swell; opens
  2. (b) swell; shrinks
  3. (c) shrink; closes
  4. (d) shrink; opens
Answer & solution

Answer: (a) swell; opens

Correct Answer: Option 1 — swell; opens
Stomata are tiny pores in the epidermis of a leaf, each bounded by two bean-shaped (kidney-shaped) guard cells. They are the doors through which gaseous exchange and transpiration take place.
When the guard cells take in water by osmosis, they become turgid (swollen). The inner wall of a guard cell, facing the pore, is thick and inelastic while the outer wall is thin and elastic; so the swelling bulges the outer wall outwards, the guard cells curve apart, and the stomatal pore opens. When water is lost, the guard cells become flaccid, straighten and the pore closes — the way the plant checks excess water loss on a hot day.
❌ Why the other options are incorrect
✗ swell; shrinks — swelling of turgid guard cells can never make the pore shrink; turgidity always widens the pore.
✗ shrink; closes — true, but only for loss of water; the question specifically says water enters the guard cells.
✗ shrink; opens — self-contradictory; flaccid, shrunken guard cells come together and shut the pore.
📌 SSC & Railway Exam Facts
• Transpiration is the loss of water as vapour from the aerial parts of a plant, mostly through stomata.
• Transpiration creates the transpiration pull, which draws water up through the xylem — the main force of ascent of sap.
• It also cools the plant and helps the absorption and upward movement of minerals.
• Stomata are usually more numerous on the lower surface of a dicot leaf; in floating plants like the lotus they occur on the upper surface.
• Guard cells of stomata are the only epidermal cells that contain chloroplasts.
RRB Technician Grade III 2024-25 – 24 December 2024 Shift 2 · Transport in plants (xylem, phloem)

Q72. Identify the INCORRECT statement related to transportation in plants.
a. Phloem helps in mineral and water absorption from the soil.
b. Root hair increases the root's surface area for water and mineral absorption.
c. Special vascular tissue in plants transports water and nutrients from the soil.
d. Roots and leaves are joined by a continuous network of xylem channels.

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

Answer: (d) Only a

Correct Answer: Option 4 — Only a
Plants have two conducting (vascular) tissues with completely different jobs. Xylem carries water and dissolved minerals upward from the roots to the stem and leaves, while phloem carries prepared food (sucrose) from the leaves to the rest of the plant, a process called translocation. Phloem therefore has no role in absorbing water and minerals from the soil, so statement a is incorrect.
Checking the rest:
• b is correct — the root tip bears thousands of fine root hairs that enormously increase the surface area for absorption; water enters them by osmosis and minerals largely by active transport.
• c is correct — the vascular tissue (xylem) is exactly the special tissue that moves water and dissolved nutrients taken from the soil.
• d is correct — the xylem of root, stem and leaf is joined into a continuous network of channels, so water rises in an unbroken column up to the leaves.
❌ Why the other options are incorrect
✗ c and d — both these statements are factually correct, so neither can be the incorrect one.
✗ Only d — the continuous xylem network between roots and leaves is a correct NCERT statement.
✗ b and c — root hairs do increase absorbing surface and vascular tissue does transport water; both statements are right.
📌 SSC & Railway Exam Facts
• Xylem — dead tissue, unidirectional (upward) flow; phloem — living tissue, bidirectional flow of food.
• Xylem elements — tracheids, vessels, xylem parenchyma, xylem fibres; phloem elements — sieve tubes, companion cells, phloem parenchyma, phloem fibres.
• Water rises through the stem by root pressure and mainly by the transpiration pull (cohesion–tension theory).
• Transpiration — loss of water vapour through stomata; it also cools the plant and is called a necessary evil.
• Translocation in phloem needs energy (ATP) and was explained by Münch's pressure-flow hypothesis.
RRB Technician Grade III 2024-25 – 24 December 2024 Shift 3 · Transpiration

Q73. There are two statements given below. Select the correct option with regards to these statements.
A. The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration.
B. During the day when the stomata are open, the transpiration pull becomes the major driving force in the movement of water in the xylem.

  1. (a) A is correct and B is incorrect.
  2. (b) Both A and B are incorrect.
  3. (c) Both A and B are correct.
  4. (d) A is incorrect and B is correct.
Answer & solution

Answer: (c) Both A and B are correct.

Correct Answer: Option 3 — Both A and B are correct.
Statement A is correct. Transpiration is the loss of water in the form of water vapour from the aerial parts of a plant — mainly the leaves, through the stomata, and to a small extent through the cuticle and lenticels.
Statement B is also correct. Water lost from the leaf cells creates a suction pressure, and because water molecules stick to one another (cohesion) and to the xylem walls (adhesion), an unbroken water column is pulled up. This transpiration pull is the major driving force for the upward movement of water in the xylem during the day, when the stomata are open. At night, when stomata close, root pressure becomes the main force.
❌ Why the other options are incorrect
✗ A is correct and B is incorrect — wrong, because transpiration pull is indeed the chief force lifting water in daytime.
✗ Both A and B are incorrect — both statements are exactly as given in NCERT, so this cannot be right.
✗ A is incorrect and B is correct — wrong, because statement A is the standard definition of transpiration.
📌 SSC & Railway Exam Facts
• Xylem carries water and minerals upward; phloem carries food (sucrose) in both directions by translocation.
• Transpiration also helps in the absorption and upward movement of minerals and cools the plant.
• Transpiration is called a 'necessary evil' in plants.
• Guttation is the loss of water in liquid form through hydathodes at leaf margins.
• Stomatal opening and closing is controlled by the turgidity of guard cells.
RRB Technician Grade III 2024-25 – 23 December 2024 Shift 2 · Photosynthesis - process and factors

Q74. The carbohydrates which are not used immediately are stored in the form of________, which serves as the internal energy reserve to be used as and when required by the plant.

  1. (a) starch
  2. (b) cellulose
  3. (c) glycogen
  4. (d) glucose
Answer & solution

Answer: (a) starch

Correct Answer: Option 1 — starch
During photosynthesis a green plant converts carbon dioxide and water into glucose using sunlight trapped by chlorophyll. Whatever glucose is not used immediately for respiration or growth is polymerised into starch, an insoluble carbohydrate stored in the leaves, stems, roots, tubers and seeds.
Starch is the ideal store because it is insoluble — it does not dissolve in cell sap, so it neither leaks away nor disturbs the osmotic balance of the cell. When energy is needed, enzymes hydrolyse starch back into glucose. Presence of starch in a leaf is the standard test for photosynthesis, shown by the iodine test in which starch turns blue-black.
❌ Why the other options are incorrect
✗ cellulose — also a glucose polymer, but it is a structural carbohydrate that builds the cell wall; it is not an energy reserve and humans cannot digest it.
✗ glycogen — the storage carbohydrate of animals and fungi, stored in the liver and muscles; it is called animal starch, not a plant reserve.
✗ glucose — the immediate product of photosynthesis, but being soluble and osmotically active it cannot be stockpiled in large amounts.
📌 SSC & Railway Exam Facts
• Photosynthesis equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ in the presence of sunlight and chlorophyll.
• Photosynthesis occurs in the chloroplast, called the kitchen of the cell.
• Starch + iodine → blue-black colour; this is the classic starch test.
• Starch is stored as grains in the leucoplasts (amyloplasts) of plant cells.
• Gases enter the leaf through stomata, guarded by bean-shaped guard cells.
RRB Technician Grade III 2024-25 – 23 December 2024 Shift 3 · Transport in plants (xylem, phloem)

Q75. Which of the following statements is correct about transport in plants?

  1. (a) Plants have low energy needs and use relatively slow transport systems.
  2. (b) In herbs and shrubs, the distances over which transport systems have to operate are very large.
  3. (c) The phloem moves water and minerals obtained from the soil.
  4. (d) The xylem transports products of photosynthesis from the leaves where they are synthesised to other parts of the plant.
Answer & solution

Answer: (a) Plants have low energy needs and use relatively slow transport systems.

Correct Answer: Option 1 — Plants have low energy needs and use relatively slow transport systems.
Plants do not move about, and a large part of the plant body is made of dead cells such as xylem vessels and sclerenchyma. Both facts mean that a plant spends far less energy than an animal of the same size. Since its energy demand is low, a plant does not need a fast pumping heart — a slow transport system driven mostly by transpiration pull and root pressure is quite enough.
The plant has two conducting tissues: xylem, which carries water and minerals upward from the roots, and phloem, which carries food (sucrose) from the leaves to all other parts by translocation using ATP.
❌ Why the other options are incorrect
✗ Distances very large in herbs and shrubs — the opposite; in small herbs and shrubs the distances are short. Long-distance transport is the problem of tall trees.
✗ Phloem moves water and minerals from the soil — wrong; that is the job of the xylem. Phloem transports prepared food.
✗ Xylem transports products of photosynthesis — wrong; the movement of photosynthetic products from leaves to other parts is translocation, carried out by the phloem.
📌 SSC & Railway Exam Facts
• Xylem — tracheids, vessels, xylem parenchyma, xylem fibres; transport is unidirectional (upward).
• Phloem — sieve tubes, companion cells, phloem parenchyma, phloem fibres; transport is bidirectional.
• Transpiration is loss of water as vapour, mainly through stomata; the suction created is the transpiration pull.
• Transpiration also cools the plant and helps absorb minerals — it is called a necessary evil.
• Translocation in phloem needs energy (ATP); movement in xylem is passive.
RRB Technician Grade III 2024-25 – 20 December 2024 Shift 3 · Transpiration

Q76. Which of the following helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves?

  1. (a) Transpiration
  2. (b) Photosynthesis
  3. (c) Translocation
  4. (d) Respiration
Answer & solution

Answer: (a) Transpiration

Correct Answer: Option 1 — Transpiration
Transpiration is the loss of water in the form of vapour from the aerial parts of a plant, mainly through the stomata of the leaves. As water evaporates from the leaf cells, a suction pull (transpiration pull) is created in the xylem column. Because water molecules stick to one another by cohesion and to the xylem walls by adhesion, this pull drags a continuous column of water upward from the roots to the leaves, and also helps the root hairs absorb more water and dissolved minerals from the soil.
Transpiration also cools the plant and helps in the upward transport of minerals.
❌ Why the other options are incorrect
✗ Photosynthesis — the process by which green plants make glucose from CO₂ and water using chlorophyll and sunlight; it consumes water but does not lift it.
✗ Translocation — the transport of prepared food (sucrose) from leaves to other parts through the phloem, using energy from ATP; direction is both upward and downward.
✗ Respiration — the oxidation of food to release energy (ATP) in the mitochondria; it has no role in water conduction.
📌 SSC & Railway Exam Facts
• Xylem carries water and minerals upward; phloem carries food in all directions.
• Transpiration is called a necessary evil — most absorbed water is lost, yet the pull is essential.
• About 90–95% of transpiration takes place through stomata; the rest is cuticular and lenticular.
• Guard cells open and close the stomata by becoming turgid or flaccid.
• Root pressure works mainly at night; transpiration pull is the major force during the day.

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