Life Processes in Plants Part 1: MCQs (Q1–Q25)
Part 1 — Plant Growth (Q1–Q25)
1. Growth in plants means:
A. Only increase in size
B. Irreversible permanent increase in size and mass
C. Increase in number of cells and irreversible increase in mass ← Correct answer: B
D. Only increase in water content
Explanations:
A) Growth is not only size — incomplete.
B) Correct. Plant growth is generally an irreversible increase in size/mass due to cell division/expansion.
C) Worded similarly but “number of cells” and “mass” is fine — option B chosen as clear NCERT phrase.
D) Water uptake causes temporary swelling — not true growth.
2. Which region in a plant is mainly responsible for primary growth in length?
A. Lateral meristem
B. Apical meristem ← Correct answer: B
C. Cambium
D. Root hair zone
Explanations:
A) Lateral meristem causes thickness, not length — incorrect.
B) Correct. Apical meristems at tips of roots/shoots produce primary growth (length).
C) Cambium (vascular cambium) contributes to secondary growth (thickness) — incorrect.
D) Root hair zone absorbs water/nutrients but not main growth region — incorrect.
3. Secondary growth in plants results in:
A. Increase in height only
B. Increase in girth (thickness) ← Correct answer: B
C. Seed germination
D. Leaf fall
Explanations:
A) Height increase = primary growth — incorrect.
B) Correct. Secondary growth from lateral meristems (cambium) increases stem/root thickness.
C) Germination is a separate process — incorrect.
D) Leaf fall (abscission) is not secondary growth — incorrect.
4. Which of these is NOT a meristematic tissue?
A. Apical meristem
B. Lateral meristem
C. Intercalary meristem
D. Xylem vessel ← Correct answer: D
Explanations:
A–C) These are meristematic tissues with actively dividing cells — incorrect choices.
D) Correct. Xylem vessels are differentiated conducting tissues, not meristematic.
5. The growth producing increase in thickness in trees is mainly due to:
A. Apical meristem activity
B. Vascular cambium activity ← Correct answer: B
C. Root cap function
D. Leaf mesophyll division
Explanations:
A) Apical meristem increases length — incorrect.
B) Correct. Vascular cambium (a lateral meristem) forms secondary xylem/phloem increasing girth.
C) Root cap protects root tip — not for thickness — incorrect.
D) Mesophyll cells divide little for thickness — incorrect.
6. Which plant hormone is primarily responsible for cell elongation and phototropism?
A. Cytokinin
B. Auxin (IAA) ← Correct answer: B
C. Abscisic acid
D. Ethylene
Explanations:
A) Cytokinins promote cell division and delay senescence — incorrect for elongation/phototropism.
B) Correct. Auxins (IAA) stimulate cell elongation, mediate phototropic response.
C) Abscisic acid inhibits growth and induces dormancy — incorrect.
D) Ethylene regulates fruit ripening and leaf abscission — incorrect.
7. Photoperiodism in plants refers to:
A. Growth due to water only
B. Response to the length of day/night affecting flowering ← Correct answer: B
C. Movement towards gravity only
D. Root growth only
Explanations:
A) Not about water — incorrect.
B) Correct. Photoperiodism is flowering response based on day/night duration.
C) Movement towards gravity = gravitropism — incorrect.
D) Not specific — incorrect.
8. Which of the following promotes breaking of seed dormancy and germination?
A. High abscisic acid
B. Low moisture
C. Gibberellins ← Correct answer: C
D. Complete darkness always
Explanations:
A) Abscisic acid enforces dormancy — incorrect.
B) Low moisture inhibits germination — incorrect.
C) Correct. Gibberellins promote germination by mobilizing food reserves.
D) Some seeds need light; others germinate in dark — not universally correct.
9. Tropic movement in plants is:
A. Movement independent of stimulus (nastic)
B. Directional growth movement in response to stimulus ← Correct answer: B
C. Rapid reversible movement like Mimosa pudica only
D. Movement of water in xylem
Explanations:
A) Nastic movements are non-directional relative to stimulus — incorrect.
B) Correct. Tropisms (phototropism, gravitropism) are directional growth responses.
C) Rapid reversible movements are nastic — incorrect.
D) Movement of water is transport, not tropic movement — incorrect.
10. Gravitropism (geotropism) in roots is usually:
A. Negative (away from gravity)
B. Variable only in stems
C. Positive (towards gravity) ← Correct answer: C
D. Random
Explanations:
A) Roots exhibit positive gravitropism (grow downward) — incorrect.
B) Stems show negative gravitropism generally — incorrect.
C) Correct. Roots grow towards gravitational pull; shoots usually away.
D) Not random — incorrect.
11. Which plant hormone is associated with fruit ripening?
A. Auxin
B. Cytokinin
C. Gibberellin
D. Ethylene ← Correct answer: D
Explanations:
A–C) Not primary in ripening — incorrect.
D) Correct. Ethylene gas promotes fruit ripening and leaf abscission.
12. Phototropism is primarily due to unequal distribution of:
A. Cytokinins
B. Auxin (IAA) ← Correct answer: B
C. Abscisic acid
D. Gibberellin only
Explanations:
A/C/D) These hormones have other primary roles — incorrect.
B) Correct. Light causes auxin redistribution; shaded side elongates.
13. Which of these statements about meristematic cells is TRUE?
A. They have thick walls and are inactive
B. They are permanently differentiated
C. They have thin walls, dense cytoplasm and divide actively ← Correct answer: C
D. They perform photosynthesis only
Explanations:
A/B) Opposite of meristem properties — incorrect.
C) Correct. Meristematic cells are actively dividing with thin walls.
D) Meristems are not specialized for photosynthesis — incorrect.
14. The process by which plants add new cells at the base of leaves or internodes (seen in grasses) is due to:
A. Apical meristem only
B. Intercalary meristem ← Correct answer: B
C. Lateral meristem only
D. Root apical meristem
Explanations:
A/C/D) Not the correct meristem for regrowth at base — incorrect.
B) Correct. Intercalary meristems allow regrowth after grazing/cutting.
15. Auxins cause elongation of cells by:
A. Making cell walls rigid
B. Increasing cell wall plasticity and promoting water uptake ← Correct answer: B
C. Removing water from cells
D. Hardening secondary walls
Explanations:
A/C/D) False effects — incorrect.
B) Correct. Auxin-mediated acid growth loosens cell walls enabling expansion.
16. Vernalization refers to:
A. Growth in the dark
B. Induction of flowering by cold treatment ← Correct answer: B
C. Flowering induced by long days only
D. Seed dormancy due to heat
Explanations:
A/C/D) Not the definition — incorrect.
B) Correct. Many plants need a period of cold to flower (vernalization).
17. Which hormone delays senescence (aging) of leaves?
A. Ethylene
B. Abscisic acid
C. Cytokinin ← Correct answer: C
D. Auxin
Explanations:
A) Ethylene promotes senescence and abscission — incorrect.
B) ABA promotes dormancy/stress responses — not anti-senescence — incorrect.
C) Correct. Cytokinins delay leaf aging, promote cell division.
D) Auxin has other roles — incorrect.
18. The permanent cessation of growth in a plant structure is known as:
A. Dormancy
B. Determinate growth ← Correct answer: B
C. Indeterminate growth
D. Tropism
Explanations:
A) Dormancy is temporary inactivity — incorrect.
B) Correct. Determinate growth ends at a genetically predetermined size (e.g., leaves, flowers).
C) Indeterminate growth continues (e.g., many stems) — incorrect.
D) Tropism is movement toward/away from stimulus — incorrect.
19. Which of these is true about dormancy in seeds?
A. Dormancy is abolished by abscisic acid (ABA)
B. Dormancy isn’t influenced by environmental cues
C. Dormancy can be broken by cold stratification or gibberellins ← Correct answer: C
D. Dormant seeds cannot germinate under any conditions
Explanations:
A) ABA induces/maintains dormancy, not abolish — incorrect.
B) Environmental cues (temperature, moisture) often break dormancy — incorrect.
C) Correct. Cold or hormone treatments (GA) can break dormancy.
D) Dormant seeds can germinate when conditions/requirements are met — incorrect.
20. Which of the following reflects cell differentiation in plants?
A. Meristematic cell dividing only
B. Parenchyma cell specializing into xylem vessel ← Correct answer: B
C. Root cap cells dividing actively forever
D. All cells keeping the same function
Explanations:
A) Meristem division is not differentiation — incorrect.
B) Correct. Differentiation gives specific structure/function (e.g., xylem conducts water).
C) Root cap cells protect tip and are short-lived; not an example of differentiation in the sense asked — incorrect.
D) Cells become specialized — incorrect.
21. Which of these is an example of nastic movement?
A. Leaf bend toward light (phototropism)
B. Closing of Mimosa pudica leaves when touched ← Correct answer: B
C. Root curvature toward gravity
D. Stem bending away from light
Explanations:
A/C/D) Tropic movements (directional with stimulus) — incorrect.
B) Correct. Nastic movement is non-directional, determined by stimulus intensity, e.g., touch response.
22. Which plant hormone is commonly involved in stomatal closure under drought?
A. Auxin
B. Cytokinin
C. Abscisic acid (ABA) ← Correct answer: C
D. Ethylene
Explanations:
A/B/D) Not the main drought/stomatal closure hormone — incorrect.
C) Correct. ABA accumulates during water stress causing stomatal closure to reduce transpiration.
23. Phototropism causes shoots to grow:
A. Toward light (positive phototropism)
B. Away from light (negative phototropism)
C. Randomly
D. Only roots to move toward light
Correct answer: A
Explanations:
A) Correct. Shoots usually show positive phototropism, bending toward light to maximize photosynthesis.
B–D) Not characteristic of shoots — incorrect.
24. Which factor does NOT strongly influence plant growth?
A. Light
B. Water
C. Mineral nutrients
D. Sound
Explanations:
A–C) Major growth factors — incorrect to choose.
D) Correct. While extreme sound may stress plants, it isn’t a classical primary influence per NCERT.
25. Which tissue provides mechanical support and is living at maturity in plants?
A. Xylem vessel (dead)
B. Collenchyma ← Correct answer: B
C. Sclerenchyma (dead at maturity)
D. Phloem sieve tube elements (conducting)
Explanations:
A) Xylem vessels are dead cells providing support/water conduction — not living — incorrect.
B) Correct. Collenchyma cells are living and provide flexible support.
C) Sclerenchyma gives rigid support but cells are dead at maturity — incorrect.
D) Phloem elements are living but mainly conducting, not primary support — incorrect.