Chapter 15: Plant Growth and Development – MCQs with Answers & Explanations

CBSE Class 11 Biology Chapter 15 – Plant Growth and Development | MCQs with Answers & Explanations (NCERT)

Course & Examination Details

Course: CBSE Class 11 Biology
Unit: Unit IV – Plant Physiology
Chapter: Chapter 15 – Plant Growth and Development
Board: Central Board of Secondary Education (CBSE)
Question Type: Multiple Choice Questions (MCQs)
Syllabus: Strictly as per NCERT Biology Textbook

Section A: Growth in Plants (MCQs 1–15)

Q1. Growth in plants is best defined as:

A. Temporary increase in size
B. Reversible increase in mass
C. Permanent and irreversible increase in size
D. Increase due to water absorption only

Correct Answer: C

Explanation:
Growth is a permanent and irreversible increase in size, mass, or number of cells, resulting from metabolic activities such as cell division and elongation.

Q2. Which tissue is mainly responsible for indeterminate growth in plants?

A. Parenchyma
B. Xylem
C. Meristematic tissue
D. Collenchyma

Correct Answer: C

Explanation:
Meristematic tissues retain the ability to divide throughout life, enabling continuous growth at root and shoot apices.

Q3. The phase of growth where cells actively divide is called:

A. Elongation phase
B. Maturation phase
C. Meristematic phase
D. Senescence phase

Correct Answer: C

Explanation:
The meristematic phase is characterized by active mitotic divisions, thin cell walls, dense cytoplasm, and prominent nuclei.

Q4. Maximum increase in size of cells occurs during:

A. Meristematic phase
B. Elongation phase
C. Maturation phase
D. Dormancy phase

Correct Answer: B

Explanation:
Cell elongation, vacuole expansion, and wall loosening occur in the elongation phase, causing rapid increase in size.

Q5. Cells attain permanent shape and function during:

A. Meristematic phase
B. Elongation phase
C. Maturation phase
D. Dedifferentiation phase

Correct Answer: C

Explanation:
In the maturation phase, cells differentiate and acquire specific structural and functional characteristics.

Q6. Arithmetic growth results in a:

A. Sigmoid curve
B. Exponential curve
C. Linear curve
D. Bell-shaped curve

Correct Answer: C

Explanation:
Arithmetic growth involves constant increase per unit time, producing a straight-line (linear) growth curve.

Q7. Geometric growth occurs when:

A. Growth is constant
B. Growth rate is proportional to size
C. Growth occurs only in roots
D. Growth is reversible

Correct Answer: B

Explanation:
In geometric growth, growth rate depends on existing size, resulting in exponential increase under ideal conditions.

Q8. Which of the following shows arithmetic growth?

A. Cell division
B. Root elongation
C. Exponential biomass increase
D. Seed germination

Correct Answer: B

Explanation:
Root elongation commonly shows arithmetic growth with a constant increase in length per unit time.

Q9. Growth rate refers to:

A. Total size of plant
B. Increase in size per unit time
C. Number of leaves formed
D. Duration of growth

Correct Answer: B

Explanation:
Growth rate measures the increase in size, mass, or area of a plant per unit time.

Q10. Which factor is NOT essential for plant growth?

A. Water
B. Oxygen
C. Nutrients
D. Carbon dioxide only

Correct Answer: D

Explanation:
Although carbon dioxide is essential for photosynthesis, growth requires multiple factors like water, oxygen, nutrients, and temperature.

Q11. Which external factor affects enzyme activity directly?

A. Light
B. Water
C. Temperature
D. Minerals

Correct Answer: C

Explanation:
Temperature directly influences enzyme activity, which controls metabolic reactions involved in growth.

Q12. Growth in plants differs from animals because plants:

A. Do not grow
B. Have determinate growth
C. Have indeterminate growth
D. Stop growing after maturity

Correct Answer: C

Explanation:
Plants show indeterminate growth due to continuous activity of meristems, unlike animals.

Q13. Sigmoid growth curve is associated with:

A. Arithmetic growth
B. Unlimited growth
C. Natural growth conditions
D. No growth limitation

Correct Answer: C

Explanation:
Under natural conditions, growth slows due to environmental limitations, forming a sigmoid curve.

Q14. Which phase shows maximum metabolic activity?

A. Meristematic
B. Elongation
C. Maturation
D. Senescence

Correct Answer: B

Explanation:
During elongation phase, synthesis of cell wall materials and vacuole enlargement require high metabolic activity.

Q15. Water is essential for growth mainly because it:

A. Provides minerals
B. Maintains turgidity
C. Supplies oxygen
D. Regulates hormones

Correct Answer: B

Explanation:
Water maintains cell turgidity, enabling cell expansion and elongation necessary for growth.

Section B: Differentiation and Development (MCQs 16–25)

Q16. Differentiation involves:

A. Loss of function
B. Specialization of cells
C. Cell death
D. Reduction in size

Correct Answer: B

Explanation:
Differentiation leads to structural and functional specialization of cells.

Q17. Formation of cork cambium from cortex is an example of:

A. Differentiation
B. Redifferentiation
C. Dedifferentiation
D. Senescence

Correct Answer: C

Explanation:
Dedifferentiation involves regaining dividing ability by mature cells.

Q18. Redifferentiation refers to:

A. Continuous division
B. Loss of specialization
C. Regaining specialization
D. Cell elongation

Correct Answer: C

Explanation:
Redifferentiation is the process by which dedifferentiated cells specialize again.

Q19. Development in plants includes:

A. Growth only
B. Differentiation only
C. Growth and differentiation
D. Senescence only

Correct Answer: C

Explanation:
Development is the sum total of growth and differentiation throughout the life cycle.

Q20. Plants are developmentally plastic because they:

A. Cannot change form
B. Show fixed growth pattern
C. Respond to environment
D. Lack hormones

Correct Answer: C

Explanation:
Developmental plasticity allows plants to modify growth and form in response to environmental conditions.

Q21. Which factor primarily controls development internally?

A. Light
B. Temperature
C. Genes
D. Water

Correct Answer: C

Explanation:
Genes regulate developmental patterns by controlling protein and enzyme synthesis.

Q22. Which example shows developmental plasticity?

A. Same leaf shape always
B. Buttercup leaves in water and land
C. Fixed stem length
D. No response to environment

Correct Answer: B

Explanation:
Buttercup shows different leaf forms under different habitats, demonstrating plasticity.

Q23. Growth without differentiation results in:

A. Functional organs
B. Specialized tissues
C. Cell mass without function
D. Complete plant

Correct Answer: C

Explanation:
Without differentiation, growth leads only to undifferentiated cell mass.

Q24. Which process is reversible?

A. Growth
B. Differentiation
C. Dedifferentiation
D. Senescence

Correct Answer: C

Explanation:
Dedifferentiation allows mature cells to revert to dividing state.

Q25. Development is influenced by:

A. Internal factors only
B. External factors only
C. Both internal and external factors
D. Age only

Correct Answer: C

Explanation:
Plant development is regulated by genes, hormones, light, temperature, and nutrients.

Section C: Plant Hormones (MCQs 26–40)

Q26. Plant hormones are effective in:

A. Large quantities
B. Moderate quantities
C. Very small quantities
D. Equal quantities

Correct Answer: C

Explanation:
Plant hormones act in minute concentrations to regulate growth and development.

Q27. Which hormone promotes cell elongation?

A. Cytokinin
B. Auxin
C. Ethylene
D. ABA

Correct Answer: B

Explanation:
Auxins promote cell elongation by increasing cell wall plasticity.

Q28. Apical dominance is controlled by:

A. Cytokinins
B. Gibberellins
C. Auxins
D. Ethylene

Correct Answer: C

Explanation:
Auxins produced at the apical bud suppress lateral bud growth.

Q29. Bolting in rosette plants is caused by:

A. Auxins
B. Cytokinins
C. Gibberellins
D. ABA

Correct Answer: C

Explanation:
Gibberellins induce rapid stem elongation known as bolting.

Q30. Which hormone delays senescence?

A. ABA
B. Ethylene
C. Cytokinin
D. Auxin

Correct Answer: C

Explanation:
Cytokinins maintain chlorophyll and protein content, delaying senescence.

Q31. The only gaseous plant hormone is:

A. Auxin
B. Ethylene
C. Gibberellin
D. ABA

Correct Answer: B

Explanation:
Ethylene is unique as it exists in gaseous form.

Q32. Fruit ripening is regulated by:

A. Auxin
B. Cytokinin
C. Ethylene
D. ABA

Correct Answer: C

Explanation:
Ethylene accelerates respiration and enzyme activity during ripening.

Q33. Triple response is shown by:

A. Auxin
B. Ethylene
C. Cytokinin
D. Gibberellin

Correct Answer: B

Explanation:
Ethylene causes reduced elongation, lateral swelling, and horizontal growth.

Q34. Abscisic acid primarily acts as:

A. Growth promoter
B. Stress hormone
C. Flowering hormone
D. Ripening hormone

Correct Answer: B

Explanation:
ABA helps plants tolerate stress by inhibiting growth and closing stomata.

Q35. Stomatal closure during drought is caused by:

A. Auxin
B. Cytokinin
C. Ethylene
D. ABA

Correct Answer: D

Explanation:
ABA induces stomatal closure to prevent water loss.

Q36. Which hormone promotes lateral bud growth?

A. Auxin
B. Gibberellin
C. Cytokinin
D. ABA

Correct Answer: C

Explanation:
Cytokinins counteract apical dominance and promote lateral buds.

Q37. Hormonal balance is important because:

A. One hormone acts alone
B. Hormones act independently
C. Hormones interact with each other
D. Hormones have no effect

Correct Answer: C

Explanation:
Plant responses depend on interactions and balance between different hormones.

Q38. Growth inhibitors include:

A. Auxins and cytokinins
B. Gibberellins and auxins
C. ABA and ethylene
D. Cytokinins and ethylene

Correct Answer: C

Explanation:
ABA and ethylene generally inhibit growth and promote senescence or dormancy.

Q39. Which hormone is used to induce rooting in cuttings?

A. Gibberellin
B. Cytokinin
C. Auxin
D. Ethylene

Correct Answer: C

Explanation:
Auxins stimulate root initiation in stem cuttings.

Q40. Which hormone activates enzymes during seed germination?

A. Auxin
B. Cytokinin
C. Gibberellin
D. ABA

Correct Answer: C

Explanation:
Gibberellins activate enzymes like amylase to mobilize stored food.

Section D: Photoperiodism and Vernalisation (MCQs 41–50)

Q41. Photoperiodism is related to:

A. Temperature
B. Water
C. Day length
D. Nutrients

Correct Answer: C

Explanation:
Photoperiodism is the response of plants to relative length of day and night.

Q42. Short-day plants require:

A. Long days
B. Short nights
C. Long uninterrupted nights
D. Continuous light

Correct Answer: C

Explanation:
Short-day plants flower only when nights exceed critical duration.

Q43. Wheat is an example of:

A. Short-day plant
B. Long-day plant
C. Day-neutral plant
D. Biennial plant

Correct Answer: B

Explanation:
Wheat flowers when day length exceeds the critical photoperiod.

Q44. Flowering independent of day length is shown by:

A. Rice
B. Wheat
C. Tomato
D. Chrysanthemum

Correct Answer: C

Explanation:
Tomato is a day-neutral plant.

Q45. Phytochrome exists in how many forms?

A. One
B. Two
C. Three
D. Four

Correct Answer: B

Explanation:
Phytochrome exists as Pr and Pfr forms.

Q46. The biologically active form of phytochrome is:

A. Pr
B. Pfr
C. Both
D. Neither

Correct Answer: B

Explanation:
Pfr form triggers physiological responses including flowering.

Q47. Vernalisation refers to:

A. Long-day treatment
B. Light treatment
C. Low-temperature treatment
D. Hormonal treatment

Correct Answer: C

Explanation:
Vernalisation is induction of flowering by cold exposure.

Q48. Vernalisation is common in:

A. Summer annuals
B. Biennials
C. Day-neutral plants
D. Aquatic plants

Correct Answer: B

Explanation:
Biennial and winter annual plants require vernalisation.

Q49. Devernalisation involves:

A. Cold treatment
B. Light treatment
C. High temperature
D. Hormonal imbalance

Correct Answer: C

Explanation:
High temperature reverses the effect of vernalisation.

Q50. Photoperiodism and vernalisation together ensure:

A. Faster growth
B. Delayed growth
C. Proper flowering time
D. Reduced yield

Correct Answer: C

Explanation:
Both processes synchronize flowering with favorable environmental conditions.

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