Plant Growth and Development — Important Questions
51 questions
With answersCBSE format
SUMMARY: The chapter "Plant Growth and Development" in Class 11 Biology explores the various processes and factors that influence the growth and development of plants. KEY TOPICS: growth regulators, photoperiodism, vernalization, seed dormancy, differentiation, dedifferentiation, redifferentiation, growth curve, auxins, gibberellins
Statement 2: Spraying GA3 on dwarf plants makes them tall.
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Correct answer: Option 1 —
Both statements are true.
Case Study / Passage Questions2 questions
Q483 Marks
A farmer notices that storing unripe bananas with ripe apples in a sealed bag accelerates the ripening of the bananas. A botany student explains the role of ethylene as a gaseous plant hormone produced by ripe fruits that diffuses to neighbouring fruits and triggers their ripening.
The hormone responsible for fruit ripening is:
AAuxin
BCytokinin
CEthylene
DAbscisic acid
Ethylene is a:
ASolid
BLiquid
CGas
DIon
Discuss the physiological effects and commercial uses of ethylene in agriculture.
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1. Option 3 — Ethylene
2. Option 3 — Gas
3. Ethylene is a gaseous plant hormone with multiple roles. It promotes ripening of climacteric fruits like banana, mango and apple by increasing respiration and softening the cell walls. It also induces senescence and abscission of leaves and flowers and breaks dormancy in some seeds. Ethrel (an ethylene-releasing compound) is sprayed on fields to synchronise flowering and fruit ripening commercially.
Q493 Marks
Garner and Allard noticed that a tobacco mutant flowered only when day-length was below a critical value. Other plants flowered only above a critical day-length. The team coined the term photoperiodism to describe the response of plants to the relative duration of day and night.
The hypothetical flowering hormone is called:
AAuxin
BGibberellin
CCytokinin
DFlorigen
Plants that flower when day-length is below a critical value are:
ALong-day plants
BShort-day plants
CDay-neutral plants
DPhotophobic plants
Explain photoperiodism and classify plants based on photoperiodic response.
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1. Option 4 — Florigen
2. Option 2 — Short-day plants
3. Photoperiodism is the response of plants to the relative length of day and night. Plants are classified as long-day, short-day or day-neutral. The actual signal is sensed by the leaves where a hypothetical hormone (florigen) is believed to be produced and then transported to the shoot apex to induce flowering. The phytochrome pigment in leaves senses the photoperiod.
Table-Based Questions2 questions
Q503 Marks
Study the table on plant growth regulators and answer:
Hormone
Major function
Application
Auxin
Cell elongation, apical dominance
Rooting of cuttings
Gibberellin
Stem elongation, breaking dormancy
Increase fruit size
Cytokinin
Cell division, delay senescence
Tissue culture
Ethylene
Fruit ripening
Synchronising harvest
Abscisic acid
Stress response, dormancy
Reduce transpiration
The hormone widely used for rooting of stem cuttings is:
AAuxin
BGibberellin
CCytokinin
DEthylene
The stress hormone that promotes stomatal closure during drought is:
AAuxin
BGibberellin
CCytokinin
DAbscisic acid
Compare the major roles of auxin, gibberellin and abscisic acid in plant growth.
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1. Option 1 — Auxin
2. Option 4 — Abscisic acid
3. Plant growth regulators are organic compounds produced by plants that influence growth and development at very low concentrations. The five major classes are auxins, gibberellins, cytokinins, ethylene and abscisic acid. Auxins, gibberellins and cytokinins are growth promoters while ethylene promotes senescence and abscission. Abscisic acid acts as a growth inhibitor and stress hormone.
Q516 Marks
Match each plant hormone with its primary physiological effect.
