Plant Growth and Development
Here You Get So Many MCQs Questions Based On NEET Of Class 11 Biology, Chapter , Plant Growth and DevelopmentIf You Want To Read Our Quality Notes Of Chapter, Plant Growth and Development, Click Here 🥰1. Which of the following best explains why a plant first grows leaves and stems before producing flowers?
A) To store maximum water before reproduction
B) To complete the vegetative phase for growth and support
C) Because flowers require less energy than leaves
D) To ensure pollination occurs early
Answer: B) To complete the vegetative phase for growth and support
2. What is the origin of all cells in a plant?
A) Meristematic tissue
B) Root cells
C) Zygote
D) Leaf primordia
Answer: C) Zygote
3. Why do leaves, flowers, and fruits have a limited size even though the plant continues to grow?
A) Genetic and developmental regulation controls organ size
B) Lack of sunlight prevents further growth
C) Nutrients stop moving to older organs
D) Older organs are replaced by new ones
Answer: A) Genetic and developmental regulation controls organ size
4. Which of the following terms describes the growth phase where plants mainly produce stems and leaves?
A) Reproductive phase
B) Vegetative phase
C) Dormant phase
D) Senescence phase
Answer: B) Vegetative phase
5. Despite all plant cells originating from a single zygote, they look and function differently. This is due to:
A) Variation in sunlight exposure
B) Differentiation of cells
C) Unequal distribution of water
D) Different nutrient intake
Answer: B) Differentiation of cells
8. Seed germination resumes when:
A) The seed is fully dry
B) Favourable environmental conditions are present
C) The seed is in darkness only
D) The seed is in cold conditions
Answer: B) Favourable environmental conditions are present
9. Which of the following is NOT an example of permanent growth?
A) Leaf expansion
B) Stem elongation
C) Wood swelling in water
D) Root thickening
Answer: C) Wood swelling in water
10. The increase in plant size is considered irreversible because:
A) Cells absorb water
B) It is a temporary phenomenon
C) Metabolic activities permanently alter cell structure
D) Plants lose leaves seasonally
Answer: C) Metabolic activities permanently alter cell structure
11. The resting stage in seeds is important because:
A) It allows seeds to photosynthesize
B) It helps seeds survive until favourable conditions return
C) It prevents water absorption
D) It causes seed death
Answer: B) It helps seeds survive until favourable conditions return
12. Which of the following is an intrinsic factor affecting plant development?
A) Temperature
B) Hormones produced within the plant
C) Light
D) Water availability
Answer: B) Hormones produced within the plant
13. Extrinsic factors that influence plant growth include:
A) Cytokinin
B) Auxin
C) Temperature, light, and nutrients
D) Genetic makeup of the plant
Answer: C) Temperature, light, and nutrients
14. Differentiation in plants refers to:
A) Permanent increase in size
B) Cells acquiring specific structure and function
C) Temporary swelling of plant cells
D) Leaf expansion
Answer: B) Cells acquiring specific structure and function
15. Which statement correctly distinguishes growth from swelling?
A) Growth is reversible, swelling is irreversible
B) Growth is permanent and irreversible; swelling is temporary and reversible
C) Both are permanent processes
D) Swelling requires metabolic energy
Answer: B) Growth is permanent and irreversible; swelling is temporary and reversible
16. Metabolic processes in growth include:
A) Only breakdown of molecules
B) Only building up of molecules
C) Both catabolic and anabolic reactions
D) Neither catabolic nor anabolic reactions
Answer: C) Both catabolic and anabolic reactions
17. Why do seeds not germinate immediately after formation?
A) They lack nutrients
B) They require dormancy to survive unfavourable conditions
C) They need to undergo photosynthesis first
D) They are already growing inside the seed coat
Answer: B) They require dormancy to survive unfavourable conditions
18. Plant growth that is permanent and irreversible is possible because:
A) It happens only in roots
B) Cells divide and elongate under metabolic control
C) The plant absorbs water
D) It is regulated by sunlight only
Answer: B) Cells divide and elongate under metabolic control
19. Which of the following is an example of extrinsic factor affecting plant development?
A) Plant hormones
B) Genetic makeup
C) Soil nutrients
D) Enzymes inside the seed
Answer: C) Soil nutrients
20. The sequence of events in plant development from zygote to mature plant is:
A) Random and uncontrolled
B) Well-organized and specific
C) Only based on light exposure
D) Only influenced by water
Answer: B) Well-organized and specific
21. Continuous growth in plants is possible due to:
A) Photosynthesis
B) Meristems
C) Leaves
D) Flowers
Answer: B) Meristems
22. Meristematic cells are special because they:
A) Do not divide
B) Can divide repeatedly and maintain themselves
C) Only perform photosynthesis
D) Stop dividing immediately after formation
Answer: B) Can divide repeatedly and maintain themselves
23. The new cells produced by meristems eventually:
A) Remain undifferentiated forever
B) Develop into different parts of the plant body
C) Die immediately
D) Perform photosynthesis only
Answer: B) Develop into different parts of the plant body
24. The type of growth where new cells are constantly added by meristem activity is called:
A) Closed form of growth
B) Temporary growth
C) Open form of growth
D) Secondary growth only
Answer: C) Open form of growth
25. Primary growth in plants is mainly due to:
A) Lateral meristems
B) Root apical and shoot apical meristems
C) Cork cambium only
D) Photosynthesis in leaves
Answer: B) Root apical and shoot apical meristems
26. Primary growth in plants results in:
A) Increase in thickness of roots and stems
B) Growth along the main axis (length)
C) Flower production only
D) Dormancy of seeds
Answer: B) Growth along the main axis (length)
27. Lateral meristems appear in which type of plants?
A) Only monocots
B) Dicotyledonous plants and gymnosperms
C) Only algae
D) Only during seed germination
Answer: B) Dicotyledonous plants and gymnosperms
28. The main lateral meristems responsible for secondary growth are:
A) Root apical and shoot apical meristems
B) Vascular cambium and cork cambium
C) Leaf mesophyll
D) Stomata
Answer: B) Vascular cambium and cork cambium
29. Secondary growth in plants refers to:
A) Growth in length
B) Growth in thickness (girth)
C) Flowering
D) Seed germination
Answer: B) Growth in thickness (girth)
30. If meristems stop dividing, the plant:
A) Continues to grow indefinitely
B) Stops growing
C) Produces more flowers only
D) Becomes a monocot
Answer: B) Stops growing
31. At the cellular level, plant growth mainly happens because of:
A) Increase in chlorophyll content
B) Increase in the amount of protoplasm
C) Decrease in cell wall thickness
D) Increase in leaf area only
Answer: B) Increase in the amount of protoplasm
32. Growth is often measured using parameters proportional to protoplasm. Which of the following is NOT one of these parameters?
A) Fresh weight
B) Dry weight
C) Length
D) Color of leaves
Answer: D) Color of leaves
33. The apical meristem of a single maize root can produce approximately how many new cells every hour?
A) 1,750
B) 17,500
C) 175,000
D) 1,75,000
Answer: B) 17,500
34. In watermelon, cell growth is mainly shown by:
A) Increase in cell number
B) Increase in cell size
C) Increase in leaf number
D) Increase in root length only
Answer: B) Increase in cell size
35. Growth of a pollen tube is measured by:
A) Increase in surface area
B) Increase in length
C) Increase in dry weight
D) Increase in cell number
Answer: B) Increase in length
36. Growth of a dorsiventral leaf is measured by:
A) Increase in length
B) Increase in width
C) Increase in surface area
D) Increase in protoplasm content only
Answer: C) Increase in surface area
37. The phase in which cells at the root or shoot apex continuously divide is called:
A) Elongation phase
B) Maturation phase
C) Meristematic phase
D) Dormant phase
Answer: C) Meristematic phase
38. Meristematic cells are characterized by all the following EXCEPT:
A) Thin primary cell walls
B) Large, visible nuclei
C) High vacuolation
D) Many plasmodesmatal connections
Answer: C) High vacuolation
39. Cells in the elongation phase show:
A) Increased vacuolation and growth in size
B) Thicker cell walls and special functions
C) No division
D) Loss of nuclei
Answer: A) Increased vacuolation and growth in size
40. The maturation phase is characterized by:
A) Continuous cell division
B) Cells reaching full size and acquiring special functions
C) Only vacuolation increase
D) Loss of protoplasm completely
Answer: B) Cells reaching full size and acquiring special functions
41. The term ‘growth speed’ refers to:
A) The total size of a plant
B) How much growth occurs in a specific amount of time
C) The height of a plant at maturity
D) Number of leaves on a plant
Answer: B) How much growth occurs in a specific amount of time
42. In arithmetic growth:
A) Both daughter cells keep dividing
B) Only one daughter cell keeps dividing while the other matures
C) Cells do not divide at all
D) Growth is exponential
Answer: B) Only one daughter cell keeps dividing while the other matures
43. A root that grows at a constant speed is an example of:
A) Geometrical growth
B) Arithmetic growth
C) Relative growth
D) Logarithmic growth
Answer: B) Arithmetic growth
44. The formula for arithmetic growth is:
A) W₁ = W₀ × eʳᵗ
B) Lt = L₀ + rt
C) RQ = CO₂/O₂
D) ATP = ADP + Pi
Answer: B) Lt = L₀ + rt
45. In geometrical growth, the initial slow growth phase is called:
A) Log phase
B) Lag phase
C) Stationary phase
D) Maturation phase
Answer: B) Lag phase
46. The rapid growth phase in geometrical growth is called:
A) Lag phase
B) Linear phase
C) Log phase or exponential phase
D) Decline phase
Answer: C) Log phase or exponential phase
47. The S-shaped curve representing growth over time is known as:
A) Linear curve
B) Sigmoid curve
C) Exponential curve
D) Parabolic curve
Answer: B) Sigmoid curve
48. The formula for exponential growth is:
A) Lt = L₀ + rt
B) W₁ = W₀ × eʳᵗ
C) RQ = CO₂/O₂
D) ATP = ADP + Pi
Answer: B) W₁ = W₀ × eʳᵗ
49. The relative growth rate measures:
A) Absolute increase in size over time
B) How much a plant grows relative to its initial size
C) Total number of cells in a plant
D) Rate of photosynthesis
Answer: B) How much a plant grows relative to its initial size
50. Absolute growth rate is different from relative growth rate because it:
A) Measures growth relative to initial size
B) Measures total growth in a specific time
C) Measures photosynthetic efficiency
D) Measures number of meristematic cells
Answer: B) Measures total growth in a specific time
51. Which of the following is essential for cell enlargement in plants?
A) Oxygen
B) Light
C) Water
D) Carbon dioxide
Answer: C) Water
52. The turgidity of plant cells helps in:
A) Photosynthesis
B) Stretching and growth of plant parts
C) Respiration
D) Transport of oxygen
Answer: B) Stretching and growth of plant parts
53. Water is important for plant growth because it:
A) Serves as a medium for enzymes to work
B) Provides all energy for plants
C) Absorbs sunlight
D) Forms cell walls directly
Answer: A) Serves as a medium for enzymes to work
54. Oxygen is required by plants mainly to:
A) Support photosynthesis
B) Release metabolic energy essential for growth
C) Make cell walls
D) Increase turgor pressure
Answer: B) Release metabolic energy essential for growth
55. Plant nutrients are important for growth because they:
A) Help in making protoplasm and act as a source of energy
B) Only increase cell size
C) Provide water to cells
D) Make cells turgid
Answer: A) Help in making protoplasm and act as a source of energy
56. Macronutrients and micronutrients in plants:
A) Are only required in the early stage of growth
B) Are not essential for protoplasm formation
C) Play a vital role in growth and development
D) Can be replaced by water
Answer: C) Play a vital role in growth and development
57. Optimum temperature for plant growth refers to:
A) The temperature at which a plant dies
B) The temperature range where a plant grows best
C) Freezing point of water
D) Maximum sunlight exposure
Answer: B) The temperature range where a plant grows best
58. Environmental signals like light and gravity affect:
A) Only flowering in plants
B) Only germination of seeds
C) Different stages of growth in plants
D) Only root growth
Answer: C) Different stages of growth in plants
59. Turgor in plant cells is caused by:
A) Water entering the cell
B) Photosynthesis
C) Nutrient absorption
D) Oxygen release
Answer: A) Water entering the cell
60. The basic needs for plant growth include:
A) Water, oxygen, nutrients, temperature, light, and gravity
B) Only water and light
C) Only oxygen and nutrients
D) Only soil type and sunlight
Answer: A) Water, oxygen, nutrients, temperature, light, and gravity
61. The process by which cells become mature and specialized to perform specific functions is called:
A) Dedifferentiation
B) Differentiation
C) Redifferentiation
D) Mitosis
Answer: B) Differentiation
62. During differentiation, tracheary elements lose:
A) Their cell walls
B) Protoplasm completely
C) Lignin in secondary walls
D) Ability to transport water
Answer: B) Protoplasm completely
63. The strong, elastic secondary cell walls of tracheary elements are made of:
A) Cellulose only
B) Lignocellulose
C) Pectin
D) Starch
Answer: B) Lignocellulose
64. Dedifferentiation refers to:
A) Cells losing the ability to divide permanently
B) Mature cells regaining the ability to divide
C) Formation of tracheary elements
D) Apical meristem activity
Answer: B) Mature cells regaining the ability to divide
65. Redifferentiation is the process where:
A) Cells divide and become undifferentiated permanently
B) Cells lose their cell wall
C) Newly formed meristematic cells divide and then mature to perform specific functions
D) Root cells elongate only
Answer: C) Newly formed meristematic cells divide and then mature to perform specific functions
66. Interfascicular cambium or cork cambium is formed by:
A) Root apical meristem
B) Mature parenchyma cells through dedifferentiation
C) Shoot apical meristem only
D) Tracheary elements
Answer: B) Mature parenchyma cells through dedifferentiation
67. The structural changes in cells during differentiation include changes in:
A) Cell wall and protoplasm
B) Only cytoplasm
C) Only nucleus
D) Only cell membrane
Answer: A) Cell wall and protoplasm
68. Which of the following tissues is formed through redifferentiation in woody dicots?
A) Xylem and phloem from cambium
B) Epidermis only
C) Stomata
D) Pollen grains
Answer: A) Xylem and phloem from cambium
69. Differentiated cells that have lost the ability to divide can divide again under certain conditions. This demonstrates the property of:
A) Plasticity
B) Dedifferentiation
C) Apoptosis
D) Photosynthesis
Answer: B) Dedifferentiation
70. Lignocellulose in secondary walls helps tracheary elements to:
A) Transport nutrients
B) Transport water under high tension
C) Photosynthesize efficiently
D) Produce more protoplasm
Answer: B) Transport water under high tension
71. A tumour in plants is formed due to:
A) Normal cell division
B) Abnormal growth of cells
C) Differentiation of meristem
D) Photosynthesis
Answer: B) Abnormal growth of cells
72. In plant tissue culture, parenchyma cells that are made to divide in a lab are examples of:
A) Differentiated cells
B) Dedifferentiated cells
C) Redifferentiated cells
D) Tracheary elements
Answer: B) Dedifferentiated cells
73. Plant growth that can continue indefinitely is called:
A) Determinate growth
B) Indeterminate or open growth
C) Secondary growth only
D) Terminal growth
Answer: B) Indeterminate or open growth
74. Growth in plants that stops after reaching a certain point is called:
A) Indeterminate growth
B) Determinate growth
C) Secondary growth
D) Apical growth
Answer: B) Determinate growth
75. Differentiation in plants is considered “open” because:
A) Cells stop dividing after a few days
B) Meristems can produce different types of cells depending on the position
C) Only root cells can differentiate
D) Differentiation is temporary
Answer: B) Meristems can produce different types of cells depending on the position
76. The type of cell a parenchyma cell becomes in a plant organ depends on:
A) Its size
B) Its age
C) Its position in the plant
D) Nutrient availability only
Answer: C) Its position in the plant
77. Root cap cells are formed from cells that are located:
A) Near the outer edge of the root
B) Away from the root apical meristem
C) In the shoot apex
D) In the vascular cambium
Answer: B) Away from the root apical meristem
78. Epidermal cells of a root are formed from cells that are:
A) In the central cylinder of root
B) Pushed to the outer edge of the root
C) In the meristem only
D) Redifferentiated tracheary elements
Answer: B) Pushed to the outer edge of the root
79. The ability of meristem to produce different cell types depending on the part of the plant is an example of:
A) Closed differentiation
B) Open differentiation
C) Terminal differentiation
D) Dedifferentiation
Answer: B) Open differentiation
80. In plant tissue culture, dedifferentiated cells can also be called:
A) Tumour cells
B) Callus
C) Root cap cells
D) Tracheary elements
Answer: B) Callus
81. Development in plants refers to:
A) Only increase in size of plant organs
B) All changes that happen during the plant’s life cycle
C) Only formation of flowers and fruits
D) Only root growth
Answer: B) All changes that happen during the plant’s life cycle
82. Senescence in plants means:
A) Seed germination
B) Rapid growth phase
C) Final stage of life or aging
D) Differentiation of meristems
Answer: C) Final stage of life or aging
83. Plasticity in plants is the ability to:
A) Resist pathogens
B) Change form in response to environmental conditions
C) Produce flowers continuously
D) Grow only in one way
Answer: B) Change form in response to environmental conditions
84. Heterophylly refers to:
A) Formation of different types of roots
B) Change in leaf shape over time or in response to environment
C) Secondary growth in stems
D) Cell division in meristem
Answer: B) Change in leaf shape over time or in response to environment
85. A good example of heterophylly due to age is seen in:
A) Buttercup
B) Cotton, coriander, and larkspur
C) Rice and wheat
D) Mango and guava
Answer: B) Cotton, coriander, and larkspur
86. In buttercup, leaf shape changes due to:
A) Age only
B) Environmental conditions (air vs water)
C) Genetic mutation only
D) Apical meristem activity
Answer: B) Environmental conditions (air vs water)
87. The sequence of events in plant cell development begins with:
A) Differentiation
B) Plasmatic growth
C) Cell division
D) Maturation
Answer: C) Cell division
88. The developmental cycle of a plant cell ends with:
A) Differentiation
B) Elongation
C) Senescence or death
D) Division
Answer: C) Senescence or death
89. Growth, differentiation, and development in plants are:
A) Independent processes
B) Deeply connected and interdependent processes
C) Only controlled by environment
D) Only controlled by meristems
Answer: B) Deeply connected and interdependent processes
90. Factors that control plant development include:
A) Only light and temperature
B) Only genetic material
C) Both intrinsic (genetic and chemical) and extrinsic (environmental) factors
D) Only nutrients and water
Answer: C) Both intrinsic (genetic and chemical) and extrinsic (environmental) factors
91. Plant growth regulators (PGRs) are:
A) Large complex molecules only
B) Small molecules that regulate various plant processes
C) Only proteins
D) Only sugars
Answer: B) Small molecules that regulate various plant processes
92. Which of the following is an indole compound PGR?
A) Gibberellic acid (GA3)
B) Indole-3-acetic acid (IAA)
C) Abscisic acid (ABA)
D) Ethylene (C2H4)
Answer: B) Indole-3-acetic acid (IAA)
93. Kinetin (N6-furfurylamino purine) belongs to which chemical class of PGRs?
A) Terpenes
B) Adenine-based molecules
C) Carotenoid derivatives
D) Gases
Answer: B) Adenine-based molecules
94. Growth-promoting regulators help in all of the following EXCEPT:
A) Cell division
B) Flowering
C) Seed formation
D) Dormancy induction
Answer: D) Dormancy induction
95. Examples of plant growth promoters include:
A) Auxins, gibberellins, cytokinins
B) Abscisic acid, ethylene
C) Oxygen, water, nutrients
D) Stomata, lenticels
Answer: A) Auxins, gibberellins, cytokinins
91. Plant growth regulators (PGRs) are:
A) Large complex molecules only
B) Small molecules that regulate various plant processes
C) Only proteins
D) Only sugars
Answer: B) Small molecules that regulate various plant processes
92. Which of the following is an indole compound PGR?
A) Gibberellic acid (GA3)
B) Indole-3-acetic acid (IAA)
C) Abscisic acid (ABA)
D) Ethylene (C2H4)
Answer: B) Indole-3-acetic acid (IAA)
93. Kinetin (N6-furfurylamino purine) belongs to which chemical class of PGRs?
A) Terpenes
B) Adenine-based molecules
C) Carotenoid derivatives
D) Gases
Answer: B) Adenine-based molecules
94. Growth-promoting regulators help in all of the following EXCEPT:
A) Cell division
B) Flowering
C) Seed formation
D) Dormancy induction
Answer: D) Dormancy induction
95. Examples of plant growth promoters include:
A) Auxins, gibberellins, cytokinins
B) Abscisic acid, ethylene
C) Oxygen, water, nutrients
D) Stomata, lenticels
Answer: A) Auxins, gibberellins, cytokinins
96. Phototropism observed by Charles Darwin and Francis Darwin refers to:
A) Growth away from light
B) Growth towards light
C) Growth towards gravity
D) Random growth
Answer: B) Growth towards light
97. Which plant part was responsible for sending the signal for bending in phototropism?
A) Roots
B) Coleoptile tip
C) Leaf blade
D) Stem base
Answer: B) Coleoptile tip
98. The first plant growth hormone discovered from coleoptile tips is:
A) Gibberellin
B) Auxin
C) Cytokinin
D) Abscisic acid
Answer: B) Auxin
99. The abnormal growth in rice seedlings called ‘bakanae’ disease led to the discovery of:
A) Ethylene
B) Abscisic acid
C) Gibberellic acid (GA3)
D) Cytokinin
Answer: C) Gibberellic acid (GA3)
100. Kinetin, a type of cytokinin, was discovered by:
A) Charles Darwin
B) F.W. Went
C) Miller and colleagues
D) E. Kurosawa
Answer: C) Miller and colleagues
101. Which plant growth regulator was discovered as inhibitor-B, abscission II, and dormin?
A) Auxin
B) Gibberellin
C) Abscisic acid (ABA)
D) Cytokinin
Answer: C) Abscisic acid (ABA)
102. The main role of abscisic acid (ABA) in plants is:
A) Promote cell division
B) Stimulate stem elongation
C) Inhibit growth and induce dormancy
D) Promote fruit ripening
Answer: C) Inhibit growth and induce dormancy
103. Ethylene, a gaseous plant growth regulator, was first observed to:
A) Cause leaf senescence
B) Promote unripe bananas to ripen near ripe oranges
C) Stimulate root elongation
D) Induce flowering in canary grass
Answer: B) Promote unripe bananas to ripen near ripe oranges
104. Ethylene regulates which of the following processes in plants?
A) Flowering and fruit ripening
B) Senescence and abscission
C) Both A and B
D) Only seed germination
Answer: C) Both A and B
105. The five major categories of plant growth regulators (PGRs) are:
A) Auxins, Gibberellins, Cytokinins, Abscisic acid, Ethylene
B) Auxins, Cytokinins, Brassinosteroids, Jasmonates, Salicylic acid
C) Gibberellins, Ethylene, ABA, Auxins, Kinetin
D) Auxins, GA3, ABA, Ethylene, Cytokinins, Brassinosteroids
Answer: A) Auxins, Gibberellins, Cytokinins, Abscisic acid, Ethylene
106. The term ‘auxin’ is derived from the Greek word ‘auxein’ which means:
A) To divide
B) To grow
C) To differentiate
D) To elongate
Answer: B) To grow
107. Which is the main naturally occurring auxin in plants?
A) NAA
B) 2,4-D
C) Indole-3-acetic acid (IAA)
D) Indole butyric acid (IBA)
Answer: C) Indole-3-acetic acid (IAA)
108. Auxins are mainly produced in:
A) Leaves
B) Meristematic tissues at stem and root tips
C) Xylem
D) Lateral buds
Answer: B) Meristematic tissues at stem and root tips
109. Which of the following phenomena is controlled by auxins?
A) Apical dominance
B) Parthenocarpy
C) Root formation from stem cuttings
D) All of the above
Answer: D) All of the above
110. Removal of the apical bud of a plant results in:
A) Inhibition of lateral bud growth
B) Activation of lateral bud growth
C) Death of the plant
D) Formation of flowers immediately
Answer: B) Activation of lateral bud growth
111. Synthetic auxins like 2,4-D are mainly used as:
A) Fertilizers
B) Herbicides
C) Pesticides
D) Growth retardants
Answer: B) Herbicides
112. Parthenocarpy, induced by auxins, refers to:
A) Formation of seeds without fruit
B) Fruit formation without fertilization
C) Leaf drop
D) Root elongation
Answer: B) Fruit formation without fertilization
113. Gibberellins are mainly classified as:
A) Neutral compounds
B) Acidic plant hormones
C) Basic compounds
D) Gaseous plant hormones
Answer: B) Acidic plant hormones
114. Which gibberellin is the most well-known and studied?
A) GA1
B) GA2
C) GA3 (Gibberellic acid)
D) GA4
Answer: C) GA3 (Gibberellic acid)
115. One of the major effects of gibberellins on plants is:
A) Reducing stem length
B) Increasing stem length
C) Causing leaf abscission
D) Preventing root formation
Answer: B) Increasing stem length
116. Gibberellins help improve fruit size and shape in which fruit?
A) Apple
B) Banana
C) Mango
D) Orange
Answer: A) Apple
117. In addition to growth, gibberellins delay:
A) Germination
B) Senescence
C) Differentiation
D) Cell division
Answer: B) Senescence
118. In the brewing industry, GA3 is used to:
A) Make fruits bigger
B) Increase sugar content in sugarcane
C) Speed up malting process
D) Induce flowering
Answer: C) Speed up malting process
119. Spraying gibberellins on sugarcane mainly helps in:
A) Increasing root growth
B) Making stems longer to increase yield
C) Inducing dormancy
D) Producing more flowers
Answer: B) Making stems longer to increase yield
120. Bolting, the rapid stem growth before flowering, can be induced by gibberellins in:
A) Apple and grapes
B) Beet and cabbage
C) Sugarcane and rice
D) Wheat and maize
Answer: B) Beet and cabbage
121. Cytokinins mainly help in which process?
A) Photosynthesis
B) Cytokinesis (cell division)
C) Respiration
D) Transpiration
Answer: B) Cytokinesis (cell division)
122. The first cytokinin discovered was:
A) Zeatin
B) Gibberellic acid
C) Kinetin
D) Indole-3-acetic acid (IAA)
Answer: C) Kinetin
123. Kinetin was isolated from:
A) Coconut milk
B) Corn kernels
C) Autoclaved herring sperm DNA
D) Oat seedlings
Answer: C) Autoclaved herring sperm DNA
124. Which natural cytokinin was discovered in corn kernels and coconut milk?
A) IAA
B) Zeatin
C) GA3
D) ABA
Answer: B) Zeatin
125. Cytokinins are mainly synthesized in:
A) Mature leaves
B) Areas of active cell division like root tips and developing buds
C) Stems only
D) Fruits only
Answer: B) Areas of active cell division like root tips and developing buds
126. One of the roles of cytokinins is to promote the growth of:
A) Roots only
B) Side shoots and adventitious shoots
C) Flower petals
D) Secondary xylem
Answer: B) Side shoots and adventitious shoots
127. Cytokinins help delay aging (senescence) of leaves by:
A) Reducing photosynthesis
B) Mobilizing nutrients
C) Increasing abscission
D) Blocking auxins
Answer: B) Mobilizing nutrients
128. Cytokinins can reduce apical dominance by countering the effect of:
A) Gibberellins
B) Ethylene
C) Auxins
D) Abscisic acid
Answer: C) Auxins
129. Ethylene is classified as which type of plant hormone?
A) Auxin
B) Gibberellin
C) Gaseous hormone
D) Cytokinin
Answer: C) Gaseous hormone
130. Ethylene is produced in large amounts by:
A) Young leaves
B) Root tips
C) Aging tissues and ripening fruits
D) Shoot apical meristem
Answer: C) Aging tissues and ripening fruits
131. One of the roles of ethylene in seedlings is to form:
A) Lateral roots
B) Apical hook
C) Flower buds
D) Stomata
Answer: B) Apical hook
132. Ethylene promotes which of the following processes in plants?
A) Senescence and abscission
B) Photosynthesis only
C) Seed dormancy only
D) Water transport only
Answer: A) Senescence and abscission
133. Ethylene plays an important role in fruits by:
A) Reducing respiration
B) Increasing respiration (respiratory climactic)
C) Preventing ripening
D) Inhibiting sugar formation
Answer: B) Increasing respiration (respiratory climactic)
134. In agriculture, which compound is commonly used as a source of ethylene?
A) IAA
B) GA3
C) Ethephon
D) Cytokinin
Answer: C) Ethephon
135. Ethylene helps in deep-water rice plants by:
A) Increasing root length only
B) Promoting elongation of stems and leaf stalks to stay above water
C) Enhancing flower color
D) Producing more chlorophyll
Answer: B) Promoting elongation of stems and leaf stalks to stay above water
136. Ethylene can also break seed and bud dormancy and promote:
A) Leaf abscission only
B) Flower formation and synchronized fruit development
C) Only root hair formation
D) Photosynthesis
Answer: B) Flower formation and synchronized fruit development
137. Abscisic acid (ABA) primarily functions as:
A) Growth promoter
B) Growth inhibitor
C) Ethylene precursor
D) Cytokinin
Answer: B) Growth inhibitor
138. ABA plays a major role in:
A) Fruit ripening
B) Leaf fall (abscission) and dormancy
C) Flower formation
D) Stem elongation
Answer: B) Leaf fall (abscission) and dormancy
139. How does ABA help plants survive drought?
A) By promoting leaf expansion
B) By closing stomata
C) By increasing photosynthesis
D) By enhancing root branching
Answer: B) By closing stomata
140. In seeds, ABA is responsible for:
A) Rapid germination
B) Delaying germination and inducing dormancy
C) Producing auxins
D) Seed coat weakening
Answer: B) Delaying germination and inducing dormancy
141. ABA helps plants conserve energy under stress by:
A) Increasing growth rate
B) Slowing down plant metabolism
C) Promoting flowering
D) Enhancing photosynthesis
Answer: B) Slowing down plant metabolism
142. The relationship between ABA and gibberellins (GAs) is:
A) Both promote growth together
B) Both inhibit growth together
C) They act antagonistically; GAs promote growth, ABA inhibits it
D) They have no relation
Answer: C) They act antagonistically; GAs promote growth, ABA inhibits it
143. Which of the following controls every stage of a plant’s growth, development, and differentiation?
A) Only environmental factors
B) Only genes
C) Plant Growth Regulators (PGRs)
D) Soil nutrients
Answer: C) Plant Growth Regulators (PGRs)
144. When two PGRs enhance each other’s effects, it is called:
A) Antagonistic effect
B) Synergistic effect
C) Dormancy
D) Senescence
Answer: B) Synergistic effect
145. When PGRs oppose each other’s action, it is called:
A) Synergistic effect
B) Antagonistic effect
C) Apical dominance
D) Germination
Answer: B) Antagonistic effect
146. Events like seed dormancy, leaf fall (abscission), and apical dominance occur due to:
A) External factors only
B) Interaction of multiple PGRs
C) Nutrient availability
D) Photosynthesis
Answer: B) Interaction of multiple PGRs
147. Along with PGRs, what else influences plant growth?
A) Genomic control (genes) and environmental factors
B) Water only
C) Soil pH only
D) Leaf color
Answer: A) Genomic control (genes) and environmental factors
148. Growth in living organisms refers to:
A) Temporary increase in size
B) Permanent increase in size, area, length, height, volume, or cell number
C) Only increase in weight
D) Only increase in cell number
Answer: B) Permanent increase in size, area, length, height, volume, or cell number
149. The regions in plants where growth occurs are called:
A) Lateral buds
B) Meristems
C) Stomata
D) Leaf primordia
Answer: B) Meristems
150. Which meristem is responsible for increasing the length of the plant body?
A) Apical meristem
B) Lateral meristem
C) Cork cambium
D) Vascular cambium
Answer: A) Apical meristem
151. The type of growth in plants that continues indefinitely in large plants is called:
A) Determinate growth
B) Indeterminate growth
C) Temporary growth
D) Arithmetic growth
Answer: B) Indeterminate growth
152. When a differentiated plant cell goes back to its earlier state, it is called:
A) Redifferentiation
B) Dedifferentiation
C) Maturation
D) Plasticity
Answer: B) Dedifferentiation
153. The ability of plants to change their growth and development depending on environmental conditions is called:
A) Senescence
B) Plasticity
C) Apical dominance
D) Differentiation
Answer: B) Plasticity
154. Which of the following are the five main types of Plant Growth Regulators (PGRs)?
A) Auxins, Cytokinins, Gibberellins, Abscisic acid, Ethylene
B) Auxins, Gibberellins, Light, Oxygen, Ethylene
C) Cytokinins, Abscisic acid, Water, Light, Nutrients
D) Auxins, Gibberellins, Cytokinins, Carbon dioxide, Oxygen
Answer: A) Auxins, Cytokinins, Gibberellins, Abscisic acid, Ethylene
155. PGRs can influence plant processes in which of the following ways?
A) Only individually
B) Only synergistically
C) Only antagonistically
D) Individually, synergistically, or antagonistically
Answer: D) Individually, synergistically, or antagonistically
