Question 1: Plant growth is unique because plants retain the capacity for unlimited growth throughout their life. This ability is attributed to the presence of which of the following?
(a) Permanent tissues.
(b) Meristems at certain locations.
(c) Dedifferentiated tissues.
(d) Secondary xylem and phloem.
Answer: (b) Meristems at certain locations.
Question 2: In plants, the type of growth wherein new cells are always being added to the plant body by the continuous activity of the meristem is termed as?
(a) Determinate growth.
(b) Closed form of growth.
(c) Open form of growth.
(d) Intercalary growth.
Answer: (c) Open form of growth.
Question 3: Which of the following meristems is responsible for the secondary growth of the plant, increasing its girth?
(a) Apical meristem and intercalary meristem.
(b) Lateral meristems like vascular cambium and cork cambium.
(c) Primary meristem.
(d) Shoot apical meristem only.
Answer: (b) Lateral meristems like vascular cambium and cork cambium.
Question 4: At a cellular level, growth is principally a consequence of an increase in the amount of which of the following?
(a) Cell wall material.
(b) Protoplasm.
(c) Vacuolar sap.
(d) Intercellular spaces.
Answer: (b) Protoplasm.
Question 5: A single maize root apical meristem can give rise to more than how many new cells per hour?
(a) 17,500.
(b) 1,500.
(c) 3,50,000.
(d) 500.
Answer: (a) 17,500.
Question 6: While the growth of a pollen tube is measured in terms of its length, the growth in a dorsiventral leaf is mostly measured in terms of?
(a) Increase in cell number.
(b) Increase in surface area.
(c) Increase in fresh weight.
(d) Increase in volume.
Answer: (b) Increase in surface area.
Question 7: The period of growth is generally divided into three phases. Which of the following is NOT one of these phases?
(a) Meristematic.
(b) Elongation.
(c) Maturation.
(d) Dedifferentiation.
Answer: (d) Dedifferentiation.
Question 8: Cells in the meristematic phase of growth are characterized by all of the following EXCEPT?
(a) Rich in protoplasm.
(b) Possess large conspicuous nuclei.
(c) Cell walls are primary, thin, and cellulosic.
(d) Increased vacuolation.
Answer: (d) Increased vacuolation.
Question 9: The cells proximal to the meristematic zone represent the phase of elongation. Which of the following features is observed in these cells?
(a) Formation of secondary cell walls.
(b) Maximal size attainment in terms of wall thickening.
(c) Increased vacuolation and new cell wall deposition.
(d) Complete cessation of metabolic activities.
Answer: (c) Increased vacuolation and new cell wall deposition.
Question 10: In arithmetic growth, following mitotic cell division, what happens to the daughter cells?
(a) Both daughter cells continue to divide indefinitely.
(b) One daughter cell continues to divide while the other differentiates and matures.
(c) Both daughter cells differentiate and mature immediately.
(d) One daughter cell undergoes meiosis while the other undergoes mitosis.
Answer: (b) One daughter cell continues to divide while the other differentiates and matures.
Question 11: The mathematical expression for arithmetic growth is Lt = L0 + rt. What does 'r' represent in this equation?
(a) Growth rate or elongation per unit time.
(b) Relative growth rate.
(c) Base of natural logarithms.
(d) Time required for maximum growth.
Answer: (a) Growth rate or elongation per unit time.
Question 12: A graph plotted against time for arithmetic growth yields which type of curve?
(a) Sigmoid curve.
(b) Parabolic curve.
(c) Linear curve.
(d) Exponential curve.
Answer: (c) Linear curve.
Question 13: In geometrical growth, the initial growth is slow (lag phase), and it increases rapidly thereafter at an exponential rate. Which of the following is true for this phase?
(a) Only one progeny cell retains the ability to divide.
(b) Both progeny cells following mitotic cell division retain the ability to divide.
(c) The growth rate is constant and independent of the initial size.
(d) The cells lose their protoplasm rapidly.
Answer: (b) Both progeny cells following mitotic cell division retain the ability to divide.
Question 14: The typical growth curve for all cells, tissues, and organs of a plant grown in a natural environment is?
(a) Linear.
(b) Stair-step.
(c) Sigmoid.
(d) Bell-shaped.
Answer: (c) Sigmoid.
Question 15: In the exponential growth equation W1 = W0 e^rt, the parameter 'r' is known as?
(a) Absolute growth rate.
(b) Efficiency index or relative growth rate.
(c) Initial size of the organ.
(d) Natural logarithm base.
Answer: (b) Efficiency index or relative growth rate.
Question 16: Given two leaves, Leaf A (10 cm²) and Leaf B (50 cm²). Both grow by 5 cm² in one week. Which of the following statements is correct regarding their relative growth rates?
(a) Both have the same relative growth rate.
(b) Leaf A has a higher relative growth rate than Leaf B.
(c) Leaf B has a higher relative growth rate than Leaf A.
(d) Relative growth rate cannot be determined from the given data.
Answer: (b) Leaf A has a higher relative growth rate than Leaf B.
Question 17: Which of the following elements is required by plants for cell enlargement and maintaining the turgidity of cells?
(a) Oxygen.
(b) Water.
(c) Light.
(d) Carbon dioxide.
Answer: (b) Water.
Question 18: What is the primary role of oxygen in the process of plant growth?
(a) It maintains cell turgidity.
(b) It helps in releasing metabolic energy essential for growth activities.
(c) It acts as a structural component of the cell wall.
(d) It induces flowering in photoperiodic plants.
Answer: (b) It helps in releasing metabolic energy essential for growth activities.
Question 19: The process by which cells derived from root apical and shoot apical meristems mature to perform specific functions is known as?
(a) Dedifferentiation.
(b) Redifferentiation.
(c) Differentiation.
(d) Senescence.
Answer: (c) Differentiation.
Question 20: During the differentiation of a tracheary element, which of the following significant changes occurs in the cell?
(a) The cell gains a large central nucleus.
(b) The cell loses its protoplasm and develops a strong, elastic, lignocellulosic secondary cell wall.
(c) The cell develops chloroplasts for photosynthesis.
(d) The cell wall becomes thin and purely cellulosic.
Answer: (b) The cell loses its protoplasm and develops a strong, elastic, lignocellulosic secondary cell wall.
Question 21: Living differentiated plant cells, which have lost the capacity to divide, can regain the capacity of division under certain conditions. This phenomenon is termed?
(a) Differentiation.
(b) Redifferentiation.
(c) Dedifferentiation.
(d) Plasticity.
Answer: (c) Dedifferentiation.
Question 22: Which of the following is an example of a tissue formed by the process of dedifferentiation?
(a) Primary xylem.
(b) Interfascicular cambium and cork cambium.
(c) Epidermis.
(d) Root cap.
Answer: (b) Interfascicular cambium and cork cambium.
Question 23: When dedifferentiated cells divide and produce cells that once again lose the capacity to divide but mature to perform specific functions, the process is called?
(a) Plasticity.
(b) Differentiation.
(c) Dedifferentiation.
(d) Redifferentiation.
Answer: (d) Redifferentiation.
Question 24: Secondary xylem and secondary phloem are examples of tissues formed through which process?
(a) Primary differentiation.
(b) Dedifferentiation.
(c) Redifferentiation.
(d) Heterophylly.
Answer: (c) Redifferentiation.
Question 25: The term 'development' in plants encompasses which of the following?
(a) Only growth.
(b) Only differentiation.
(c) All changes that an organism goes through during its life cycle from germination of seed to senescence.
(d) Only the reproductive phase of the plant.
Answer: (c) All changes that an organism goes through during its life cycle from germination of seed to senescence.
Question 26: Plants follow different pathways in response to environment or phases of life to form different kinds of structures. This ability is called?
(a) Elasticity.
(b) Plasticity.
(c) Photoperiodism.
(d) Vernalisation.
Answer: (b) Plasticity.
Question 27: Heterophylly, a classic example of plasticity, is observed in the developmental stages of which plants?
(a) Cotton, coriander, and larkspur.
(b) Mango, apple, and banana.
(c) Wheat, rice, and maize.
(d) Tomato, potato, and brinjal.
Answer: (a) Cotton, coriander, and larkspur.
Question 28: In buttercup, heterophylly is an example of plasticity occurring in response to?
(a) Phases of life (juvenile vs adult).
(b) Environmental conditions (terrestrial vs aquatic habitat).
(c) Photoperiodic changes.
(d) Temperature variations.
Answer: (b) Environmental conditions (terrestrial vs aquatic habitat).
Question 29: Plant growth regulators (PGRs) are generally divided into two groups based on their functions. Which of the following PGRs belongs to the growth inhibitor group?
(a) Auxins.
(b) Gibberellins.
(c) Cytokinins.
(d) Abscisic acid.
Answer: (d) Abscisic acid.
Question 30: Ethylene is a unique plant growth regulator because it can fit into either the growth promoter or inhibitor group. However, it is largely considered as a?
(a) Growth promoter.
(b) Growth inhibitor.
(c) Rooting hormone only.
(d) Flowering hormone only.
Answer: (b) Growth inhibitor.
Question 31: Who observed that the coleoptiles of canary grass responded to unilateral illumination by growing towards the light source (phototropism)?
(a) F.W. Went.
(b) Charles Darwin and his son Francis Darwin.
(c) E. Kurosawa.
(d) F. Skoog and Carlos O. Miller.
Answer: (b) Charles Darwin and his son Francis Darwin.
Question 32: Auxin was isolated for the first time from the tips of coleoptiles of oat seedlings by which scientist?
(a) Charles Darwin.
(b) F.W. Went.
(c) H.H. Cousins.
(d) E. Kurosawa.
Answer: (b) F.W. Went.
Question 33: The 'bakane' (foolish seedling) disease of rice seedlings was caused by a fungal pathogen named?
(a) Phytophthora infestans.
(b) Gibberella fujikuroi.
(c) Puccinia graminis.
(d) Ustilago tritici.
Answer: (b) Gibberella fujikuroi.
Question 34: The active substances causing the 'bakane' disease in rice seedlings were later identified as?
(a) Indole-3-acetic acid.
(b) Gibberellic acid.
(c) Kinetin.
(d) Abscisic acid.
Answer: (b) Gibberellic acid.
Question 35: F. Skoog and his co-workers observed that from the internodal segments of tobacco stems, the callus proliferated only if the nutrient medium was supplemented with extracts of vascular tissues, yeast extract, coconut milk, or DNA, in addition to which PGR?
(a) Auxins.
(b) Gibberellins.
(c) Ethylene.
(d) Abscisic acid.
Answer: (a) Auxins.
Question 36: Skoog and Miller crystallized the cytokinesis-promoting active substance from autoclaved herring sperm DNA and termed it as?
(a) Zeatin.
(b) Kinetin.
(c) IAA.
(d) Ethylene.
Answer: (b) Kinetin.
Question 37: During the mid-1960s, three independent researches reported the purification and chemical characterization of three different kinds of inhibitors. Which of the following was NOT one of them?
(a) Inhibitor-B.
(b) Abscission II.
(c) Dormin.
(d) Kinetin.
Answer: (d) Kinetin.
Question 38: Who confirmed the release of a volatile substance from ripened oranges that hastened the ripening of stored unripened bananas?
(a) F.W. Went.
(b) E. Kurosawa.
(c) H.H. Cousins.
(d) Charles Darwin.
Answer: (c) H.H. Cousins.
Question 39: The term 'Auxin' is applied to indole-3-acetic acid (IAA) and other natural and synthetic compounds having certain growth-regulating properties. They are generally produced by?
(a) Mature leaves only.
(b) Growing apices of stems and roots.
(c) Maturing fruits.
(d) Senescent tissues.
Answer: (b) Growing apices of stems and roots.
Question 40: Which of the following is an example of a synthetic auxin widely used in agriculture?
(a) Indole-3-acetic acid (IAA).
(b) Indole butyric acid (IBA).
(c) Naphthalene acetic acid (NAA) and 2,4-D.
(d) Gibberellic acid (GA3).
Answer: (c) Naphthalene acetic acid (NAA) and 2,4-D.
Question 41: The phenomenon where the growing apical bud inhibits the growth of lateral (axillary) buds is known as?
(a) Parthenocarpy.
(b) Apical dominance.
(c) Dedifferentiation.
(d) Phototropism.
Answer: (b) Apical dominance.
Question 42: Decapitation (removal of shoot tips) usually results in the growth of lateral buds. This technique is widely applied in?
(a) Enhancing fruit ripening.
(b) Tea plantations and hedge-making.
(c) Preventing premature leaf fall.
(d) Breaking seed dormancy.
Answer: (b) Tea plantations and hedge-making.
Question 43: Auxins are commonly used to induce parthenocarpy in which of the following plants?
(a) Apples.
(b) Grapes.
(c) Tomatoes.
(d) Pineapples.
Answer: (c) Tomatoes.
Question 44: Which synthetic auxin is widely used as an herbicide to kill dicotyledonous weeds but does not affect mature monocotyledonous plants?
(a) IAA.
(b) IBA.
(c) NAA.
(d) 2,4-D (2,4-dichlorophenoxyacetic acid).
Answer: (d) 2,4-D (2,4-dichlorophenoxyacetic acid).
Question 45: Auxins also control xylem differentiation and help in?
(a) Opening of stomata.
(b) Cell division.
(c) Overcoming apical dominance.
(d) Hastening fruit ripening.
Answer: (b) Cell division.
Question 46: There are more than 100 gibberellins reported from widely different organisms. Which gibberellin was one of the first to be discovered and remains the most intensively studied form?
(a) GA1.
(b) GA2.
(c) GA3.
(d) GA4.
Answer: (c) GA3.
Question 47: Gibberellins have the ability to cause an increase in length of the axis. This property is used to increase the length of?
(a) Apple fruits.
(b) Tomato fruits.
(c) Grapes stalks.
(d) Pineapples.
Answer: (c) Grapes stalks.
Question 48: Which plant growth regulator is used to speed up the malting process in the brewing industry?
(a) Auxin.
(b) Gibberellic acid (GA3).
(c) Kinetin.
(d) Ethylene.
Answer: (b) Gibberellic acid (GA3).
Question 49: Spraying sugarcane crop with gibberellins increases the length of the stem. This can lead to an increase in yield by as much as?
(a) 5 tonnes per acre.
(b) 10 tonnes per acre.
(c) 20 tonnes per acre.
(d) 50 tonnes per acre.
Answer: (c) 20 tonnes per acre.
Question 50: Gibberellins promote bolting (internode elongation just prior to flowering) in rosette plants. Which of the following plants is an example?
(a) Cabbage and beet.
(b) Cotton and mustard.
(c) Wheat and maize.
(d) Sunflower and marigold.
Answer: (a) Cabbage and beet.
Question 51: Kinetin, the first discovered cytokinin, does not occur naturally in plants. Natural cytokinins, like zeatin, were later isolated from which sources?
(a) Coconut milk and apple juice.
(b) Corn-kernels and coconut milk.
(c) Autoclaved herring sperm DNA.
(d) Fungal extracts.
Answer: (b) Corn-kernels and coconut milk.
Question 52: Cytokinins are synthesized primarily in regions where rapid cell division occurs. Which of the following is NOT a typical site of cytokinin synthesis?
(a) Root apices.
(b) Developing shoot buds.
(c) Young fruits.
(d) Mature, senescing leaves.
Answer: (d) Mature, senescing leaves.
Question 53: Which combination of plant growth regulators is highly effective in helping plants overcome apical dominance?
(a) Auxins and Gibberellins.
(b) Cytokinins and Auxins (by antagonizing the auxin effect).
(c) Ethylene and Abscisic acid.
(d) Gibberellins and Abscisic acid.
Answer: (b) Cytokinins and Auxins (by antagonizing the auxin effect).
Question 54: Cytokinins help delay leaf senescence. This effect is primarily due to their role in?
(a) Promoting the degradation of chlorophyll.
(b) Promoting nutrient mobilization.
(c) Increasing the rate of respiration.
(d) Closing the stomata.
Answer: (b) Promoting nutrient mobilization.
Question 55: Ethylene is a simple gaseous plant growth regulator. It is synthesized in large amounts by tissues undergoing?
(a) Rapid cell division.
(b) Seed germination.
(c) Senescence and ripening of fruits.
(d) Primary growth of roots.
Answer: (c) Senescence and ripening of fruits.
Question 56: The influence of ethylene on plants includes horizontal growth of seedlings, swelling of the axis, and the formation of which structure in dicot seedlings?
(a) Apical hook.
(b) Root nodules.
(c) Tendrils.
(d) Spines.
Answer: (a) Apical hook.
Question 57: The sharp rise in the respiration rate of fruits during ripening, a process highly promoted by ethylene, is called?
(a) Respiratory climax.
(b) Respiratory climactic.
(c) Respiratory climacteric.
(d) Respiratory quotient.
Answer: (c) Respiratory climacteric.
Question 58: Ethylene breaks seed and bud dormancy and initiates germination in which of the following?
(a) Peanut seeds and potato tubers.
(b) Wheat seeds and maize grains.
(c) Apple seeds and peach buds.
(d) Cotton seeds and tomato fruits.
Answer: (a) Peanut seeds and potato tubers.
Question 59: Which plant growth regulator promotes rapid internode/petiole elongation in deep water rice plants, helping their leaves/upper parts to remain above water?
(a) Gibberellic acid.
(b) Auxin.
(c) Cytokinin.
(d) Ethylene.
Answer: (d) Ethylene.
Question 60: Ethylene is widely used in agriculture because of its beneficial effects. Which of the following is the most widely used source of ethylene?
(a) Indole acetic acid.
(b) Ethephon.
(c) Zeatin.
(d) Kinetin.
Answer: (b) Ethephon.
Question 61: Ethephon, in an aqueous solution, is readily absorbed and transported within the plant and releases ethylene slowly. It hastens fruit ripening specifically in which fruits?
(a) Bananas and oranges.
(b) Tomatoes and apples.
(c) Grapes and watermelons.
(d) Pineapples and mangoes.
Answer: (b) Tomatoes and apples.
Question 62: Which PGR is known to accelerate abscission in flowers and fruits (e.g., thinning of cotton, cherry, walnut)?
(a) Auxin.
(b) Gibberellin.
(c) Ethephon (Ethylene).
(d) Abscisic acid.
Answer: (c) Ethephon (Ethylene).
Question 63: Abscisic acid (ABA) acts primarily as an inhibitor of plant growth and metabolism. It is well known for inhibiting which process?
(a) Cell division in the apical meristem.
(b) Seed germination.
(c) Fruit ripening.
(d) Leaf senescence.
Answer: (b) Seed germination.
Question 64: During times of severe water stress, ABA stimulates which physiological response to prevent water loss?
(a) Rapid root growth.
(b) Increased transpiration.
(c) Closure of stomata.
(d) Wilting of stems.
Answer: (c) Closure of stomata.
Question 65: Because ABA increases the tolerance of plants to various kinds of stresses, it is often referred to as the?
(a) Senescence hormone.
(b) Stress hormone.
(c) Dormancy hormone.
(d) Climacteric hormone.
Answer: (b) Stress hormone.
Question 66: In the context of seed development, maturation, and dormancy, ABA acts as an antagonist to which plant growth regulator?
(a) Auxins.
(b) Cytokinins.
(c) Gibberellins.
(d) Ethylene.
Answer: (c) Gibberellins.
Question 67: The phenomenon where some plants require a specific duration of light and dark periods to induce flowering is termed?
(a) Vernalisation.
(b) Photoperiodism.
(c) Phototropism.
(d) Etiolation.
Answer: (b) Photoperiodism.
Question 68: Plants that require exposure to light for a period exceeding a well-defined critical duration for flowering are called?
(a) Short day plants.
(b) Long day plants.
(c) Day-neutral plants.
(d) Facultative short day plants.
Answer: (b) Long day plants.
Question 69: In short day plants, flowering is induced when they are exposed to light for a period that is?
(a) Exactly equal to the critical duration.
(b) More than the critical duration.
(c) Less than the critical duration.
(d) Regardless of the duration.
Answer: (c) Less than the critical duration.
Question 70: Which group of plants do not show any correlation between exposure to light duration and the induction of flowering response?
(a) Long day plants.
(b) Short day plants.
(c) Day-neutral plants.
(d) Night-neutral plants.
Answer: (c) Day-neutral plants.
Question 71: For plants requiring specific photoperiods, which of the following is equally important as the duration of light?
(a) The intensity of light.
(b) The duration of the dark period.
(c) The quality (wavelength) of light only.
(d) The ambient temperature during the light period.
Answer: (b) The duration of the dark period.
Question 72: The site of perception of light/dark duration for the photoperiodic response in plants is the?
(a) Shoot apex.
(b) Floral meristem.
(c) Leaves.
(d) Roots.
Answer: (c) Leaves.
Question 73: It has been hypothesized that a hormonal substance migrates from the site of light perception to the shoot apices to induce flowering. This migration occurs only under?
(a) High temperature conditions.
(b) Inductive photoperiodic conditions.
(c) Conditions of water stress.
(d) Presence of gibberellins.
Answer: (b) Inductive photoperiodic conditions.
Question 74: The dependence of flowering on prior exposure to low temperatures in some plants is known as?
(a) Stratification.
(b) Photoperiodism.
(c) Vernalisation.
(d) Wintering.
Answer: (c) Vernalisation.
Question 75: Vernalisation prevents precocious reproductive development late in the growing season and ensures that the plant has sufficient time to reach maturity. It specifically refers to the promotion of flowering by a period of?
(a) High temperature.
(b) Low temperature.
(c) Alternating high and low temperatures.
(d) Continuous light.
Answer: (b) Low temperature.
Question 76: Some important food plants like wheat, barley, and rye have two kinds of varieties: winter and spring. The 'winter' varieties are planted in autumn because?
(a) They cannot survive the summer heat.
(b) They need the cold winter months to undergo vernalisation and flower in spring.
(c) They grow faster in the dark.
(d) They are day-neutral plants.
Answer: (b) They need the cold winter months to undergo vernalisation and flower in spring.
Question 77: Biennial plants are monocarpic plants that normally flower and die in their second season. Which of the following is a classic example of a biennial plant that responds to vernalisation?
(a) Tomato.
(b) Sugarbeet.
(c) Rice.
(d) Maize.
Answer: (b) Sugarbeet.
Question 78: Statement I: In geometric growth, both daughter cells retain the ability to divide and continue to do so. Statement II: The growth curve in geometric growth is typically linear. Choose the correct option.
(a) Both Statement I and Statement II are correct.
(b) Both Statement I and Statement II are incorrect.
(c) Statement I is correct but Statement II is incorrect.
(d) Statement I is incorrect but Statement II is correct.
Answer: (c) Statement I is correct but Statement II is incorrect.
Question 79: Assertion (A): Plant growth is open and continuous throughout its life. Reason (R): Plants possess meristems at specific locations which constantly add new cells. Choose the correct option.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Answer: (a) Both A and R are true and R is the correct explanation of A.
Question 80: Which of the following PGRs is chemically derived from terpenes?
(a) Indole-3-acetic acid.
(b) Gibberellic acid.
(c) Kinetin.
(d) Ethylene.
Answer: (b) Gibberellic acid.
Question 81: Kinetin, an adenine derivative, belongs to the class of plant growth regulators known as?
(a) Indoles.
(b) Terpenes.
(c) Purines.
(d) Carotenoids.
Answer: (c) Purines.
Question 82: Abscisic acid (ABA) is a derivative of which of the following compounds?
(a) Adenine.
(b) Indole compounds.
(c) Carotenoids.
(d) Terpenes.
Answer: (c) Carotenoids.
Question 83: Assertion (A): 2,4-D is extensively used to prepare weed-free lawns by gardeners. Reason (R): 2,4-D selectively kills mature monocotyledonous plants while sparing dicotyledons. Choose the correct option.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Answer: (c) A is true but R is false.
Question 84: Match List I with List II. List I: 1. Auxin, 2. Gibberellin, 3. Cytokinin, 4. Ethylene. List II: A. Bolting, B. Root hair formation, C. Apical dominance, D. Delay of senescence. Choose the correct match.
(a) 1-C, 2-A, 3-D, 4-B.
(b) 1-A, 2-C, 3-B, 4-D.
(c) 1-C, 2-A, 3-B, 4-D.
(d) 1-D, 2-B, 3-C, 4-A.
Answer: (a) 1-C, 2-A, 3-D, 4-B.
Question 85: Which plant growth regulator promotes female flowers in cucumbers, thereby increasing the yield?
(a) Gibberellin.
(b) Auxin.
(c) Ethylene.
(d) Cytokinin.
Answer: (c) Ethylene.
Question 86: Statement I: Dormancy is a state where seeds fail to germinate even when external environmental conditions are favorable. Statement II: ABA plays a primary role in inducing seed dormancy. Choose the correct option.
(a) Both Statement I and Statement II are correct.
(b) Both Statement I and Statement II are incorrect.
(c) Statement I is correct but Statement II is incorrect.
(d) Statement I is incorrect but Statement II is correct.
Answer: (a) Both Statement I and Statement II are correct.
Question 87: Growth is measured by various parameters. Which parameter is considered the most appropriate measure for the growth of a single cell like an egg or pollen grain?
(a) Increase in fresh weight.
(b) Increase in volume.
(c) Increase in length.
(d) Increase in cell number.
Answer: (b) Increase in volume.
Question 88: In the context of differentiation, the formation of a tracheary element involves the loss of protoplasm and the development of strong lignocellulosic cell walls. This helps the cell to withstand?
(a) Extremely low temperatures during winter.
(b) Attack from herbivorous animals.
(c) Extreme tension even under strong water columns.
(d) Direct exposure to high-intensity sunlight.
Answer: (c) Extreme tension even under strong water columns.
Question 89: Assertion (A): The growth curve for most biological systems is a sigmoid curve. Reason (R): Growth is initially slow, then rapid, and eventually slows down due to limited nutrient supply. Choose the correct option.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Answer: (a) Both A and R are true and R is the correct explanation of A.
Question 90: Which plant growth regulator initiates rooting in stem cuttings, an application widely used for plant propagation?
(a) Ethylene.
(b) Gibberellins.
(c) Auxins.
(d) Abscisic acid.
Answer: (c) Auxins.
Question 91: The 'Richmond-Lang effect', characterized by the delay of leaf senescence, is a physiological effect classically attributed to which PGR?
(a) Auxin.
(b) Gibberellic acid.
(c) Cytokinin.
(d) Ethylene.
Answer: (c) Cytokinin.
Question 92: Which plant growth regulator induces the development of adventitious shoot buds when applied to a tissue culture medium with a low concentration of auxin?
(a) Cytokinin.
(b) Gibberellin.
(c) Abscisic acid.
(d) Ethylene.
Answer: (a) Cytokinin.
Question 93: Ethephon promotes abscission of flowers and fruits. In which of the following crop plants is it commercially used to thin fruits?
(a) Mango and papaya.
(b) Cotton, cherry, and walnut.
(c) Wheat and rice.
(d) Sugarcane and beet.
Answer: (b) Cotton, cherry, and walnut.
Question 94: Pineapples are notoriously difficult to bring to flower synchronously. Which plant growth regulators are applied to promote synchronized flowering in pineapples?
(a) Auxin and Ethylene.
(b) Cytokinin and Gibberellin.
(c) ABA and Auxin.
(d) Ethylene and ABA.
Answer: (a) Auxin and Ethylene.
Question 95: Statement I: Shoot apices themselves do not perceive the photoperiodic stimulus. Statement II: The leaves perceive the stimulus and transmit a signal to the shoot apices. Choose the correct option.
(a) Both Statement I and Statement II are correct.
(b) Both Statement I and Statement II are incorrect.
(c) Statement I is correct but Statement II is incorrect.
(d) Statement I is incorrect but Statement II is correct.
Answer: (a) Both Statement I and Statement II are correct.
Question 96: What term is used for the period of cold treatment required by some plants to flower, which prevents them from flowering in the very season they are planted?
(a) Stratification.
(b) Vernalisation.
(c) Etiolation.
(d) Photoperiodism.
Answer: (b) Vernalisation.
Question 97: Assertion (A): Certain seeds fail to germinate even when external conditions are optimal. Reason (R): The seeds may possess hard, impermeable seed coats or chemical inhibitors like abscisic acid. Choose the correct option.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Answer: (a) Both A and R are true and R is the correct explanation of A.
Question 98: In the typical sigmoid growth curve, what is the phase characterized by the slowing down of the growth rate eventually leading to zero growth?
(a) Lag phase.
(b) Log phase.
(c) Exponential phase.
(d) Stationary phase.
Answer: (d) Stationary phase.
Question 99: Which of the following is true concerning the role of gravity in plant growth?
(a) Gravity is irrelevant to plant development.
(b) Only the shoot system responds to gravity.
(c) Gravity determines the directional growth of root and shoot systems.
(d) Gravity only affects the movement of water within the xylem.
Answer: (c) Gravity determines the directional growth of root and shoot systems.
Question 100: Statement I: Development is considered as the sum of growth and differentiation. Statement II: In higher plants, development is strictly controlled by intrinsic factors only, without environmental influence. Choose the correct option.
(a) Both Statement I and Statement II are correct.
(b) Both Statement I and Statement II are incorrect.
(c) Statement I is correct but Statement II is incorrect.
(d) Statement I is incorrect but Statement II is correct.
Answer: (c) Statement I is correct but Statement II is incorrect.
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