Evaluate the physiological impact of Ethylene during fruit ripening:
(i) Ethylene is highly effective in fruit ripening. (ii) It enhances the respiration rate during fruit ripening. (iii) The sharp rise in respiration rate during fruit ripening is called respiratory climactic. (iv) Respiratory climactic reduces ethylene biosynthesis in fruit tissues.
Statements (i), (ii), and (iii) accurately describe fruit ripening and respiratory climactic. Statement (iv) is incorrect because respiratory climactic accompanies rapid fruit ripening induced by ethylene.
Question 72 of 100
📘 CLASS XI
Examine the role of Ethylene in deep water rice plants:
(i) Ethylene promotes rapid internode/petiole elongation in deep water rice plants. (ii) Rapid elongation helps leaves and upper shoot parts to remain above water. (iii) Ethylene submerges the shoot apex under water to induce dormancy. (iv) Internode elongation in deep water rice is inhibited by ethylene.
Statements (i) and (ii) are correct because ethylene promotes internode/petiole elongation, keeping rice shoot parts above water. Statements (iii) and (iv) are incorrect.
Question 73 of 100
📘 CLASS XI
Regarding the effects of Ethylene on roots and root hairs, consider:
(i) Ethylene promotes root growth. (ii) Ethylene promotes root hair formation. (iii) Root hair formation increases the water and nutrient absorption surface. (iv) Ethylene prevents root hair differentiation to conserve energy.
Statements (i), (ii), and (iii) are correct because ethylene promotes root growth and root hair formation, increasing absorption surface. Statement (iv) is incorrect.
Question 74 of 100
📘 CLASS XI
Analyze the practical applications of Ethephon in horticulture:
(i) Ethephon releases ethylene slowly in aqueous solution within plants. (ii) Ethephon hastens fruit ripening in tomatoes and apples. (iii) Ethephon accelerates thinning (fruit drop) in cotton, cherry, and walnut. (iv) Ethephon promotes female flowers in cucumbers, increasing yield.
All four statements (i), (ii), (iii), and (iv) are true statements detailing ethephon slow ethylene release, fruit ripening, thinning, and female flower induction in cucumber.
Question 75 of 100
📘 CLASS XI
Consider the multiple physiological roles of Abscisic Acid (ABA):
(i) Acts as a general plant growth inhibitor and inhibitor of plant metabolism. (ii) Inhibits seed germination. (iii) Stimulates stomatal closure under stress conditions. (iv) Induces seed dormancy to withstand desiccation and unfavourable conditions.
All four statements (i), (ii), (iii), and (iv) are correct regarding ABA growth inhibition, germination inhibition, stomatal closure, and seed dormancy/desiccation resistance.
Question 76 of 100
📘 CLASS XI
Examine the antagonistic relationship between Abscisic Acid (ABA) and Gibberellins (GAs):
(i) In seed germination, GAs promote germination while ABA inhibits germination. (ii) ABA induces seed dormancy, whereas GAs break seed dormancy. (iii) In most plant growth situations, ABA acts as an antagonist to GAs. (iv) ABA and GAs act synergistically to promote rapid stomatal opening.
Statements (i), (ii), and (iii) are correct because ABA and GA act as classic antagonists regarding seed dormancy and germination. Statement (iv) is incorrect because ABA stimulates stomatal closure, not opening.
Question 77 of 100
📘 CLASS XI
Regarding the interaction of multiple PGRs in controlling specific developmental events, evaluate:
(i) Seed and bud dormancy involves interaction between ABA, ethylene, and GAs. (ii) Apical dominance involves interaction between auxins and cytokinins. (iii) Leaf abscission involves interaction between auxins, ethylene, and ABA. (iv) Every developmental event in plants is regulated by exactly one isolated PGR acting independently.
Statements (i), (ii), and (iii) are correct because events like dormancy, apical dominance, and abscission involve multiple PGR interactions. Statement (iv) is incorrect because PGRs act synergistically, complementarily, or antagonistically in combination.
Question 78 of 100
📘 CLASS XI
Examine the role of extrinsic environmental factors in regulating plant growth via PGRs:
(i) Light and temperature control plant developmental events via PGRs. (ii) Vernalisation is a temperature-dependent developmental response. (iii) Flowering in many plants is controlled by photoperiodic light exposure. (iv) Photoperiodic and vernalisation signals bypass PGRs and act purely mechanically.
Statements (i), (ii), and (iii) are correct because light and temperature influence vernalisation, flowering, and dormancy via PGR pathways. Statement (iv) is incorrect because environmental signals control growth via PGRs.
Question 79 of 100
📘 CLASS XI
Which of the following statements regarding the summary of plant development are true?
(i) Growth is an irreversible increase expressed in parameters like size, area, length, height, volume, and cell number. (ii) Growth conspicuously involves increased protoplasmic material. (iii) Meristems are the primary sites of growth in plants. (iv) Plant growth is strictly determinate in all plant organs throughout the life cycle.
Statements (i), (ii), and (iii) are correct summary points. Statement (iv) is incorrect because plant growth is indeterminate in higher plants due to meristems.
Question 80 of 100
📘 CLASS XI
Consider the open nature of differentiation and flexible development in plants:
(i) Both growth and differentiation in higher plants are open. (ii) Cells arising out of the same meristem can form different mature structures based on position. (iii) Development is flexible because differentiation is open. (iv) Plant cells possess fixed non-plastic fates that cannot be modified by environment.
Statements (i), (ii), and (iii) are correct summary points regarding open growth, open differentiation, position-dependent cell structure, and flexible development. Statement (iv) is incorrect because plants exhibit plasticity.
