Examine the role of Auxins in fruit and leaf abscission:
(i) Auxins prevent fruit and leaf drop at early stages. (ii) Auxins promote abscission of older mature leaves and fruits. (iii) Synthetic auxin 2,4-D accelerates premature drop of young fruits. (iv) Premature abscission of young leaves is stimulated by high endogenous auxin levels.
Statements (i) and (ii) are correct because auxins prevent early drop but promote abscission of older mature organs. Statements (iii) and (iv) are incorrect because auxins prevent early fruit and leaf drop.
Question 62 of 100
📘 CLASS XI
Consider the practical application of Auxins in hedge-making and tea plantations:
(i) Apical bud inhibits growth of lateral buds due to apical dominance. (ii) Decapitation removes apical bud, allowing lateral buds to grow into branches. (iii) Dense branching in tea plantations and hedges is achieved by periodic decapitation. (iv) Decapitation reinforces apical dominance and completely stops lateral branching.
Statements (i), (ii), and (iii) are correct because removing the shoot tip breaks apical dominance, promoting lateral branching in hedges and tea bushes. Statement (iv) is incorrect because decapitation relieves apical dominance.
Question 63 of 100
📘 CLASS XI
Evaluate the effect of 2,4-D on monocotyledonous vs dicotyledonous plants:
(i) 2,4-D is a synthetic auxin widely used as a weedicide. (ii) 2,4-D selectively kills dicotyledonous weeds. (iii) Mature monocotyledonous plants are unaffected by 2,4-D. (iv) 2,4-D is used by gardeners to prepare weed-free lawns.
All four statements (i), (ii), (iii), and (iv) are correct regarding 2,4-D synthetic auxin herbicide selectivity for dicot weeds while sparing monocot lawn grasses.
Question 64 of 100
📘 CLASS XI
Examine the effects of Gibberellins on fruit size, shape, and market period:
(i) Gibberellins increase length of grape stalks. (ii) Gibberellins cause fruits like apples to elongate and improve shape. (iii) Gibberellins delay senescence, extending the market period for fruits. (iv) Gibberellins cause rapid softening and early decay of harvested fruits.
Statements (i), (ii), and (iii) are correct because gibberellins elongate grape stalks, improve apple shape, and delay senescence. Statement (iv) is incorrect because gibberellins delay senescence, extending market period.
Question 65 of 100
📘 CLASS XI
Consider the commercial uses of Gibberellic acid (GA3) in brewing and sugarcane industries:
(i) GA3 speeds up the malting process in the brewing industry. (ii) Spraying sugarcane with gibberellins increases stem length. (iii) Sugarcane yield is increased by as much as 20 tonnes per acre upon GA treatment. (iv) GA3 degrades sucrose in sugarcane stems, severely reducing sugar yield.
Statements (i), (ii), and (iii) are correct regarding brewing malting and sugarcane yield enhancement (up to 20 tonnes per acre). Statement (iv) is incorrect because gibberellins increase stem length where carbohydrates are stored, increasing yield.
Question 66 of 100
📘 CLASS XI
Analyze the effect of Gibberellins on juvenile conifers and rosette plants:
(i) Spraying juvenile conifers with GAs hastens maturity period. (ii) GA treatment leads to early seed production in juvenile conifers. (iii) GAs promote bolting (internode elongation prior to flowering) in beet and cabbages. (iv) Rosette habit plants respond to GAs by complete inhibition of stem elongation.
Statements (i), (ii), and (iii) are correct regarding juvenile conifer maturity, early seed production, and bolting in beet and cabbage. Statement (iv) is incorrect because gibberellins promote internode elongation in rosette plants.
Question 67 of 100
📘 CLASS XI
Regarding the natural occurrence and discovery of Cytokinins, analyze these statements:
(i) Kinetin was discovered from autoclaved herring sperm DNA. (ii) Kinetin is a natural plant hormone found in root tips. (iii) Zeatin was isolated from corn-kernels and coconut milk. (iv) Zeatin is a naturally occurring cytokinin.
Statements (i), (iii), and (iv) are correct because kinetin was discovered from autoclaved herring sperm DNA and zeatin is a naturally occurring cytokinin isolated from corn-kernels and coconut milk. Statement (ii) is incorrect because kinetin does not occur naturally in plants.
Question 68 of 100
📘 CLASS XI
Which of the following cellular processes are promoted by Cytokinins?
(i) Production of new leaves and chloroplasts in leaves. (ii) Lateral shoot growth and adventitious shoot formation. (iii) Overcoming apical dominance. (iv) Rapid leaf abscission and chlorosis.
Statements (i), (ii), and (iii) are correct regarding leaf/chloroplast production, lateral shoot growth, and overcoming apical dominance. Statement (iv) is incorrect because cytokinins delay leaf senescence.
Question 69 of 100
📘 CLASS XI
Examine the role of Cytokinins in delaying leaf senescence:
(i) Cytokinins promote nutrient mobilization in plant tissues. (ii) Nutrient mobilization helps in the delay of leaf senescence. (iii) Richmond-Lang effect refers to delay of leaf senescence by cytokinins. (iv) Cytokinins accelerate chlorophyll degradation in detached leaves.
Statements (i), (ii), and (iii) are correct regarding nutrient mobilization and delay of senescence. Statement (iv) is incorrect because cytokinins preserve chlorophyll and delay senescence.
Question 70 of 100
📘 CLASS XI
Consider the triple response of dicot seedlings to Ethylene:
(i) Horizontal growth of seedlings. (ii) Swelling of the axis. (iii) Apical hook formation in dicot seedlings. (iv) Excessive vertical elongation of shoot axis.
Statements (i), (ii), and (iii) form the classic triple response of dicot seedlings to ethylene. Statement (iv) is incorrect because ethylene causes horizontal growth and axial swelling, not vertical elongation.
