CBSE Questions for Class 11 Medical Biology Plant Growth And Development Quiz 1 - MCQExams.com

Solution

Correct answer is option A.

Explanation for correct option:

• Auxin is a plant hormone. IAA is a type of auxin present in the plant.
• Auxins help to initiate rooting in stem cuttings. This property is widely used for plant propagation by stem cuttings.
• Auxin also promotes apical dominance, hence its used in tea plantation.

• Gibberellin - regulate various developmental processes, including stem elongation, germination, dormancy, flowering, flower development, and leaf and fruit senescence.
• Ethylene - majorly used for ripening fruits and for the production of more flowers and fruits.
• Abscisic acid - an inhibitory rather than stimulatory hormone. It is involved in the closure of stomata, bud and seed dormancy.
• Cytokinin - promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence.

• Auxin is a plant growth regulator that promotes apical dominance.
• Bioassay is the method to find the potential effect of any hormone or enzyme on living tissues.
• Avena coleoptile curvature is the experiment done by Frits Warmolt Went in 1926 on avena sativa (oats).
• He checked the efficiency of the auxin hormone in the Avena plant by transporting the hormone in the coleoptile of it and then observed the increase in the length of the plant.
  

• Gibberellins (Gibberellic Acids) are plant hormones that regulate various developmental processes, including stem elongation, germination, dormancy, flowering, flower development and leaf and fruit senescence. Spraying of gibberellins on juvenile conifers speeds up maturity thus leading to early seed formation.
• Ethephon is a plant growth regulator used to promote fruit ripening, abscission, flower induction, and other responses. It is responsible for early ripening in tomato and apple.
  

• Auxin is the phytohormone that handles apical dominance and positive phototropism. 
• It can cause the cells to elongate on the shaded side, so this side grows more. 
• This unequal growth of the two sides results in the stem's growth towards the light.

$$\textbf{Correct option: }$$ B

$$\textbf{ Solution: }$$ 

$$\textbf{ Option (A): }$$

$$\bullet$$The process in which differentiated cells loses their ability to divide and later reformed from the dedifferentiated cells. 

$$\bullet$$This allows the cells to regain a specific function. 

$$\textbf{ Option (B): }$$

$$\bullet$$Dedifferentiation is a process which makes the cells less specialized in order to return to an original state in terms of functionality. 

Hence, the correct option is (B)