Question

ABA is involved in
A. Shoot elongation
B. Increased cell division
C. Dormancy of seed
D. Root elongation

Answer 1

Hint: Abscisic acid (ABA) is a type of plant hormone. ABA functions in many plant developmental processes. It is especially important for plants in the response to environmental stresses,that includes drought, soil salinity, cold tolerance, freezing tolerance and also heavy metal ion tolerance.

Complete step-by-step answer:
ABA was originally believed by some to be involved in abscission, according to which it received its name. This is now known to be the case which is present only in a small number of plants. ABA-mediated signaling also plays an important role in plant responses to environmental stress and plant pathogens.
The plant genes for ABA biosynthesis and sequence of the pathway have been explained.
In preparation for winter, ABA is produced in the terminal buds. This slows down plant growth and directs the leaf primordia to develop scales which helps to protect the dormant buds during the season of winter.
ABA also helps in the inhibition of the division of cells in the vascular cambium.
Abscisic acid is also produced in the roots which functions to decrease soil water potential and other situations in which the plant may be under stress. ABA then translocates to the leaves, where it rapidly changes the osmotic potential of stomatal guard cells, which cause them to shrink and make stomata to close.
The ABA-induced stomatal closure helps in the reduction of transpiration (evaporation of water out of the stomata), thus preventing further water loss from the leaves in times of low water availability.
Seed germination is inhibited by ABA which is antagonist to gibberellin.
ABA also helps in preventing the loss of dormancy of seed.

Thus the correct answer is option C.

Note: Various methods can help to quantify the concentration of abscisic acid in a variety of plant tissue. The quantitative methods used are based on HPLC and GC, and ELISA. Recently, 2 independent FRET probes have been developed that can measure intracellular ABA concentrations in real time in vivo.