Question

The activity of α–amylase in the endospore of barley germinating seed is induced by:
A. Ethylene
B. Cytokinin
C. Indole acetic acid
D. Gibberellin

Answer 1

Hint: This growth hormone is involved in seed germination in certain plants varieties. They are also one of the longest known classes of plant hormones.

Complete answer:
1. Gibberellins also known as gibberellic acid (GAs) are involved in the seed germination of certain plants.
2. In a classical experiment involving the germination of barley seeds, researchers showed that the release of gibberellin from the embryo triggered the synthesis of an enzyme known as the α -amylase.
3. This enzyme digests starch in the endosperm of the seed. This results in the availability of glucose for absorption by the embryo. Although these enzymes can mobilize starch reserves in many types of seeds, gibberellins control and coordinate the activities of these seed enzymes that appear to be restricted to cereals and other types of grasses.
4. In addition to the mobilization of food reserves in newly germinated grass and cereal seeds, application of gibberellins substitutes for low-temperature and light requirements for the seed germination of plants such as lettuce, oats, and tobacco.

So, the correct answer is “Option D”.

Note: 1. Indole-3-acetic acid (IAA) is the main type of auxins in plants.
It controls many important physiological processes including cell enlargement, differentiation, and division, tissue differentiation, and responses to light (phototropic nature) and gravity (geotropic nature)
2. Ethylene is a gaseous plant hormone. It is regarded as a multifunctional phytohormone (plant hormone) that regulates both growth and senescence
3. Cytokinin (CKs) are a class of plant growth hormones that promote cell division (cytokinesis) in plant roots and shoots where there is increased meristematic activity. They are also involved the cell growth and differentiation primarily. They also affect apical dominance axillary bud growth and leaf senescence
4. The endosperm is a mass of cellular or nuclear tissue that is produced inside the seeds of most of the flowering plants following the process of fertilization.
It is triploid (having three sets of genetic material copies) in most plant species.
It surrounds the embryo and provides its nutrition in the form of starch.
It can also contain oils and protein as a source of food.