Question

During the adverse season, ‘Therophytes’ survive by
(a)Bulbs
(b)Tubers
(c)Rhizomes
(d)Seeds

Answer 1

Hint: Bulbs, tubers, and rhizomes are all structures formed due to vegetative propagation which means that the new offsprings produced by them are genetically identical to the parent plant. Whereas seeds are a result of sexual reproduction and thus the offspring are not genetically identical to the parents.

Complete answer:
Therophytes are said to be those plants that are annual, complete their life cycle in a short period of time, and are able to withstand extreme conditions in the form of seeds. These plants are generally found in places like the deserts. So, during adverse conditions therophytes survive by seeds. This is advantageous because seeds have a tough seed coat which protects the embryo from the extreme conditions outside. As well as the seed is in dormancy with minimum metabolism and only 10-15% water in it.

Additional Information: Bulbs: Bulbs are usually the structures which consist of a short-stemmed plant with fleshy leaves or leaf bases which act as food storage reserves in periods of dormancy. Examples of plants that have bulbs include Dahlia, Tulips, Hyacinth, etc.
Tubers: Tubers are enlarged structures found in some plants for the storage of food and thus they are rich in starch. They are the structures of perennation during extreme conditions and also a means of asexual reproduction. Examples include potato, sweet potato, yam.
Rhizomes: Rhizomes are modified plant stems that grow horizontally inside the soil. New shoots and roots arise from the nodes of a rhizome and it is a means of asexual reproduction. Examples include ginger, turmeric.
So, the correct option is ‘Seeds’.

Note: - A seed germinates by imbibing water which means it absorbs a large amount of water that results in the breaking of the seed coat.
-The seed coat contains a small pore at the micropyle which allows the entry of oxygen and water during seed germination.
-Seeds are formed by fertilized ovules.