Give reason for the following

(i) Adrenaline is referred to as emergency hormone.

Give reason for the following

Despite availability of plenty of water, leaves of certain plants wilt during the day and recover in the evening.

Give reason for the following

Hybrid seeds should be raised every year.

Give reason for the following

The wing of a bat is said to be homologous to the wing of a bird and analogous to the wing of an insect.

Give reason for the following

Symptoms of deficiency of certain nutrients appear in the old leaves first.

Mention the most significant role of each of the following :

Fovea centralis    

Mention the most significant role of each of the following :

Lymphocytes

19.

Mention the most significant role of each of the following :

Bundle of His  

Mention the most significant role of each of the following :

 Calyptra