Question

Give biological reasons for the following.
(i) The wall of the ventricle is thicker than the auricles.
(ii) The renal cortex has a dotted appearance.
(iii) Wooden frames of doors get jammed during the monsoon season.
(iv) Throat infections can lead to ear infections.
(v) The hand automatically shows the direction to turn a cycle without thinking.

Answer 1

(i) The wall of the ventricles are thicker than the walls of auricles due to different muscular development related to their different functions. Ventricles, particularly left ventricle has to pump the blood into aorta under a high pressure against force of gravity. So, they are adapted to withstand greater pressure.
(ii) Renal cortex has a dotted appearance because it contains malpighian capsule. Also, nephrons are highly coiled in this region.
(iii) Wooden frames of doors and windows get jammed due to process of imbitition. Imbibition is a process in which water is absorbed by solid surface. Wood of door absorbs or imbibes moisture from their surroundings because of which it swells up.
(iv) The anterior wall of middle ear contains an opening that leads directly into Eustachian tube. This tube connects the middle ear to throat. Hence the passage for infection is common and it may lead to ear infection.
(v) The hand automatically shows the direction to turn a cycle without thinking is due to the conditioned reflexes. These reflexes are learned responses to stimuli acquired individually during the life of an organism.