(i) The wall of the ventricles are thicker than the walls of atria due to different muscular development related to their different functions. Ventricles, particularly left venticle has to pump the blood into aorta under a high pressure, against force of gravity. As such they are adapted to withstand greater pressure. 

(ii) Renal cortex has a dotted appearance as it is dark in colour and nephrons are highly coiled in this region. 

(iii) Wooden frames of doors and windows get jammed due to process of imbibition. In this process, water is adsorbed or absorbed by surface attraction. Wood have a strong affinity for water (hydrophillic). Thus, they absorb or imbibe water or moisture from their surroundings and swell 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) It occurs due to conditioned reflexes. These reflexes are learned responses to stimuli acquired individually during the life of an organism.