Question

4. Give reasons for the following:

(a) Arteries are thick walled.

(b) Blood goes only once in one cycle through the heart in fishes.

(c) Plants have low energy need

Answer 1

a. as the pumped blood flows from the heart to the other parts of the body through arteries therefore to coup up the high pressure with less friction, the walls of the arteries r made thick...so that blood can pass fastly n smoothly...
b. fishes have single circulation, in these the blood mixes up and doesnt get separated through compartmentsfishes r primitive compared to higher animals.. it is based on evolution i guess...
c. plants have less metabolic activities as compared to animals. for eg. plants dont locomote but animals do locomote and also in case of animals there r many co curicular activities but plants dont have them...
i hope it helped u...