What is the name of the extensions of the epidermal cells of a root which help in respiration?

Name the pores in a leaf through which respiratory exchange of gases takes place.

Name the areas in a woody stem through which respiratory exchange of gases takes place.

Out of photosynthesis and respiration in plants, which process occurs :

(a) all the time ?

(b) only at daytime ?

Name the organs of breathing in fish.