what is the primary reason for increase in heart rate during excercise?

Discuss factors that affect the rate at which a person's heart recovers?

what part of the heart's action does the pulse represent?

heart rate increases because the body needs to get more oxygen more quickly to muscles when they are working during exercise. and also to get rid of the waste products of metabolism i.e. uric acid and co2.

pulse rate represents systole, Read your textbook or refer to your school notes and do your own homework.