Please help ASAP! Question in photo!

High mass stars have to generate a lot of energy in order to balance the force of gravity. Therefore they are very hot and luminous. That explains their position high on the Main Sequence. On the other hand, low mass stars have to generate little energy in order to balance the force due to gravity.

endo:

regulates body hormones, aldosterone, vasopressin

neural:

signal, regulates body using electric signals, reflex

endo has to do with hormones; aldosterone and vasopressin are both hormones. i also had this question and got it right : d

condenser is used to focus in the light microscope.