In what way do membranes vary among eukaryotic cells?

the dark variety, as they are not visible on the dark tree barks

explanation:

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.

the tricuspid valve is present between right atrium and right ventricle

multiply it by 5 in order for you to understand i cant give an exact answer.