Witch is a factor that keeps earth in orbit around the sun

Explanation:

gravity keeps earth around the sun in orbit

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.

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.