Which of the following statements correctly describes a reaction associated with photosystem I A) Light energy excites electrons in the thylakoid membrane electron transport chain. B) Electrons released from the chlorophyll are replaced by electrons derived from water. C) The P680 chlorophyll donates a pair of electrons directly to NADP^ + producing NADPH.
D) Electrons are passed from the P680 chlorophyll to oxygen (O 2 )

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.

answer///multiple alleles;