QUESTION 47 Oxygen transports electrons to the mitochondrion. directly transfers electrons and protons to NAD and FAD. directly receives electrons and protons from NAD and FAD. is the only substrate of aerobic respiration. is the final electron acceptor in aerobic respiration.

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.

thinking it would be d not too sure but i think it's right

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.