The chemical process for respiration

Take a deep breath, then release the air out. When you do this, you are taking in oxygen and releasing carbon dioxide, two important gasses involved in cellular respiration. Cellular respiration is the process in which cells break down molecules for energy. In order to do this, the cells use that oxygen that you breathe in and produce that carbon dioxide that you breathe out.

Think about when you are hungry and feel lethargic. You feel this way because your body does not have food to turn into energy in the form of adenosine triphosphate, or ATP. In cellular respiration, your body breaks down a sugar called glucose from the food you eat to get that ATP, which provides energy to the rest of your body so it can function.

So let's recap what happens in cellular respiration. Oxygen that you breathe in and glucose from your food are turned into carbon dioxide that you breathe out, water that you urinate and sweat out, and energy in the form of ATP.

substitution is the answer in this case

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

i hope this : )