Your question states: Explain why it makes sense that the levels of estrogen and progesterone are low in the blood of a female during menstruation.I'm a guy, but I just happen know this information.The reason why the levels of estrogen and progesterone are low in the blood of a female during menstruation is to basically produce (FSH) or follicle stimulating hormone. We need to remember that menstruation is part of the menstrual cycle, which to would help a women/teen to handle/establish a well and healthy pregnancy, (if that makes sense). The average cycle would basically be i think about like 25-28 days. And one thing to remember is that when there is a <span>ripening egg,this causes estrogen levels to rise. This would be the reason why its low.
DNA replication needs to occur because existing cells divide to produce new cells. Each cell needs a full instruction manual to operate properly. So the DNA needs to be copied before cell division so that each new cell receives a full set of instructions!
