Location of receptors in brain that inform as to need to excrete/urinate

There are fewer than 100 naturally occurring elements in the universe, but there are millions of different unified substances. explain how this can be true.

Once an egg cell is fertilized by sperm, the cell then, as the embryo develops, it receives nourishment and eliminates wastes by transferring substances from its blood to its mother's blood. a. becomes a fetus immediately and exits the womb b. begins to divide and implants itself in the wall of the uterus c. remains in the uterus without dividing for several months d. travels back to the ovaries until the fetus is developed

All other things being equal the size of a population will decrease if