What is a pheromone?

a chemical used with the members of the same species to communicate over a distance

any behavior or stimulus, not just odor, that inititates reproductive activity

any chemical that causes strong attraction or repulsion

Blood, made up of red and white blood cells, work together to form

Four types of motile cells in human body?

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