What is ozone?

I really need help guys

After fertilization, which type of cellular division is responsible for the growth and development of a complex, multicellular organism?

The cluster of developing cells from conception until birth is called an

Viruses can be transmitted through air, water, food, insect bites, and direct skin contact. once a virus gains entry into the body, it invades a host cell in order to? a. synthesize antibodies for defense b. deactivate the host cell's defenses c. access cell processes for reproduction d. metabolize host proteins and grow