2. When your nerves send a message to your muscles, these two protein strands reach out and touch one another. The movement that occurs gives us the name .

Although animals share many common characteristics, there is also a great amount of diversity found in animals. which animals are ectothermic, obtain dissolved oxygen in water through gills, have scales, have fins, and live in water?

By 2 weeks after fertilization the morula has implanted into the uterine lining and transforms into a(n) . this time is when the , or the organ that will provide nourishment to the fetus by exchanging nutrients and waste products, begins to develop.

Which of the following is a lifestyle behavior? a. getting enough sleep b. exercise c. tobacco use d. all of the above