Severe or sudden changes in Earth's atmosphere can cause entire species of animals to die. When all of the members of species die out, it is called A
mutation.

B
natural selection.

C
extinction.

D
revision.

What are the doorways into and out of cells, attached to the membrane, and built in the rough er.

How does photosynthesis show the conservation of mass and energy?

Which of the following is an advantage of using embryonic stem cells in medical research? a. the use of embryonic stem cells is much less expensive than the use of adult stem cells. o b. no living tissue is damaged when scientists use embryonic stem cells. o c. embryonic stem cells are able to differentiate into a wider range of cells than adult stem cells. d. there is no controversy surrounding the use of embryonic stem cells.