How did cyanobacteria change life on earth? a. they produced food from light. c. they became extinct. b. they moved onto land. d. they turned into a gas.

Which enzyme is responsible for “unzipping" the dna by breaking the hydrogen bonds between the nucleotides?

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.

Which statement about plant classification below is true? a. all vascular plants are angiosperms, but not all nonvascular plants are mosses. b. no nonvascular plants bear seeds, but not all vascular plants bear seeds c. not all nonvascular plants bear seeds, but all vascular plants do bear seeds. d. not all angiosperms produce flowers, but all gymnosperms produce cones.