According to the big bang theory, the universe began about

Why is it important to reduce the number of chromosomes in half when forming gametes for sexual reproduction?

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

What is true of all organisms in the kingdoms protista, plantae, fungi, and animalia? a. they are multi-celled. b. they are photosynthetic. c. they have cells that contain membrane-bound organelles. d. they contain cells that lack membrane-bound organelles.