Xylem contains specialized cells that provide support for a plant stem. How does the structure of one of these cells help it carry out this function?
A. It changes shape to allow gas exchange.
Ο Ο
B. It sticks out from the stem.
C. It has stiff walls.
D. It has tiny openings.
SUBMIT

Blood, made up of red and white blood cells, work together to form

Which conditions are necessary for natural selection to occur? select all of the answers that apply. a. inheritable adaptations vary among individuals. b. the population size is increasing. c. more individuals are born than can survive. d. fitness varies among individuals. e. the environment changes suddenly and drastically.

Which list is in order from simplest to most complex? a bacteria - virus - plant - protist b protist - bacteria - virus - plant c virus - bacteria - plant - protist d virus - bacteria - protist - plant