12. Which of the following would exert pressure on a population of squirrels? a. Disease
b. Predators
C. Availability of food
d. All of the above

answer; ///i believe the answer your looking for is (ribosomes);

amber has allowed scientists to study dna that has been preserved over millions of years.

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.