Which of the following processes requires a proton gradient across a membrane?
a)simple diffusion
b)substrate level phosphorylation
c)endocytosis
d)oxidative phosphorylation
e)exocytosis

Color blindness is a recessive trait. the gene for color blindness is on the x chromosome. the family tree below shows the trait of color blindness. the only unknown is the mother in the first generation

Cladistics is a way of classifying organisms by examining the characteristics of their ancestors and descendants and depicting the relationships in a cladogram. which of the following best describes a challenge in classifying organisms this way? a. there are millions of species on earth, and a cladogram is not a practical means for classifying all of them. b. it is impossible to tell which organisms are most closely related to each other using a cladogram. c. cladograms are detail-oriented and do not provide a useful understanding of evolutionary relationships. d. there is a limited number of ways to organize the information, so most cladograms end up looking very similar.

What is a photon? a. part of a ribosome b. a light particle c. a carbon dioxide molecule d. part of a chloroplast b.a light particle