Which of the following describes an example of molecular movement across a membrane through active transport?
O Channel proteins bind with extracellular solutes and release them inside the cell.
O Hydrocarbons enter the cell by dissolving in the lipid bilayer of the membrane.
Proton pumps move hydrogen ions out of the cell against a concentration gradient.
O Vesicles carrying waste products fuse with the membrane during endocytosis.

In a relatively small iguana population the allelic frequency is tracked for three generations. webbing is a recessive allele; no webbing is the dominant allele. during one very rainy spring and summer, a flood washes all the iguana without webbed feet out to sea. by the fall, and three generations later, you have the gene pool seen here.

Which flexible structure that supports the nerve cord and led to the backbone

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.