Active transport occurs in cells, for example, when the na-k pump is at work. any process that involves active transport most often involves the a) movement of molecules without any predictable pattern. b) movement of molecules from a lower concentration to a higher concentration. c) movement of molecules from a higher concentration to a lower concentration. d) movement of molecules from a lower to higher concentration and then back to the point of origin.

4. rat liver is able to metabolize glucose by both the glycolytic and the pentose phosphate pathway. which of the following are properties of both the glycolytic and pentose phosphate pathway? a. nad+ is involved b. co2 is liberated c. phosphate esters are intermediates d. glyceraldehyde 3-phosphate is an intermediate e. fructose 6-phosphate is an intermediate4. rat liver is able to metabolize glucose by both the glycolytic and the pentose phosphate pathway. which of the following are properties of both the glycolytic and pentose phosphate pathway? a. nad+ is involved b. co2 is liberated c. phosphate esters are intermediates d. glyceraldehyde 3-phosphate is an intermediate e. fructose 6-phosphate is an intermediate

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.

The embryos of a bird, a reptile, and a mammal are similar in appearance. how does comparing the physical appearance of embryos of different species support the theory of evolution? a. it shows that these organisms share a common ancestor. b. it provides evidence that these organisms eat the same foods. c. it shows that these organisms share the same habitat. d. it provides evidence that these organisms suffered a genetic mutation.