How does armillaria affect agricultural practices?

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.

Pulmonary arteries carry highly oxygenated blood. true or false?

Which of the following is the function of the nociceptors? a. detecting odors in the nose b. detecting painful stimuli c. detecting central body temperature d. detecting touch and pressure