The beginning of spring in the northern hemisphere is marked by the

Which group of algae is characterized by unicellular organisms and includes some members that would be better classified as zooflagellates? euglenophytes red algae sporozoans green algae

Explain why biological control methods are generally environmentally superior to chemical pest control methods.

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.