Human blood, which has a ph of approximately 7.4, is a/an substance. a. acidic b. slightly alkaline c. salty thick d. neutral

What was carolus linnaeus' classification system of organisms based on? a. physical characteristics of organisms b. food habits of organisms c. habitat of organisms d. size of organisms

The cluster of developing cells from conception until birth is called an

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.