According to cell theory, viruses are considered nonliving because they
a. do not contain organelles.
b. do not contain organic compounds.
c. cause diseases in other organisms. eliminate
d. lack the ability to reproduce without a host.

Types of scientific inquiry that biologist engage in that cannot be completely controlled

Nucleic acids offer variability because they contain alternate forms of genes called .

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.