How do we know if a disorder is genetic?

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.

What type of reaction is photosynthesis

During dna replication,each strand of dna is used as a template to produce a complementary strand of dna. this process is shown below. which base will attach to location