Although DiGeorge syndrome can be passed down through families, it often arises de novo, meaning the child has the syndrome, but neither parent does. DiGeorge syndrome is highly penetrant, meaning that having the variant on one chromosome ensures that you will have some symptoms. Given what you know so far about DiGeorge syndrome, which of the following is the most likely explanation? . A. An error occurs during maternal or paternal meiosis, creating a new variant.
B. This could only be explained if one of the parents has been misidentified.
C. One of the parents actually has the variant, but no symptoms.
D. Both parents are carriers of DiGeorge syndrome.

We want most cells to be even in and out which is called

To answer this question, researchers studied populations of the dusky salamander (desmognathus ochrophaeus) living on different mountain ranges in the southern appalachian mountains. the researchers tested the reproductive isolation of pairs of salamander populations by leaving one male and one female together and later checking the females for the presence of sperm. four mating combinations were tested for each pair of populations (a and b)—two within the same population (female a with male a and female b with male b) and two between populations (female a with male b and female b with male a). the proportion of successful matings for each mating combination was measured. for example, when all the matings of a particular combination were successful, the researchers gave it a value of 1; when none of the matings were successful, they gave it a value of 0. then the researchers calculated an index of reproductive isolation that ranged from 0 (no isolation) to 2 (full isolation). the reproductive isolation value for two populations is the sum of the proportion of successful matings of each type within populations (aa + bb) minus the sum of the proportion of successful matings of each type between populations (ab + ba). the table provides data for the geographic distances and reproductive isolation values for 27 pairs of dusky salamander populations.

Select the correct answer. which mutation is harmful to the organism? a. a mutation allowing moths to camouflage better on blackened tree bark b. a mutation making staphylococcus aureus resistant to the antibiotic methicillin c. a mutation inhibiting human immunodeficiency virus from attaching to and entering the cell d. a mutation causing uncontrolled cell division e. a mutation giving plant leaves a bitter taste to discourage herbivores from eating them