Name the blood vessels that convey blood to the brain

The tasmanian devil, a marsupial carnivore, is facing extinction due to devil facial tumor disease (dftd) which causes bulging cancerous lumps and lesions to erupt around the face and neck — often causing enough deformation to make seeing or eating difficult. dftd has evolved into a contagious cancer, a trait that is unique among cancers. devil mating behavior involves biting around the head and neck, allowing cells from one individual — especially cells from the crumbly dftd tumors — to be transferred to the wounds or face of a new individual. this marsupial was once found across australia, but sea levels rose, isolating the tasmanian population, while the australian population went extinct. what would be an outcome of genetic isolation that is likely to have impacted the spread of dftd? a) reduced territory puts diseased individuals in greater contact with non-diseased ones. b) inbreeding results in less variation in facial features so the cancer is generally fatal. c) genetic isolation has made it difficult for scientists to develop a vaccine against dftd. d) the lack of genetic variation in the immune system of tasmanian devils minimizes resistance to the disease.

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.

If a human has 23 pairs of chromosomes in every muscle cell of its body how many chromosomes will be in a human egg or sperm