In Drosophila melanogaster, the wild-type eye colour is dark red. A fly from a true-breeding strain with scarlet eyes is crossed to a fly from a true-breeding strain with brown eyes. All the offspring have dark red eyes. The F1 flies are intercrossed to produce an F2 generation. This comprises 472 flies with dark-red eyes, 138 with scarlet eyes, 145 with brown eyes and 45 with white eyes. A. Three genes are segregating in this cross
B. Two independently assorting genes are segregating in this cross
C. Two linked genes are segregating in this cross
D. The phenotypes result from interactions between genes
E. The brown eye colour is the result of epistasis

Over the past 60 years, many amphibian species have experienced significant population declines and some species have become extinct. scientists suspected that local human activities such as the destruction of wetlands, regional pollution, and deforestation were the main reasons for these losses. however, research over the past 20 years reveals significant amphibian population declines in protected areas of the world, such as nature preserves and parks. these global declines suggest widespread problems including increased ultraviolet radiation, acid rain, and disease. in switzerland, for example, 14 of the 20 native amphibian species are threatened with extinction. chytridiomycosis is a fungal disease first identified in 1998 as a cause of massive amphibian deaths. in some severely impacted populations, a few individuals have survived, perhaps because of some natural resistance. if these resistant individuals continue to survive and prosper, new resistant populations might emerge. this would be an example of the founder effect artificial selection genetic drift natural selection sexual selection

This is a situation in which genes are attached to an organism's sex chromosomes; the sex of an organism influences the expression of a gene.

Hormones are chemical molecules produced by endocrine glands. one such endocrine gland is the thyroid gland, which synthesizes the thyroid hormone, which in turn affects the heart muscles. which two statements describe the probable reason for the function of the hormone? the cells in the heart have specific receptors that allow for the intake of hormones. the heart and the endocrine glands have the exact same types of cells. all cells make the same types of hormones. thyroid hormones show their effect on the heart by means of specialized cells. thyroid cells and cardiac cells have different dna.