How do mammals, including humans, solve the "dosage problem" caused by the presence of an x and y chromosome in one sex and two x chromosomes in the other sex? a. they don't; the fact that females have twice as much x chromosome protein products as males is critical for sex determination in mammals. b. females produce twice the rna transcripts as males do, but in females half of them are destroyed before being translated. c. in males, the x chromosome is up-regulated so that its genes are transcribed and translated twice as much as the x chromosomes in females. d. in females, one of the x chromosomes is condensed and largely inactive so that each sex has one active x chromosome. e. male rna transcripts from the x chromosome have leaders that cause them to be translated at twice the rate as those in females. f. they don't, but the x chromosome contains genes whose expression is not quantitatively sensitive, so the differences are not important.

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.

Which list is in order from simplest to most complex? a bacteria - virus - plant - protist b protist - bacteria - virus - plant c virus - bacteria - plant - protist d virus - bacteria - protist - plant

What did not occur in the proterozoic eon a)the oxygen levels increase greatly in the atmosphere,b)the emergence of the eukarya , c)muti cella’s eukaryotic organisms began to diversify,d)anaerobic bacteria kept thriving with more oxygen