Freckles are small, spots of a skin pigment called melanin. most fair-skinned, red-haired people have them. freckles are controlled primarily by the mc1r gene. freckles are a dominant trait: parents who have freckles tend to have children with freckles. bill and barb both have freckles. yet of their four children, one child does not have freckles! what must be the genotypes of bill and barb? a) bb and bb b) bb and bb c) bb and bb d) bb and bb

Calvin ate a candy bar, which caused his body's blood glucose levels to become unbalanced. his body responded by initiating a feedback mechanism to return his body to homeostasis. place the steps of this feedback mechanism in order, starting with the blood glucose imbalance that occurred after calvin consumed the candy bar. a) calvin's blood glucose levels decreased. b) calvin's pancreas stopped secreting insulin. c) calvin's body cells started to take up glucose and store it as glycogen. d) calvin's blood glucose levels increased. e) calvin's pancreas started secreting insulin.

How is ribosomal rna useful as a molecular clock? a. a large portion of the dna ring is not vital to structure or function, allowing it to accumulate neutral mutations. b. its rate of mutation increases over time as organisms continue to evolve and differentiate from each other. c. a slow mutation rate makes it useful for determining evolutionary relationships between ancient species. d. it is only found in select organisms, making it easier to compare relationships between species that have it.

Most animal cells membranes have proteins that pump ions out of the cell and potassium ions into the cell