A friend is interested in isolating genes that are expressed solely in liver cells but only has access to skin cells. She asks you for advice on whether to start her studies. What will you say?

Could both the food competition hypothesis and the sexual competition hypothesis explain why giraffes have long necks? Why or why not?

Cell differentiation always involvesa. transcription of the myoD gene.b. the movement of cells.c. the production of tissue-specific proteins.d. the selective loss of certain genes from the genome.

Which of the following is a valid difference between embryonic stem cells and the stem cells found in adult tissues?a. In laboratory culture, only adult stem cells are immortal.b. In nature, only embryonic stem cells give rise to all the different types of cells in the organism.c. Only adult stem cells can differentiate in culture.d. Embryonic stem cells are generally more difficult to grow in culture than adult stem cells.

A friend is interested in isolating genes that are expressed solely in liver cells but only has access to skin cells. She asks you for advice on whether to start her studies. What will you say?

What did Linnaeus' system of naming organisms ensure?a. Two different organisms never end up with the same genus and species name.b. Two different organisms have the same genus and species name if they are closely related.c. The genus name is different for closely related species.d. The species name is the same for each organism in a genus.

Scientists have recently developed a process by which a skin cell from a human can be triggered to develop into a human heart muscle cell. This is possible because .a. most cells in the human body contain the genetic instructions for making all types of human cells;b. a skin cell is produced when all genes in the cell are expressed; turning off some genes in the cell results in a heart cell;c. scientists can add new genes to old cells to make them take different forms;d. a skin cell expresses only recessive alleles, so it can be triggered to produce dominant heart cell alleles;e. it is easy to mutate the genes in skin cells to produce the alleles required for other cell types

A genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud instead of farther back helped make possible the evolution of the tetrapod limb. This type of change is illustrative ofa. the influence of environment on development.b. paedomorphosis.c. a change in a developmental gene or in its regulation that altered the spatial organization of body parts.d. heterochrony.

Your bone cells, muscle cells, and skin cells look different becausea. each cell contains different kinds of genes.b. they are present in different organs.c. different genes are active in each kind of cell.d. they contain different numbers of genes.