Stem cells are cells that can differentiate into many different kinds of cells. Scientists have discovered that the environment supporting the cells influences stem-cell differentiation. For example, stem cells grown on strong, flexible surfaces became muscle cells. What MOST likely happened to stem cells grown on a hard, rigid surface? A.
They became nerve cells.
B.
They became red blood cells.
C.
They became skin cells.
D.
They became bone cells.

Examine the two squirrel populations in the accompanying figure. the populations are separated by a geographic barrier. if after a long period of time the two species are no longer separated, what evidence is needed to determine if speciation has occurred? the figure shows two populations of squirrels separated by a geographic barrier. examine the two squirrel populations in the accompanying figure. the populations are separated by a geographic barrier. if after a long period of time the two species are no longer separated, what evidence is needed to determine if speciation has occurred? the figure shows two populations of squirrels separated by a geographic barrier. polyploidy is creating new species. the two populations are not interbreeding freely. hybrid offspring of the two populations begin to appear. one species will increase into a population size twice as large as the other species.

What happens during interphase? (1)the nucleus grows to its full size. (2)the cell grows to its full size. (3)the nucleus divides into two nuclei. (4)the cell divides into two cells.

Which of the following statements is most likely correct about a rock belonging to the jurassic age and a rock belonging to the cambrian age? options: 1) they have identical fossils of organisms that have evolved over time. 2) both have animal fossils preserved in them due to weathering and erosion. 3) they contain different fossils because life on earth has changed through time. 4) the fossils in them were formed on the surface of earth due to exposure to sunlight.