Scientists apply the concept of a molecular clock to estimate the time two species evolved separately.

Which data are most useful for the estimation?

A. common traits of the two species
B. homologies among the two species
C. DNA sequence differences between the two species
D. DNA fingerprinting of common fossils

Describe two recent or ongoing space missions.

According to the cell theory, which describes cells? a. all organisms are composed of multiple cells. b. all cells have the same structure and function. c. cells are found in everything on earth. d. living organisms are not created spontaneously

The blue particles in this image are able to cross the cell membrane through simple diffusion. how will they be transported? outside the cell inside the cell o a. the substances will move directly across the membrane from outside the cell to inside the cell. b. the substances will move through channels in the membrane proteins from outside the cell to inside the cell. o c. the substances will move through channels in the membrane proteins from inside the cell to outside the cell. o d. the substances will move directly across the membrane from inside the cell to outside the cell.