The cell membrane is a highly selective barrier that controls the movement of substances in and out of the cell. In fact, polar molecules are unable to go across unless

List three principles of the cell theory

What would a solar eclipse look like if the Moon were smaller than it is now?

Most plants appear green because chlorophyll Select one: a. does not absorb green light. b. reflects violet light. c. absorbs green light. d. none of the above

Describe the role of blood in excretion.

According to biological classification, which of these pairs represents animals that are the MOST closely related? A) crabs and fish B) crabs and snakes C) crabs and penguins D) crabs and grasshoppers

Which structure does this organism use for movement? a. cilia b. contractile vacuole c. flagella d. pseudopodia?

How does cell division differ in plant cells and animal cells?

Air pollution can be controlled by A.) permitting more storm runoff B.). Burning more coal C.). Eliminating sewage D.) putting scrubbers on power plants

consider the structure and function of fats to predict which animal would have more fat: one that live close to the poles or one that lives close to the equator?

What does the electrochemical communication do in the body?