Cell differentiation occurs when various genes are expressed to a different extent in different cells. What does it mean for a gene to be "turned off," or not expressed?

The immediate reaction of the body to stress is most often called

How does simple diffusion differ from facilitated diffusion

At night, a land breeze forms because A) water releases less solar energy during the day; warm ocean air moves into land. B) land cools more quickly than water; cool land air moves to replace rising warm air over the water.

Outline methods to control malaria?

What is the largest division of plants

Which statement best describes an ecosystem maintaining a state of approximate equilibrium? (1) Nutrients from decayed organisms are recycled in a forest ecosystem. (2) All the frog species in a South American rain forest become extinct.

Which of these shows the correct pathway through the heart's four chambers after it enters from the vena cava? a. left ventricle - -> right atrium - -> left ventricle - -> left atrium b.

Describe how a planet, solar system, galaxy, and the universe are related in terms of size?

What structural parts do chimpanzees and humans have in common?

What is the function of the xylem? phloem? vascular cmabium? epidermis?