Why do brains have valves

This is the result of uncontrolled cell division. Often caused by mutations. Mutations may be caused by environmental factors such as radiation or chemicals. Example: Tumor in the lung

What causes an object with mass to have weight?

Which characteristics s common in young rivers

jill has a beaker. in this beaker there are two layers. the top layer is transparent with yellow tint to it, and the bottom layer is transparent and clear. jill decides that the bottom layer is probably water.

How does selective cutting compare with clear cutting?

the esophagus, stomach, and small intestines all function together. which level of organization is being described

A muscle cramp is a sudden, painful contraction of a muscle, during which movement is difficult. What is happening at the cellular level during a muscle cramp? A. The proteins in the myofibrils become denatured, preventing relaxation. B.

When designing an experiment to test a hypothesis, the experiment must be replicable?

What is the appropriate term for a group of all the individuals that can mate with each other living within a specified area?

What is the optimum ph of most enzymes in the body