Although you get wet while swimming, a tough protein within the skin prevents it from soaking up moisture like a sponge. This substance is: A) carotene B) hemaglobin C) keratin D) collagen

The nervous system regulates some actions of the body automatically. Which of the following is NOT a reflex action?

Que son fuentes de energia renovable?

Why do scientists think that introns and exons contribute to evolutionary flexibility?

What is the limiting factor in oligotrophic lakes?

The Doppler Effect means that an observer ahead of a train hears the train at a higher frequency sound than does any observer behind the train. True or Flase

The phase of cell division during which the chromatids are pulled apart and move to the opposite

What is occurring in the endocrine system during a "fight or flight" response? Release of adrenaline by the adrenal glands Release of cortisol by the adrenal glands Release of adrenaline by the gonads Release of cortisol by the gonads

Describe interactions between organisms within an ecosystem. Give an example of a specific relationship that organisms may have, and how this relationship affects the ecosystem.

Which process removes carbon dioxide from the atmosphere A: Respiration B: Humans breathing C: Carbonate formation D: Nitrogen fixation

Which type of RNA functions as a carrier of the genetic code?