The amount of gas exchanged is smaller in a damaged air sac.

Explain why.

The _ of a cell increases faster than its _ so cells must divide instead of continuing to grow larger in order to be able to exchange materials with its _.

What is needed to give living things energy?

Can your blood be blue if not explain.

At the end of the electron transport chain this compound is formed

If birth rates fall below the replacement level, than a country is in which stage of demographic transition?

Which of the following statements about the greenhouse effect is true? A. Life on earth is suffering because of the greenhouse effect. B. All greenhouse gases are harmful. C. Life on earth would not exist without the greenhouse effect.

Do all organism in the same ecosystem have the same carrying capacity

The locomotive behavior of earthworms is enabled by contraction of their longitudinal and circular muscles; this is seen through their typical burrowing behavior.

When the wind blows, this spins.

Which class of biomolecule do the molecules in the table belong to? A. proteins B. carbohydrates C. nucleic acids D. lipids