Which vitamin is produced by the skin in response to ultraviolet light?

(A) vitamin A

(B) vitamin B

(C) vitamin C

(D) vitamin D

The assisted transport of a molecule across the cell membrane without an expenditure of energy is known as what?

Because the final stages of cellular respiration require oxygen the are said to be

State one factor, other than the tilt of the Earth's axis, that causes seasons to change on earth.

A hypothesis that is not supported by the data that has been collected and analyzed is

Dr. Tanaka discovered a new virus. The virus has a single strand of a nucleic acid, but she does not know if it is DNA or RNA. After running tests, she concludes that it is DNA. Which of the following would lead her to that conclusion? A.

Which of the following is NOT an age-related change affecting the heart? A. decline in cardiac reserve B. fibrosis of cardiac muscle C. atherosclerosis D. thinning of the valve flaps

When they match is burn chemical and potential l energy is converted to thermal and

What is the molten iron and nickel in the core of the earth thought to contribute to

If the seawater carbonate ion concentration is 270_mol/kg, what is the approximate rate of calcification, and approximately how many days would i take 1 square meter of reef to accumulate 30mmol of calcium carbonate (CaCO3) ?

What is the importance of decomposers in an ecosysyem such as mold?