Where is over 95% of incoming ultraviolet radiation absorbed? .
a. the stratosphere.
b. the mesosphere.
c. the troposphere.
d. the thermosphere. ?

Living cells cannot use heat to provide the activation energy for biochemical reactions because which choice(s) complete the sentence correctly? a) answer choice ii. eliminate b) answer choices ii and iv. c) answer choice iii and iv. d) all answers can complete the sentence.

Tides that occur during the new and full moons

What substance acts to prevent sudden ph changes in bodily fluids?