Photosynthesis is an example of
an exothermic reaction.
an endothermic reaction.
a reaction that gives off heat.
a reaction that emits energy.

Food contains a sugar called ( ), which is broken down in a process called cellular ( ). this process uses ( ) to break down food molecules and provide energy for cells. fill in the parentheses

Any sound above what db can cause hearing loss in human beings

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.