An example of a wave that can be transmitted through a vacuum is
a. light
b. sound
c. both sound and light
d neither sound or light

What percentage of light hits earth's surface directly?

Are gametes exactly the same? explain why or why not?

Which of the following must be true for a fossil organism to be useful as an index fossil? a. the fossil organism must be widespread geographically. b. the fossil organism must be abundant. c. the fossil organism must be limited to a short span of geologic time. d. all of the above.