*Question*
Q: What man-made substance tends to break down ozone in the stratosphere? Choices: - gasoline - steel - plastic - cfcs A:
**Answer**
cfcs

*Question*
Q: In studying energy, what term do scientists use to refer to the matter and its environment involved in energy transfers? Choices: - molecule - ecosystem - world - system A:
**Answer**
system

*Question*
Q: What category of animals in the vertebrate group has a relatively small brain but highly developed sense organs? Choices: - mammals - arthropods - primates - fish A:
**Answer**
fish

*Question*
Q: Morphological and molecular data indicate that wings evolved how many times in insects? Choices: - many times - twice - never - once A:
**Answer**
once