While a carpenter was doing some remodeling in Kate's kitchen, her infant son cried from the hammering noise at first, but stopped responding to the noise after he got used to it. The son's response is best thought of as an example of:

A researcher has conducted an experiment in which she

assigned all of her students four hours of homework the night before a test, in order to see what effect the extra stress has on test performance. The study is flawed because the researcher did not include a(n) _____ a) control group. b) experimental group. c) independent variable. d) random sample.

The female reproductive cell is called the __________

a) gamete b) sperm c) zygote d) ovum