The artificial selection of different breeds of dogs is an example of speciation.

Hydropower and wind power are similar in that both are

Two organisms present in the same genus are usually more closely related to each other than to organisms in other genera.

Desertification and deforestation are similar in that both involve

Lyell’s Principles of Geology was the first text to give evidence that the Earth

In which of the following areas is human population growth the lowest?

Chlorofluorocarbons (CFCs) are damaging to the world’s freshwater supply.

What is 34+23{“version”:”1.1″,”math”:”34+23″}?

If 3 pencils cost $1.50, how much do 9 pencils cost?

Which of the following correctly simplifies this expression: 10-(-3){“version”:”1.1″,”math”:”10-(-3)”}