Anatural selectional requires genetic variation

What was the land like over 500 million years ago? what was under the sea?

Veronica and her little sister, monique, are playing on a seesaw. if veronica weighs 75 pounds, and monique weighs 60 pounds, which statement is true?

Describe how viruses and bacteria can be used as biological weapons. what are some of the potential threats and potential benefits? do you agree with the use of viruses and bacteria as biological weapons? why or why not?