What is natural selection?

Which best describes red blood cells? a. they are colorless b. they protect against disease-carrying microorganisms c. they transport oxygen throughout the body d. they aid in blood clotting

Complete the statements to identify the first two steps of meiosis i. (1 ) the first and longest step of meiosis i is called i. (2)the second step of meiosis i is called i.

Which gas found in the earth's atmosphere greatly impacts the daily range of temperature on earth. a) oxygen b) hydrogen c) nitrogen d) water vapor