Soil erosion occurs a. where animals eat away all the plants c. on steep slopes b. when forests are removed d. all of the above

Tropical rain forests support more species per unit area than any other terrestrial ecosystem. what is one way rain forests are important to the health of the biosphere?

Which feature would you expect to find in a population in which sexual selection depends on male competition?

The structure of a dna molecule is best described as a. one long strand of nucleic acids b. two strands of dna nucleotides joined by hydrogen bonds c. two strands of amino acids joined by hydrogen bonds d. one long strand of amino acids