What were the major contributions of the H. M.S. Challenger to the study of oceanography?

How many trophic levels are there in the following food chain? phytoplankton - shrimp - perch - pike - osprey

If water were a non polar molecule, how would its properties be different ? a.) water would be a much lighter molecule b.) water would be able to climb up inside plants c.)water would not be able to form hydrogen bonds d.) water would stick together much more strongly

Which of the following is not a symptom of desertification? a) decrease in salt content of the soil b) lowering of the water table c) reduced surface water d) increased soil erosion e) loss of native vegetation