Which example represents an abiotic factor in an aquatic ecosystem? A. Water lilies float on top of a pond.
B. A population of bass is living in a lake.
C. The pH of a lake is decreased by acid rain.
D. Dragonflies feed on small insects near a pond.

Which of the following is the best definition for the process of photosynthesis? a.) plants digest sugars to make energy. b.) plants use oxygen and glucose to make carbon dioxide. c.) plants use sunlight and carbon dioxide to make sugars. d.) plants use sunlight to make chlorophyll and chloroplasts.

How does the human body lever work?

Which line in the graph above best illustrates an effect of the carbon dioxide level in the blood on breathing rate before, during and after a period of exercise? 1.b,2.c,3.a,4.d