Which of the following statements is correct with respect to the photosynthetic pathway of grass or a cactus? in a cactus, carbon is fixed only during the day. in grass, carbon is fixed only during the night. in a cactus, carbon is fixed only during the night.

What kind of seafood would you expect to have the highest levels of mercury and why? kelp, because they use the sun to photosynthesize on the bottom trophic level. oysters, because they filter feed on plankton on a lower trophic level. small fish, because they eat plankton on a higher trophic level. sharks, because they feed on organisms on a higher trophic level.

Variety of living organisms; includes genetic, species, and ecological types.

Some substances but not other can cross the (blank) membrane of a cell