Which is true of the amount of matter in ecosystems? a). It decreases over time.
b). It remains constant.
c). Scientists cannot determine how it changes.
d). It increases over time.

Which of the following structures is not found in both plant and animal cells? a) chloroplast b) cytoskeleton c) ribosomes d) mitochondria

In which situations is the principle of cross-cutting relationship useful in determining relative age?

Migration is a. the movement of organisms from a native location to a foreign location b. the movement of organisms from a foreign location to a native location the movement of organisms from their water supply to their food supply d. the seasonal movement of organisms between locations c. select the best answer from above