Which of the following scenarios represents change to an ecosystem brought about by biotic factors?
a. a wildfire caused by lightning striking a tree
b. a flood caused by a severe storm
c. a landslide caused by cattle overgrazing
d. a volcano

People who exercise for an hour may have lower cholesterol levels. is that a statement? a law? or a hypothesis?

Which of these statements best describes the st. lawrence seaway? the st. lawrence seaway connects the st. lawrence river with the arctic ocean. the st. lawrence seaway provides an important trading route between the u.s. and mexico. the st. lawrence seaway provides an important trading route for the u.s, but has little value for canada. the st. lawrence seaway connects the great lakes, the st. lawrence river, and the atlantic ocean.

List two modern organisms that have pentameral symmetry