How do lichens prepare bare rock to support the growth of plants? A. They use nitrogen from the air to make nutrients that plants can use.
B. They release acids that help break down the rock to form soil.
C. They replace smaller trees and shrubs that can't get enough sunlight.
D. They add nutrients to the rock and have roots that hold the rock together.

Legumes, a type of plant, require rhizobia, a type of soil bacteria, to survive since these organisms fix nitrogen during photosynthesis. rhizobia use the legumes for food. what would most likely happen to the legume population if rhizobia suddenly became extinct?

Cells are adapted to preform specific functions. which of the following terms refers to this capability?

Why are carbon dioxide concentrations expected to increase? a carbon dioxide concentrations are expected to increase, because fossil fuel burning is expected to increase b. carbon dioxide concentrations are expected to increase, because of an increase in agriculture. c.carbon dioxide concentrations are expected to increase, because more land will have to be cleared for increasing populations and agricultural use. d. all of the above select the best answer from the choices provided mark this and return save and exit next submit submit