What do the ecosystems of a puddle, lake, river, jungle, mountain-top grassland, and deep-sea vent have in common?

a. they are defined by their abiotic factors only.

b. they are defined by their biotic factors and abiotic factors.

c. energy never leaves the system once it enters.

d. they are defined by their biotic factors only.

What is the main reason that attitudes are more often revealed in spoken rather than written language? a. in writing, we try to put the "best face" on what we write. b. we speak far more often than we write. c. in writing, we can more easily conceal our attitudes. d. in spoken language, we are often careless in our use of words.

The type of fossil where the name literally means "turning to stone".

What is the name of the protein found in erythrocytes that transports respiratory gases and provides the red color?