Biologists sometimes divide living organisms into two groups: autotrophs and heterotrophs. these two groups differ in

Autotrophs and heterotrophs differ in the mode in which they USE DIFFERENT sources of carbon.

Autotrophs are organisms that synthesize their own food, thereby they obtain carbon from inorganic sources.

Examples of autotrophic organisms include plants and algae.

Heterotrophs are organisms that cannot synthesize their own food, thereby they need to obtain carbon from other organisms.

Examples of heterotrophic organisms include animals and fungi.

In conclusion, autotrophs and heterotrophs differ in the mode in which they USE DIFFERENT sources of carbon.

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the fossil record provides evidence of a common ancestor to many species.

answer: ice crystals in air

the water from the water body or another source of water gets evaporated as water vapor as an effect of heat on water. these water vapor rises in the upper layers of the earth atmosphere under high atmospheric pressure. the atmospheric pressure of these water molecules starts to decrease due to the effect of cold air. the invisible water vapor condenses into visible water droplets and ice crystals.these ice crystals and water droplets being less denser than the surrounding air floats on air as clouds.