On the Galapagos Islands, Darwin observed tortoises with domed and saddle-shaped shells. How did Darwin's observations of these tortoises help him form the theory of evolution by natural selection?

Biomass can be used to generate electricity. biomass relies heavily on agricultural crops. plants release carbon dioxide and water in combustion. plants use photosynthesis to originally generate the energy that is needed. the chemical energy of these plants all started with what energy source?

Select the word from the list that best fits the definition a system made of 25 satellites

The climate on the leeward side of a mountain differs from that on the windward side mostly in