Clear wheat her from this prediction
Mass transit can help reduce air pollution in urban cities because there are fewer cars on the roads, creating less pollution.
A nucleotide consists of all of the following except a nitrogenous base. The are of course the main building blocks of genetic information in many life forms.
I would say energy myself, and this is because energy plays a key role in all of these. With trophic levels energy is being transferred amongst the levels. Food chain's is a map of how the energy is passed along the chain. Food web is a web of how energy is transferred, and this is why I would say energy is a keyword.
They cannot move freely but they can vibrate
