marine mammals, which are air breathers, can swim for hours at the surface of the water with minimal negative affect. If they dive deeper in the water for periods of time they are lost likley in pain. Explain why there would be such a difference?

tissue

explanation:

it is actually formed by geoup of cells which is tissue

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products

what is this saying?

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.