The differences between two molecules include the type of sugar that forms a section of the molecules and the identity of one of the four nitrogenous bases that make up
another section of the molecules. These two molecules are -
A proteins
B lipids
C nucleic acids
D complex carbohydrates

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

d. planting trees

the trees take in carbon to make oxygen.