What process adds carbon dioxide to the air? O nitrogen cycle
O water cycle
O respiration
O photosynthesis

Respiration

Explanation:

During respiration, oxygen is taken in and carbon dioxide is given out.

During photosynthesis, carbon dioxidr is taken in and oxygen is released.

During water cycle, water vapour is released.

During nitrogen cycle, nitrogen is released

C

Explanation:

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

it is a limiting nutrient limited by a single nutrient in the ecosystem, & the single goes very slow.