Biology is used in agriculture to produce

Agricultural biologicals (or biologics) are beneficial crop production and protection tools that are largely created from living organisms, derived from natural materials, contain them, or use naturally-occurring processes. They complement traditional crop protection tools, using nature’s own defenses to help safeguard plants against pests.

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.

it's diluted or concentrated

in a diluted solution, you can add a lot more solute but in concentrated only a little more can be added