Primary prodution is when plants produce their own food and use them for their living and growth. Common primary produces include: grass, milk weed, oxalis. Primary production helps to maintain the ecosystem, both terrestrial and aquatic. Factors that involve primary production includes sunlight, air, water. Living systems produce energy rich organic substances from low energy inorganic substances in primary production. Solution Primary prodution is when plants produce their own food and use them for their living and growth. Common primary produces include: grass, milk weed, oxalis. Primary production helps to maintain the ecosystem, both terrestrial and aquatic. Factors that involve primary production includes sunlight, air, water. Living systems produce energy rich organic substances from low energy inorganic substances in primary production..