growth factor: a protein that is involved in cell differentiation and growth
protein: any of a large group of nitrogenous organic compounds that are essential constituents of living cells; consist of polymers of amino acids; essential in the diet of animals for growth and for repair of tissues; can be obtained from meat and eggs and milk and legumes
green algae: algae that are clear green in color; often growing on wet ricks or damp wood or the surface of stagnant water