A plant physiologist studies a large variety of plant processes, such as how chemicals are transported throughout the plant, how plants capture the energy from the sun, and how plants defend themselves from attack by microbes or insects. Plant physiologists also study the process of plant growth and development: how plant cells perceive their place and role within the plant, how factors such as light and gravity affect what plant cells will do, and how plant hormones signal to cells about environmental conditions. Thus, plant physiologists may study the mechanisms by which plants produce compounds of medicinal value or the effect of increased carbon dioxide concentrations or drought stress on plant growth. Such research can lead to identification of medicines, may serve to determine how plants respond to the proposed greenhouse effect, and may be used to create plants resistant to drought stress. Overall the study of plant...