It is desirable to use biomass, or plant-based materials, as feedstocks for chemical synthesis and energy production. Through photosynthesis plants are able to efficiently capture and store energy from sunlight, and finding ways to use biomass for green chemistry applications is extremely advantageous in advancing the goals of the field. Sources of biomass can be grouped into several categories, including cellulose, lipids, lignin, terpenes, and proteins. Cellulose is often found in structural parts of plants. Lignin is a polymer often found along with cellulose in woodlike parts of plants. Lipids and lipid oils are often extracted from seeds and soybeans. Terpenes are found in pine trees, rubber trees, and a selection of other plants as well. Proteins are found in relatively small quantities in many types of plants and also in larger quantities in animals. Some efforts are also underway to use genetic transplants to create plants that produce increased amounts of proteins. One of the primary challenges in using biological feedstocks to produce chemicals or energy involves separation and purification of the desired materials.