C3 plants involve direct carbon fixation of CO2. C3 plants must be in areas where CO2 concentration  is high, temperature and light intensity are moderate, and the ground water is abundant. The stomata is closed in hot areas to prevent water loss. A palm tree is a good example of a C3 plant. They are usually found in moderate temperature areas.

predation is where a predator feeds on its prey. Predators may or may not kill its prey prior to feeding on them, but the act of it always results in the death of its prey. Seaguls searching and feeding on fish, like in this picture is a good example of predation.

A population is a group of organisms, living in a certain area. The organisms are able to interbreed. It also refers of a given species in a community of living things. The population of algae is found in a certain are such as lakes and oceans.

Radial symmetry is when the organisms resemble a pie where several cutting planes produce roughly identical pieces. It exhibits no right or left sides. Starfish have radial symmetry. Even thought some say they are bilateral, they are only bilateral when are larvae.

An autotroph is an organism that produces its own food, using energy from light (photosynthesis). They are producers in a food chain, such as plants and algae. Plants are autotrophs.