Gymnosperm leaf: this is a leaf of a gymnosperm plant, or a plant that has seeds not enclosed in an ovary, like pine trees.
Population: a population is a group of organisms living together in the same place at the same time and all sharing a common gene pool, like these trees in the forest.
Commensalism: a symbiotic relationship where one species benefits and the other is not bothered. For example, the flies on this cow are eating other bugs on the cow's skin while the cow just sits there and is not affected by the flies.
Predation: when organisms kill and consume other organisms, for example, these herons are trying to catch fish to eat for their breakfast.
Prokaryote: a prokaryotic organism is one that lacks a membrane bound nucleus and organelles. Bacteria is the most common form and clorox gets rid of many household bacterium.