Khan Academy
Khan Academy: Prokaryote Metabolism
Learn how prokaryotes get energy and nutrients, and find out the difference among chemotrophs, phototrophs, heterotrophs and autotrophs.
CK-12 Foundation
Ck 12: Life Science: 5.3 Bacteria Nutrition
Learn about different types of bacteria and the ways they get nutrition.
BiologyWise
Biology Wise: Facts About Autotrophs and Heterotrophs
Explains what autotrophs and heterotrophs are, the several types of each, their roles in an ecosystem's food chains, and the differences between them.