Khan Academy: Energy and Transport: Hypotonic, Isotonic, and Hypertonic Solution

Video lesson looks at hypotonic, isotonic and hypertonic solutions (tonicity) and seeing the effect of various types of solution on the direction of osmosis. [6:29]

Take this nine-question unit test over energy and transport.

Osmosis of water from an area of lower to an area of higher solute concentration across a semipermeable membrane. [8:03]

Introduction to passive and active transport. [8:06]

A concentration gradient occurs when the concentration of particles is higher in one area than another. In passive transport, particles will diffuse down a concentration gradient, from areas of higher concentration to areas of lower...

Enzymes as catalysts for reactions in biological systems; discussion of substrates, active sites, induced fit, and activation energy. [8:12]

Introduction to cellular respiration, including glycolysis, the Krebs Cycle, and the electron transport chain. [14:19]

Learn more about ATP: how it stores energy, and how that energy is released when it's converted to ADP and phosphate. [6:19]

The quest for energy has always been a balancing act. As humans have gained greater control over their environment, they've found abundant resources - and faced numerous challenges. This article traces the history of our quest for energy.

An information page about activation energy. Learn about activation energy, transition states, and reaction rates.