Benchmark 5E
The Living Environment: Flow of Matter and Energy
Grades 6-8, page 120

Energy can change from one form to another in living things. Animals get energy from oxidizing their food, releasing some of its energy as heat. Almost all food energy comes originally from sunlight.

NSES Content Standard C
Life Science: Populations and ecosystems
Grades 5-8, page 158
For ecosystems, the major source of energy is sunlight. Energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis. That energy then passes from organism to organism in food webs.

NSES Content Standard C 
Life Science: The cell
Grades 9-12, page 184
Plant cells contain chloroplasts, the site of photosynthesis. Plants and many microorganisms use solar energy to combine molecules of carbon dioxide and water into complex, energy rich organic compounds and release oxygen to the environment. This process of photosynthesis provides a vital connection between the sun and the energy needs of living systems.

NSES Content Standard C 
Life Science: Matter, energy, and organization in living systems
Grades 9-12, page 186
The chemical bonds of food molecules contain energy. Energy is released when the bonds of food molecules are broken and new compounds with lower energy bonds are formed. Cells usually store this energy temporarily in phosphate bonds of a small high-energy compound called ATP.