Complete the crossword, then click on "Check" to check your answer. If you are stuck, you can click on "Hint" to get a free letter. Click on a number in the grid to see the clue or clues for that number.

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 Check 

Across: 1. Chemical process by which energy is released from food using oxygen. (7,11) 3. Member of the group of foods that includes sugar and starch. (12) 4. Apparatus used to measure the energy content of a food. (11) 7. Sum of all chemical reactions that occur in an organism and keep it alive. (10) 8. Energy-rich food containing double the chemical energy of protein and carbohydrate. (3) 9. One of about twenty types of building blocks that make up proteins. (5,4) 11. Fuel food. (7) 12. Turns milky in the presence of carbon dioxide. (4,5) 13. Gas essential for aerobic respiration. (6)

Down: 2. Waste product of respiration. (6,7) 5. Type of energy released by respiration. (4) 6. Unit used to measure energy. (9) 10. Food essential for growth. (7)