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Exothermic Reactions

Chemical reactions that release energy as a product.

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Energy for Life

Energy for Life

Credit: U.S. Navy photo by Journalist 3rd Class Stephen P. Weaver.
Source: http://commons.wikimedia.org/wiki/File:US_Navy_031112-N-5821W-001_Lt._Ian_Johnston,_assigned_to_NAS_Sigonella's_Tactical_Support_Center_practices_the_breast_stroke_in_NAS_Sigonella's_NAS_II_pool.jpg
License: CC BY-NC 3.0

This swimmer grabs a breath as he competes in the breaststroke. He needs that breath to help his cells get energy because swimming burns up a lot of energy. What does breathing have to do with cells using energy? Everything!

Why It Matters

  • Cells of living things need energy for all life processes. Whether you’re just sitting still or swimming competitively, all of your cells need energy. In fact, your cells need energy just to stay alive.
  • Cells can’t make their own energy. Energy can’t be created or destroyed. It can only change form.
  • Credit: Ben Mills
    Source: http://en.wikipedia.org/wiki/File:ATP-xtal-3D-balls.png
    License: CC BY-NC 3.0

    Cells use energy in the form of ATP (above) [Figure2]


  • How do your cells get energy? You can find out with the interactive animation “Where Do You Get Your Energy?” at this link: http://www.exploratorium.edu/traits/cell_explorer.html

Explore More

At the link below, explore the process of cellular respiration. Then answer the questions that follow.

  1. What form of energy do cells use?
  2. What molecule do cells use for energy?
  3. Glucose is the energy molecule that enters cells from the bloodstream. Cells can’t use glucose for energy. What happens to the glucose that enters cells?
  4. Where does glucose get its energy? How do plants and animals get glucose?
  5. How efficient is cellular respiration? How does its efficiency compare with burning gasoline? What happens to the energy that isn’t converted to usable form?
  6. Which type of process is cellular respiration: endothermic or exothermic? Explain.
  7. How do cells use ATP?


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