You will hear a lecture. After listening to the lecture, in 10 seconds, please speak into the microphone and retell what you have just heard from the lecture in your own words. You will have 40 seconds to give your response.

Current Status:

Beginning in 3 seconds

Rate速率

0.4 0.8 1 1.5 2.0

Skip

Current Status:

Beginning in seconds

Finish

Answer

 Why does burning a food item provide information about its value as a food? The nutritional value of food can be measured on many different scales. The most basic measurement scale is the free energy content of the food. In other words, how much energy is released when chemical bonds within the food are broken? The energy content of food is measured in calories, the amount of kinetic energy required to raise the temperature of one ml of water, one degree. Food is burned under controlled conditions, breaking chemical bonds and releasing free energy. The burning is chemically similar to the breakdown of food in cellular respiration although the process occurs much more quickly and in a less controlled fashion during ignition. Calorimeter can measure the energy in food, but can not measure the digested energy of what we have.