Biology, Eighth Edition (Raven)

Chapter 48: The Digestive System

Bomb Calorimeter

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 C. 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.

View the animation below, then complete the quiz to test your knowledge of the concept.


1.	In a bomb calorimeter the food chamber is filled with

		A)	nitrogen.
		B)	water.
		C)	carbon dioxide.
		D)	oxygen.

2.	The amount of heat necessary to raise 1 kilogram of water by 1 degree Celsius is

		A)	1 kcal.
		B)	the density of water.
		C)	the heat chamber.
		D)	the heat difference.

3.	178 grams of salmon has

		A)	20 kcals.
		B)	365 kcals.
		C)	225 kcals.
		D)	195 kcals.

4.	A 61 gram tomato has

		A)	20 kcals.
		B)	365 kcals.
		C)	225 kcals.
		D)	195 kcals.

5.	56 grams of cheddar cheese has

		A)	20 kcals.
		B)	365 kcals.
		C)	225 kcals.
		D)	195 kcals.