Question

The complete digestion of starch in humans yields 4 kilocalories per gram. What is the energy yield for cellulose in humans?

a) 4 kilocalories per gram
b) 0 kilocalories per gram
c) 2 kilocalories per gram
d) 8 kilocalories per gram

Answer 1

Humans cannot digest cellulose due to the lack of necessary enzymes, so cellulose provides 0 kilocalories per gram. Starch, on the other hand, is digested into glucose yielding 4 kilocalories per gram.

Step-by-step explanation:

The energy yield for cellulose in humans is 0 kilocalories per gram. Humans lack the enzyme necessary to digest cellulose, which is the main component of dietary fiber. While the complete digestion of starch yields 4 kilocalories per gram as it is broken down into glucose units that can be absorbed by the human body, cellulose passes through the digestive tract without being broken down into absorbable nutrients, providing no caloric energy. Therefore, the correct answer is b) 0 kilocalories per gram.