Question

Metabolism Essay Question (10 pts)

According to the law of conservation of matter, matter is neither created nor destroyed. This means that the same number and type of atoms exist after a chemical change as were present before the chemical change.

So . . .

1. When someone goes on a diet and loses weight, what happens to the body fat that they lose? Where does it go? What do the molecules of fat turn into? (5 pts)

HINT: If you are tempted to say that it “turns into energy” STOP! Matter does NOT “turn into” energy. Energy can be released during chemical reactions . . . but the atoms are still there, just rearranged into different (and usually smaller) molecules!

2. How would going on a diet that severely restricted carbohydrate intake affect the answer to Part A above? Explain your answer! (5 pts)

HINT: See the section on “Lipolysis” on page 1011 in your textbook and think about the following questions:

• How and why does carbohydrate availability affect lipid digestion?
• How will this change the end products?

Answer 1

Answer 1:

• The fat present in the body is converted to carbon dioxide and water.
• The carbon dioxide is exhaled and the water enters into circulation until it is lost as urine or sweat.
• If 10kg of fat is loosed, 8.4kg is concerted as carbon dioxide and is exhaled by lungs and the remaining 1.6kg turns into water and is excreted as urine.

Answer 2:

• In the short-term duration, the low-carbohydrate diets may decrease the weight as less energy is produced.
• The body begins to use body glycogen from the liver and muscles which replace the carbohydrates.

Answer 3:

• Lipid breakdown is prevented in presence of carbohydrates and more lipids are stored in the body.
• The end product is accumulation of fats.