Download DIGESTION OF FOOD

WHY IS DIGESTION OF LARGE FOOD MOLECULES
ESSENTIAL?
Animals require food in order to provide energy for cells to do work and to
maintain good health.
Food molecules, often called nutrients, cannot always be used by the body in the
form in which they are ingested. Most food molecules exist as large complex
organic molecules which require breaking down into small simple soluble
molecules which can enter the blood, move around the body (in the blood
circulatory system) and enter cells where they are needed for a particular
function. The process of breakdown is known as digestion.
The nutrients which require digestion are:
1. complex carbohydrates, which are broken down into monosaccharides
2. proteins, which are broken down into amino acids
3. lipids, which are broken down into glycerol and fatty acids.
Nutrients such as vitamins and minerals can be used directly without digestion.
Basically, food molecules cannot be used unless they are simple enough to pass
across plasma membranes. In actual fact, large food molecules must be broken
down into smaller, soluble molecules so they can be absorbed into the
bloodstream.
Make sure you understand why the digestion of large food molecules is essential
KQ 1) Why is it necessary to digest some types of food molecule?
KQ 2) Why do vitamins and minerals not require digestion?
KQ 3) Name a nutrient other than a vitamin or mineral which does not need
digestion.