MYP Biology 4.1 Nutrition Notes

What Is Nutrition and Why Do Organisms Need It?

1. Nutrition is the process of taking in substances organisms need for survival.Food supplies two essential things:
   1. Energy, to power every process inside cells.
   2. Materials, to build and repair body structures.
2. No organism can make every molecule it needs. Food fills those gaps.

How Does the Body Know When It Needs Food?

1. The body constantly monitors its internal energy and nutrient levels.
2. Falling levels trigger hunger signals from the brain.
3. Cravings appear when specific nutrients are low.
   1. Low energy often causes cravings for carbohydrate-rich foods.
   2. Low mineral levels may lead to cravings for salty foods.
4. These signals help the body keep its internal conditions balanced.

What Nutrients Does the Body Need?

Food contains several nutrient groups, each playing a distinct role.

1. Carbohydrates
   1. Main source of immediate energy.
   2. Broken down into glucose.
   3. Extra glucose is stored as glycogen.
2. Fats
   1. Provide long-term energy storage.
   2. Insulate the body and protect organs.
   3. Form a key part of cell membranes.
3. Proteins
   1. Needed for growth and repair.
   2. Build enzymes and hormones.
   3. Can be used for energy in emergencies.
4. Vitamins
   1. Needed in small amounts.
   2. Help enzymes function.
5. Minerals
   1. Simple elements needed for reactions.
6. Water
   1. Medium for chemical reactions.
   2. Helps with temperature control and transport.

How Does Food Become Usable Energy?

1. Food must be broken into smaller molecules before cells can use it.
2. Carbohydrates become glucose, which enters the bloodstream.
3. Cells release energy from glucose through respiration.
4. This energy powers everything from movement to growth.

What Is Energy Balance?

1. The body must match the energy it takes in with the energy it uses.
2. If intake is higher, excess energy is stored as fat.
3. If intake is lower, the body uses stored reserves.
4. Energy needs depend on activity, age, and body size.

Why Do Different Organisms Have Different Nutritional Needs?

1. Nutritional requirements depend on size, environment, and activity level.
2. Fast-moving animals need more ready-to-use energy.
3. Growing organisms need more protein for tissue formation.
4. Animals in cold habitats rely on fats for insulation.
5. Some species require specific minerals based on their environment.

What Happens When the Body Lacks a Nutrient?

1. Not getting enough of a nutrient leads to a deficiency.Deficiencies interfere with vital processes.
   1. Lack of iron reduces oxygen transport.
   2. Lack of vitamin D weakens bones.
   3. Lack of protein slows growth and repair.