Biology Unit 4.1: Nutrients

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Unit 4.1 Nutrients

1. List the chemical elements that make up:
• carbohydrates,
• fats,
• proteins.

Carbohydrates: starch, glucose
Fats: glycerol and fatty acids
Proteins: long chains of amino acids

2. Define nutrition as taking in of nutrients which are organic substances and mineral ions, containing raw materials or energy for growth and tissue repair, absorbing and assimilating them.

3. Describe the structure of large molecules made from smaller basic units, i.e.
• simple sugars to starch and glycogen,
• amino acids to proteins,
• fatty acids and glycerol to fats and oils.

This is basically point 1, but it goes into a bit more detail on structure.

4. Describe tests for:
• starch (iodine solution),
• reducing sugars (Benedict’s solution),
• protein (biuret test),
• fats (ethanol).

Iodine: tests for starch, blue-black if present, brown if not
Benedict's solution: tests for glucose, brick red if present, blue if not
Biuret test: tests for protein, purple if present, blue if not
Ethanol: tests for fats, will emulsify if present, won't if not

5. List the principal sources of, and describe the importance of:
• carbohydrates,
• fats,
• proteins,
• vitamins (C and D only),
• mineral salts (calcium and iron only),
• fibre (roughage),
• water.

Carbohydrates provide our bodies with energy. They can be found in food products such as rice, noodles, bread and potatoes. Fats also provide our bodies with energy, and they help our bodies absorb a multitude of vitamins. They can be found in plants and fish, such as lentil beans and salmon. Proteins come from meat, fish and eggs; they help our bodies with processes of growth and repair.

Vitamin C can be found in citrus fruits and is used for maintaining healthy skin and absorbing iron. A vitamin C deficiency is called scurvy. Vitamin D comes from oily fish, and it helps to absorb calcium and maintain strong bones. A deficiency in vitamin D is rickets.

Calcium comes from milk, and it helps maintain the strength and health of bones. A person would have weak bones without the intake of calcium. Iron can be found in red meats, and is used to produce haemoglobin. Anaemia is a vitamin D deficiency.

Fibre is used to prevent constipation, by adding bulk to faeces. It can be found in wholegrain foods, fruits and vegetables, and nuts.

Water makes up 70% of the human body. It has many important roles, such as transporting nutrients around the body and regulating body temperature. If a person doesn't intake enough water, they will become dehydrated.

6. Describe the use of microorganisms in the manufacture of yoghurt.

1. Milk is heated to be pasteurised
2. After the milk has cooled, bacteria called Lactobacillus bacteria is added. This breaks down lactose in milk to form lactic acid.
Lactic acid lowers the pH of the yoghurt so it doesn't go off, and denatures milk proteins, which gives yoghurt its sharp taste.

7. Describe the deficiency symptoms for:
• vitamins (C and D only),
• mineral salts (calcium and iron only).

Refer to point 5!