Food

Question 1

What does a balanced diet consist of?

Answer 1

Should include appropriate proportions of:

1. Carbohydrates
2. Lipids
3. Proteins
4. Minerals
5. Vitamins
6. Water
7. Dietary Fibre

Question 2

What are Carbohydrates?

Answer 2

1. They contain carbon, hydrogen and oxygen
2. Provide substances for respiration, and so provide energy and may reduce cholesterol
3. Makes up 5% of body mass
4. E.G potato, rice and wheat, pasta, sugar

Question 3

What are sugars?

Answer 3

• They are a type of carbohydrate
• They are soluble in water
• Simple sugar is a monosaccharide e.g. glucose and fructose
• disaccharide e.g. maltose, sucrose and lactose
• If you have too much sugar you may have diabetes or tooth decay

Question 4

What is the test for sugar (glucose)?

Answer 4

Add 5cm cubed of Benedict’s solution, place in a water baths and the light blue will turn to brick red if sugar is present

Question 5

What is starch?

Answer 5

• Starch is a large complex carbohydrate
• They are insoluble in water
• Made up of hundreds of glucose molecules and so it is a polymer of glucose
• It is a polysaccharide (made up of simple sugars bonded together)
• Has to be broken down into simple sugars during digestion, so that they can be absorbed into the blood

Question 6

What is glycogen?

Answer 6

• Glycogen is a large complex carbohydrate
• Polymer of glucose
• Found in liver and muscles, where it acts as a store of energy for these organs
• Has to be broken down into simple sugars during digestion, so that they can be absorbed into the blood

Question 7

What is cellulose?

Answer 7

• Polymer of glucose
• Makes up plant cell walls
• Human cannot digest, however it form dietary fibre or roughage

Question 8

What is the test for starch?

Answer 8

Place a sample in a spotting tile, add iodine and if turns from brown to bluey/black starch is present

Question 9

What are lipids (fats and oils)?

Answer 9

1. There are two forms solid (butter) and liquid (oil)
2. They contain carbon, hydrogen and oxygen
3. Makes up 10% of body mass
4. Provide energy, act as an energy store and they provide, insulation, protection, buoyancy and release energy
5. E.G butter, milk, cheese, eggs, nuts, oily fish

Question 10

What are lipids made up of?

Answer 10

A triglyceride

One glycerol and 3 fatty acid

Question 11

What happens when lipids are digested?

Answer 11

Glycerol and fatty acids are absorbed into the bloodstream

Question 12

What happens if you have too much lipids?

Answer 12

Can lead to heart disease

Question 13

What is the test for lipids?

Answer 13

Add ethanol, shake and if lipids are present ethanol will turn cloudy

Question 14

What are proteins?

Answer 14

1. They make up 18% of body mass
2. They are made up of long chains of amino acids, there are 20 different types of amino acids all containing, hydrogen, oxygen, carbon and nitrogen and 2 contain sulphur, there are lots of different combinations for different purposes
3. They help for growth and cell repair (repair of tissue) and help to provide energy in emergencies
4. E.G. meat, fish, eggs and proteins

Question 15

What happens if you have too little protein?

Answer 15

Kwashiorkor

Question 16

What is the test for protein?

Answer 16

5cm cubed of protein and 5cm cubed of Biuret solution, blue to purple if protein is present

Question 17

Describe Calcium

Answer 17

1. Source: milk, cheese, eggs
2. Role: Teeth and bone development
3. Deficiency: hypocalcemia and rickets

Question 18

Describe Iron

Answer 18

1. Source: liver, eggs, spinach, red meat
2. Role: needed to make haemoglobin in RBC for healthy blood to help carry oxygen
   - Deficiency: anemia

Question 19

Describe Water

Answer 19

1. Source: food and drink
2. Role: almost every bodily function relies of water, need a constant supply to replace the water lost through urinating, breathing and sweating

Question 20

Describe Dietary Fibre

Answer 20

1. Source: wholemeal bread

2. Role: aids the movement of food through the gut

Question 21

Describe Vitamin A

Answer 21

1. Source: liver, butter, carrots
2. Role: keeps the cells in the eye healthy and protects the surface of the eye and connective tissue, helps to improve vision and keep your skin and hair healthy, makes chemicals in the retina
3. Deficiency: night blindness and damaged cornea

Question 22

Describe Vitamin B

Answer 22

• Source: cereals, eggs, fish
• Role: helps will cell respiration
• Deficiency: dry skin, mouth sores, anaemia

Question 23

Describe Vitamin C

Answer 23

1. Source: fresh fruit and vegetables e.g. orange
2. Role: helps heal, sticks together cells lining surfaces in the body such as the mouth, prevent scurvy
3. Deficiency: scurvy

Question 24

Describe Vitamin D

Answer 24

1. Source: fish liver oils, eggs
2. Role: helps bones absorb calcium and phosphate, Vitamin D is also made by your body when your skin is exposed to sunlight
3. Deficiency: rickets, poor teeth

Question 25

How do the energy requirements vary in different people?

Answer 25

1. Activity level: active people need more energy
2. Age: children and teenagers need more energy than older people as they need to grow and they are generally more active
3. Pregnancy: pregnant woman need more energy than other woman, and they need to provide the energy that their babies need to develop

Question 26

How do you test for the energy in food?

Answer 26

• Food can be burnt to see how much energy it contains (calorimetry)
  1. You need a dry food that will burn well for example a peanut or pasta
  2. Then weigh a small amount of the food and then skewer it on a mounted needle
  3. Next add 25 cm cubed of water to a boiling tube which is held with a clamp (to measure the amount of heat energy that is released when the food is burnt)
  4. Measure the temperature of the water
  5. Then set fire to the food by placing it over a bunsen burner (make sure that the water isn’t near as may affect results)
  6. Immediately hold the burning food under the boiling tube until it goes out. Then relight the food and hold it under the tube, keep doing this until the food won’t catch fire again
  7. Then measure the temperature of the water
  8. Finally calculate the amount of energy in the food

Question 27

How would you calculate the amount of energy in the food?

Answer 27

energy of food (J) = mass of water (g) x temperature change of water (℃) x 4.2
(1 cm cubed of water is the same as 1g of water)

Question 28

How would you calculate the amount of energy in Joules per gram?

Answer 28

energy per gram of food (J/g) = energy of food (J) / mass of food (g)
-You need to do this calculation so that you can compare the energy values of different foods fairly

Question 29

How can the accuracy of this experiment be increasing?

Answer 29

• Quite a lot of energy released from burning is lost to the surroundings, hence why energy value on packet would be much higher than your own
• No constant distant, did not account for sut building up (use new test tube each time?), time the different chips were under fire i.e more time to heat up??
• Insulate the boiling tube e.g. with foil would minimise heat loss and keep more energy in the water, making your results more accurate.
• Room at constant temperature

Question 30

How is the energy in food measured? How do you work out BMI?

Answer 30

In Kilojoules
Mass (Kg) / Height (m) sqaured
Body Mass Index works better over 18-20 as doesn’t take into account age (i.e. may still be growing), sex, body size, level of physical activity (muscle weighs more than fat)

Question 31

What is the structure of carbohydrates, proteins and lipids?

Answer 31

1. Large molecules made up from smaller basic units
   - Starch and glycogen from simple sugar
   - Protein from amino acids
   - Lipids from fatty acids and glycerol