Chapter 4: Food & Digestion

Question 1

Three reasons we need food?

Answer 1

i) Supply us with fuel for energy ii) provide materials for growth and repair of tissues iii) help fight disease and keep bodies healthy

Question 2

Diet must include which five groups of food?

Answer 2

Carbohydrates, lipids proteins, minerals, vitamins…as well as water & fibre

Question 3

What % do carbohydrates make up of the mass of the human body?

Answer 3

5%

Question 4

What do carbohydrates do?

Answer 4

They are the body’s main ‘fuel’ for supplying cells with energy

Question 5

What are the main types of carbohydrates?

Answer 5

Starch is found in cereals, cornflour, potatoes, pasta and flour. Sugar is found in fruit (fructose), vegetables, honey, milk (lactose) and malt products

Question 6

What are lipids?

Answer 6

Lipids are fat and oils…make up 10% of our body’s mass

Question 7

What is role of lipids?

Answer 7

They from part of the structure of your cells and are used as long term stores of energy

Question 8

What are lipids made up of?

Answer 8

Lipids are made of two main types of molecule: glycerol and fatty acids. (Too much lipid is unhealthy, especially saturated fat and cholesterol. These can cause heart disease.)

Question 9

What % of mass of body do proteins make up?

Answer 9

18%…the second largest fraction after water

Question 10

What foods are protein rich?

Answer 10

Meat, fish, cheese and eggs

Question 11

What are proteins for?

Answer 11

They do most of the work in cells and are required for the structure, function, and regulation of the body’s tissues and organs. Different proteins have different functions

Question 12

What are proteins made of?

Answer 12

Proteins are made from long chains of 20 different amino acids.

Question 13

Why do we need minerals in our bodies?

Answer 13

Minerals are needed in small amounts to help the body function properly and stay strong. Calcium and iron are two important minerals.

Question 14

Name six type of minerals in our bodies

Answer 14

Calcium, phosphorus, sodium, chlorine, magnesium, iron

Question 15

What are examples of mineral deficiency diseases?

Answer 15

Rickets: not enough calcium; anaemia: not enough iron

Question 16

What are vitamins and why are they important?

Answer 16

A group of organic compounds which are essential for normal growth and nutrition and are required in small quantities in the diet because they cannot be synthesized by the body.

Question 17

What are the different types of vitamins, what are they good for and what are their sources?

Answer 17

Vitamin A - good vision - healthy skin - growth (green and yellow vegetables, dairy products) Vitamin B (thiamin, riboflavin and niacin) - release of energy from foods - healthy skin (breads, milk, eggs) Vitamin B12 - red blood cells - meat - milk - fish Vitamin C - healthy skin - protects cells - helps absorb iron (fruit, vegetables) Vitamin D - helps absorb calcium - strong teeth and bones (margarine, oily fish)

Question 18

How do you test for glucose?

Answer 18

Glucose + water + drops of Benedict’s solution…heated. Liquid goes from blue to orange

Question 19

How do you test for starch?

Answer 19

Starch + iodine…goes from red to black

Question 20

What is energy from food?

Answer 20

Food energy is chemical energy that animals (including humans) derive from food through the process of cellular respiration.

Question 21

How do you measure the energy of a food?

Answer 21

The energy content in a food sample can be measured using simple calorimetry (=measuring the amount of heat given out or taken in by a process, such as the combustion of a fuel) Process: 1. pour cold water into a boiling tube 2. record the starting temperature of the water 3. record the mass of the food sample 4. heat the food until it catches fire 5. heat the water using the flame from the burning food 6. record the final temperature of the water Work out the energy transferred to the water with this equation: energy transferred (J) = mass of water (g) × 4.2 (J/g°C) × temperature increase (°C) e.g. When 0.5 g of food is burned, 10 cm3 of water warms up by 20°C. What is the energy content of the food in J/g? Answer: - 1 cm3 of water has a mass of 1 g - energy transferred to water = 10 × 4.2 × 20 = 840 J - energy content of food = 840 ÷ 0.5 = 1680 J/g

Question 22

What is digestion?

Answer 22

Digestion is the breakdown of large molecules into smaller, soluble molecules that can be absorbed into the body. Digestion happens inside the gut, and relies on enzymes.

Question 23

What do enzymes do?

Answer 23

Digestion is speeded up by enzymes

Question 24

What also helps chemical digestion?

Answer 24

Physical digestion…mouth, muscles in wall of stomach churn up food

Question 25

What do the muscles of the intestine do?

Answer 25

There are two types of muscles: circular & horizontal….they expand & contract = peristalsis

Question 26

What is the duodenum

Answer 26

the mouth, stomach and first part of small intestine

Question 27

What is the ileum?

Answer 27

the last part of the small intestine where the digested food is absorbed…it has a very large surface area (tiny projections known as villi that increase surface area…c 300m2!!) = food absorbed quickly and efficiently into the blood

Question 28

What does the large intestine do?

Answer 28

Absorbs water out of the remains and stores the poo-poo…oh yes the big bad poo pop. Guy, you know all about poo poo, dont you?

Question 29

What are the three types of digestive enzymes?

Answer 29

Amylase (produced in salivary glands, pancreas, small intestine) turns starch → sugars Protease (produced stomach, pancreas, small intestine) turn proteins → amino acids Lipase (produced pancreas, small intestine) turns Lipids → fatty acids + glycerol

Question 30

What goes on in the stomach?

Answer 30

Stomach walls secretes hydrochloric acid…v acidic…it kills bacteria & protects from food poisoning

Question 31

What role does bile and pancreatic juice play?

Answer 31

They are alkaline and neutralises the acid going down the guy

Question 32

Large colon, faeces, rectum, anus…

Answer 32

oh yes…more pooopooo