Food and Digestion Flashcards

1
Q

What does the process of breaking down food involve?

A

Ingestion, digestion, absorption, assimilation and egestion

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2
Q

What is the role of bile? Where is it produced and stored?

A

It neutralises stomach acid and emulsifies fats

Produced by the liver and stored in the gall bladder

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3
Q

How does the structure of the villus help absorption of the products of difestion in the small intestine?

A

There’s a really big surface area for absorption, because the walls of the small intestine are covered in millions and millions of tiny projections called villi

Each cell on the surface of a villus also has its own microvilli - little projections that increase the surface area even more

Villi have a single permeable layer of surface cells (one cell thick) and a very good blood supply (network of capillaries) to assist quick absorption

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4
Q

What is digestion?

A

The breakdown of large insoluble molecules to smaller soluble ones

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5
Q

What is the alimentary canal?

A

A muscular tube which runs from your mouth to your anus and all the organs

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6
Q

How does food move through your gut?

A

By peristalsis - waves of muscular contraction

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7
Q

What is the function of the stomach?

A

It pummels the food with its muscular walls

It produces the protease enzymes, pepsin

It produces hydrochloric acid to kill bacteria and to give the right pH for pepsin (pH2 - acidic)

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8
Q

What is the function of the small intestine?

A

It produces proteases, amylase, maltase and lipase enzymes for digestion

This is where nutrients are absorbed out of the alimentary canal into the body

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9
Q

What is the function of the pancreas?

A

Produces protease, amylase and lipase enzymes for digestion

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10
Q

How would you test for glucose?

A

Add Benedict’s reagent (which is blue) to a sample and heat it.

Make sure the solution doesn’t boil.

If the test’s positive it will form a coloured precipitate

The colour of precipitate goes from blue to green to yellow to orange to brick red

The higher the concentration of glucose, the further the colour change goes - you can use this to compare the amount of glucose in different solutions

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11
Q

How would you test for starch?

A

Iodine solution will turn from orange brown to blue-black if starch is present

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12
Q

Test for protein?

A

Biuret reagent will turn from light blue to lilac

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13
Q

What is assimilation?

A

When digested molecules have been absorbed, they’re moved into body cells and are used to build new parts of cells

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14
Q

What are faeces?

A

Semi solid waste material stored in the rectum and ejected from the anus

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15
Q

What is the difference between excretions and egestion?

A

Egestion is the process of getting rid of unused waste materials

Excretion is the removal of metabolic chemical waste

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16
Q

What are the breakdown products of carbohydrase?

A

Glucose

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17
Q

What are the breakdown products in protease?

A

Amino acids

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18
Q

What are the breakdown products of lipase?

A

Fatty acids and glycerol

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19
Q

What is absorption?

A

The products of digestion (food molecules) are absorbed into your bloodstream in the small intestine.

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20
Q

What is egestion?

A

All of the undigested food forms faeces which then leaves the body through the anus

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21
Q

How is the ileum adapted to absorb digested food?

A

The surface area is covered in vlili, which in turn are covered in microvilli. This increases the surface area. Small intestine is folded to increase surface area. Outer surface is just one cell thick. Each villus has a capillary so a good blood supply. Each villus has a lacteal to transport fatty acids and glycerol.

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22
Q

What does amylase do? Where is this enzyme produced? where does it act?

A

Turn starch to maltose.

This is excreted by the salivary glands and acts in the mouth OR is produced by the panreas and acts in the small intestine.

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23
Q

What does maltase do? Where is this enzyme produced? where does it act?

A

Turns maltose to glucose.

Produced in the walls of the small intestine and acts in the small intestine.

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24
Q

What do proteases do? Where is this enzyme produced? where does it act?

A

Turn proteins to amino acids. Pepsin is produced in the stomach wall and acts in the stomach.

Others are produced in the pancreas and work in the small intestine.

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25
Q

What does lipase do? Where is this enzyme produced? Where does it act?

A

Turns lipids into fatty acids and glycerol.

It is produced in the pancreas and acts in the small intestine.

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26
Q

Describe an experiement to measure the energy content of food (calorimetry)

A

Food can be burnt to see how much energy it contains
1) weigh a small amount of dry food (peanuts/crisps) and put it on a needle
2) add 25cm3 to a boiling tube held with a clamp
3) measure the temperature of the water and using a Bunsen burner set fire to the food
4) hold the burning food under the boiling tube until it goes out
5) continue to relight the food and burn it until it will no longer relight
Then measure the temperature of the water again

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27
Q

How do energy requirements vary in different people?

A

The amount of energy each person needs is different. There are 3 things it depends on:
ACTIVITY LEVEL: Active people need more energy than people who sit around all day
AGE:children and teenagers need more energy than older people. They need energy to grow
PREGNANCY: pregnant women need more energy than other women as they’ve got to provide the energy their babies need to develop

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28
Q

Name four types of sugars

A

fructose

sucrose

glucose

lactose

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29
Q

Name a protein deficiency disease

A

kwashiorkor

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30
Q

What is the function of the oesophagus?

A

It is a muscular tube that conencts the mouth and stomach

31
Q

What is mechanical digestion?

A

Where teeth bite and chew food, cutting it into smaller pieces that have a large surface area so enzymes can act on food more quickly and stomach muscles

32
Q

What parts of your body break down foods using enzymes?

A

The mouth, the stomach and the duodenum.

33
Q

What are the three classes of enzymes and what do they each break down?

A

Carbohydrases act on carbohydrates. Proteases act on proteins. Lipases break down lipids.

34
Q

What enzyme does saliva contain?

A

Amylase.

35
Q

What are examples of carbohydrases and what digestive action does it have and where?

A

Amylase turns starch to maltose, it is produced by the salivary glands to act in the mouth and in the pancreas to act in the small intestine. Maltase turns maltose into glucose, produced in the small intestine and acts in the small intestine.

36
Q

Examples of proteases and what they do

A

Pepsin turns proteins into peptides. Tripsin turns proteins into peptides. Peptidases turns peptides into amino acids.

37
Q

How can pepsin work in the stomach?

A

Though the stomach is very acidic pepsin has an optimum pH of about 2.

38
Q

Function of the large intestine?

A

To absorb most of the remaining water from the contents, leaving a semi solid waste material called faeces.

39
Q

Why do humans need food?

A

To supply with fuel and to provide materials for growth and repair.

40
Q

What should a balanced diet include?

A

Appopriate portions of carbohydrate, protein, lipids, vitamins, minerals, water an dietary fibre

41
Q

What are proteins made up of?

A

Amino acids

42
Q

What are lipids made up of?

A

Fatty acids and glycerol

43
Q

What chemical elements make up carbohydrates?

A

Carbon, hydrogen and oxygen

44
Q

What chemical elements make up protein?

A

Carbon, hydrogen, oxygen and nitrogen

45
Q

What chemical elements make up lipids?

A

Carbon, hydrogen and oxygen

46
Q

What are proteins made up of?

A

Long chains of amino acids which all contain carbon, hydrogen, nitrogen and oxygen atoms

47
Q

What are lipids made up of?

A

Fatty acids and glycerol

48
Q

Sources of carbohydrates

A

Pasta, rice, sugar, fruit

49
Q

Sources of protein

A

Meat, fish, cheese, milk

50
Q

Sources of lipids

A

Butter, oily fish, olive oil, nuts

51
Q

Sources of the minerals calcium and iron

A

Calcium - dairy products, fish, vegetables

Iron - red meat, eggs, spinach

52
Q

Sources of vitamin A, C and D

A

Vitamin A - carrots, liver, butter

Vitamin C - fresh fruit and vegetables

Vitamin D - found in fish liver oils, also made in skin in sunlight

53
Q

What is the function of carbohydrates?

A

Supplying cells with energy

54
Q

What is the function of proteins?

A

Needed for growth and repair of tissue, and to provide energy in emergencies

55
Q

What is the function of lipids?

A

Essential to cellular structure, provides energy, acts as an energy store, provides insulation

56
Q

What unit is energy content measured in?

A

Kilojoules

57
Q

What is the function of calcium?

A

Making teeth and bones

58
Q

What is the function of Vitamin A?

A

It makes a chemical in the retina and protects the surface of the eye - helps to improve vision

Keeps your skin and hair healthy

59
Q

What is the function of Vitamin C?

A

Sticks together cells lining surfaces such as the mouth - prevents scurvy

60
Q

What is the function of Vitamin D?

A

Helps bones absorb calcium

61
Q

What is the function of iron?

A

Needed to make haemoglobin in the red blood cells, helps carry oxygen

62
Q

What is the function of water?

A

Almost every bodily function relies on water - we need a constant supply to replace water lost through urinating, breathing and sweating

63
Q

Sources of water

A

food and drink

64
Q

What is the function of dietary fibre?

A

Aids the movement of food though the gut (peristalsis)

65
Q

Source of dietary fibre

A

wholemeal bread

66
Q

Why does peristalsis occur?

A

To squeeze balls of food through the gut otherwise it would get clogged up with food

67
Q

What is the calcuation for the amount of energy in the food?

A

1) calculate the amount of energy in joules

energy in food (J) = mass of water (g) x temperature change of water x 4.2

2) calculate the amount of energy in joules per gram:

energy per gram of food (J/g) = energy in food (J) / mass of food (g)

68
Q

How can the accuracy of the calorimetry experiment be increased?

A

Quite a bit of energy released from burning is lost to the surroundings - insulating the boiling tube e.g. with foil, would minimise heat loss and keep more energy in the water making your results more accurate

69
Q

What is ingestion?

A

Putting food or drink into your mouth

70
Q

What is chemical digestion?

A

Enzymes and bile

71
Q

What is the function of the mouth?

A

1) Salivary glands in the mouth produce amylase enzyme in the saliva
2) Teeth break down food mechanically

72
Q

Describe the structure of carbohydrates

A

Starch and glycogen are large, complex carbohydrates, which are made up of many smaller units from simple sugar (e.g. glucose or maltose molecules) joined together in a long chain

73
Q

What is the general structure of carbohydrates, proteins and lipids?

A

large molecules made up from smaller basic units

74
Q

What is the role of enzymes?

A

They act as biological catalysts in metabolic reactions