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AQA Biology > B3 Organisation And The Digestive System > Flashcards

B3 Organisation And The Digestive System Flashcards

1
Q

Define cell

A

The basic building blocks of all living organisms

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2
Q

Define tissue

A

A group of cells with similar structure and function working together

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3
Q

Define organ

A

Collection of tissues working together to perform a specific function

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4
Q

Define organ system

A

Group of organs that all work together to perform specific functions

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5
Q

Define digestion

A

The breakdown of carbohydrates, proteins and fats into small soluble substances to be absorbed into the blood.

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6
Q

Summarise the digestive system

A

1) Mouth: chews food into smaller pieces so it can be easily digested. Food mixes with saliva so the body can absorb the food. (Amylase enzymes are the primary enzymes in saliva, produced in the salivary glands).
2) Throat
3) Oesophagus: muscular tube which moves ingested food to the stomach by a process called peristalsis
4) Stomach: digestion continues
5) Small Intestine: Food has consistency of a liquid/paste. Continues breaking down food using enzymes released by the pancreas, and bile from the liver. Soluble food molecules are absorbed into the blood.
6) Large Intestine: Undigested food is squeezed into large intestine (by small intestine). Excess water is absorbed from the food into blood, leaving you with faeces.
7) Rectum: Faeces is stored here.
8) Anus: Faeces leave.

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7
Q

Describe 3 ways the stomach helps digestion

A
  • Muscular wall: pummels food
  • Produces protease enzyme pepsin
  • Produces hydrochloric acid which kills bacteria and gives the right pH for the protease enzyme to work (pH 2 - acidic)
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8
Q

What 3 types of tissue is the stomach made of, and how do they help with digestion?

A
  • Muscular tissue: churns food and digestive juices together
  • Glandular tissue: Produces digestive tissues to break down the food
  • Epithelial tissue: Covers inside and outside of the organ
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9
Q

What 3 enzymes does the pancreas produce?

A

Protease, amylase, and lipase enzymes

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10
Q

Where is bile produced?

A

In the liver

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11
Q

Where is bile stored?

A

Gall bladder

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12
Q

What does bile do?

A

Emulsifies fat and eliminates waste products from the blood.

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13
Q

What does the duodenum (part of small intestine) do?

A

Mixes food with digestive enzymes and bile

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14
Q

What does the ileum (part of small intestine) do?

A

Absorbs digested food into the blood and lymph

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15
Q

What does the colon (part of large intestine) do?

A

Reabsorbs water

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16
Q

What does the rectum (part of large intestine) do?

A

Stores faeces

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17
Q

What does the anus (part of large intestine) do?

A

Where faeces leaves

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18
Q

What is the purpose of carbohydrates?

A

Provides us with fuel that makes all of the other reactions of life possible.

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19
Q

What do carbohydrates contain?

A

Carbon, hydrogen, oxygen

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20
Q

What are small carbohydrate units also known as?

A

Simple sugars

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21
Q

Describe the structure of complex carbohydrates

A

Made up of long chains of simple sugar units bonded together

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22
Q

List foods which are rich in carbohydrates

A

Rice, bread, potatoes, pasta

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23
Q

What happens to most of the carbohydrates once we eat them?

A

The carbohydrates are broken down to glucose and are used in cellular respiration to provide energy for metabolic reactions.

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24
Q

Why are lipids important?

A

Most efficient energy store in body and an important source of energy in your diet.

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25
Q

What are lipids made up of?

A

Carbon, hydrogen, oxygen

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26
Q

What are carbohydrates made up of?

A

Units of sugar

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27
Q

Are lipids insoluble or soluble in water?

A

Insoluble

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28
Q

Describe how lipids are made up

A

Made of 3 molecules of fatty acid + 1 molecule of glycerol (the glycerol is always the same; fatty acids vary)

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29
Q

Describe how the make up of lipids will determine whether it will be a liquid oil/solid fat.

A

Different combinations of fatty acids will determine whether the lipid will be a liquid oil/solid fat.

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30
Q

Why are proteins important?

A

Used for building up the cells and tissues of your body and are the basis of all enzymes.

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31
Q

What percentage of body mass is protein?

A

15-16%

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32
Q

What are proteins made of?

A

Carbon, hydrogen, oxygen, nitrogen

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33
Q

List foods which are rich in protein

A

Meat, fish, pulses (beans), cheese

34
Q

Describe the structure of protein molecules (made of what?)

A

Protein molecules are made of long chains of small units called amino acids.

35
Q

How many different amino acids are there?

A

20

36
Q

Describe how different proteins are made

A

Different proteins are a result of different arrangements of amino acids

37
Q

Describe the shape of amino acid chains and how this is useful

A

The chains of amino acids are folded into 3D shapes. These 3D shapes allow other molecules to fit into the protein.

38
Q

List 2 factors that affect the bonds, which hold together the proteins in 3D amino acid shapes

A

Temperature and pH

39
Q

Describe how the 3D shapes of amino acids can be broken, and how can this affect the protein?

A

The bonds that hold the proteins in these shapes are sensitive to temperature and pH, so they can easily be broken. If the shape of the protein is lost, it may not be able to function as it will become denatured.

40
Q

Define catalyst

A

Special chemicals used to speed up reactions but aren’t used up in the reaction.

41
Q

Define enzyme

A

Proteins that act as biological catalysts: they speed up reactions without being used up.

42
Q

An enzyme’s shape is important. Explain why this is true, in terms of amino acids.

A

Long chains of amino acids are folded to produce a molecule with an active site that has a unique shape: it can bind to a specific substrate molecule.

43
Q

What is a substrate?

A

A reactant

44
Q

What is the lock and key theory?

A

An enzyme’s active site and its substrate are complementary in shape.

45
Q

The active site of amylase is only complementary to ______?

A

Starch

46
Q

Define metabolism

A

The sum of all the reactions in a cell or the body.

47
Q

Describe how enzymes can be reused again

A

1) Enzymes and substrates collide = enzymes and substrates complexes.
2) Substrates are broken down.
3) Products are released.
4) Enzyme is free to act again.

48
Q

List the three metabolic reactions which are sped up by different enzymes

A
  • Building large molecules from smaller ones
  • Changing one molecule into another
  • Breaking down large molecules into smaller ones
49
Q

What happens to a reaction if you increase the temperature?

A

The rate of reaction increases

50
Q

When you increase the temperature, the rate of reaction increases. However, this is only true up until what degrees?

A

40 degrees

51
Q

What happens to the enzyme, when it reaches 40 degrees?

A

Long chains of amino acids unravel, causing the shape of the active site to change.
The substrate will no longer be able to fit in the active site.
As a result, the enzyme can no longer act as a catalyst therefore the rate of reaction will drop dramatically.

52
Q

Human enzymes work best at what degrees?

A

37 degrees (human body temperature)

53
Q

Why are enzymes important in humans, in terms of keeping us alive?

A

No reactions would happen fast enough to keep you alive without enzymes.

54
Q

Why is being ill a danger to enzymes?

A

The temperature will become too high: once temperature reaches 41 degrees, the enzymes will denature and will result in your death.

55
Q

How does pH affect enzymes?

A

A change in pH will cause the shape of the molecule to change shape. This means that the specific shape of the active site is lost, meaning the enzyme can no longer act as a catalyst.

56
Q

List 2 factors which affect the rate of enzyme action

A

Temperature and pH

57
Q

Most enzymes work inside the cells of your body. Where do digestive enzymes work?

A

Outside the cells

58
Q

Where are digestive enzymes produced?

A

Produced by special cells in glands (salivary glands and pancreas) and in the lining of your digestive system.

59
Q

Why is it important for food molecules to be broken down into smaller pieces?

A

So the food molecules will have a larger surface area, meaning the enzymes will have a larger area to work on.

60
Q

Describe why it’s important that different areas of the digestive system have different pH levels

A

Different enzymes work best at different pH levels. Enzymes can work efficiently in the region, depending on the pH level.

61
Q

What do carbohydrases break down? And what do they break them down into?

A

Break down carbohydrates into simple sugars

62
Q

What do proteases break down? And what do they break them down into?

A

Break down proteins into amino acids

63
Q

What do lipases break down? And what do they break them down into?

A

Break down lipids into fatty acids and glycerol

64
Q

What enzyme catalyses the breakdown of carbohydrates?

A

Amylase

65
Q

What enzyme catalyses the breakdown of proteins?

A

Protease

66
Q

What enzyme catalyses the breakdown of lipids?

A

Lipase

67
Q

Where is amylase found?

A

Pancreas, small intestine, salivary glands

68
Q

Where is protease found?

A

Pancreas, small intestine, stomach

69
Q

Where is lipase found?

A

Pancreas, small intestine

70
Q

What is protease known as, in the stomach?

A

Pepsin

71
Q

Pepsin works best in what sort of pH?

A

Acidic pH

72
Q

In addition to pH, the stomach also produces a relatively concentrated solution of ___?

A

Hydrochloric acid

73
Q

The stomach produces a thick layer of mucus. How does this help (in digestion)?

A

Coats walls and protects them from being digested by the acid and enzymes.

74
Q

Why is it important that the stomach produces hydrochloric acid?

A

Hydrochloric acid allows the protease enzymes to work effectively.

75
Q

What causes stomach ulcers?

A

When the mucus, produced by the stomach, is lost.

76
Q

What happens when you have a stomach ulcer?

A

The production of hydrochloric acid will increase. The lining of the stomach will then be attacked by the acid and enzymes.

77
Q

Enzymes made in the pancreas and small intestine work best in what sort of condition?

A

Alkaline conditions

78
Q

Acidic liquid from the stomach needs to become an alkaline mixture in your small intestine. Explain how bile is used to turn acidic liquids into alkaline mixtures.

A

1) Liver makes bile which is then stored in the gall bladder.
2) Food travels through the small intestine from the stomach.
3) Bile is squirted onto the food through the bile duct.
4) Bile neutralises the acid added to the food (HCl). Also emulsifies fat to form small droplets which increase the surface area (efficient for enzymes). Bile is alkaline to neutralise HCl.
(The alkaline conditions and large surface area increases the rate of fat breakdown by lipase.)

79
Q

When gall stones form, what do they block?

A

They block the gall bladder and bile ducts.

80
Q

List the dangers of gall stones

A
  • Pain

- Stop bile being released onto food, reducing effective digestion.

AQA Biology (3 decks)

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