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Biology 2 > Nutrition, Digestion and Enzymes > Flashcards

Nutrition, Digestion and Enzymes Flashcards

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1
Q

What are carbohydrates, lipids and proteins?

A

Large molecules which are made up from smaller, more basic units

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2
Q

What chemical elements are in carbohydrates?

A

Carbon, hydrogen and oxygen

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3
Q

What are the characteristics of monosaccharides?

A

They are simple, 1 unit sugars which dissolve easily in water

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4
Q

What are examples of monosaccharides?

A

Glucose and fructose

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5
Q

What are the examples of disaccharides?

A

Sucrose, lactose and maltose

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6
Q

What are the characteristics of polysaccharides?

A

Complex molecules used for storage, they don’t taste sweet and do not easily dissolve in water. They are large complex carbohydrates made up of many smaller units joined together in a long chain

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7
Q

What are examples of polysaccharides?

A

Starch, glycogen, cellulose

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8
Q

What chemical elements are in proteins?

A

Carbon, hydrogen, oxygen, nitrogen (+ sulphur)

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9
Q

What are proteins made up of?

A

Long chains of amino acids. The sequence can determine the shape of the protein molecule

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10
Q

What chemical elements make up lipids?

A

Carbon, hydrogen and oxygen

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11
Q

What are lipids built from?

A

Fatty acids and glycerol

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12
Q

What is the test for glucose?

A

You add Benedict’s solution/reagent (2cm cubed) tp 2cm cubed of liquefied food (with water as a solvent) and heat in a water bath for 5 minutes, if the test is positive it will form a precipitate

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13
Q

How does the colour of the precipitate change with Benedict’s solution?

A

Blue -> green -> yellow -> orange -> brick red

The higher the glucose concentration the further along this scale the colour of the precipitate will be

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14
Q

What is the test for starch?

A

Add iodine solution to 2cm cubed of liquefied food and if present then the sample changes from orange brown to blue black however if there is no starch present the solution will stay orange brown

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15
Q

What are good sources of carbohydrates?

A

Pasta, rice, sugar +

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16
Q

What is the function of carbohydrates?

A

To provide energy

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17
Q

What are good sources of lipids (fats+oils)?

A

Butter, oily fish +

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18
Q

What is the function of lipids?

A

Provide energy, insulation and acts as an energy store

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19
Q

What are good sources of proteins?

A

Meat, fish +

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20
Q

What is the function of proteins?

A

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

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21
Q

What is a good source of vitamin A?

A

Liver

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22
Q

What is the function of vitamin A?

A

Helps to improve vision and keep skin and hair healthy

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23
Q

What is a good source of vitamin C?

A

Oranges and other citrus fruits

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24
Q

What is the function of vitamin C?

A

Helps cells sticking together in the lining of various organs and is needed to prevent scurvy

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25
Q

What is a good source of vitamin D?

A

Eggs

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26
Q

What is the function of vitamin D?

A

Needed for calcium absorption and prevents rickets

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27
Q

What is a good source of water?

A

Food and drink

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28
Q

What is the function of water?

A

Almost every bodily function relies on water. Constant supply needed to replace water lost through urination, breathing and sweating

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29
Q

What is a good source of dietary fibre?

A

Wholemeal bread

30
Q

What is the function of dietary fibre?

A

Aids the movement of food through the gut and prevents constipation

31
Q

What is a balanced diet?

A

It gives all the essential nutrients you need in the right proportions, the 6 essentials are carbohydrates, proteins, lipids, vitamins, minerals and water and you also need fibre to keep the gut in working order

32
Q

What factors can affect energy requirements in different people?

A

Activity level - Active people need more energy than people who sit around all day
Age - Children and teenagers need more energy than older people in order to help them grow, and because they are generally more active
Pregnancy - Pregnant women need more energy than other women because they have to provide enough energy for their babies to develop

33
Q

How do you investigate the energy content in food?

A

Weigh a small amount of food and skewer it on a mounted needle
Add 25cm cubed of water to a boiling tube (held in a clamp) which will be used to measure the amount of heat energy released from the burning food
Measure the original temperature of the water and set fire to the food (ensure the bunsen burner is away from the water so the temperature is not affected)
Hold the food under the boiling tube until it goes out, then continue relighting the food until it won’t catch light
Measure the temperature of the water at the end

34
Q

How do you calculate the amount of energy released in the food?

A

Energy in food (in joules) = mass of water (in g) x temperature change of water (in degrees Celsius) x 4.2

35
Q

How do you calculate the energy in joules per gram?

A

Energy per gram of food (J/g) = Energy in food (in J) / Mass of food (mg)
Used to compare energy values of food

36
Q

How can the energy content in food experiment be improved?

A

Energy released from the food can be lost to the surroundings (energy value on pack of food will be higher)
Insulating the boiling tube (eg with foil) would minimise heat loss and keep more energy in the water - would make results more accurate

37
Q

How much energy would 1 gram of fat release?

A

Approx. 40KJ of energy

38
Q

How much energy would 1 gram of protein release?

A

Approx. 20kJ of energy

39
Q

How much energy would 1 gram of carbohydrate release?

A

Approx 17-18 kJ of energy

40
Q

What is the role of the mouth in digestion?

A

Salivary glands in the mouth produce amylase enzymes in the saliva which is chemical digestion.
Teeth break down food mechanically

41
Q

What is the oesophagus?

A

The muscular tube that connects the mouth and stomach

42
Q

What is the role of the stomach in digestion?

A

It pummels food with the muscular walls and peristaltic movements of the stomach mix up and break down the contents
It produces the protease enzyme pepsin to break down protein molecules
It produces hydrochloric acid (pH 2) to kill bacteria and give the right pH for the protease enzyme to work

43
Q

What is the role of the small intestine in digestion?

A

Produces protease, amylase, and lipase enzymes to complete digestion
Where the nutrients are absorbed out of the alimentary canal

44
Q

What is the role of the large intestine in digestion?

A

Excess water is absorbed from the food

45
Q

What is the role of the pancreas in digestion?

A

Produces protease, lipase and amylase and releases them into the small intestine

46
Q

Why and how is mucus produced in the oesophagus?

A

Mucus is produced by goblet cells in the oesophagus reducing friction as food is passed through

47
Q

What are the five stages of digestion?

A 
Ingestion
Digestion
Absorption
Assimilation
Egestion
48
Q

What is ingestion?

A

Putting food or drink in your mouth

49
Q

What is digestion?

A

After you have ingested something you need to digest it. Digestion is the break down of large and insoluble molecules into smaller, soluble molecules
Mechanical - teeth, stomach muscles
Chemical - digestive enzymes

50
Q

What is absorption?

A

The process of moving molecules through the walls of the intestine into the blood

51
Q

What is assimilation?

A

When digested molecules have been absorbed they’re moved into body cells. The digested molecules then become a part of the cells (assimilation). Eg when amino acids from digested proteins are assimilated they’re used by cells to make cellular proteins

52
Q

What is egestion?

A

All of the undigested substances (things that you can’t digest) form faeces which is of no use to the body. This exits the body via the anus

53
Q

Extra information about the stomach.

A

There are special cells in the lining that secrete mucus to protect the lining from the acids and enzymes
It has a tight ring of muscles at the top and bottom to control the entry and exit of materials

54
Q

How is the small intestine adapted to its function?

A

It’s very long, so there is time to break down and absorb all the food before it reaches the end
There’s a really big surface area for absorption because the walls of the small intestine are internally folded and covered in tiny projections called villi
Each villus has microvilli that increase surface area mode

55
Q

How are villi adapted?

A

They have a single permeable layer of surface cells which help make absorption easier
They have a good supply which also makes absorption easier

56
Q

What do digestive enzymes do?

A

They break down big molecules that are too big to pass through the walls of the digestive system into small molecules that can

57
Q

What do amylases do?

A

They break down starch into maltose

58
Q

What do maltases do?

A

They break down maltose into glucose

59
Q

What do proteases do?

A

They break down proteins into amino acids

60
Q

What do lipases do?

A

They break down lipids into fatty acids and glycerol

61
Q

Where is bile produced?

A

It is produced in the liver and is stored in the gall bladder before it is released into the small intestine

62
Q

Why is bile produced?

A

It is used to neutralise the acid in the stomach because the pH is too acidic for the enzymes in the small intestine to work which work best in alkaline conditions.
It also emulsifies fat; it breaks it down into small droplets which increase the surface area for lipase to work on, increasing the rate of digestion

63
Q

What is a catalyst?

A

A substance which increases the speed of a reaction without being changed or used up

64
Q

What are enzymes used for?

A

They act as biological catalysts which speed up different metabolic reactions which keep the cell active

65
Q

How does temperature affect enzymes?

A

At low temperatures enzymes are inactive because there is less kinetic energy for collisions
As temperature increases, rate increases, more heat energy allows for more collisions between enzymes and substrates
At high temperatures, rate decreases because the enzyme becomes denatured and loses its active site

66
Q

What is the optimum temperature for most enzymes?

A

37°, the temperature of the body

67
Q

How does the optimum pH graph compare to the optimum temperature graph?

A

Optimum pH graph has a much narrower range because enzymes are sensitive to pH

68
Q

What is the optimum pH for most enzymes?

A

It is often pH 7, however pepsin has to work in stomach acid so it’s optimum pH is pH2

69
Q

What happens if pH is too high or low?

A

It interferes with the bonds holding the enzyme together which changes the shape of the active site and denatures the enzyme

70
Q

What is an experiment to investigate temperature on enzyme activity?

A

How fast a substrate disappears:
1) Amylase catalyses the breakdown of starch to maltose
2) It is easy to detect starch (the substrate) using iodine solution which will change from browny orange to blue black if starch is present
3) You can time how long it takes for the starch to disappear by regularly sampling the starch and amylase solution and use the times to compare rates of different temperatures
4) By changing the temperature of the water bath you can see how temperature affects the activity of amylase (compare how long it takes for the iodine solution to stay brown)
Other variables need to be controlled

Biology 2 (5 decks)

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