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Biology > Enzymes and Digestion > Flashcards

Enzymes and Digestion Flashcards

1
Q

What are the seven food groups? How do you remember these?

A

carbohydrates (starch and gluose)

protein

lipids (fats and oils)

fibre

vitamins

minerals

water

Careless Pauline Let Finnian Vaporise My Water

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2
Q

What are simple sugars called?

A

monosaccharides

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3
Q

What are complex sugars called?

A

polysaccharides

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4
Q

What is starch made of?

A

thousands of glucose molecules

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5
Q

Give an example of a simple sugar (monosaccharide)

A

glucose

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6
Q

Give an example of a complex sugar (polysaccharide)

A

starch

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7
Q

What are carbohydrates?

A

they include simple sugars (monosaccharides) such as glucose and complex sugars (polysaccharides) such as starch (which is made of thousands of glucose molecules)

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8
Q

What are elements of glucose?

A

Carbon

Hydrogen

Oxygen

(C, H, O)

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9
Q

What is the formula for glucose?

A

C6H12O6

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10
Q

What is the equation for respiration?

A

glucose + oxygen —> carbon dioxide + water + ATP

C6H12O6 + 6O2 —> 6CO2 + 6H2O + ATP

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11
Q

What is the function of glucose?

A

short-term energy supply which is used in respiration

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12
Q

What are some sources of glucose?

A

e.g. in fruits, sweets

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13
Q

What are elements of starch?

A

Carbon

Hydrogen

Oxygen

(C, H, O)

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14
Q

What is the structure of starch?

A

thousands of glucose molecules

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15
Q

What is the function of starch?

A

short-term energy storage which is broken down into glucose for respiration

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16
Q

What is the function of starch in plants?

A

stores starch

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17
Q

What is the function of starch in humans?

A

eat foods containing starch which broken down into glucose in digestion

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18
Q

What are some sources of starch?

A

e.g. in bread, potatoes, pasta, rice

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19
Q

If you need a quick burst of energy what food should you eat and why?

A

eat food containing glucose (instead of starch) as it doesn’t need to be digested and can be absorbed into the bloodstream directly

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20
Q

What are the elements of protein?

A

Carbon

Hydrogen

Oxygen

Nitrogen

Sulphur

(C, H, O, N, S)

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21
Q

What is the structure of proteins?

A

chains of amino acids (20 different types)

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22
Q

What is the function of proteins?

A

there are a variety of functions:

needed to maintain cell function

needed to grow and repair cells and tissues

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23
Q

What are some sources of proteins?

A

e.g. meat, fish, eggs, dairy

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24
Q

What is the function of proteins in enzymes?

A

enzymes speed up chemical reactions in your body, e.g., the breakdown of food or respiration

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25
Q

What is the function of proteins in muscles?

A

muscle proteins called actin and myosin enable all muscular movement

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26
Q

What is the function of proteins in cellular messengers?

A

receptor proteins on the cell membrane transmit signals to other proteins inside cells

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27
Q

What is the function of proteins in antibodies?

A

antibodies are proteins that help defend your body against harmful microbes

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28
Q

What is the function of proteins in hairs and nails?

A

a protein called keratin forms your hair and fingernails

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29
Q

What is the function of proteins in the brain and nerves?

A

ion channel proteins control nervous system signalling by allowing ions in and out of nerve cells

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30
Q

What is the function of proteins in blood?

A

the haemoglobin protein carries oxygen in your blood to every part of your body

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31
Q

Complete this gapfill:

Lipids are good for … energy … - the body generally uses … first and stores … and …. If we run out of … our body breaks down the … and uses it as fuel for … - it is like a reserve energy source

A

Lipids are good for long-term energy storage - the body generally uses carbohydrates first and stores lipids and fat. If we run out of carbohydrates our body breaks down the fat and uses it as fuel for respiration - it is like a reserve energy source

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32
Q

What are the elements of lipids?

A

Carbon

Hydrogen

Oxygen

(C, H, O)

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33
Q

What are the subunits of lipids?

A

glycerol and three fatty acids

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34
Q

What is the function of lipids?

A

long-term energy storage

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35
Q

What are the types of lipids?

A

they include fats (solid at room temperature) and oils (liquid)

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36
Q

What are some sources of lipids?

A

e.g. butter, dairy, oil, nuts

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37
Q

What are some sources of lipids (fats)?

A

e.g. butter

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38
Q

What are some sources of lipids (oils)?

A

e.g. olive oil

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39
Q

What are elements of fibre?

A

Carbon

Hydrogen

Oxygen

(C, H, O)

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40
Q

What is the structure of fibre?

A

thousands of glucose molecules

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41
Q

What is the function of fibre in plants?

A

makes up plant cell walls (cellulose)

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42
Q

What is the function of fibre in humans?

A

humans cannot digest fibre, but eating fibre helps to keep the digestive system healthy and to prevent constipation

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43
Q

What are some sources of fibre?

A

e.g. vegetables, fruit

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44
Q

What is fibre made of?

A

CHECK

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45
Q

What are minerals?

A

inorganic substances (salts) needed by the body in small amounts

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46
Q

What are some examples of minerals?

A

calcium, iron, magnesium, iodine

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47
Q

What is the function of minerals (calcium)?

A

to make healthy bones

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48
Q

What is the function of minerals (iron)?

A

blood - needed to make haemoglobin (molecule in Red Blood Cells)

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49
Q

What are some sources of minerals (calcium)?

A

e.g. milk

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50
Q

What are some sources of minerals (iron)?

A

e.g. meat and liver

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51
Q

What are vitamins?

A

organic substances needed by the body in small amounts

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52
Q

What are some examples of vitamins?

A

Vitamin A, Vitamin C, Vitamin D

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53
Q

What is the function of vitamins?

A

to take part in important chemical reactions in the body

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54
Q

What are some sources of vitamins (Vitamin A)?

A

e.g. carrots

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55
Q

What are some sources of vitamins (Vitamin C)?

A

e.g. oranges and lemons (citrus fruit)

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56
Q

What are some sources of vitamins (Vitamin D)?

A

e.g. milk

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57
Q

How much of the body is water?

A

about 67%

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58
Q

What is the formula for water?

A

H2O

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59
Q

What is the function of water?

A

to carry substances around the body and replace lost water

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60
Q

What are some sources of water?

A

e.g. drinks, vegetables (cucumber which is 95% water and tomatoes)

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61
Q

What is the function of carbohydrates?

A

short-term energy supply

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62
Q

What is the function of protein?

A

cell function, growth and repair of cell tissues

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63
Q

What is the function of lipids?

A

long-term energy storage and supply

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64
Q

What is the function of fibre?

A

to keep the digestive system healthy and prevent constipation

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65
Q

What is the function of vitamins?

A

to take part in important chemical reactions in the body

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66
Q

What is the function of minerals?

A

to make healthy blood, bones and other tissues

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67
Q

What is the function of water?

A

to carry substances around the body and replace lost water

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68
Q

Complete this gapfill:

We can test for glucose using …. If glucose is present, the colour will change from … to … when heated.

What should you use to heat for the colour change to happen?

A

We can test for glucose using Benedict’s reagent. If glucose is present, the colour will change from blue to brick red when heated.

To heat, use a bunsen burner or water bath

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69
Q

What is the colour gradient for the amount of glucose present when tested with Benedict’s reagent (from a lot of glucose present to little)?

A

red

orange

yellow

green

blue

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70
Q

Complete this gapfill:

We can test for starch using …. If starch is present, the colour will change from … to …/…

A

We can test for starch using iodine. If starch is present, the colour will change from brown to blue/black

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71
Q

Complete this gapfill:

We can test for protein using … (= copper sulphate + sodium hydroxide). If protein is present, the colour will change from … to …

A

We can test for protein using Biuret reagent (= copper sulphate + sodium hydroxide). If protein is present, the colour will change from light blue to purple

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72
Q

The substance tested for is starch. Complete the table:

Solution used:

Colour of solution at start:

Colour of solution at end:

Heat required?:

A

Solution used: iodine

Colour of solution at start: yellow

Colour of solution at end: blue/black

Heat required?: no

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73
Q

The substance tested for is glucose. Complete this table:

Solution used:

Colour of solution at start:

Colour of solution at end:

Heat required?:

A

Solution used: Benedict’s reagent

Colour of solution at start: blue

Colour of solution at end: red

Heat required?: yes

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74
Q

What is a balanced diet?

A

the right balance of different food groups providing the body with all essential nutrition and the right amount of energy (calories)

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75
Q

What is malnutrition?

A

a condition resulting from eating a diet that does not contain the right amount of nutrients

it happens when your diet is unbalance long-term

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76
Q

What is undernutrition and starvation?

A

not ontaining enough nutrients/calories

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77
Q

What are the causes of undernutrition and starvation?

A

e.g. not eating enough

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78
Q

What are the symptoms of undernutrition and starvation?

A

underweight

weakness

loss of fat and muscle tissue

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79
Q

What is overnutrition and obesity?

A

taking in too many nutrients/calories

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80
Q

What are the causes of overnutrition and obesity?

A

overeating

genetic

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81
Q

What are the symptoms of overnutrition and obesity?

A

weight gain

excess fat

heart disease

diabetes

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82
Q

What is BMI?

A

(body mass index)

= a measure of body fat based on height and weight

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83
Q

Who does BMI apply to?

A

adult men and women

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84
Q

How do you calculate BMI?

A

weight (kg) ÷ height (m)2

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85
Q

What are the BMI values for adults?

A

<18 underweights

18-25 normal weight

>25 overweight

>30 obese

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86
Q

How can we know if someone is overweight or obese?

A

calculate their BMI

however, BMI is not always useful as it is only fine for average people

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87
Q

What are deficiency diseases?

A

not enough of a particular food group (i.e. unbalanced diet)

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88
Q

What are some deficiency diseases?

A

night blindness

scurvy

rickets

anaemia

kwashiorkor

goitre

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89
Q

What are the causes of night blindness?

A

deficiency in Vitamin A —> degeneration of rod cells in the retina

rod cells enable us to see

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90
Q

What are the symptoms of nighblindness?

A

poor vision in low light levels

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91
Q

What is the cause of scurvy?

A

deficiency in Vitamin C

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92
Q

What are the symptoms of scurvy?

A

poor wound healing

bleeding, particularly in gums

loss of teeth

fatigue

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93
Q

What are the causes of rickets?

A

deficiency in Vitamin D or calcium; lack of sunlight

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94
Q

What are the symptoms of rickets?

A

brittle bones

bow legs

poor teeth

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95
Q

What is the cause of anaemia?

A

deficiency in iron

the body will lack Red Blood Cells and won’t be able to transport oxygen efficiently

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96
Q

What are the symptoms of anaemia?

A

low energy levels

lethargy

dizziness

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97
Q

What is the cause of kwashiorkor?

A

deficiency in protein

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98
Q

What are the symptoms of kwashiorkor?

A

swollen belly

poor muscle growth

weight loss

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99
Q

What is the cause of goitre?

A

deficiency in iodine

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100
Q

What are the symptoms of goitre?

A

swollen lump in thyrdoid glanf

slow metabolism

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101
Q

What is the energy in food used for?

A

movement, body heat and growth

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102
Q

What is the energy process for eating food?

A

food (chemical energy) —> respiration —> movement (kinetic energy), body heat (heat energy), growth and repair (chemical energy)

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103
Q

What happens if you take in too much energy?

A

you gain weight

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104
Q

What happens if you take in too little energy?

A

weight loss

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105
Q

What does how much energy we need depend on?

A

activity levels

temperature

age

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106
Q

What does one calorie equate to?

A

1 calorie = quantity of heat energy required to raise the temperature of 1g of water by 1oC

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107
Q

What is the equation for 1 joule?

A

1 joule = 4.2 x calories

(e.g. 100 cal = 420J)

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108
Q

What is the equation for food energy (calories)

A

food energy (calories) = mass of water (g) x temperature rise (oC)

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109
Q

What is the equation for food energy (calories ÷ grams)

A

food energy (calories ÷ grams) mass of water (g) x temperature rise (oC) ÷ mass of food

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110
Q

Do you think the BMI is always a good measure of obesity?

A

no

it is only good for average people

it cannot, e.g., take into account muscle weight

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111
Q

How could you treat deficiency symptoms?

A

taking supplements

incorporate the deficiency into your diet –> eat more e.g. Vitamin A if you suffer from night blindness

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112
Q

Why do you think scurvy was particularly prominent amongst sailors?

A

cannot eat fresh fruit (e.g. oranges) as they do not have access to them

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113
Q

Why would people suffering from anaemia have low energy levels and feel dizzy?

A

deficiency in iron —> body will lack Red Blood Cells and won’t be able to transport oxygen efficiently —> lack of oxygen for respiration

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114
Q

What kind of people might be at risk of developing Kwashiorkor in the UK?

A

vegans (although they can take B12 supplements)

people with an unbalanced diet

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115
Q

Who needs more energy and why?

male or female

A

male

on average their proportions are bigger

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116
Q

Who needs more energy and why?

child who exercises or child who doesn’t exercise

A

child who exercises

respiring and losing energy

117
Q

Who needs more energy and why?

70 year old or teenager

A

teenager

growing

118
Q

Who needs more energy and why?

cycle dispatch rider or receptionist

A

cycle dispatch rider

respiring and losing energy

119
Q

Who needs more energy and why?

girl in summer or girl in winter

A

girl in winter

cold —> needs to retain body heat

120
Q

Who needs more energy and why?

woman who is pregnant or woman who is not pregnant

A

woman who is pregnant

eating for two

121
Q

How can people avoid putting on weight? What are the options?

A

avoid added sugar as it is not a necessary dietary requirement

balanced diet and exercise

122
Q

In what way will a boy’s body who has just eaten a Twix use up energy while sitting watching tv?

A

respiration

heat

digestion

123
Q

Design an experiment to find out how the energy content differs in food

A

weigh the food so the mass is known

use a calculator to detect and measure the temperature in the water before and after burning the food with a thermometer

use a temperature change to work out the energy change of the food

repeat the experiment three times with each type of food

measure the temperature once the food is completely burned off

use the same mass of water and foo

make sure to wear goddles for safety

124
Q

How do you measure the energy content of food in the lab? What is the independent variable, the dependent variable and the two control variables?

A

fill a boiling tube with water (10cm3) - the amount of water is a control variable

measure the temperature at the start

measure the mass of food - the type of food is the independent variable, the mass of the food is a control variable

mount the food on a mounted needle (or into a fireproof dish)

set fire to the food into it until it catches alight

hold the burning food underneath water until it is burned

measure the temperature of water at the end - the temperature of the water is the dependent variable

calculate the energy in food

125
Q

Label this structure of the digestive system

A
126
Q

What is the function of the mouth?

A

starting point of digestion

127
Q

What is the function of the teeth?

A

break up food particles mechanically in mouth

128
Q

What is the function of the tongue?

A

mixes food with saliva

129
Q

What is the function of the oesophagus?

A

transport of food to stomach

130
Q

What is the function of the stomach?

A

storage and digestion of food (initial digestion)

131
Q

What is the function of the duodenum (small intestine)?

A

main digestion of food

132
Q

What is the function of the pancreas?

A

secretes digestive juiced and enzymes into duodenum to enable digestion

133
Q

What is the function of the gall bladder?

A

site of bile storage

134
Q

What is the function of the liver?

A

site of bile salt production

135
Q

What is the function of the ileum (small intestine)?

A

main absorption of nutrients

digested food moved to the ileum

136
Q

What is the function of the large intestine?

A

absorption of water

material that has not been digested and absorbed moves along the large intestine - food is compacted

137
Q

What is the function of the rectum?

A

temporary storage of faeces

undigested and compacted material enters the rectum

138
Q

What is the function of the anus?

A

defecation

139
Q

How does food move along the digestive system?

A

peristalsis

140
Q

What is peristalsis?

A

a series of wave-like muscle contractions in the wall of the oesophagus and the small and the large intestine that moves food along the dgestive system

141
Q

How is food absorbed into the blood stream?

A

the ileum is lined by thousands of villi

nutrients are absorbed into the blodstream by diffusion

blood concentration is kept high as in the ileum food molecules are constantly supplied through peristalsis and in the bloodstream the absorbed molecules are taken away through blood flow

142
Q

Why do we need the digestive system?

A
  1. digestion (breakdown) of food molecules
  2. absorption (uptake) of food molecules into the bloodstream
143
Q

Can you swallow when standing on your head? Why?

A

yes

peristalsis helps food move along - not controlled by gravity but controlled by muscles

144
Q

Which part of the digestive sysem is affected when you suffer from diarrhoea?

A

large intestine (absorption of water) —> diarrhoea is very watery

145
Q

How is absorption in the digestive system made efficient?

A

large surface area

short diffusion distance

high concentration gradient

146
Q

How is a large surface area achieved to make absorption efficient?

A

the ileum is lined by thousands of villi

many microvilli on each cell of the villus wall

147
Q

How is a short diffusion distance achieved to make absorption efficient?

A

villus wall is thin (one layer of cells thick)

blood vessels are directly under the villus wall

148
Q

How is a high concentration gradient achieved to make absorption efficient?

A

continuos flow of blood which requires nutrients

peristalsis brings along food constantly

149
Q

At the end of the ileum, there is a … concentration graidient. Why?

A

at the end of the ileum, there is a low concentration graidient

this is because there are fewer nutrients

active transport happens at the end of the ileum

150
Q

What is digestion?

A

the breakdown of food

151
Q

Why does food need to be digested?

A

only small molecules can be absorbed (= diffuse) across villi into the bloodstream

some molecules are too large and cannot move across the ileum into the bloodstream

152
Q

Complete this table for the food molecule water:

Are these digested?:

What are they broken down into?:

Enzyme involved:

A

Are these digested?: no - absorbed directly into the bloodstream

What are they broken down into?: N/A

Enzyme involved: N/A

153
Q

Complete this table for the food molecule glucose (carbohydrate):

Are these digested?:

What are they broken down into?:

Enzyme involved:

A

Are these digested?: no - absorbed directly into the bloodstream

What are they broken down into?: N/A

Enzyme involved: N/A

154
Q

Complete this table for the food molecule starch (carbohydrate):

Are these digested?:

What are they broken down into?:

Enzyme involved:

A

Are these digested?: yes

What are they broken down into?: glucose molecules

Enzyme involved: carbohydrase (amylase and maltase)

155
Q

Complete this table for the food molecule protein:

Are these digested?:

What are they broken down into?:

Enzyme involved:

A

Are these digested?: yes

What are they broken down into?: amino acids

Enzyme involved: protease

156
Q

Complete this table for the food molecule lipids:

Are these digested?:

What are they broken down into?:

Enzyme involved:

A

Are these digested?: yes

What are they broken down into?: one glycerol molecule and three fatty acids chain

Enzyme involved: lipase

157
Q

Complete this table for the food molecule fibre:

Are these digested?:

What are they broken down into?:

Enzyme involved:

A

Are these digested?: cannot be digested

What are they broken down into?: N/A

Enzyme involved: N/A

158
Q

Complete this table for the food molecule vitamins:

Are these digested?:

What are they broken down into?:

Enzyme involved:

A

Are these digested?: no

What are they broken down into?: N/A

Enzyme involved: N/A

159
Q

Complete this table for the food molecule minerals:

Are these digested?:

What are they broken down into?:

Enzyme involved:

A

Are these digested?: no

What are they broken down into?: N/A

Enzyme involved: N/A

160
Q

What three food molecules are digested?

A

starch (carbohydrase)

protein

lipids

161
Q

How is food digested?

A

mechanical digestion (teeth and tongue)

chemical digestion (enzymes)

162
Q

What are enzymes?

A

proteins that speed up chemical reactions (for example, the breakdown of food molecules)

biologial catalysts

163
Q

What would happen without enzymes?

A

we would starve

164
Q

How do enzymes work in digestion?

A

each enzyme binds to a particular molecule (called their substrate) and breaks it down into products

without an enzyme the breakdown of a molecule would be much slower

enzymes are specific to a particular molecule (i.e. each enzyme can only bind to one type of molecule)

different enzymes are needed to catalyse different reactions

165
Q

Does the body need one type of enzymes or lots of different enzymes?

A

lots of different enzymes

166
Q

How is starch digested?

A

starch is digested into maltose and glucose by carbohydrase enzymes called amylase and maltase

167
Q

How are proteins digested?

A

protein is digested into amino acids by the enzyme protease

168
Q

How are lipids digested?

A

lipids are digested into glycerol and fatty acids by the enzyme lipase

169
Q

What enzyme breaks down carbohydrates?

A

carbohydrase

170
Q

What enzyme breaks down proteins?

A

protease

171
Q

What enzyme breaks down lipids?

A

lipase

172
Q

What enzyme breaks down maltose?

A

maltase

173
Q

What enzyme breaks down starch (amylose)?

A

amylase

174
Q

In the test for glucose the solution needs to be heated. Give two precautions you would use to heat the solution safely

A

tie your hair back so it does not catch fire

tuck bags and chairs under the table so you can’t trip and fall into the flame or the water bath

175
Q

What is the name of the reagent used to test for protein?

A

Biuret reagent

176
Q

Using Biuret reagent, Jill tested two foods, A and B, for protein. A had no protien but B did. What are the colours she obtained for A and B?

A

A: light blue

B: purple

177
Q

A student wants to test some food samples for glucose. Choose two pieces of appartus the student should use out of the following options:

test tube

Bunsen burner

microscope

funnel

A

Bunsen burner

test tube

178
Q

What is the name of the reagent the student should use to test for glucose?

A

Benedict’s reagent

179
Q

Using Benedict’s reagent, what would the colour change be for a food that contains glucose?

A

at the start of the test: blue

at the end of the test: brick red

180
Q

A student decided to test a food sample to see if it contained starch. Name the reagent the student should use and what colour changes would be observed if starch was present

A

reagent: iodine

colour change: brown to blue/black

181
Q

What is the test solution and colour of positive result for lipids?

A

test solution: water and ethanol

colour: cloudy white

182
Q

Why would you crush a food sample when testing for a simple sugar?

A

to increase the surface area

183
Q

What reagent would you use to test a food sample for a simple sugar?

A

Benedict’s reagent

184
Q

Why is a water bath used when testing a food sample for a simple sugar instead of heating the test tube directly with a Bunsen burner?

A

so it heats the whole sample evenly, not just the base

185
Q

Why would you leave a heated food sample for two minutes before observing a colour change?

A

to allow the sample to heat up

186
Q

Two food samples were tested. Complete this table:

The colour of reagent A at the start:

Colour of reagent A at the end for a food sample containing glucose:

Colour of reagent A at the end for a food sample containing protein:

A

The colour of reagent A at the start: blue

Colour of reagent A at the end for a food sample containing glucose: brick red

Colour of reagent A at the end for a food sample containing protein: purple

187
Q

Label this diagram of a calorimeter

A
188
Q

How do you use a calorimeter to determine the energy in food?

A

first, the food is wieghed so we know the mass of it

the food is then placed and burned in a metal chamber that sits inside a well-insulated vessel fo water

the food is lit using the ignition wires

the heat released by burning the food is transferred to the water which surrounds the food chamber

the increase in temperature of the water and the measured mass of both the food and the water are used to determine the heat released by the substance

189
Q

Use the graph to describe the changes in the mass of the rats in Group A from day 18 to day 50

A

the mass stays constant and then rises

190
Q

Use the graph to describe the changes in the mass of the rats in Group B from day 18 to day 50

A

the mass rises and then falls

191
Q

What conclusions can you draw as to the effect of milk on the growth of the rats in Hopkins’ experiment?

A

milk is needed for growth as it contains calcium/ vitamins

milk is needed everyday

192
Q

Suggest why Hopkins swapped the diets after 18 days

A

to show the change due to milk, not the differences between groups (rats)

193
Q

To enable a valid comparison to be made between the two groups, other variables need to be kept the same. Suggest two such variable and explain how it could be kept the same

A

temperature: keep the room thermostat and the same temperature

genetic differences: same species of rats

194
Q

Which vitamin helps with night vision and what is a source of this vitamin?

A

Vitamin A

e.g. carrot

195
Q

Which vitamin helps with skin and gum development and what is a source of this vitamin?

A

Vitamin C

e.g. citrus fruit; oranges

196
Q

What does Vitamin D help and what is a source of this vitamin?

A

bone/tooth development

e.g. milk

197
Q

Name the appartus a student could use to measure 20cm3 of water accurately

A

meauring cylinder

198
Q

Calculate the enegery content of a biscuit in J using the formula:

energy content in J = rise in temperature in oC x volume of water in cm3 x 4.2

temperature of the water at the start = 18 oC

temperature of the water at the end = 33 oC

volume of water = 20 cm3

A

energy content in J = rise in temperature in oC x volume of water in cm3 x 4.2

= (33-18) x 20 x 4.2

= 15 x 20 x 4.2

= 1260

199
Q

Five results using a boiling tube of water were different from each other. The student thought this was because different amounts of energy were lost and not transferred to the water. Suggest two reasons why the energy might not be transferred to the water

A

energy lost to surroundings

energy heating up glass, not water

200
Q

Peter wants to find out if potato crisps contain as much energy as crispbread. Suggest three things he must do to make the experiment a fair test

A

same mass of food

same volume of water

burning food at the same distance from the test tube

201
Q

What results will Peter get when he burns 1.0g of potato crisps instead of 1.0g of crispbread? Why?

A

the temperature change of water will be much greater because there is more energy in potato chips

202
Q

Use the table to give two reasons for choosing crispbread rather than potato chips as part of a healthy and balanced diet

A

more fibre

less fat (less likely to gain weight)

203
Q

Label this diagram of a villus

A
204
Q

Label this diagram of villi

A
205
Q

Why does bread start tasting sweet when you chew it for a long time?

A

the amylase in your saliva breaks down the bread into glucose - glucose is sweet

206
Q

Design an experiment to find out if the digestion of starch is more efficient with compared to without enzymes

A

independent variable = the quantity of enxymes

choose a range of three enzyme quantities - none present, small quantity present, large quantity present

measure how long it takes for starch to be digested by using iodine to see whether glucoseis produced (if it is then the reagent will turn blue/black) - measure the time with a stopwatch

repeat the experiment three times for each quantity

do not change the mass of the starchy food or the temperature of the room in which the experiment takes place

keep the type of food constant

207
Q

What is an enzyme?

A

proteins that speed up biochemical reactions

208
Q

enzymes catalyse … (breaking down) reactions

enzymes catalyse … (building up) reaction

A

enzymes catalyse catabolic (breaking down) reactions

enzymes catalyse anabolic (building up) reaction

209
Q

What do enzymes do to biochemical reactions? How do enzymes work?

A

enzymes speed up biochemical reactions up to 106x

enzymes work by lowering the activation energy (= energy needed to start a chemical reaction)

210
Q

Each enzyme … to a particular molecule (…) and catalyses the conversion into the products

Enzymes are … for a particular … (i.e. each enzyme can catalyse … particular reaction)

Different enzymes are needed to catalyse … reactions

A

Each enzyme bind to a particular molecule (substrate) and catalyses the conversion into the products

Enzymes are specific for a particular substrate (i.e. each enzyme can catalyse only one particular reaction)

Different enzymes are needed to catalyse different reaction

211
Q

Why are different enzymes are needed to catalyse different reactions?

A

to control reactions

otherwise you would use up all the energy in a cell and the cell would probably die

212
Q

The amino acid chain of the protein (enzyme) … in a specific way and gives the protein its …

Part of the folded protein forms the … when the substrate is bound

The shape of the substrate … to the shape of the active site = fits like a key into a lock (= … model)

A

The amino acid chain of the protein (enzyme) folds in a specific way and gives the protein its shape

Part of the folded protein forms the active site when the substrate is bound

The shape of the substrate complementary to the shape of the active site = fits like a key into a lock (= lock and key model)

213
Q

How does enzyme action work?

A

substrate binds to active site

enzyme-substrate complex forms

reaction takes place

product no longer fits into active site and is released

enzyme is free to be used again

(Note: enzymes are not used up/changed during reaction)

214
Q

What is catalase?

A

a detox enzyme

found in most living tissues

215
Q

What is the equations for hydrogenperoxide being affected by the enzyme catalase?

A

hydrogenperoxide –(catalase)–> water + oxygen

H2O2 –(catalase)–> H2O + O2

oxygen is released very, very quickly

216
Q

What must cells do to hydrogenperoxide?

A

cells must break down this toxic molecule into safe products

217
Q

What is the effect of temperature of enzyme activity

  1. below optimum T
  2. optimum T
  3. above optimum T
A
  1. rate of reaction increases as temperature increases as there is more kinetic energy and therfore more collisions andmore enzyme-substrate complexes
  2. highest rate of reaction (around 37oC in humans)
  3. rate of reaction decreases rapidly as the enzyme denatures and the active site changes shape and therefore cannot bind
218
Q

What is the effect of pH of enzyme activity

  1. optimum pH
  2. and 3. below/ above optimum pH
A
  1. highest rate of reaction
  2. and 3. rate of reaction decreases rapidly as the enzyme denatures and the active site changes shape

the rate of reaction lowers as you move away from the optimum pH

219
Q

What is denaturation?

A

change in the shape of a protein

it is irreversible

220
Q

Why do people die of fever?

A

enzymes denature at high temperature

respiration enzymes denature

221
Q

Different enzymes have a … optimum pH

A

Different enzymes have a different optimum pH

222
Q

Where does food digestion happen?

A

there are three areas where digestion happens:

mouth (teeth and tongue)

stomach

duodenum (small intestine)

223
Q

Where is the first area that enzymes act in digestion?

A

the mouth

224
Q

What type of digestion is in the mouth?

A

mechanical and chemical

225
Q

What type of digestion is in the stomach?

A

chemical

226
Q

What type of digestion is in the duodenum?

A

chemical

227
Q

What digestion happens in the mouth?

A

starch is digested into maltose by the enzyme carbohydrase (amylase) made in the salivary glands

228
Q

What is maltose?

A

a small carbohydrate consisting of two glucose molecules

229
Q

What digestion happens in the stomach?

A

protein is digested into amino acids by the enzyme protease (pepsin) made in the stomach lining

the stomach is very acidic (ph = 2-3) and so pepsin works best at a low pH

230
Q

What is pepsin?

A

special protease that only acts in the stomach - needed as the stomach is very acidic

231
Q

Where does most digestion happen?

A

in the duodenum

232
Q

What is digested in the duodenum?

A

starch

protein

lipids

233
Q

How is starch digested in the duodenum?

A

starch is digested into maltose and glucose by amylase made in the pancreas and maltase made in the duodenum

234
Q

How is protein digested in the duodenum?

A

protein is digested into amino acids by the enzyme protease (trypsin) made in the pancreas

235
Q

In what pH does trypsin work best in?

A

a neutral pH

236
Q

How are lipids digested in the duodenum?

A

lipids are digested into glycerol and fatty acids by the enzyme lipase made in the pancreas

lipase action is helped by bile produced in the liver and stored in the gall bladder

237
Q

Is bile an enzyme?

A

no

238
Q

What does bile do?

A

bile neutralises the pH when food exists the stomach - food moves out of the stomach at a low pH but lipase doesn’t work at a low pH so bile is needed so lipase can properly function

bile emulsifies (breaks down) lipids into droplets which increases the surface area helping lipase action - lots of little droplets have a big surface area which makes digestion of lipids by lipase much faster

239
Q

What is starch broken down into?

A

maltose

glucose

240
Q

Which enzyme is involved in the breakdown of maltose (starch)?

A

carbohydrase (amylase)

241
Q

Which enzyme is involved in the breakdown of glucose (starch)?

A

carbohydrase (amylase and maltase)

242
Q

Where is maltose (starch) digested?

A

mouth

243
Q

Where is glucose (starch) digested?

A

duodenum

244
Q

Where is amylase to breakdown maltose in the mouth produced?

A

salivary glands

245
Q

Where is amylase to breakdown glucose and maltose in the duodenum produced?

A

pancreas

246
Q

Where is maltase to breakdown glucose and maltose in the duodenum produced?

A

duodenum

247
Q

What is protein broken dowin into?

A

amino acids

248
Q

Which enzymes are involved in the breakdwon of amino acids?

A

protease (pepsin)

protease (trypsin)

249
Q

Which protease works best at low pH and which protease works best in neutral pH?

A

low pH = pepsin

neutral pH = trypsin

250
Q

Where are amino acids broken down by protease (pepsin) digested?

A

stomach

251
Q

Where are amino acids broken down by protease (trypsin) digested?

A

duodeum

252
Q

Where is protease (pepsin) produced?

A

stomach lining

253
Q

Where is protease (trypsin) produced?

A

pancreas

254
Q

What are lipids broken down into?

A

glycerol and fatty acids

255
Q

Which enzyme is involved in the breakdown of lipids?

A

lipase

256
Q

Where are lipids digested?

A

duodenum

257
Q

Where is lipase produced?

A

pancreas

258
Q

What do you need to have for a graph (similar to CORMMS)?

A

Scale must be bigger than half of the available graph paper and both axes must be linear (e.g. 0, 10, 20, 30…)

Line straight (use a ruler), point to point

Axes must be the correct way around (x = independent, y = dependent)

Axes must be labelled correctly

Points must be plotted accurately (i.e. exaclty right to the number)

= SLAAP

259
Q

Describe and explain the results from 100C to 45oC

A

as the temperature increases, the rate of carbon dioxide in bubbles per minute increases

this is because the molecules have more kinetic energy and collide more often

260
Q

Describe and explain the results from 45oC to 80oC

A

as the temperature increases, the enzymes dentaure and the rate of carbon dioxide production decreases

261
Q

The graph suggests that 45oC is the optimum temperature for the production of carbon dioxide. Describe how you could modify this experiment to test this hypothesis

A

more detailed temperature changes; use smaller intervals between 30oC and 50oC (N.B. you must include a range)

repeat the experiment

262
Q

The rate of carbon dioxide production during an experiment was measured by counting the number of bubbles produced per minute. Explain why this is not a precise way to measure carbon dioxide production and suggest a more precise way of doing this

A

bubbles are difficult to count; collect the bubbles in a measuring cylinder

263
Q

Which letter shows where bile is made?

A

F (the liver)

264
Q

Explain how bile is involved in digestion?

A

bile neutralised the pH

bile emulsifies lipids into lots of little droplets which increases the surface area helping lipase action

265
Q

In which part of the body is most villi found?

A

ileum (small intestine)

266
Q

Explain how the structure of a villus is adapted for the absorption of the products of digestion

A

it has a large surface area with lots of capillaries

blood circulates to maintain the concentration gradient

the capillary walls are one single cell thick to allow for a short diffusion distance

267
Q

From the diagram select the letter, or letters, that show where the change of pH 7 to 2 takes place

A

C

268
Q

From the diagram select the letter, or letters, that show where the digestion of enzymes takes place

A

A, C, F

269
Q

From the diagram select the letter, or letters, that show where absorption takes place

A

F, G, C, A

270
Q

From the diagram select the letter, or letters, that show where egestion takes place

A

egestion = defecation

H

271
Q

Describe two ways in which bile helps digestion

A

it neutralises the pH when the food exits the stomach

it emulsifies lipids into droplets

272
Q

The horse is a mammal and the digestive system is similar to that of humans. Chose the correct letter to match each statement:

This is where plant food is chewed:

This is where faeces is stored:

This is where most villi are found:

A

This is where plant food is chewed: B

This is where faeces is stored: D

This is where most villi are found: C

273
Q

Explain how food is moved along the oesophagus

A

peristalsis; muscle contractions in the wall of the oesophagus

274
Q

Describe and explain the results shown by the graph

A

lipase works best with bile, least well in acidic solution and better in alkaline conditions

bile neutralises the pH

bile emulsifies fat

enzymes denature

275
Q

What is the product of digestion of the maltose?

A

glucose

276
Q

Name three macronutrients in the diet

A

protein

lipids

carbohydrates

277
Q

Name two micronutrients in the diet

A

minerals

vitamins

278
Q

Which mineral is found in meat and dark green leafy vegetables?

A

iron

279
Q

What is fibre exaclty?

A

it is used to make cellulose - plant cell walls

280
Q

Give one fact about the structure of starch

A

it is made up of many glucose subunits - coiled shape

281
Q

What are molecules like after digestion?

A

small

soluble

282
Q

Is liver part of the digestive system?

A

no

food doesn’t pass through it

283
Q

What is the name for the tube that takes enzymes from the pancreas into the digestive system?

A

the pancreatic duct

284
Q

Which two types of vessel are found inside veery villus?

A

lacteal

blood capillary

285
Q

Desrcibe the surface of a villus

A

one layer of cells

have microvilli

286
Q

3 samples of lipase were kept in 3 test-tubes

One has pH 2 buffer added, one has pH 7.5, and one had pH 9

Which pHs denature the lipase?

A

ph 9 and ph 2

287
Q

Which enzyme breakdown hydrogen peroxide into water and carbon dioxide?

A

catalase

288
Q

Recall this diagram about the digestive system

A

Biology (24 decks)

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