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Biology > 3 - Substance Exchange > Flashcards

3 - Substance Exchange Flashcards

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1
Q

When does the need for a specialized exchange surface arise?

A

As the size of an organism, and its SA:V ratio increases

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2
Q

What is required for an efficient exchange surface?

A

Large SA

Thin

Good blood supply / Ventilation

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3
Q

Fish membrane

A

Impermeable - gases can’t diffuse through skin

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4
Q

How many pairs of gills do bony fish have?

A

4 Pairs

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5
Q

What supports each fish gill?

A

An arch

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6
Q

What is located across each arc supporting fish gills?

A

Multiple projections called gill filaments, with lamallae on them which participate in gas exchange

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7
Q

How do blood and water flow across the lamellae?

A

In a counter-current

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8
Q

Benefit of counter-current exchange system in fish

A

Maintains a steep concentration gradient so the maximum amount of oxygen is diffusing into the deoxygenated blood from the water

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9
Q

How are projections held apart?

A

By water flow

This means they stick together in the absence of water and the fish cannot survive

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10
Q

What is required to maintain a continuous unidirectional flow in fish?

A

Ventilation

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11
Q

How does ventilation begin in fish?

A

Fish opens its mouth, followed by lowering the floor of buccal cavity

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12
Q

Effect of lowering the floor of buccal cavity

A

Enable water to flow in

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13
Q

What happens after water flows in, in fish ventilation?

A

The fish closes its mouth, causing the buccal cavity floor to raise, increasing the pressure

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14
Q

What causes the water to be forced over the gill filaments in fish ventilation?

A

The difference in pressure between the mouth cavity and opercular cavity

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15
Q

Role of operculum in fish ventilation

A

Acts as a valveand pump and lets water out and pumps it in

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16
Q

How is oxygen obtained in insects?

A

Oxygen needs to be transported directly to tissues undergoing respiration

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17
Q

Spiracles

A

Small openings of tubes along the thorax and abdomen

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18
Q

Trachea / tracheoles

A

Network of small tubes that carry oxygen around the insect body

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19
Q

How is oxygen transported directly into respiring tissues in insects?

A

With the help of spiracles and either bigger trachea or smaller tracheoles

Gases move in and out through diffusion

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20
Q

What is mass transport in insects a result of?

A

Muscle contraction and volume changes in the tracheoles

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21
Q

Stomata

A

Small holes in leaves which allow gases to enter and leave

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22
Q

Purpose of air spaces in leaves

A

Allows gases to move around the leaf and easily come into contact with photosynthesising mesophyll cells

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23
Q

The Lungs

A

A pair of lobed structures with a large surface area located in the chest cavity that are able to inflate

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24
Q

Rib Cage

A

Surrounds the lungs to protect them

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25
Q

How is friction between the lungs and ribs prevented?

A

Secretion of a lubricating substance

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26
Q

Diaphragm

A

Separates the lungs from the abdomen area

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27
Q

What contracts to raise and lower the ribcage respectively?

A

External and internal intercostal muscles

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28
Q

How does air enter humans?

A

Through the nose, along the trachea, bronchi and bronchioles

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29
Q

Where does gaseous exchange take place in humans?

A

Alveoli - tiny sacs filled with air

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30
Q

What structures allow the flow of air into and out of the lungs?

A

Trachea, bronchi and bronchioles

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31
Q

How are human airways held open?

A

Rings of cartilage, which are incomplete in the trachea to allow the passage of food down the oesophagus behind the trachea

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32
Q

Wall of trachea and bronchi

A

Composed of several layers which together make a thick wall

The wall is mostly composed of cartilage, in the form of incomplete C rings

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33
Q

Inside surface of Cartilage of trachea and bronchi

A

Layer of loose tissue

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34
Q

Inner lining of Cartilage of trachea and bronchi

A

Epithelial layer composed of ciliated epithelium and goblet cells

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35
Q

What are bronchiole walls made of?

A

Smooth muscle and elastic fibre

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36
Q

How are the alveoli adapted for transport?

A

1 cell thick - surrounded by capillaries which are also 1 cell thick - reduces diffusion distance

Constant blood supply by capillaries maintains a steep concentration gradient

Large number of alveoli - Increase SA

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37
Q

Role of Cartilage in gas exchange

A

Supporting the trachea and bronchi

Plays an important role in preventing the lungs from collapsing in the event of pressure drop during excitation

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38
Q

Ciliated Epithelium in gas exchange

A

Present in bronchi, bronchioles and trachea

Moving mucus along to prevent lung infection by moving it towards the throat where it can be swallowed

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39
Q

Goblet cells in gas exchange

A

Present in trachea, bronchi and bronchioles

Involved in mucus production to trap bacteria and dust to reduce the risk of infection with the help of lysozymes which digest bacteria

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40
Q

Smooth Muscle in gas exchange

A

Their ability to contract enables them to play a role in constricting the airway

Controlling diameter which controls the flow of air from the alveoli

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41
Q

Elastic fibres in gas exchange

A

Stretch when we exhale and recoil when we inhale, thus controlling flow of air

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42
Q

2 stages of ventilation

A

Inspiration

Expiration

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43
Q

Inspiration

A

External intercostal muscles contract
Internal muscles relax

Ribs raise upwards
Diaphragm contracts and flattens

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44
Q

Effect of intercostal muscles and diaphragm in inspiration

A

Cause the volume inside the thorax to increase, lowering the pressure

The difference between the pressure inside the lungs and atmospheric pressure creates a gradient, causing air to be forced into the lungs

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45
Q

Expiration

A

Internal intercostal muscles contract
External muscles relax, lowering rib cage

Diaphragm relaxes and raises upwards

Decreases the volume in the thorax, forcing air out of the lungs

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46
Q

Spirometer

A

Used to measure lung volume

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47
Q

Vital Capacity

A

The max volume of air that can be inhaled or exhaled in a single breath

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48
Q

Tidal Volume

A

The volume of air we breathe in and out at each breath at rest

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49
Q

How can breathing rate be calculated from the spirometer?

A

Counting the number of peaks in a minute

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50
Q

Residual Volume

A

Volume of air always present in lungs

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51
Q

Expiratory reserve volume

A

Additional volume of air that can be exhaled on top of the tidal volume

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52
Q

Digestion

A

The hydrolysis of large biological molecules into smaller molecules which can be absorbed across cell membranes

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53
Q

Amylase

A

In the mouth, digests larger Carbohydrate polymers

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54
Q

Maltase

A

In the ileum, break down monosaccharides

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55
Q

Sucrase and lactases

A

Break down the disaccharides sucrose and lactose respectively

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56
Q

How are lipids digested?

A

Lipases hydrolyses the ester bond between the monoglyceride and fatty acid

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57
Q

What happens before lipids are broken down in the ileum?

A

Lipids are emulsified into micelles by bile salts released from the liver

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58
Q

Where are lipids broken down?

A

Ileum

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59
Q

How are lipids emulsified into micelles?

A

By bile salts released by the liver

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60
Q

Effect of emulsification of lipids

A

Increases the SA and speeds up the chemical reaction

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61
Q

Endopeptidases

A

Hydrolyses peptide bonds between specific amino acids in the middle of the polypeptide

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62
Q

Exopeptidases

A

Hydrolyses bonds at the ends of a polypeptide

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63
Q

Dipeptidase

A

Hydrolyses dipeptides into individual amino acids

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64
Q

What happens to products of digestion?

A

Absorbed by cells lining the ileum of mammals

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65
Q

How are amino acids absorbed?

A

Facilitated diffusion through specific carrier molecules in the surface membrane of epithelial cells

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66
Q

Why can monoglyceride and fatty acids easily diffuse across the cell membrane?

A

They are polar

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67
Q

Advantage of monoglyceride and fatty acids being polar

A

Easily diffuse across the cell membrane into the eithelial cells lining the epithelium

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68
Q

What happens once monoglyceride and fatty acids are inside the cell?

A

They are transported to the endoplasmic reticulum where they are reformed into triglycerides.

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69
Q

What happens once monoglycerides and fatty acids have been reformed into triglycerides by the endoplasmic reticulum?

A

They move out of the cells by vesicles in the lymph system

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70
Q

Haemoglobin

A

Water soluble globular protein, Consisting of 2 beta polypeptide chains and 2 alpha helices

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71
Q

What does each molecule in haemoglobin molecule form?

A

A complex containing a haem group

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72
Q

How does haemoglobin carry oxygen in the blood?

A

Oxygen can bind to the haem group

Each molecule can carry 4 oxygen molecules

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73
Q

What does the affinity of oxygen for haemoglobin depend on?

A

Partial pressure of oxygen

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74
Q

What happens as partial pressure of oxygen increases?

A

The affinity of haemoglobin for oxygen increases

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75
Q

Effect of respiration on affinity of oxygen for haemoglobin

A

During respiration, oxygen is used up and therefore the partial pressure decreases, decreasing the affinity of oxygen for haemoglobin

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76
Q

Loading

A

Oxygen binds tightly to haemoglobin

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77
Q

Result of decreased affinity of oxygen for haemoglobin

A

Oxygen is released in respiring tissues where it is needed

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78
Q

What happens after the unloading process of oxygen>

A

Haemoglobin returns to the lungs where it binds to oxygen again

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79
Q

Why does fetal haemoglobin have a greater affinity for oxygen?

A

It needs to be better as absorbing oxygen as by the time oxygen reaches the placenta, the oxygen saturation of the blood has decreased

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80
Q

How is fetal haemoglobin different from adult haemoglobin?

A

It has a higher affinity for oxygen in order for the foetus to survive at low partial pressure

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81
Q

Effect of CO2 on haemoglobin affinity for oxygen

A

Presence of CO2 decreases the haemoglobin affinity for oxygen, causing it to be released

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82
Q

Bohr effect

A

Presence of CO2 decreasing the affinity of haemoglobin for oxygen, causing it to be released

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83
Q

How does CO2 cause oxygen to be released from haemoglobin?

A

CO2 creates slightly acidic conditions which change the shape of the haemoglobin protein, making it easier for the oxygen to be released

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84
Q

Why is a circulatory system needed in large organisms?

A

The SA:V is not large enough to for difussion alone to supply substances like oxygen, glucose and other molecules to cells where they are needed

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85
Q

Common Features of a circulatory system

A

Suitable medium

Means of moving medium

Mechanism to control flow around the body

Close system of vessels

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86
Q

Suitable transport medium in mammals

A

In mammals the transport medium is the blood

It is water based so substances can easily dissolve into it

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87
Q

Means of moving the medium (blood) in mammals

A

Animals often have a pump known as the heart to maintain pressure differences around the body

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88
Q

Mechanism to control flow around the body

A

Valves are used in veins to prevent any backflow

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89
Q

Close system of vessels

A

The circulatory system in most animals and plants is closed and is branched to deliver substances to all parts of the body

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90
Q

Circulatory system in mammals

A

Closed double circulatory system

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91
Q

2 Pumps of the heart

A

One pumps blood to the lungs to be oxygenates

The other is larger and stronger and pumps the oxygenated blood around the body to supply vital organs and tissues

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92
Q

Atrium - Features

A

Thin walled and elastic

Can stretch when filed with blood

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93
Q

Ventricle

A

Thick muscular wall to pump blood around the body or to the lungs

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94
Q

Why are 2 Pumps required in the heart?

A

Maintain blood pressure around the whole body

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95
Q

Why would just 1 pump in the heart not be able to maintain blood pressure around the whole body?

A

The slow down of blood as it passes the lungs would cause it to lose all pressure

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96
Q

4 main vessels connecting the heart

A

Aorta

Pulmonary artery

Pulmonary vein

Vena cava

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97
Q

Aorta - role

A

Connected to the left ventricle and carries oxygenated blood to all parts of the body, except the lungs

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98
Q

Pulmonary artery

A

Connected to the right ventricle and carries deoxygenated blood to the lungs where it is oxygenated and the CO2 is removed

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99
Q

Pulmonary vein

A

Connected to the left atrium and brings oxygenated blood back from the lungs

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100
Q

Vena cava

A

Connected to the right atrium and brings deoxygenated blood back from the tissues except the lungs

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101
Q

Why is the heart myogenic

A

Due to its ability to initiate its own contractions

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102
Q

Sinoatrial node

A

Located in the wall of the right atrium

Region of specialisedfibres which is the pacemaker of the heart

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103
Q

Role of sinoatrial node as pacemaker

A

Initiates a wave of electrical stimulation which causes the atria to contract at roughly the same time

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104
Q

Why do the ventricles not start contractin until the atria have finished?

A

Due to the presence of tissue at the base of the atria which is unable to conduct the wave excitation

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105
Q

Where is the atrioventricular valve located?

A

Between the 2 atria

106
Q

Role of AV valve in ventricle contraction

A

Once the electrical wave reaches the AV valve, it passes on the excitation to ventricles, down the bundle of His to the apex of the heart

107
Q

Bundle of His in ventricle contraction

A

Branches into purkyne fibres which carry the wave upwards, causing the ventricles to contract, thus emptying them

108
Q

Why do the ventricles contract upwards?

A

In order to force the most blood possible upwards out of the aorta and pulmonary artery

109
Q

3 stages of the cardiac cycle

A
  1. Cardiac diastole
  2. Atriole systole
  3. Ventricular systole
110
Q

Adaptations of the arteries

A

Thick wall to withstand high pressure

Elastic tissue to allow them to stretch and recoil

Smooth muscle - vary flow of blood

Smooth endothelium - reduce friction and ease flow of blood

111
Q

Role of arteries

A

Carry blood away from the heart towards the rest of the body

112
Q

Role of arterioles

A

Feed blood into capillaries

113
Q

Adaptations of Arterioles

A

Thinner

Less muscular walls

114
Q

Where are arterioles located?

A

Branch off arteries

115
Q

Smallest blood vessel

A

Capillaries

116
Q

Role of Capillaries

A

Site of metabolic exchange

117
Q

Adaptation of arterioles

A

1 cell thick for fast substance exchange

118
Q

Venules

A

Larger than capillaries but smaller than veins

119
Q

Role of Veins

A

Carry blood from the body to the heart

120
Q

Adaptation of Veins

A

Wide lumen - maximise volume of blood carried to heart

Thin walled - blood under low pressure

Valves - prevent backflow of blood

121
Q

Tissue fluid

A

A liquid containing dissolved oxygen and nutrients which serves as a means of supplying the tissues with essential solutes in exchange for waste products such as CO2

122
Q

When is hydrostatic pressure created?

A

When blood is pumped along the arteries, into arterioles and then capillaries

123
Q

Effect on hydrostatic pressure on the capillaries

A

Forced blood fluid out of the capillaries

124
Q

Effect of hydrostatic pressure on tissue fluid

A

Pushes some of the fluid back into the capillaries

125
Q

Why do the tissue fluid and blood have a negative water potential?

A

They both contain solutes

126
Q

Why is the water potential of the blood more negative than the water potential of tissue fluid?

A

The blood contains more solutes

127
Q

Effect of tissue fluid having a more positive water potential than the blood

A

Causes water to move down the water potential gradient from the tissue fluid to the blood by osmosis

128
Q

What happens to remaining tissue fluid which is not pushed back into the capillaries?

A

Carried back via the lymphatic system

129
Q

What does the lymphatic system contain?

A

Lymph fluid

Less oxygen and nutrients than tissue fluid

130
Q

Main purpose of the lymph fluid

A

Carry waste products

131
Q

Role of lymph nodes in the lymph system

A

Filter out bacteria and foreign material from the fluid with the help of lymphocytes

132
Q

Role of lymphocytes

A

Destroy pathogens as part of the immune system

133
Q

Why do plants require a transport system?

A

Ensure that all the cells of a plant receive a sufficient amount of nutrients

134
Q

Role of Xylem tissue

A

Enables water as well as dissolved minerals to travel up the plant in the passive process of transpiration

135
Q

Role of phloem tissue

A

Enables sugars to reach all parts of the plant in the active process of translocation

136
Q

What are xylem and phloem components of?

A

Vascular bundle

137
Q

Role of vascular bundle

A

Enables the transport of substances as well as provide structural support

138
Q

How are the xylem vessels arranges?

Benefit?

A

In an X shape in the centre of the vascular bundle

Enables the plant to withstand various mechanical forces such as pulling

139
Q

What is the X shape arrangement of the xylem vessels surrounded by?

A

Endodermis

140
Q

Endodermis

A

Outer layer of cells which supply xylem vessels with water

141
Q

Where is the xylem located?

A

On the inside in non-wooded plants to provide support and flexibility in the stem

142
Q

Where is the phloem found?

A

On the outside of the vascular bundle

143
Q

Cambium

A

Between the xylem and phloem

Meristem cells involved in the production of new xylem and phloem tissue

144
Q

What does the vascular bundle in leaves form?

A

The midrib and veins of a leaf

145
Q

Transpiration

A

The process by which water moves through xylem vessels in plants

146
Q

Structure of Xylem vessels

A

Long cylinders made of dead tissue with open ends, therefore they can form an open column

147
Q

Role of pits in xylem vessels

A

Enables water to move sideways between vessels

148
Q

Lignin in xylem vessels

A

Thickens xylem vessels

Deposited in spiral patterns to enable the plant to remain flexible

149
Q

The process of transpiration

A

Plants absorb water through the roots, which then move through the plant and is released into the atmosphere as water vapour through pores in the leaves

150
Q

transpiration stream

A

The movement of water up the stem, enabling processes such as photosynthesis, growth and elongation as it supplies the plant with water

151
Q

Roles of transpiration stream

A

Supplies plant with water and required minerals

Enables plant to control its temperature via evaporation of water

152
Q

How does transpiration involve osmosis?

A

Water moves from the xylem to mesophyll cells

153
Q

Evaporation in transpiration

A

Evaporation from the surface of mesophyll cells into intercellular spaces

154
Q

Diffusion in Transpiration

A

Diffusion of water down a water potential gradient and out of the stomata

155
Q

Xerophytes

A

Plants adapted to living in dry conditions

156
Q

Adaptations of xerophytes

A

Smaller leaves - reduce SA for water loss

Densely packs mesophyll and thick waxy cuticle to prevent water loss via evaporation

157
Q

How do xerophytes respond to low water availability?

A

Closing stomata to prevent water loss

158
Q

Role of hairs and pits in xerophyes

A

Serve as a mean for trapping moist air, reducing the water vapour potential gradient

159
Q

Why do xerophytes roll their leaves?

A

Reduce the exposure of the lower epidermis to the atmosphere, trapping air that is moist

160
Q

What happens once water enters through root hair cells?

A

Moves into the xylem tissue located in the centre of the root

161
Q

What causes water to move into the xylem tissue from the root hair cells?

A

Water potential gradient

162
Q

Why is the water potential higher inside the soil than inside the root hair cells?

A

Dissolved substances in cell sap

163
Q

Purpose of root hair cells

A

Provide a large SA for the movement of water to occur

164
Q

How are minerals absorbed through the root hair cells?

A

Active transport

165
Q

What is the push of water upwards aided by?

A

Root pressure

166
Q

Root pressure

A

The action of the endodermis moving minerals into the xylem by active transport drives water into the xylem by osmosis, pushing it upwards

167
Q

Cohesion-tension theory

A

Combination of surface tension of water and cohesion helps maintain the flow of water in the xylem up the stem

168
Q

What is cohesion-tension theory supported by?

A

Capillary action where the forces involved in cohesion cause the water molecule to adhere to the walls of the xylem

169
Q

Where do translocation primary occur?

A

Phloem vessels

170
Q

Structure of phloem vessels

A

Tubes made of living cells involved in translocation of nutrients to storage organs and growing parts of the plant

171
Q

What do phloem vessels consist of?

A

Sieve tibe elements and companion cells

172
Q

Role of sieve tube elements

A

Form a tube to transport sugars such a as sucrose, in the dissolved form of sap

173
Q

Role of companion cells

A

Involved in ATP production for active processes such a as loading sucrose into sieve tubes

174
Q

How is the cytoplasm of the sieve tube elements and companion cells linked?

A

Plasmodesmata

175
Q

Plasmodesmata

A

Gaps between cell walls which allow communication and flow of substances such as minerals between the cells

176
Q

How does sucrose enter the phloem?

A

Active transport

Companion cells use ATP to transport hydrogen ions into the surrounding tissue, creating a diffusion gradient, which causes H+ to diffuse back into the companion cells

177
Q

What allows Sucrose molecules to return to the companion cells?

A

Facilitated diffusion involving co-transporter proteins

Allows the returning H+ ions to bring sucrose molecules into the companion cell

178
Q

Result of increased sucrose concentration in companion cells

A

Sucrose diffuses out of the companion cells down the concentration gradient into the sieve tube elements, via the plasmodesmata

179
Q

Effect of sucrose entering sieve tube elements

A

Water potential inside tube is reduced. Causing water to enter from the xylem via osmosis, increasing the hydrostatic pressure of the sieve tube element

180
Q

Result of high hydrostatic pressure of the sieve tube element

A

Water moved down the sieve tube from an area of high hydrostatic pressure to an area of low hydrostatic pressure

181
Q

Effect of removing sucrose from sieve tube element

A

Increases water potential in sieve tube, meaning water leaves sieve tube by osmosis back into the xylem

Reduces the pressure in the phloem at the sink

182
Q

Evidence for mass transport

A

Pressure in sieve tube elements - shown by sap being released when the stem of a plant is cit

Sucrose concentration is higher in leaves than roots

Increase in sucrose levels in the leaves are followed by a similar increase in sucrose concentration in the phloem

Metaboloc poisons inhibit translocation of sucrose in the phloem

183
Q

Evidence against mass transport

A

Function of sieve plate is unclear as they would appear to hinder mass flow

Not all solutes move at the same speed, as they should if it is mass flow

Sucrose is delivered at similar rates to all regions, rather than going more quickly to those with the lowest concentration

184
Q

Ringing Experiment

A

Bark and phloem of tree removed, leaving only xylem

Tissues above missing ring swell with sucrose and tissue below dies

shows sucrose is transported in the phloem

185
Q

Tracer experiments

A

Plants are grown in an environment containing radioactivity labelled CO2.
Incorporated into the sugar production in photosynthesis

Movement of these sugars can be traced using autoradiograohy
Exposed areas appear black

These regions correspond to the areas where the phloem is and therefore suggest that this is where the sugars are transported

186
Q

Gills

A

Filaments of thin tissue that are highly branched and folded

187
Q

What happens as water flows through the gills?

A

Oxygen in the water diffuses quickly into the bloodstream

188
Q

Counter-current system in fish

A

Blood flows through the lamellae in the opposite direction of the flow of water through the gills

189
Q

Mesophyll cells

A

Site of photosynthesis and are lpcated in the middle layer of plant leaves

Large SA for rapid gas exchange

190
Q

Epidermis

A

Underside of the leaf

191
Q

Guarg cells

A

Swell to open stomata

192
Q

Where does plant gas exchange take place?

A

Mesophyll cells

193
Q

Role of waxy cuticle in terrestrial insects

A

Prevents water loss

194
Q

Role of hairs on spiracles

A

Decrease the water potential gradient between inside the trachea and the environment

195
Q

Adaptations to reduce water loss in insects

A

Closing of spiracles

Hairs around the spiracles

Waxy cuticle on body

196
Q

Features of xerophytic plants

A

Waxy cuticle

Stomata in sunken pit

Fewer stomata

Hairs on epidermis

Curled leaves

197
Q

Trachea

A

Entrance to the human gas exchange system

198
Q

What provides protection and structure to the trachea?

A

Ridges of cartilage surrounding the front of the trachea

199
Q

Why is there no cartilage at the back of the trachea?

A

So that the oesophagus is not restricted

200
Q

Bronchi

A

The trachea divides into 2 bronchi

Air flows along each bronchus to a lung

201
Q

What are bronchi made from?

A

Cartilage and smooth muscle

202
Q

Bronchioles

A

Each bronchus divides into many smaller bronchioles

The many bronchioles branch throughout the lungs into small air-sacs called alveoli

203
Q

What is ventilation controlled by?

A

Ribcage

Intercostal muscles

Diaphragm

204
Q

What surrounds each alveolus?

A

A network of capillaries

205
Q

What makes up the epithelium?

A

A single layer of epithelium cells that line the walls of the alveoli

206
Q

Muscle contraction in inspiration

A

External intercostal muscles contract

Diaphragm contracts and moves down

Energy required to power muscle contraction

207
Q

Thoracic cavity in inspiration

A

External intercostal muscles move the ribcage up and out

Diaphragm moves down

Volume of thoracic cavity increases

208
Q

Lung pressure decrease in inspiration

A

Increasing volume in thoracic cavity causes pressure in the lungs to decrease

Pressure gradient established between outside and inside lungs

209
Q

Air flow in inspiration

A

Air flows inside the lungs down the pressure gradient

Air flows down the trachea and into the alveoli

210
Q

Hydrolysis of protein

A

Amino acids

211
Q

Hydrolyses of carbobhydrates

A

Disaccharides and monosaccharides

212
Q

Hydrolysis of lipids

A

Farry acids and monoglycerides

213
Q

Where is amylase produced?

A

Salivary glands and pancreas

214
Q

Role of amylase

A

Catalyses hydrolysis of starch into maltose by breaking a glycosidic bond

215
Q

Membrane-bound disaccharidases

A

Enzymes in the cell membranes of epithelial cells in the ileum

Catalyse hydrolysis of disaccharides

216
Q

How are monosaccharides transported into the epithelial cells in the ileum?

A

Transporter proteins

217
Q

What monosaccharides use co-transporter proteins?

A

Glucose and galactose

218
Q

Which monosaccharide uses facilitated diffusion?

A

Fructose

219
Q

Where is lipase produced

A

Produced by the pancreas and released by the small intestine

220
Q

Where are bile salts produced?

A

Liver

221
Q

Role of bile salts

A

Help digest lipids by forming small lipid droplets called micelles

222
Q

Emulsification

A

Process of forming micelles

223
Q

Role of micelles

A

Allow the monoglycerides and fatty acids to be absorbed by the epithelial cells in the ileum

224
Q

Where are sodium-dependent co-transporter proteins located?

A

Epithelial cells membrane

225
Q

Role of co-transporter proteins

A

Actively transport sodium ions into the blood, causing the concentration of sodium ions in the epithelial cells to decrease

226
Q

What happens when sodium ions bind to a co-transporter proteins?

A

Amino acids or monosaccharides also bind to the protein

227
Q

What is the effect of amino acids or monosaccharides binding to the transporter protein

A

Transporter proteins undergoes a conformation change, allowing it to cross the epithelial cells membrane

228
Q

Quaternary structure of haemoglobin

A

Haemoglobin is a protein made from 4 different polypeptide chains

The 4 chains give haemoglobin a quaternary structure

229
Q

Haem groups

A

Each polypeptide chain of haemoglobin has a haem group

A haem groups is a prosthetic group attached to a protein

Contains an iron ion

230
Q

What makes haemoglobin red?

A

Iron ion

231
Q

Dissociation

A

When RBCs reach tissues, oxygen is released from oxyhaemoglobin

232
Q

Shape of oxygen dissociation curve

A

S-Shaped

233
Q

Coronary artery

A

Supplies blood to the heart

234
Q

Movement of deoxygenated blood from the heart

A

Pumped out of the heart to the lungs via the pulmonary artery in the right ventricle

235
Q

Movement of oxygenated blood from the lungs

A

Flows into the heart via the pulmonary vein in the left atrium

236
Q

Movement of oxygenated blood from the heart

A

Pumped out of the heart and around the body via the aorta in the left ventricle

237
Q

Blood pressure in aorta

A

Very high

238
Q

What happens as oxygenated blood is pumped around the body?

A

Oxygen dissociates from the blood at respiring cells in the body and the blood becomes deoxygenated

239
Q

Movement of deoxygenated blood from the body

A

Flows into the heart from the body via the vena cava in the right atria

240
Q

How does oxygenated blood enter the kidney?

A

Through the renal artery

241
Q

How does deoxygenated blood leave the kidney?

A

Renal vein

242
Q

Role of AV valves

A

Prevent backflow of blood into the atria

243
Q

Role of Semi-lunar valves

A

Prevent backflow of blood into the ventricles

244
Q

Pulmonary vein

A

Pumps oxygenated blood into the atria

245
Q

Atria contraction

A

Blood from the lungs flow into the left atrium and blood from the body flows into the right atrium simultaneously

The atria contract, increasing pressure

Blood in atria forced into ventricles

Ventricles relaxed and filled with blood

246
Q

Ventricular Contraction

A

Contraction of ventricles increases pressure

Pressure shuts AV valves to prevent backflow of blood

Blood in ventricles is forced out of the heart through the pulmonary artery or aorta

247
Q

What happens as the ventricles relax and the AV valves reopen reopen?

A

Blood flows into the ventricles and the atria from the pulmonary vein and vena cava

248
Q

Role of arterioles

A

Control direction of blood flow by constricting and contracting

249
Q

Vein wall

A

Thin muscle and elastic tissue

250
Q

Artery wall

A

Elastic fibre to allow them to stretch

251
Q

Role of capillaries

A

Creates a large surface area for exchange of substances between bloodstream and tissues

252
Q

Steps in the Formation of Tissue Fluid

A

Fluid is forced out of the capillaries by pressure filtration

Substances in the tissue fluid diffuse into cells

Water ppotential insidecapillaries decreases

Water moves by osmosis back into capillaries from tissue fluid

Excess tissue fluid flows into the lymphatic system

253
Q

How might the endothelium of arteries become damaged?

A

Deposition of WBCs and lipids

254
Q

What happens in WBCs and fatty materials continue to be deposited in the artery walls?

A

The materials will begin to form hard, fibrous plaque

255
Q

Atheroma

A

Presence of fibrous plaque

256
Q

Effects of the narrowing lumen due to plaque build up

A

Blood flow through arteries is restricted

The narrower lumen also increases blood pressure

257
Q

Effect of arethomas

A

Cause heart disease

258
Q

Risk factors for cardiovascular disease

A

Smoking

Diet

High blood pressure

259
Q

What are the walls of Xylem lined with?

A

Lignin - waterproof polymer which reinforces the walls of the vessel elements to provide structural support

260
Q

Sieve tube elements

A

Cells that make up the phloem vessel

Living - contain cytoplasm but no nucleus

Walls made of cellulose

261
Q

Role of sieve plates

A

Lare pores allow sap to move through the sieve tube element

Allow sugars to be transported through the phloem

262
Q

Translocation

A

The process by which sucrose produced in photosynthesis is transported from the leaves to the sink cells

Biology (7 decks)

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