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OCR A level bio > Module 3 > Flashcards

Module 3 Flashcards

1
Q

Alveoli

A

Tiny air sacs that serve as primary gas exchange surface.
Have a thin epithelial cell layer, collagen and elastin fibres

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2
Q

Breathing rate

A

Number of breaths per min

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3
Q

Bronchi

A

Divisons of trachea that lead into lungs. Small tubes supported by incomplete rings of cartilage

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4
Q

Bronchioles

A

Many divisions of the bronchi. Contain smooth muscle to restrict airflow to the lungs but dont have cartilage. Lined with thin layer of epithelial cells

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5
Q

Cartilage

A

Strong, flexible connective tissue that supports the walls of the trachea and bronchi, preventing collapse. Incomplete ring shape

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6
Q

Ciliated epithelial cells

A

Specialised cells with tiny hair like cilia found in trachea lining that waft mucus up to back of throat- swallow

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7
Q

Countercurrent flow

A

Adaption for gas exchange in bony fish.
Blood in gill filaments and water moving up the gills flow in opposite directions, maintaining steep o2 gradient

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8
Q

Elastic fibre

A

Fibres of elastin that allow alveoli to stretch as air is drawn in and recoil to normal size- expelling air. Found in trachea, bronchi and bronchioles

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9
Q

Exchange surface

A

Surface where materials are exchanged from one region to another. Effective exchange surface has a large SA, thin layers, good blood supply and ventilation to maintain steep diffusion gradient

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10
Q

Expiration

A

Diaphragm relaxes and reverts to a dome. External intercostal muscles relax, moving ribs down and in
Volume of thorax decreases and thoracic pressure exceeds air pressure and air moves out

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11
Q

Gill filaments

A

Main site of gas exchange in fish, which water flows.
Found in large stacks, known as gill plates and have gill lamellae- large SA for exchange

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12
Q

Gill lamellae

A

Fine branches of filaments. Adapted for gas exchange by large SA and good blood supply

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13
Q

Gill plates

A

Large stacks of gill filaments

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14
Q

Gills

A

Organs of gas exchange in fish. In gill cavity made up of gill lamellae, filaments and plates

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15
Q

Goblet cells

A

Specialised cells that secret e mucus onto trachea lining. Mucus traps harmful substances and microorganisms preventing their entry into lungs

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16
Q

Inspiration

A

Diaphragm contracts and flattens and external intercostal muscles contract, moving ribs up and out

Volume of thorax increases and thoracic pressure falls below air pressure

Air moves into trachea

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17
Q

Internal intercostal muscles

A

Muscles found between the ribs which are responsible for forced exhalation

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18
Q

Operculum

A

A flap which covers gills of bony fish. Protects gills and helps maintain a constant stream of water over them

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19
Q

Smooth muscle

A

Involuntary muscle found in walls of trachea and bronchi.
Constricts the lumen of bronchi by contracting, reducing air flow to lungs

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20
Q

Spiracles

A

Small external openings along the thorax and abdomen of most insects, through which air enters, and air+water leave the gas exchange. Spirical sphincters open and close the spiricals to control gas exchange

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21
Q

Spirometer

A

Device to examine patterns of breathing and determine different aspects of lung volume

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22
Q

Tidal volume

A

Volume of air that moves in and out of lungs during a normal breath

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23
Q

Trachea (mammals)

A

Primary airway which carries air from nasal cavity down to the chest.

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24
Q

Trachea (insects)

A

Large tubes from spiracles, into and along an insects body. Supported by spirals of chitin.

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25
Q

Tracheal fluid

A

Fluid found at end of tracheoles. Amount of fluid effects SA available for gas exchange and water loss

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26
Q

Tracheoles

A

Divisions of tracheae that run through tissues of an insect, forming complex network. Main site of gas exchange and completely permeable to gases

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27
Q

Ventilation

A

Movement of fresh air into lungs and stale air out of lungs via inspiration and expiration

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28
Q

Vital capacity

A

Largest volume of air that can be breathed in following strongest possible exhalation

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29
Q

Affinity

A

Tendency of one substance to bind with another

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30
Q

Aorta

A

Artery that takes up oxygenated blood away from heart to body

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31
Q

Arteriole

A

Type of blood vessel which connects arteries and capillaries. Walls of arterioles contain large amount of smooth muscle, some elastic fibres and some collagen

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32
Q

Artery

A

Type of blood vessel that carries blood away from heart to tissues, under high pressure. The walls of arteries contain collagen, smooth muscles and elastic fibres

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33
Q

Atrial fibrillation

A

Arrythmia which involves rapid contraction of atria, preventing complete ventricular filling

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34
Q

Atrial systole

A

Stage of cardiac cycle in which atria contract, pushing blood into ventricles. AV valves pushed open fully and atria emptied of blood

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35
Q

AVN

A

Group cells located between atria that slows down the wave of excitation and pass between ventricle along bundle of his

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36
Q

AV valves

A

Valves found between atria and ventricles. Prevent backflow of blood from venticles into atria. Two typesL Bicuspid and tricuspid

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37
Q

Bicuspid valves

A

AV valves found between left atrium and left ventricle

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38
Q

Blood

A

Transport medium in mammalian circulatory system. Consists of plasma, red blood cells, white blood cells and platelets

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39
Q

Bohr effect

A

Loss of affinity of haemoglobin for oxygen as partial pressure of co2 increases

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40
Q

Bradycardia

A

Slow resting rate below 60bpm

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41
Q

Bundle of his

A

A collection of purkyne fibres which run from AVN down to apex of ventricles

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42
Q

Capillaries

A

Blood vessels that form a large network through tissues of body and connect arterioles to venules. Site of exchange of substances between blood and tissues

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43
Q

Carbonic anhydrase

A

Enzyme which catalyses the reversible reaction between water and co2 to produce carbonic acid

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44
Q

Cardiac cycle

A

Sequence of events in one complete contraction and relaxation of the heart. Arteriole systole, ventricular systole and diastole

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45
Q

Cardiac output

A

Volume of blood pumped by the heart through the circulatory system in one min

Cardiac output = heart rate x stroke volume

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46
Q

Chloride shift

A

Chloride ions move into erythrocytes in exchange for hydrogen carbonate ions which diffuse out erythrocytes. Maintains electrochemical equilibrium of the cell

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47
Q

Circulatory system

A

Transport system in animals

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48
Q

Closed circulatory systems

A

Circulatory system where blood pumped in heart is contained in blood vessels. Blood doesnt come into direct contact with cells

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49
Q

Diastole

A

Stage of cardiac cycle which heart muscle relaxes. Atria and ventricles fill with blood

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50
Q

Double circulatory system

A

Circulatory system which blood flows through the heart twice in two circuits. Blood pumped from heart to lungs before returning to heart.
Then pumped around body where returns to heart

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51
Q

Ectopic heartbeat

A

Additional heartbeats outside normal heart rhythm

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52
Q

ECG

A

Indirectly measures the spread of electrical activity through the heart by measuring tiny changes in the skins electrical conductivity. Produces a trace which is used to detect abnormalities in heart rhythm

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53
Q

Haemoglobin

A

Red pigments in erythrocytes which binds reversibly to four oxygen molecules to form oxyhaemoglobin. Globular protein that consists of 4 polypeptide chains each with a prosthetic haem group

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54
Q

Haemoglobinic acid

A

Product formed when haemoglobin accepts free hydrogen ions.
Enables haemoglobin to act as buffer, reduce changes in blood PH

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55
Q

Heart rate

A

Number of times heart beats in one minute

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56
Q

Hydrostatic pressure

A

Pressure exerted on sides of vessels by a fluid

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57
Q

Inferior vena cava

A

Vein which returns deoxygenated blood to heart from lower body

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58
Q

Lymph

A

Modified tissue fluid which drains into the lymphatic system. Carries less oxygen and fewer nutriens than tissue fluid

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59
Q

Myogenic

A

Cardiac muscle tissues which initiates its own contraction without outside stimulation from nervous impulses

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60
Q

Oncotic pressure

A

Movement of water into blood by osmosis due to tendency of plasma proteins to lower water potential of blood

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61
Q

Open circulatory system

A

Circulatory system in which the transport medium pumped by the heart is not contained within vessels, but moves freely.
Transport fluid comes into direct contact with cells
e.g. Invertibrates

62
Q

Oxygen dissociation curve

A

Graph which describes relationship between partial pressure of 02 and percentage saturation of Hb in blood

63
Q

Plasma

A

Main component of blood that carries red blood cells
Yellow liquid that carries proteins, nutrients, mineral ions, hormones

64
Q

Pulmonary arteries

A

Arteries which carry deoxygenated blood away from heart to lungs

65
Q

Pulmonary veins

A

Veins which carry oxyenated blood from lungs to heart

66
Q

Purkyne tissue

A

Specialised cardiac muscle fibres which make up the bundle of His and conduct the wave of excitation through the septum, from AVN down to the apex of ventricles

67
Q

Semi lunar valves

A

Valves found between ventricles and arteries. Prevent backflow of blood from arteries into ventricles

68
Q

Septum

A

Wall of muscle seperating left side of heart from right, preventing oxygenated and deoxygenated blood mixing

69
Q

Single circulatory system

A

Circulatory system which blood travels one circuit. Blood travels through heart and pumped around the body before returning to the heart.

In fish

70
Q

SAN

A

Group of cells in the wall of right atrium that generate electrical activity causing atria to contract. Hearts pacemaker

71
Q

Stroke volume

A

Volume of bomb pumped by left ventricle

72
Q

Superior vena cava

A

Vein which returns deoxygenated blood to heart from head and upper body

73
Q

Tachycardia

A

Resting heart rate over 100bpm

74
Q

Tissue fluid

A

Fluid surrounding cells of animals

75
Q

Tricuspid valves

A

AV valves found between right atrium and right ventricle

76
Q

Vein

A

A blood vessel which carries blood towards the heart under low pressure. Have a wide lumen, smooth inner lining and valves. The walls of veins contain large amounts of collagen, smooth muscle and elastic fibre

77
Q

Ventricular systole

A

Stage of cardiac cycle in which the ventricles contract, pushing blood into the arteries. Semi lunar valves are pushed open fully

78
Q

Venule

A

Blood vessel which connects the capillaries and veins. Walls of the venues contain small amounts of collagen and smooth muscle

79
Q

Active loading

A

Process which hydrogen ions are actively pumped out of companion cells using ATP, before diffusing down a conc gradient, back into cells via cotransporter proteins whilst carrying sucrose

80
Q

Adhesion

A

Hydrogen bonds between carbohydrates in xylem vessel walls and water molecules. Capillarity of water and transpiration pull

81
Q

Apoplast route

A

One of two pathways by which water and minerals move across the root. Water moves through intracellular spaces between cellulose molecules in cell wall

82
Q

Casparian strip

A

Waterproof strip surrounding the endodermal cells of the root that blocks the apoplast pathway, forcing water through symplast route

83
Q

Cohesion

A

Formation of hydrogen bonds between water molecules

84
Q

Cohesion-tension theory

A

Explains movement of water from soil to leaves, in a continuous stream

85
Q

Companion cells

A

Active cells of phloem located adjacent to the sieve tube elements. They retain their nucleus and organelles, producing ATP for metabolic processes in both themselves and sieve tube elements

86
Q

Dicotyledonous plants

A

Plants which produce seeds that contain two cotyledons. Two primary leaves

87
Q

Hydrophytes

A

Plant which is adapted to live and reproduce in very wet habitats

88
Q

Phloem

A

Living plant transport vessel responsible for transfer of assimilates to all parts of the plant. Contains sieve tube elements and companion cells

89
Q

Plasmodesmata

A

Small pores between adjacent seive tube elements and companion cells that allow communication and exchange of materials

90
Q

Potometer

A

Apparatus used to measure water uptake from a cut shoot

91
Q

Root hair cells

A

Specialised cells responsible for uptake of water and minerals from the soil. Long hair like extensions called root hairs, adapted for exchange surfaces

92
Q

Seive plates

A

Perforated end walls of seive tube elements that allow plant assimilates to flow between cells unimpeded

93
Q

Seive tube elements

A

Main cells of the phloem. Elongated cells laid end to end with seive plates between. Contain few organelles

94
Q

Sinks

A

Regions of a plant which removes assimilates

95
Q

Sources

A

Regions of plants that produces assimilates

96
Q

Symplast route

A

One of two pathways which water and minerals move across the route. Water enters the cytoplasm through the plasma membrane and moves between adjacent cells via plasmodesmata. Water diffuses down its water potential gradient by osmosis

97
Q

Translocation

A

Movement of organic compounds in the phloem from source to sink

98
Q

Transpiration

A

Water loss from plant leaves and stems via diffusion and evaporation. Rate of transpiration is effected by light, temp, humidity air movement and soil water availablitg

99
Q

Transpiration stream

A

Flow of water from roots to leaves in plants, where it is lost by evaporation to environment

100
Q

Vascular bundle

A

Vascular system in herbaceous dicotyledonous plants. Consists of two transport vessels, xylem and phloem

101
Q

Xerophytes

A

Plants adapted to live and reproduce in dry habitats where water availability is low etc cacti

102
Q

Xylem

A

Non living plant transport vessel responsible for transfer of water and minerals from roots to shoots and leaves

103
Q

Two types of epithelial cells in lungs airways

A

Ciliated and squamous

104
Q

How do alveoli create a surface for efficient gas exchange system

A

Wall is one cell thick for shorter diffusion distance

Large amount of them provide large SA

Cells secrete surfactant to maintain SA

Small size - larger SA:V ratio

105
Q

What is tidal volume

A

Volume of air inhaled in each breathe

106
Q

What is vital capacity

A

Maximum volume of air inhaled in one breath

107
Q

Significance of SA:V ratio relationship w rate of diffusion in large plants

A

Large plants have a low SA:V RATIO , so diffusion is too slow to supply requirements so needs a transport system for water etc

108
Q

How does Squamous epithelium improve efficiency of gas exchange

A

Shorter diffusion distance,

109
Q

During the electrical stimulation of the heart, there is a short delay between the excitation of the atria and excitation of the ventricles.
Explain why this delay is essential

A

To allow time for the atria to fully contract
And so ventricles don’t contract too early

110
Q

Purkyne tissue carries the excitation wave down the septum to the apex of the heart. Explain why the excitation wave is carried to the apex.

A

So that ventricular contractions start at apex to push blood upwards

Complete emptying of ventricles

111
Q

One of the symptoms of smoking is the development of a smoker’s cough.
Explain how smoking causes a smoker’s cough and how the cough itself can lead to further problems in the lungs over a long period of time.

A

Causes tar

Mucus builds in airways build up

Cigarette smoke stimulates goblet cells to release more mucus

Effects

Formation of scar tissue
Frequent coughing damages airway
Flow of air restriction

112
Q

Lungs contain many air sacs, what’s their name an why there are so many

A

Alveoli provide larger SA

113
Q

What are the role of elastic fibres in alveoli during ventilation

A

To prevent bursting
To recoil

114
Q

b) For efficient gaseous exchange to occur, a steep diffusion gradient must be maintained between the air in the air sacs and the blood.
A steep diffusion gradient can be maintained by ventilating the lungs. This refreshes the air in the air sacs.
(i) Explain how refreshing the air in the air sacs helps to maintain a steep diffusion gra

A

Increases partial pressure of oxygen in air sac

So conc of o2 in the air sac is higher than that in the blood

115
Q

Describe and explain one other way in which a steep diffusion gradient is maintained in the lungs.

A

Continuous blood flow in the capillaries to bring in more co2

116
Q

Using the mammalian gaseous exchange system as an example, explain how the different cells and tissues enable the effective exchange of gases.

A

Thin epithelium provides short diffusion distance

Erythrocytes transports gases to and from exchange system

Ciliated epithelium removes dust

Cartilage holds airway open

117
Q

Describe how the spirometer would be used to measure tidal volume.

A

Not breathing through nose
Measures height of waves from trace
Measure three and find mean

118
Q

Describe how you could use a spirometer trace to measure the rate of oxygen uptake

A

Measure vol of o2 used
Find difference in height of two peaks- vol changed
Measure time taken to use o2
Volume/time

119
Q

As part of an allergic response, certain cells in the lungs release histamine.
Histamine is a cell signalling molecule that stimulates smooth muscle in the wall of structure A
to contract.
Suggest how histamine stimulates smooth muscle contraction

A

Histamines bind to receptors on cell surface as has complementary shape
Triggers response in cell

120
Q

Another action of histamine is to make capillary walls more permeable.
Suggest two effects this increased permeability may have on the surrounding tissue

A

More tissue fluid formed
Increase pressure in tissue
Swelling
More white blood cells pass into tissue

121
Q

What’s the process of cardiac cycle

A

Atrial walls start to relax and ventricle walls start to contract
SAN generates electrical signals and walls of atria contract
AVN recieves electrical signals from SA node and electrical signals transmitted down septum
Ventricular walls contact and AV valves close
Ventricular valves relax and semilunar valves close

122
Q

What might superventricular tachycardia do to blood flow from heart

A

Lower output of blood leaves heart for each ventricular contraction

Ventricles don’t have enough time to fill before contraction.

123
Q

Why is the foremen ovals open in foetus before birth

A

Lungs not functioning
Haemoglobin not oxygenated in the lungs
Pulmonary circuit bypassed

124
Q

State one difference between fetal haemoglobin and adult haemoglobin and give one reason why this difference is essential to the foetus

A

Fetal Haemoglobin in has a higher affinity for o2
As there is lower partial pressure in placenta

125
Q

What is the role of Haemoglobin in transporting o2

A

Haemoglobin has a high affinity for o2
Oxygen binds to Hb in lungs

Oxyhaemoglobin

126
Q

How are hydrocarbonate ions produced in erythrocytes

A

Co2 enters erythrocytes
Co2 combines with water
Forms carbonic acid

127
Q

High concentrations of carbon dioxide in the blood reduce the amount of oxygen transported by haemoglobin.
Name this effect and explain why it occurs

A

Bohr effect

Reduces affinity of Hb for oxygen
Alters structure of Hb

128
Q

Describe how the components of tobacco smoke can affect the cardiovascular system of smokers.

A

Nicotine increases stickiness of platelets
Thrombosis causes release of adrenaline
Causes constriction of arterioles

Carbon monoxide
Combines permenantly Hb
Reduces o2 carrying capacity of blood

129
Q

Why is the fetal haemoglobin curve to the left of the adult Haemoglobin curve

A

Placenta has a low po2
Adult oxyhaemoglobin will release o2

Fetal Haemoglobin has higher affinity for o2

130
Q

Describe and explain how substances that are dissolved in the blood plasma, such as oxygen or glucose, enter the tissue fluid from the capillaries.

A

Diffusion from high conc to low conc
Hydrostatic pressure in capillary higher than in tissue fluid
Capillary walls are leaky

Fluids forced out capillary

131
Q

Explain why cartilage is essential in the trachea.

A

Provides strength to keep airway open

During inspiration volume of thorax increases
Lower pressure in lungs

132
Q

What causes the fluctuation of pressure as blood flows along the aorta

A

Systole increases pressure
Diastole decreases pressure

Contraction of ventricle

133
Q

Describe the pressure changes in blood as if flows through circulatory stem from aorta to veins

A

Pressure drops as distance from heart increases
Greatest pressure drop whilst blood in arteries
Pressure constant in veins

134
Q

Describe and explain how the wall of the artery is adapted to withstand and maintain high hydrostatic pressure

A

Withstand
-Wall is thick
-Thick layer of collagen which provides strength
-Endothelium folded so not damaged when stretched

Maintain
-Thick layer of smooth muscle which constricts lumen
-Thick layer of elastin which causes recoil

135
Q

Why is the wall of the left ventricle thicker than wall of left atrium

A

More muscle to create more force which is needed to create a higher pressure

Push blood against greater resistance

Pushes blood further to all parts of body

136
Q

How do pressure changes in heart bring about closure of AV bicuspid valve

A

Ventricular systole raises ventricular pressure and higher than atrial pressure

Chordae tendinae prevents inversion

137
Q

What’s the role of SAN and AVN in coordinating cardiac cycle

A

SAN is pacemaker of the heart and sends impulses over atria walls
AVN delays impulse and sends impulses down septum

138
Q

How is hydrostatic pressure generated in the heart

A

Contraction of ventricle wall

139
Q

How is action of heart initiated and coordinated

A

SAN initiates excitation
Wave of excitation spreads across over atrial muscle
Atrial systole
Contraction is synchronised
Delay at AVN
Excitation down septum

140
Q

What are the pores which most water vapour is lost form a leaf

A

Stomata

141
Q

How are guard cells surrounding the leaf pores adapted to their role

A

Have an unevenly thickened cell wall which is able to change shape and bend

Prescience of chloroplasts to produce ATP

142
Q

How does the cohesion tension theory explain how water moves from roots to leaves

A

Evaporation at top of xylem

Creates tension in xylem

Water molecules are cohesive

143
Q

What is a transpiration and a transpiration stream

A

Transpiration
- loss of water vapour from Ariel parts of stomata

Transpiration stream
-movement of water up xylem vessels from roots to leaves

144
Q

How does active loading take place

A

Hydrogen ions pumped up companion cells
Increases hydrogen ion conc gradient outside companion cells
H ions flow back into companion cells
Sucrose moves with H ions down conc gradient

145
Q

What are xerophytic features of a leaf and explain how each feature reduces loss of water vapour

A

Thick cuticle reduces evaporation through leaf surface

Folded r which reduces exposed SA

Has hairs which trap water vapour

146
Q

What sugar molecule is most commonly translocated

A

Sucrose

147
Q

Two adaptions of seive tubes that enables mass flow

A

Elongated elements join end to end
No nucleus

148
Q

How are assimilates loaded into phloem

A

Active transport of H ions creates conc gradient
Facilitated diffusion of h+ into companion cells
Sucrose move in with h ions by cotransport
Sucrose diffuses through plasmodesmata into seive tube

149
Q

How does transpiration contribute to mechanism of water transport up stem

A

Water loss from leaf is replaced via apoplast/symplast/vacuolar pathway
Down water potent gradient
By water in xylem

In xylem loss of water causes low hydrostatic pressure at top
Water moves down pressure gradient under tension in mass flow

150
Q

Two adaptions of leaves which reduce evaporation

A

Hairy leaves trap water vapour
Fewer stomata reduces diffusion

151
Q

Significance of relationships between rate of diffusion an SA:V for large plants

A

Large plants have a small Sa:V

Diffusion too slow to supply requirements

OCR A level bio (10 decks)

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