Organisms Exchange Substances With Their Environment Flashcards
(162 cards)
1
Q
What substances do organisms need to exchange in order to survive
A
Take in oxygen and nutrients
Remove carbon dioxide and urea
2
Q
What happens to SA:V ratio the larger the organism gets
A
Larger the organism the lower the SA:V
3
Q
What happens to the SA:V ratio the smaller an organism gets
A
Smaller the organism the higher the SA:V
4
Q
What does greater mass mean in regards to organism metabolic rate
A
The greater the mass the higher the organisms metabolic rate
5
Q
What is metabolic rate
A
The amount of energy expended by that organism in a time period- usually daily
6
Q
Unicellular organisms
SA:V ratio, diffusion distance and advantage and disadvantage
A
Large SA:V ratio
Diffusion distance is short
Advantage- can exchange materials directly with their environment
Disadvantage- lose heat energy quickly
7
Q
Multicellular organisms
SA:V ratio, diffusion distance, advantage and disadvantage
A
Small SA:V
Diffusion distance is large
Advantage- lose less energy as heat
Disadvantage- no surfaces exposed to the outside so need internal mass transport systems
8
Q
Behavioural adaptations for cold environments
A
Small mammals lose heat energy easily so they need to eat large amounts of high energy foods
They may also hibernate during colder months
9
Q
Physical adaptations from cold environments
A
Adapted animals will have a streamlined, compact body shape giving smaller SA:V
Mammals with larger SA:V may have thick fur to insulate
10
Q
Behavioural adaptations for hot deserts
A
Large organisms spend most of day in water to help lose heat
May be nocturnal so they are most active in cooler temperatures
11
Q
Physical adaptations for hot environments
A
Organisms with low SA:V often have large eras to increase surface area to lose more heat
12
Q
Adaptations to help with water loss
A
Nocturnal
High SA:V have kidney adaptations to produce less urine to compensate for water loss
13
Q
What occurs during digestion
A
Large biological molecules are hydrolysed to smaller molecules that can be absorbed across cell membranes
14
Q
Where does the absorption of nutrients occur
A
The small intestine
15
Q
How is the small intestine adapted to maximise the movement of substances
A
Internal walls are folded into villi
Villi have thin walls to keep diffusion pathway short
Villi have lots of capillaries to help maintain the concentration gradient
Villi contains muscles which helps mix the contents of ileum
16
Q
Where are the epithelial cells in the small intestine
A
Line the ileum
17
Q
How are the epithelial cells that line the ileum adapted from digestion
A
Have microvilli to increase the surface area further
Lots of mitochondria for active transport
Carrier proteins for active transport
Channel proteins for facilitated diffusion
18
Q
What enzyme does the salivary glands produce
A
Amylase
19
Q
How do the salivary glands help digestion
A
Breaks glycosidic bonds in starch to form maltose
20
Q
What enzyme does the pancreas produce
A
Pancreatic amylase
21
Q
How does the pancreas help digestion
A
Breaks glycosidic bonds to hydrolyse starch to form maltose
22
Q
What does the small intestine produce for digestion
A
Membrane bound disaccharidases in the cell membrane of epithelial cels
23
Q
How does the small intestine (ileum) help digestion
A
Breaks glycosidic bonds to hydrolyse disaccharides into monosaccharides
24
Q
What are the three membrane bound disaccharidases
A
Maltase
Sucrase
Lactase
25
How is glucose and galactose transported
Actively transported using sodium ions through co transporter proteins
26
How is fructose absorbed
By facilitated diffusion
27
What enzymes break down proteins in a series of hydrolysis reactions
Peptidases
Proteases
28
Where does protein digestion occur
In the small intestine and stomach
29
What enzyme does the HCl in the stomach provide optimum pH for
Enzyme pepsin
30
How are other peptidases e.g trypsin secreted into the small intestine
By the pancreas
31
Digestion of proteins in the stomach
Proteins are chewed and swallowed into stomach
HCl denatures proteins unfolding their 3D structure
Enzymatic digestion by pepsin forms shorter polypeptides
32
Digestion of proteins in the small intestine
Trypsin and proteases continue enzymatic digestion by forming dipeptides and tripeptides and amino acids
Tripeptides and dipeptides are further broken down into amino acids which are then absorbed into the blood
33
What are the three types of the protease enzyme
Endopeptidases
Exopeptidases
Dipeptidases
34
What are endopeptidases
Hydrolyse peptide bonds within a large protein to create smaller polypeptide chains
35
What are exopeptidases
Hydrolyse terminal peptide bonds
36
What are dipeptidases
Type of exopeptidase
Located on membrane of epithelial cells in the small intestine
They work specifically on dipeptides to hydrolyse the peptide bonds holding them together, this then creates two single amino acids
37
How are amino acids absorbed
Through active co transport with sodium ions
38
What do lipases do
They are enzymes which hydrolyse the ester bonds in triglycerides to form fatty acids and monoglycerides
39
Where are lipases made
In the pancreas and secreted into the small intestine
40
Where are bile salts produced, stored and released
Produced by the liver
Stored in the gall bladder
Released into the small intestine
41
What do bile slats help break down and how does this help speed up the action of lipases
Large fat globules by emulsifying them into smaller droplets meaning the surface area is increased so more is exposed to enzyme
42
What are micelles
Tiny structures formed when monogylcerides and fatty acids stay in contact with the bile salts to help absorption of fatty acids and monogylcerides into the bloodstream
43
Process of the absorption of lipids
Micelles contain bile salts, fatty acids and monogylcerides and fatty acids and monoglycerides are carried to the cell
Fatty acids and monoglycerides diffuse across membrane
Monoglycerides and fatty acids are transported to ER where they recombine to form triglycerides
Inside the Golgi they bind with cholesterol and proteins and are packaged to form chylomicrons
Chylomicrons travel in a vesicle to the cell membrane and are exocytosed from the epithelial cell
Chylomicrons enter lymphatic capillaries called lacteals which transport them to other tissues in the body
44
What is the structure of an insect
Air filled pipes called trachea which then divide into smaller tubes called tracheoles which continue to divide until they penetrate into individual body cells meaning gases are directly exchanged between cells
45
How does air enter the insects trachea
Through pores on the surface of the exoskeleton called spiracles
46
What are adaptations of insects that help gas exchange
Tracheoles have thin walls- short diffusion distance
Tracheoles are highly branched- increases surface area
Muscles can pump forcing air in and out- maintains conc gradient
Spiracles can be closed- prevents water loss
47
How do insects ventilate
Insects can compress the tracheae and so pump gases in and out of the body
Pumping raises pressure so forces air out of spiracles down conc gradient e.g during intense movement
48
What is the structure of fish
Each gill is made of lots of thin plates called gill filaments which are attached to a bony gill arch
The gill filaments have lots of tiny folds called lamellae
49
Where does gas exchange occur in the fish
In the lamellae
50
What is a concurrent flow
Water and blood flow over and through the lamellae in the same direction
51
What is a countercurrent flow
Water and blood flow over and through the lamellae in opposite directions to each other
52
What are the adaptions of fish that helps gas exchange
Thin walls of lamellae- short diffusion distance
Large number of filaments and lamellae— increases surface area
Countercurrent flow system- maintains conc gradient
Large number of capillaries around lamellae
Ventilation by operculum - ensures constant fresh water flow over gills to replace lost oxygen
53
Where does water enter the fish and where does it leave
Takes in water through it buccal cavity and leaves via the operculum openings on each side of fishes head
54
How does the lamellae remain supported and moist
By the water that is continually pumped through the mouth and over the gills
55
Process of ventilation for fish
Mouth opens, operculum shuts
Water enters through cavity due to increased volume and decreased pressure
Mouth closes, operculum opens
Increased pressure forces water out over the gills
56
What is the structure of humans gas exchange
Air flows into mouth then down the trachea
Then trachea splits into bronchi which further branches into bronchioles and end in small air sacs called alveoli
57
Where does gas exchange take place in humans
The alveoli
58
What are lungs made up of to carry out their function
Specialised tissues
59
What is the function of the cartilage
Provides strength to trachea and bronchus
60
What is the function of surfactant
It’s a phospholipid layer which maintains moisture but reduces surface tension to stop alveoli collapsing
61
What is the function of the smooth muscle
Can contract to constrict the airways
62
What is the function of the goblet cells
Secrete mucus which traps particles of dust and bacteria
63
What is the function of the ciliated epithelial cells
Beat regularly to move mucus up the airways to the mouth to be removed
64
What is the function of the elastin
Allows lung tissue to stretch when breathing in to fill up lungs and recoil when breathing out to help force air out
65
What is the function of the squamous epithelium
Lines alveoli and gives short diffusion pathways for oxygen and carbon dioxide
66
What are the adaptations for human gas exchange
Alveoli and capillaries are very thin- short diffusion distance
Large number of alveoli- increases surface area
Large number of capillaries surrounding the alveoli- maintain steep concentration gradient
Constant ventilation of air in and out- maintains steep concentration gradient
Capillaries that surround alveoli are very thin- red blood cells slow down to squeeze through one at a time increasing time for diffusion
67
Features of inspiration
Diaphragm contracts (moves down)
External intercostal muscles contract pulling ribcage up and out
Increases volume
Reduces pressure
Active process
68
Features of expiration
Diaphragm relaxes (moves up)
External intercostal muscles relax, ribcage moves in and down
Decreases volume
Increases pressure
Passive process
69
As oxygen enters does it travel down or against its gradient
Down
70
As carbon dioxide leaves does it move down or against its gradient
Down
71
What is ventilation rate
How many breaths per minute
72
What is tidal volume
The volume of air in each breath
73
What is the certain volume of air that remains in the lungs to make sure they never fully deflate called
Residual volume
74
How can you measure lung function
Using a spirometer
75
What is forced expiratory volume
Max volume of air breathed out in 1 second
76
What is forced vital capacity
Max volume of air possible to forcefully breathe out of lungs
77
What does lung disease reduce the rate of
Reduces rate of gas exchange so body cells receive less oxygen so patients suffer with tiredness and weakness
78
What is restrictive diseases and example
Difficult to breathe in
E.g fibrosis
79
What is obstructive diseases
Difficult to breathe out
E.g asthma
80
What are the causes, effects and symptoms of tuberculosis
Causes- bacteria inhaled by droplet infection which forms small hard lumps
Effects- damaged alveoli, scar tissue is thick (longer diffusion distance) elasticity is reduced (lungs cannot expand as much)
Symptoms- persistent cough, shortness of breath and fatigue
81
What are the causes effects and symptoms of pulmonary fibrosis
Causes- formation of scar tissue
Effects- scar tissue is thick (longer diffusion distance) elasticity is reduced
Symptoms- dry cough, fatigue and shortness of breath
82
What are the causes effects and symptoms of asthma
Causes- airways become inflamed due to an allergic reaction, lots of mucus produced
Effects- airways constrict (reduces air flow so less oxygen diffuses into blood)
Symptoms- wheezing, shortness of breath and tight chest
83
What are the causes effects and symptoms of emphysema
Causes- caused by foreign particles (from smoking) being trapped into alveoli, causes inflammation and enzymes breaks down elastin
Effects- damaged alveoli (smaller SA) loss of elastin means alveoli cannot recoil so less air is expelled
Symptoms- wheezing and shortness of breath
84
Why do multicellular organisms require a transport system
They have a low SA:V
85
What are the two types of circulatory system
Open
Closed
86
What is a closed circulatory system
Blood is confined to blood vessels only
Like in fish and mammals
87
What are the two forms of a closed circulatory system
Single
Double
88
What is a single closed circulatory system
Consists of two chambers in the heart meaning the blood passes through the heart once for every circuit
89
What is a double closed circulatory system
Heart has 4 chambers meaning the blood passes through the heart twice for every circuit
90
Why is the double closed circulatory system more efficient
Increases pressure and therefore the speed of oxygenated blood to tissues
91
What are the coronary arteries
The hearts own oxygenated blood supply
92
What is the flow diagram of the movement of blood
Aorta
Arteries
Arterioles
Capillaries
Venules
Veins
Vena cava
93
What are the features of blood vessels
Smooth muscle layer- contracts to control the flow of blood in arteries, arterioles and veins
Elastic layer- allows vessel to stretch and recoil in arteries, arterioles and veins
Endothelium- thin inner lining which reduces friction in all vessels
94
How are the arteries and veins different
Arteries carry blood away, veins carry blood towards heart meaning
Arteries have narrower lumen, veins have wider lumen
Arteries have thick muscular walls and elastic layer, veins have thinner layers
Endothelium is folded in arteries to allow stretching, veins have valves
95
Features of the capillaries
Smallest blood vessels
Very close to cells and are very thin so short diffusion pathway
Gaps called fenestrations allow substances to diffuse out between
Large number of capillaries increase surface area
96
The vena cava is the final blood vessel to return to the heart
Does it have a low or high pressure
Low
Highest is aorta
97
What happens to the pressure as blood moves along the vessels and why
Blood loses pressure due to its branching and increasing size of lumen
98
What is tissue fluid
The liquid that surrounds the cells, formed by blood plasma leaking from the capillaries
99
What is hydrostatic pressure
The pressure the fluid id putting on the walls of the vessel
100
What happens at the arteriole end
The hydrostatic pressure is greater than the osmotic pressure so this causes fluid to move out of the capillary and this forms tissue fluid
101
What remains in the blood when fluid moves into the capillary
Red blood cells, platelets and plasma proteins because they are too large
102
What happens once exchange has occurred in regards to tissue fluid
Carbon dioxide and other wastes leave the cell and enter the tissue fluid
103
What happens at the venule end
Hydrostatic pressure is lower than the osmotic pressure so water moves by osmosis into the capillaries carrying the waste products to from plasma
104
What happens to any excess tissue fluid
It’s collected in the lymphatic system to form lymph which then gets retuned to the circulatory system
105
Why does the hydrostatic pressure decrease along the capillary
There is less water in the capillary as you move along
106
How are red blood cells (erythrocytes) adapted for oxygen transport
Bioconcave shape- large surface area
Flat and thin- short diffusion pathway
No nucleus
107
What is the protein structure of haemoglobin
Globular protein with a quaternary structure
108
Structure of polypeptide chains of haemoglobin
Four polypeptide chains each made up of a haem group which contains iron ion which gives haemoglobin its red colour
Each molecule of haemoglobin can bind up to four oxygen molecules as oxygen binds to haem group
109
What does associates mean
Binds
110
What does dissociates mean
Leaves
111
How does oxygen form oxyhaemoglobin
Oxygen diffuses into red blood cells where it associates with haemoglobin to form oxyhaemoglobin
112
What happens at respiring tissues in regards to oxygen
Oxygen dissociates and turns back into haemoglobin
113
What is associates also known as
Loading
114
What is dissociates also known as
Unloading
115
What does haemoglobins affinity for oxygen mean
How easily it will bind to oxygen
116
What are the conditions that alters haemoglobins affinity for oxygen
The partial pressure of oxygen
Haemoglobin saturation
The partial pressure of carbon dioxide
117
What is partial pressure
Measure of concentration of that gas in a mixture of gases
118
What does higher concentration of oxygen mean for partial pressure
Higher partial pressure
119
What does higher partial pressure of oxygen mean for haemoglobins affinity for oxygen
Higher
120
Where will haemoglobin have a higher affinity for oxygen
In oxygen rich areas
121
Where will haemoglobin have a lower affinity for oxygen
In oxygen starved areas
122
What is the saturation of haemoglobin
Oxygen binding to the 4 polypeptide chains
123
How does the saturation of haemoglobin affect its affinity for oxygen
As each oxygen molecule binds it change the shape of the haemoglobin in a way that makes it easier for further oxygen molecules to bind
However it becomes harder for the final oxygen to bind
124
How does the partial pressure of carbon dioxide affect the affinity of haemoglobin for oxygen
High partial pressure of carbon dioxide means more oxygen is unloading as high carbon dioxide means low pH which alters the tertiary structure of haemoglobin decreasing its affinity for oxygen so increases the dissociation for oxygen
125
What does a further left curve on a graph mean for affinity
Higher affinity
Higher pH, low carbon dioxide
126
What does a further right curve on a graph mean
Lower affinity
Low pH, higher carbon dioxide
127
What is the haemoglobins affinity for oxygen for a foetus in the womb
Higher affinity- curve shifted to left
Foetus needs to “steal” oxygen away from mothers haemoglobin
If foetus and mother had same affinity there would be no incentive for oxygen to move
128
What is the affinity for animals living in low oxygen environments
Higher affinity- curve shifted to left
Less oxygen available so haemoglobin has to be able to load more oxygen at a lower partial pressure of oxygen to make sure enough oxygen is absorbed
129
What is the affinity for small organisms with a high SA:V or organisms with a high metabolic rate
Lower affinity- curve shifted to the right
High SA:V means higher metabolic rate which means more respiration so more oxygen demand
So they need to unload oxygen more easily to meet high oxygen demand for faster respiration
130
What side of the heart has thicker ventricle wall and why
Left side to pump oxygenated blood all around the body
131
What side of the heart contains deoxygenated blood
Right
132
What is the only vein to carry oxygenated blood
Pulmonary vein
133
What is the only artery to carry deoxygenated blood
Pulmonary artery
134
What are semilunar valves
Valves found in the aorta and pulmonary artery to prevent back flow of blood into ventricles
135
What side are bicuspid valves located on
Left
136
What side are tricuspid valves located on
Right
137
What is the atrial systole
Ventricles relax, atria contract, this decreases volume so increases pressure with forces AV valves open fully and blood is pushed into ventricles
138
What is the ventricular systole
Atria relax, ventricles contract which decreases volume and increases pressure forcing AV valves close and when pressure increases enough SL valves are forced open and blood is pumped out by arteries
139
What is the diastole
Both atria and ventricles relax, pressure in the arteries is now higher than ventricles so SL valves shut, blood starts to enter atria and this starts to increase pressure of the atria and eventually it exceeds ventricle pressure and AV valves open slightly and blood begins to flow into ventricles
140
What are the stages of the cardiac cycle called
Atrial systole
Ventricular systole
Diastole
141
What is cardiovascular disease
Any disease associated with the heart or blood vessels
142
What are atheromas
Fibrous plaques made up of fatty material which narrow the lumen
143
Process of atheroma formation
Endothelium of artery is damaged causing high blood pressure
White blood cell moves to damaged site absorbing cholesterol
Fatty acid deposit and cholesterol build up to from an atheroma
Atheroma gets covered by fibrous cap which lowers elasticity and creates a narrower lumen
Rough surface of the plaque causes platelets to form a blood clot to form a thrombus
Heart gets deprived of oxygen causing an attack
144
Risk factors for cardiovascular disease
High blood pressure
Smoking
Genetics
Age
145
Properties of water
Metabolite- for reactions
Solvent- transports substances
High latent heat of vaporisation- cooling effect
High specific heat capacity- buffers changes in temperature
Strong cohesion- produces surface tension
146
What do plants need carbon dioxide for
Photosynthesis
147
How do gases move in and out of the leaf
Through the stomata
148
Function of waxy cuticle
Waxy layer at top of leaf to reduce water loss
149
Function of upper epidermis
Transparent layer on top of leaf
For protection
150
Function of palisade mesophyll
Lots of chloroplasts for photosynthesis
151
Function of spongy mesophyll
Air spaces for gas exchange
152
What is the function of the xylem
Transport water and mineral ions
153
What is the function of the phloem
Transports dissolved sugars in the plant
154
What is the structure of the xylem
Elongated tubes formed from dead cells
No end walls between cells
Gaps in cell wall
Thick walls made of lingin
155
Process of cohesion- tension theory
Water evaporates from spongy mesophyll into the atmosphere
Lowers water potential in leaf
Water from xylem travels down conc gradient into leaf
Lowers hydrostatic pressure on top of xylem
Water is pulled up the xylem
Cohesive forces between water prevents breaking- forming a water column
Lowers water potential on bottom of xylem
Water enters root hair cells
Water from soil enters root hair cells
156
Evidence to support cohesion tension theory
If stem is damaged water does not leak out
Trunk of trees reduce in diameter in day when transpiration is greatest
At night when transpiration is lowest diameter increases as there is less tension
157
What are xerophytes
Plants in hot dry or windy climates that need extra adaptions to prevent them loosing too much water
158
What are the adaptations of xerophytes
Small surface area- fewer stomata
Sunken stomata- maintains humid air to reduce water potential gradient
Stomata hairs- maintains humid air
Rolled leaves- reduces effects of wind
Reduced number of stomata
Thicker waxy cuticle- prevent evaporation
159
What is translocation
Process by which products of photosynthesis are transported from a source to a sink
160
Structure of phloem
Elongated living cells called sieve tubes
No nucleus or organelles
Each sieve tubes is supported by a companion cell which has organelles including mitochondria to produce ATP
End walls known as sieve plates as they contain holes
161
Process of mass flow hypothesis
Sucrose manufactured from photosynthesis
Sucrose is diffused into companion cell and active transport of hydrogen ions
Sucrose is co transported with hydrogen ions into the phloem
Higher concentration in sucrose leads to lower water potential
Water leaves xylem into phloem by mass flow
Sucrose being used at the sink
Sucrose is actively transported form sieve tubes to companion cells which lowers water potential
Water moves into cells via osmosis which lowers hydrostatic pressure
162
Evidence to support mass flow
When sieve tubes are cut sap is released
Honeydew tends to flow faster out of aphids higher up
Sucrose concentration is higher in leafs than roots
