Exchange Flashcards
1
Q
What is the equation for photosynthesis?
A
6CO2 + 6H2O —-> C6H12O6 + 6O2
2
Q
What is the equation for respiration?
A
C6H12O6 + 6O2 —-> 6CO2 + 6H2O
3
Q
How are leaves adapted?
A
Large SA
Thin
Selectively permeable
Diffusion gradient
4
Q
Why is it good that leaves have a large SA?
A
Greater surface for diffusion
5
Q
Why is it good that leaves are thin?
A
Short diffusion pathway
6
Q
Why is it good that leaves are selectively permeable?
A
Controls what comes in and out
7
Q
Why is it good that leaves have a diffusion gradient?
A
Large diffusion gradient increases the rate of diffusion
8
Q
How are fish adapted?
A
Small SA:Vol
Waterproof, gas tight coating
Surrounded by water (salt water has lower water potential)
Specialised internal gas exchange system (gills)
9
Q
What are the features of gills?
A
Large SA provided by gill lamellae
Rich blood supply
Countercurrent flow
10
Q
What is countercurrent flow?
A
Blood + water flows in opposite directions
Most O2 rich blood + water comes into contact
Most O2 poor blood + water comes into contact
11
Q
What is good about countercurrent flow?
A
Maintains favourable concentration gradient across exchange surface
12
Q
Where are the gills positioned?
A
Behind their head
13
Q
How do gills work?
A
Water enters the mouth + forced over gills then out through the opening
14
Q
What are gills made of?
A
Gill filaments staked on top of each other covered in lamellae
15
Q
What do highly active fish do?
A
Swim with their mouths open
16
Q
Why do some fish swim with their mouths open?
A
Since it maintains high rate of water flow across the gills to provide sufficient O2 for rate for respiration
17
Q
What is an example of a fish that swims with their moths open?
A
Sharks
Mackerel
18
Q
What does the rate of respiration and photosynthesis effect?
A
Vol of gas
Type of gas
19
Q
Why can’t insects use their body surface to exchange respiratory gases?
A
Bodies aren’t permeable
Molecules can’t diffuse in or out
Don’t have a large SA
20
Q
Why do insects have mechanisms that allow them to conserve water?
A
Since they are terrestrial
21
Q
What do terrestrial insects have to balance?
A
Their need to conserve water with gas exchange
22
Q
If you were to increase the SA of an insect what would it conflict with?
A
Water conservation
23
Q
How do insects reduce water loss?
A
Rigid exoskeleton
Waterproof
Small SA
Spiracles - open + close to prevent water loss
24
Q
What is the internal network of tubes called in an insect?
A
Tracheae
25
What is the trachea supported by in insects to prevent water loss?
Rings
26
What does the trachea in insects divide into?
Tracheoles
27
What do tracheoles in insects allow to happen?
Air to be brought directly to respiring tissues
28
Why are insects small?
Not enough O2 for them to grow bigger
Trachea system cannot sustain enough O2
Rely on diffusion rather than transport system
Must have a short diffusion pathway
29
What are the three ways gases move in and out of the tracheal system in insects?
Diffusion gradient
Muscle contractions
Water filled tracheoles
30
How does the diffusion gradient allow gases to diffuse in and out of insects?
During respiration O2 is used
O2 conc at tracheole ends fall
Creates diffusion gradient
O2 diffuses from atmosphere into tracheoles then cells
CO2 is produced by respiring cells
Diffusion gradient in opposite direction
CO2 diffuses out of the tracheoles + into atmosphere
31
How does muscle contractions allow gases to diffuse in and out of insects?
Abdominal pumping - contraction of insect muscles
Trachea squeezed and reduced in volume
Some air expelled from trachea
Uses energy
32
What is abdominal pumping common in?
Large insects
33
How does water filled tracheoles allow gases to diffuse in and out of insects?
Anaerobic respiration produces lactate
Lactate is water soluble so lowers W.P of muscle cells
Water moves into muscle cells from tracheoles
Volume in tracheole ends decrease
Drawing in air
34
What happens to the level of oxygen in the trachea when spiracles are closed?
They are low
35
What causes spiracles to open?
When level of O2 is too low and when level of CO2 is too high
36
The tracheal system relies on diffusion and a short diffusion pathway, what factor will this limit in all insects?
Size - must be small to ensure a short diffusion pathway
37
What are the organelles of a palisade cells?
```
Cell wall
Cell membrane
Chloroplast
Mitochondria
Amyloplast
SER
RER
Golgi apparatus
Ribosomes
Vacuole
Nucleus
```
38
What do stomatas create?
Short diffusion pathway
39
What do air spaces all?
An increased SA + allows gases to diffuse around
40
What do spongy mesophyll layer allow?
Maximum diffusion
41
What do the stomata, air spaces and spongy mesophyll layer all provide?
Short + fast diffusion pathway
42
What does the stomata control?
Diffusion of gases and water vapour
43
What is the stomata surrounded by?
Guard cells
44
What do card cells control?
Opening + closing of the stomata
45
Why is the stomata open in the daytime?
Photosynthesis
| Needs lots of CO2
46
Why is the stomata closed in the dark/night?
No photosynthesis
| No need for CO2
47
What does the transpiration stream do?
Transports water from roots to leaves
48
How is the transpiration stream created?
As water evaporates from the surface of the leaf
49
What is the transpiration stream supported by?
Cohesion Tension Theory
50
What are xerophytes?
Plants living in an area with short water supply
51
Where are xerophytes' roots?
Near the surface since that is where the water is
52
How is the leaf adapted to reduce water loss?
```
Thick cuticle
Rolling up leaves
Hairy leaves
Sunken stomata
Reduced SA:Vol
```
53
How does a thick cuticle reduce water loss?
Less water can evaporate off its surface
54
How does rolling up of leaves reduce water loss?
Traps still, moist air so WP gradient between inside and outside so they're the same so no water loss
55
How does hairy leaves and sunken stomatas reduce water loss?
Trap still, moist air so WP gradient is reduced between inside and outside so less water evaporated
56
How does a reduced SA:Vol reduce water loss?
Smaller SA:Vol = slower rate of diffusion
57
What is an example of a plant with a thick cuticle?
Holly
58
What is an example of a plant that rolls up its leaves?
Marram grass
59
What is an example of a plant with hairy leaves?
Heather
60
What is an example of a plant with sunken stomatas?
Pine tress
61
What is an example of a plant with a reduced SA:Vol?
Pine tree leaves
62
Why is the volume of O2 that needs to be absorbed + the volume of CO2 that needs to be reduced large in mammals?
They're large organisms with a large volume of cells
| Maintain a high body temp as they have a high metabolic + respiratory rate
63
What is the structure of the lungs?
Lobed structure
64
Describe the trachea
Flexible airway supported by cartilage rings
65
What are the muscular walls of the trachea lined with?
Ciliated epithelium and goblet cells
66
Why is the trachea supported by cartilage rings?
To prevent the trachea from collapsing since the pressure falls when breathing in
67
Describe the bronchi
Two divisions of the trachea, each leading to one lung
68
Why do the bronchi produce mucus?
To trap dirt particles
69
What are the bronchi lined with to trap dirt particles?
Ciliated epithelium + goblet cells
70
Describe the bronchioles
Series of branching subdivisions of the bronchi
71
What are the walls of the bronchioles made up of?
Muscle lined with epithelium cells
72
What does mucus allow the bronchioles to do?
Constrict so they can control air flow in and out of the alveoli
73
Describe alveoli?
Air sacs at the end of bronchioles
74
What is between the alveoli?
Collagen and elastic fibres
75
What is the alveoli lined with?
Epithelium cells
76
What do the elastic fibres allow alveoli to do?
Stretch as they fill with air and spring back during breathing out in order to expel CO2
77
What is the alveolar membrane?
Gas-exchange surface
78
What is breathing?
Ventilation
79
What is inspiration/inhalation?
When air pressure of the atmosphere is greater than air pressure inside of the lungs, so air is forced into the lungs
80
What is expiration/exhalation?
When air pressure is of the atmosphere is lower than air pressure inside of the lungs, so air is forced out of the lungs
81
The pressure changes due to what muscles?
Diaphragm
Internal intercostal muscles
External intercostal muscles
82
What is the diaphragm?
A sheet of muscle that separates the thorax from the abdomen
83
Where do the intercostal muscles lie?
Between the ribs
84
Label a diagram of the lungs
Look up A-level diagram
85
Describe inspiration
```
External contract + internal relax
Ribs pull upwards + outwards
So vol of thorax increases
Diaphragm contracts = flattens
So vol of thorax increased
Atmospheric pressure greater
So air forced IN
```
86
Describe expiration
```
External relaxes + internal contract
Ribs move downwards + inwards
So vol of thorax decreases
Diaphragm relaxes = pushed up
So vol of thorax decreases
Pulmonary pressure greater
So air forced OUT
```
87
What type of process is inspiration (breathing in)?
Active
88
What type of process is expiration (breathing out)?
Passive
89
What is each alveolus surrounded by?
Network of pulmonary capillaries
90
How thick are the pulmonary capillaries?
Width of one red blood cell
91
How thick are the alveolus walls?
One layer of cells thick
92
Why are the diffusion of gases rapid between alveoli and blood?
RBCs slowed as they pass through capillary
Very thin walls = short diffusion pathway
Large SA
Constant breathing movements + constant circulatory blood = steep concentration
93
What does the blood flow through the pulmonary capillaries maintain?
Concentration gradient
94
Why is good that RBCs are faltened against pulmonary capillary walls?
Short distance between RBCs and alveolar air
95
Describe the path which O2 goes from an alveolus to the blood
Enters through the alveolar epithelium then enters the blood through the endothelial cell of the capillary
96
Describe the structure of the ileum
```
Walls folded
Villi
Thin walls, lined with epithelium cells
Rich network of capillaries
Large SA
```
97
Why does the ileum have a large SA?
For an increased rate of absorption
98
How do villi increase efficiency of absorption?
Large SA for diffusion
Thin walls = short diffusion pathway
Well supplied with blood vessels
Epithelium cells posses microvilli = further increased SA
99
Why do villi have muscles?
To help them to move so they can mix the contents of the ileum and maintain a conc gradient
100
How are amino acids absorbed?
Co-transport
101
Describe the structure of bile salts
One end lipophilic (fat soluble) + hydrophobic
| Other end lipophobic + hydrophilic
102
Because of their structure, how do bile salts arrange themselves?
Lipophilic ends in fat droplets, leaving lipophobic end sticking out
103
How are monosaccharides absorbed?
Glucose = active transport with NA+ via co-transporter protein
104
How are amino acids absorbed?
Co-transport
105
How are monoglycerides and fatty acids absorbed?
Micelles help move them towards epithelium as constantly break up and reform to release them
Fatty acids + monoglycerides lipid-soluble so diffuse easily across epithelium
106
Describe the oesophagus
Carries food from the mouth to stomach
107
Describe the stomach
Muscular sac with an inner layer that produced enzymes
108
What is the role of the stomach?
To store and digest food
109
Describe the ileum
Long muscular tube where food is further digested by enzymes produced by its walls + glands
110
Describe the large intestine
Absorbs water from the secretions of many digestive glands
111
Describe the rectum
Final section of the intestines, where the faeces is stored before being removed by the anus
112
What is the process of the faeces being removed?
Egestion
113
Describe the salivary gland
Secretes amylase via a duct, situated in the mouth
114
Describe the pancreas
Large gland situated below the stomach
115
What does the pancreas secrete?
Pancreatic juice
116
What does pancreatic juice contain?
Protease, lipase and amylase
117
What two stages does digestion take place in?
Physical breakdown
| Chemical breakdown
118
Describe physical breakdown
Large food is broken down into smaller pieces by means of structures
119
Describe chemical breakdown
Large insoluble molecules hydrolysed by enzymes into smaller soluble molecules
120
What is needed to hydrolyse a larger molecule?
More than one enzyme
121
What do all digestive enzymes functions by?
Hydrolysis
122
What is hydrolysis?
Splitting up larger molecules by adding H2O to the bonds that hold them together
123
What are carbohydrates hydrolysed by?
Carbohydrase/amylase
124
What are lipids hydrolysed by?
Lipase
125
What are proteins hydrolysed by?
Protease
126
What are the hydrolysis products of carbohydrates?
Monosaccharides
127
What are the hydrolysis products of lipids?
Fatty acids + glycerol
128
What are the hydrolysis products of proteins?
Amino acids
129
How are carbohydrates digested?
```
Amylase produced by salivary gland
Hydrolyses alternative glycosidic bond of starch
Maltose formed
Hydrolysed by disaccharidase maltase
Form monosaccharide alpha glucose
```
130
How are lipids digested?
Lipase produced in pancreas
Hydrolyses ester bond in triglyceride
Forms fatty acids + monoglycerides
Lipids split into micelles by bile salts
131
How are micelles formed?
Large lipid molecule emulsified by bile salts
Forms small lipid molecules
Lipase digestion
Form micelles
132
Where are the bile salts produced?
Liver
133
What is a monoglyceride?
Glycerol molecule with one fatty acid attached
134
What are proteins digested by?
Peptidases (proteases)
135
What do endopeptidase do?
Hydrolyses peptide bonds within protein molecules
136
What do exopeptidase do?
Hydrolyses peptide bonds at the ends of protein molecules
| By removing single amino acids from proteins
137
What do dipeptidase do?
Hydrolyses peptide bond between 2 amino acids of a dipeptide
138
Where is a dipeptidase located?
Cell-surface membrane of epithelial cells in the small intestine (ileum)
139
What two examples of endopeptidases that are synthesised in the pancreas and secreted into the small intestine?
Trypsin
| Chymotrypsin
140
What is an example of an endopeptidase that is released into the stomach by cells in its lining?
Pepsin
141
What conditions does pepsin only work in?
Acidic
