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Biology Topic 3- Exchange surfaces > Gas exchange > Flashcards

Gas exchange Flashcards

1
Q

What are examples of exchange surfaces?

A

Respiratory gases
Heat
Nutrients like ions glucose and amino acids
Excretory products like urea

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2
Q

What happens to the surface area to volume ratio as an organism becomes larger

A

An organism increases as the surface area to volume ratio decreases

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3
Q

By what process does a single celled organism able to obtain everything it needs

A

Diffusion

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4
Q

What kind of SA:V ratio do smaller animals have and why may this be a problem

A

They have a large surface area to volume ratio so have a higher rate of heat loss at a faster rate

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4
Q

Why are single celled organisms able to use diffusion

A

It has a large surface area to volume so it has a faster rate of diffusion

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4
Q

What adaptations do small animals use for keeping warm

A

High rate of respiration (metabolic rate) to generate heat

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5
Q

Why do large animals have an advantage when they need to keep warm

A

They have a small surface area to volume ratio so wont lose as much heat at a slower rate

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6
Q

What are 2 features of a flatworms body which allows for gas exchange

A

Small organism so it has a large surface area to volume ratio for faster diffusion
It is think so allows for a short diffusion pathway

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7
Q

Explain why a logarithmic scale was used to plot body mass

A

To fit all the values on a graph axis

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8
Q

Explain why someone may measure oxygen uptake per gram of body mass

A

You need to transform the values in to something that allows for comparison between different body masses

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9
Q

What are the key points on surface area to volume ratio

A

The smaller the organism the larger the surface area to volume ratio so it loses heat more quickly and will have a higher metabolic rate to release more heat via aerobic respiration so the organism needs more oxygen and glucose so breathes faster and has a higher heart rate

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10
Q

What does Ficks law state

A

Diffusion rate is proportional to
surface area x difference in conc
divided by diffusion distance

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11
Q

What makes a good exchange surface

A

Large surface area
Large concentration gradient
Short diffusion distance

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12
Q

So how can you increase the rate of diffusion according to Ficks law?

A

By increasing the surface area
Increasing the concentration gradient
Decreasing the diffusion distance

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13
Q

How does oxygen get from the lung to the blood

A

Oxygen diffuses from the alveoli into the blood by diffusing across the alveolar epithelium
Then through the capillary endothelium
Then combines with haemoglobin in red blood cells

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14
Q

What does the respiratory system contain

A

Ring of cartilage
Trachea
Bronchus
Bronchiole
Alveoli
Intercostal muscles
Pleural membrane
Diaphragm

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15
Q

What is ventilation

A

A sequence of breathing movements that moves gases to and from the internal gas exchange surface
During ventilation air always flows from a higher pressure to lower pressure

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16
Q

What are the steps when we breathe in

A

When breathing in:
1) External intercostal muscles and diaphragm contract
2)The ribcage rises and the diaphragm flattens
3) Increase in thoracic cavity volume with a decrease in pressure (below atmospheric)
4)Air moves into the lungs down a pressure gradient

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17
Q

What are the steps when we breathe out

A

When breathing out:
1) The external intercostal muscles and diaphragm relax
2) The ribcage drops and the diaphragm rises
3) Decrease in thoracic cavity volume with an increase in pressure (above atmospheric)
4)Air moves out of the lungs down a pressure gradient

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18
Q

How do you carry out forced expiration

A

Relaxation of external intercostal muscles and diaphragm
Contraction of the internal intercostal muscles
The muscles are antagonistic (opposing)

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19
Q

What pathway does the oxygen take from the air to get into the bloodstream

A

From the mouth to the trachea to the bronchi to the bronchioles to the alveoli

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20
Q

What adaptations of the lungs allow it to have a shorter diffusion distance

A

Alveoli epithelium is thin or one cell thick
Capillary endothelium is one cell thick or close to the alveoli
Alveoli epithelium has thin squamous cells

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21
Q

What adaptations of the lungs allow it to have a large concentration gradient

A

Ventilation of lungs and blood circulation maintains a large concentration gradient

22
Q

What adaptations of the lungs allow it to have an increased surface area

A

Many alveoli and many capillaries surrounding the alveoli provide a large surface area

23
What is the equation for the rate of diffusion
Surface area x Conc gradient divided by diffusion distance
24
What adaptations do insects have to limit water loss
Waterproof covering over their body surfaces. Usually contain an exoskeleton covered with a waterproof cuticle Small SA:V ratio to minimise the area over which water is lost
25
What is the movement of oxygen through the insect
1)Oxygen enters the insect through spiracles and into the tracheae. The spiricle closes 2) Oxygen diffuses through the tracheae into the tracheoles down a concentration gradient 3) Oxygen is delivered directly to the tissues to be used for aerobic respiration
26
What do insects have in its structure
Spiricles Tracheae Tracheoles
27
What do the spiracles do
Gas enters and leaves the insect through these tiny pores. Opened and closed to control water loss by evaporation
28
What does the tracheae do
A network of tubes supported by strengthened rings
29
What do the tracheoles do
Small tubes which extend throughout the body tissues to allow oxygen to diffuse directly into the cells
30
Why is the diffusion pathway for insects always short
Every cell of an insect is only a very short distance from one of the tracheae or the tracheoles
31
Why does diffusion happen in a gas exchange system (tracheal system) of insects for oxygen
1)Tissues aerobically respire using oxygen which reduces the concentration of oxygen at the tissue 2) Oxygen diffuses from an area of high concentration in the tracheae to low concentration at the tissue 3) This lowers the oxygen concentration in the tracheae so oxygen diffuses into the trachea from outside the insect via the spiracles
32
Q Why does diffusion happen in a gas exchange system (tracheal system) of insects for carbon dioxide
1) Aerobic respiration produces CO2 increasing the concentration at the tissue 2) CO2 diffuses from an area of high concentration in the tissue to low concentration at the tracheae 3) CO2 then moves from a high concentration in the tracheae to a low concentration outside the insect via the spiracles
33
What are the stages of the flow of water over the gills
1) The mouth opens and our operculum shuts 2) Mouth volume increases and pressure decreases 3)Water moves in down a pressure gradient 4) Mouth closes and operculum opens 5) Mouth volume decreases and pressure increases 6) Water is forces out over gills down a pressure gradient
34
What organ does a fish have to allow it to exchange gases in water
Gills
35
What does a fish gas exchange system contain
A gill arch Gill filaments Gill lamellae Blood vessel bringing deoxygenated blood to the gill from the body Blood vessel taking oxygenated blood away from the gill to the body
36
How are gills adapted for efficient gas exchange
The gill filaments are covered in many lamellae which provides a large surface area Gill lamellae positioned at right angles to the filaments to increase the surface area Lamellae contain many capillaries to provide a large surface area The epithelium of the lamellae is thin providing a short diffusion pathway Countercurrent flow maintains conc gradient for oxygen along whole length of gill oxygen diffuses from the water into the blood along the whole length of the gill lamellae
37
What is countercurrent flow
The position of the filament and lamellae means the blood and water flow in opposite directions
38
Why is countercurrent flow important
It ensures the maximum amount of oxygen from the water passes into the blood flowing through the gills
39
How does countercurrent flow work
Water and blood flow in opposite directions This maintains the concentration gradient of oxygen so the oxygen concentration is always higher in the water than in the blood along the whole length of the gill lamellae So diffusion of oxygen occurs along the whole length of the gill lamellae
40
Why is parallel flow less efficient for gas exchange than countercurrent flow
Equilibrium is reached as they have the same concentration so there is no net movement of oxygen and only 50% of the water is absorbed diffusion of oxygen doesnt occur across the whole length of the gill lamellae
41
What also may be an adaptation among fish
Higher rate of oxygen uptake for respiration
42
Suggest why gills cannot obtain enough oxygen from air
The density of water stops the lamellae from collapsing so out of water lamellae collapses which decreases the surface area
43
What are the features of plant cells
Plants need both CO2 for photosynthesis and oxygen for aerobic respiration Plant cells require oxygen 24 hours a day for aerobic respiration CO2 is needed only during the day when theres sunlight
44
What are the equations for photosynthesis and aerobic respiration
CO2+H20 ---> C6H12O6+O2 C6H12O6+O2-->CO2+H20
45
What happens during daylight
There is more photosynthesis than respiration so theres a net diffusion of carbon dioxide into the leaf and net diffusion of oxygen out
46
What happens during night
There is no photosynthesis so oxygen diffuses into the leaf for respiration and carbon dioxide diffuses out as a waste product
47
What does a dicotyledonous leaf contain
Cuticle Upper epidermis Palisade and spongy mesophyll Lower epidermis Guard cells Stomata Chloroplasts Vacuole Nucleus Cell wall Cytoplasm Air spaces
48
How do guard cells reduce water loss
Gases enter and exit the leaf through the stomata Guard cells open and close the stomata to reduce water loss
49
How is a leaf adapted for gas exchange
Irregular shaped spongy mesophyll cells provide a large surface area Mesophyll cells are in contact with air spaces providing a short diffusion pathway
50
How is a leaf adapted for gas exchange (2)
Leaves are thin and flat providing a large surface area to volume ratio Spaces are filled with air rather than water so diffusion occurs faster in gases rather than liquids
51
How is a concentration gradient maintained in the leaf during the daytime for CO2
High rate of photosynthesis in the day Mesophyll cells use CO2 so CO2 diffuses into the cells down a concentration gradient from the air spaces This lowers the CO2 concentration in the air spaces CO2 diffuses into the leaf through the stomata down a concentration gradient
52
What are xerophytes
The plants that live in day climates which have adapted to reduce water loss
53
What xerophytic adaptations reduce water loss
Rolled leaves Waxy cuticle Sunk in pits Leaf hairs
54
What are the adaptations for leaves
Leaves are spines which reduces the surface area : volume ratio Thick waxy cuticle so theres less evaporation from leaf surface and increased diffusion pathway Rolled up leaves trap water vapor so water potential gradient decreased Stomata sunk in pits traps water vapor so water potential gradient decreases Leaf hairs surronding the stomata traps water vapor so water potential gradient decreases

Biology Topic 3- Exchange surfaces (4 decks)

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