AQA AS Level Biology > Gas Exchange > Flashcards

Gas Exchange Flashcards

(54 cards)

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1
Q

What is the tracheal system?

A

Network of small tubes called tracheoles to carry oxygen around the body.

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2
Q

What are the openings along an insects thorax and abdomen?

A

Spiracles

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3
Q

What are spiracles function?

A

Gases diffuse through into and out the tracheoles.

Prevents water loss.

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4
Q

Is the tracheal system efficient?

A

Yes
It is the most efficient gas exchange system.

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5
Q

What are gills?

A

Filaments of thin tissue that are highly branched and folded.

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6
Q

Why is the structure of gills helpful?

A

Creates a large surface area for diffusion.

Also has lamellae attached which further increases the surface area.

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7
Q

Do fish have a small or large surface area to volume ratio? Why’s is special adaptations required?

A

Small surface area to volume ratio so requires a specialised gas exchange system.

Also lower concentration of oxygen in water than air.

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8
Q

What features maximise gas exchange in fish?

A

Gill, fill filaments and lamellae - Large surface area to volume ratio
Thin lamellae - Short diffusion distance
Good blood supply in capillaries - Maintained conc gradient

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9
Q

What is Fick’s law?

A

Diffusion = (s.a x diff in conc) / length of diffusion path

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10
Q

What is fish anatomy going from gills to lamellae?

A

Four layers of gills which are made up of stacks of gill filaments. These gill filaments have lots of lamellae on them.

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11
Q

Benefit of lamellae?

A

Creates a large surface area for faster diffusion

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12
Q

What happens when a fish opens its mouth?

A

Water rushes in and over the gills then out through a hole in the side of the head

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13
Q

How does fish keep a large surface area to volume ratio?

A

Many gill filaments with many lamellae

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14
Q

How does fish keep a short diffusion distance?

A

lamellae are very thin and have an extremely large capillary network running into each one

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15
Q

How does fish keep a constant concentration gradient?

A

Countercurrent flow mechanism

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16
Q

What is the countercurrent flow mechanism?

A

Where water runs over the gills in the opposite direction of where the blood runs through the capillaries.

This ensures equilibrium never occurs as constant diffusion occurs.

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17
Q

What’s the benefit of countercurrent flow mechanism?

A

Ensures a diffusion gradient is maintained across the entire length of gill lamellae.

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18
Q

Why do insects have an exoskeleton?

A

Hard fibrous material for protection

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19
Q

Why do insects have a lipid layer?

A

To prevent water loss

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20
Q

Why do insects have a tracheal system and not lungs?

A

High surface area to volume ratio so do not need a specialised gas exchange system

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21
Q

What adaptations do insects have to limit water loss?

A

Small surface area to volume ratio that water can evaporate from

Insects have a waterproof waxy cuticle exoskeleton which reduces evaporation

Spiracles can relax and contract to control water movement.

Small hairs around spiracles to increase humidity.

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22
Q

What are spiracles?

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A

Round, valve like openings across the abdomen which can open and closer to allow for movement of oxygen, carbon dioxide and water.

The trachea are attached to these openings.

23
Q

What are trachea?

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A

A network of internal tubes with rings within them to keep them open and strengthen the tube.

24
Q

What are tracheoles?

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A

The trachea branch into smaller tubes called the tracheoles which are deeper in the abdomen.

Extend throughout all tissue to deliver oxygen to cells.

25
How does diffusion happen in insects?
When cells respire they use up oxygen and produce carbon dioxide which diffuses out due to the concentration gradient between tracheoles and atmosphere.
26
How does mass transport happen in an insect?
An insect contracts and relaxes their abdominal muscles to move gases on mass.
27
How does osmosis happen in an insect?
When an inset flies, anaerobic respiration begins pretty quickly which produces lactate. This lowers water potential which causes water to move into the cells from the tracheoles by osmosis. Volume in tracheoles increase and so pressure decreases so air from atmosphere is drawn in.
28
How do insects keep a large surface area?
Large number of small tracheoles
29
How do insects keep a short diffusion distance?
Walls of tracheoles are thin. Short distance between tracheoles and spiracles.
30
How do insects keep a steep diffusion gradient?
Use of oxygen and production of carbon dioxide
31
Suggest and explain why a reduced tidsl volume affects exchange of CO2 between blood and alveoli. [3]
[1] More CO2 remains in lungs [2] Reduced concentrarion gradient [3] Less movement of CO2 out of blood
32
Whys is the counter current principle efficient? [2]
[1] Constant concentratioon gradient [2] Along the whole of the lamellae
33
How do insects transport oxygen around the body efficiently?
Thin tracheoles which provide a short diffusion path for air to pass directly into some cells. Many tracheoloes for large surface area for diffusion. Reduce the tracheal fluid in the tracheoloes to increase surface area exposed to air.
34
Why do dicotyledonous (flowering plants) need gas exchange?
CO2 for photosynthesis Need for oxygen for respiration
35
Where do dicotyledonous plants exchange gases?
Mesophyll cells
36
How are mesophyll cells adapted for their function?
Many mesophyll which provide a large surface area. Thin cell membrane for a short diffusion distance. Air around them provides a steep concentration gradient.
37
How do stomata regulate water loss or gain?
Kept open during the day to allow for gas exchange - CO2 for photosynthesis and so oxygen can leave.
38
How do stomata become turgid?
Water enters the cell
39
What are xerophytes?
Plants with adaptations to reduce water loss
40
Where do xerophytes inhabit?
Where there is low availibity of water. Eg Desert
41
Adaptations of xerophytic plants to reduce water loss?
Waxy, waterproof cuticle to prevent evaporation. Curled leaves with stomata within to protect from wind. Reduced number of stomata. Stomata sunk in pits to trap moist air and reduce concentration gradient. High around stomata to reduce concentration gradient. Shallow and wide root systems.
42
How does oxygen flow within the human respiratory system
Oxygen from the air moves down the trachea, bronchi and bronchioles into the alveoli (down a pressure gradient). Once in the alveoli, the oxygen diffuses across the alveolar epithelium, then the capillary endothelium, ending up in the blood in the capillary. This movement happens down a diffusion gradient. The expiration of CO2 happens the same way but in reverse.
43
How are Alveoli Adapted for Gas Exchange
There is a large number of alveoli providing a large surface area for gas exchange/diffusion. The alveolar epithelium is one cell thick – so there's a short diffusion pathway (which speeds up diffusion) A rich network of capillaries provides good blood flow which ensures a steep concentration gradient is maintained
44
What is tidal volume?
Volume of air moved in each normal breath
45
What is tidal volume normally?
0.5 dm3
46
What is ventilation rate?
Number of breaths per minute.
47
What is the normal ventilation rate?
15 breaths per minute
48
What is pulmonary ventilation rate?
Volume of air moved per minute
49
PVR equation
PVR = Tidal Volume x breathing rate
50
What is the forced expiratory volume?
Maximum volume of air that can be breathed out in 1 second
51
What is the forced vital capacity?
Maximum volume of air it is possible to breathe forcefully out of the lungs after a really deep breath in
52
What is vital capacity?
Maximum volume of air that can be moved by the lungs in one breath
53
What is total lung capacity?
vital capacity + residual volume
54
What is a mutagenic agent?
Increases the chance of mutations which causes cancer
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