IB Biology Topic B3.1.2 Properties of Gas-exchange Surfaces Revision Notes (SL/HL)

IB Biology Topic B3.1.2 Properties of Gas-exchange Surfaces Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Four Properties Make a Surface Good at Gas Exchange

Definition

Permeability

The ability of a substance (e.g., oxygen, carbon dioxide, or water) to pass through a membrane or surface.

An efficient gas-exchange surface shares four key properties.
1. It is permeable, so gases can pass through.
2. It is thin, so the diffusion distance is short.
3. It is moist, so gases can dissolve.
4. It has a large surface area, so many molecules cross at once.

Tip

Use LAMP to recall the four properties: Large surface area, Accessible (thin), Moist, Permeable.

Permeability Lets Gases Cross the Surface

A gas-exchange surface must be permeable so oxygen and carbon dioxide can move through it.
Both gases are small, non-polar molecules that diffuse easily across cell membranes.
The alveolar walls in human lungs are highly permeable, letting gases diffuse between the air and the blood.
A surface that was not permeable would block gas exchange and starve the cells of oxygen.

Common Mistake

Do not confuse thin with fragile.
Thin surfaces are held in place by supporting structures such as capillaries and elastic fibres.

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Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

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Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

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Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Four Properties Make a Surface Good at Gas Exchange

Definition

Permeability

The ability of a substance (e.g., oxygen, carbon dioxide, or water) to pass through a membrane or surface.

An efficient gas-exchange surface shares four key properties.
1. It is permeable, so gases can pass through.
2. It is thin, so the diffusion distance is short.
3. It is moist, so gases can dissolve.
4. It has a large surface area, so many molecules cross at once.

Tip

Use LAMP to recall the four properties: Large surface area, Accessible (thin), Moist, Permeable.

Permeability Lets Gases Cross the Surface

A gas-exchange surface must be permeable so oxygen and carbon dioxide can move through it.
Both gases are small, non-polar molecules that diffuse easily across cell membranes.
The alveolar walls in human lungs are highly permeable, letting gases diffuse between the air and the blood.
A surface that was not permeable would block gas exchange and starve the cells of oxygen.

Common Mistake

Do not confuse thin with fragile.
Thin surfaces are held in place by supporting structures such as capillaries and elastic fibres.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic B3.1.2: Properties of Gas-exchange Surfaces Notes

Four Properties Make a Surface Good at Gas Exchange

Permeability Lets Gases Cross the Surface

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Four Properties Make a Surface Good at Gas Exchange

Permeability Lets Gases Cross the Surface

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics