Unit 2.2 Adaptions Fir Gas Exchange

Question 1

Name four types of gas exchange surfaces

Answer 1

External gills
Internal gills
Lungs
Tracheae

Question 2

What must organisms exchange in order to survive?

Answer 2

Organisms must exchange materials between themselves and their surroundings in order to survive.
These materials can be:

Respiratory gases (oxygen and carbon dioxide)

Nutrients (glucose, fatty acids, amino acids, vitamins, minerals)

Excretory products (urea)

Heat

Question 3

What are the possible processes when organisms exchange materials amongst themselves? Describe them. Any exceptions?

Answer 3

Except for heat, exchnaging these materials can either be active or passive processes

Actively (metabolic energy is required) - active transport

Passively (no metabolic energy is required) - diffusion/osmosis

Question 4

Explain the surface area to volume ratio

Answer 4

What?
How?
Why?

As an organism gets bigger the surface area to volume ratio decreases. In other words, the volume of cells demanding materials increases but the surface area to provide them decreases

(An objects SA:Vol ratio is like a way of describing how close every internal part of a structure or organism is to its surface)

Question 5

Equation for working out SA:Vol ratio

Answer 5

S.A : Vol ratio = surface area
-——————
Volume

Question 6

Why would an organism have a high SA:Vol ratio?

Answer 6

A high S.A. : Vol Ratio shows that every part of an object is quite close to the edge. This means substances can diffuse in and out quickly, as there is only a short distance from the edge to the middle. A specialist exchange system would not be required.

Question 7

Why would an organism have a low SA:Vol ratio?

Answer 7

A low SA: Vol Ratio means that there are parts of the object that are a long way from the edge. This means that it takes longer for substances to defuse in or out, as there is a longer distance from the edge to the middle. This specialist exchange system would be required.