6.1: Exchange between organisms and their environment

Question 1

The external environment is different from the internal environment found within what?

Answer 1

The external environment is different from the internal environment found:

1. Within an organism
2. Within its cells

Question 2

The external environment is different from the internal environment found within an organism and within its cells.
To survive, organisms transfer materials between the 2 environments.
This transfer takes place at exchange surfaces and always involves what?

Answer 2

This transfer:

1. Takes place at exchange surfaces
2. Always involves crossing cell plasma membranes

Question 3

Tissue fluid

Answer 3

Tissue fluid is the environment around the cells of multicellular organisms

Question 4

Tissue fluid

Answer 4

Tissue fluid is the environment around the cells of multicellular organisms

Question 5

The external environment is different from the internal environment found within an organism and within its cells.
To survive, organisms transfer materials between the 2 environments.
This transfer takes place at exchange surfaces and always involves crossing cell plasma membranes.
The majority of cells are too far from exchange surfaces for diffusion alone to supply or remove their tissue fluid with the various materials needed to keep its composition relatively constant.
Therefore, once absorbed, materials are rapidly distributed to the tissue fluid and the waste products returned to the exchange surface for removal.
This involves a mass transport system.
It is this mass transport system that maintains the diffusion gradients that do what?

Answer 5

It is this mass transport system that maintains the diffusion gradients that bring materials:
1. To
2. From
the cell-surface membranes

Question 6

In a mass transport system, what do all the substances do?

Answer 6

In a mass transport system, all the substances move in the same direction at the same speed

Question 7

In a mass transport system, all the substances move in the same direction at the same speed.
Example

Answer 7

For example, the:

1. Mammalian circulatory system
2. Vascular system of a plant

Question 8

In a mass transport system, all the substances move in the same direction at the same speed.
Mass transport systems are just as important for what as they are for supplies?

Answer 8

Mass transport systems are just as important for the rapid removal of waste as they are for supplies

Question 9

In a mass transport system, all the substances move in the same direction at the same speed.
Mass transport systems are just as important for the rapid removal of waste as they are for supplies.
Even what can take place via a mass transport system?

Answer 9

Even communication from one cell to another can take place via a mass transport system

Question 10

In a mass transport system, all the substances move in the same direction at the same speed.
Mass transport systems are just as important for the rapid removal of waste as they are for supplies.
Even communication from one cell to another can take place via a mass transport system.
Example

Answer 10

For example, hormones in a blood stream

Question 11

In a mass transport system, all the substances move in the same direction at the same speed.
Mass transport systems are just as important for the rapid removal of waste as they are for supplies.
Even communication from one cell to another can take place via a mass transport system.
The greater the what of an organism, the greater the demands on its mass transport system?

Answer 11

The greater the metabolic rate of an organism, the greater the demands on its mass transport system

Question 12

The what of an organism will affect the amount of each material that is exchanged?

Answer 12

The:
1. Size
2. Metabolic rate
of an organism will affect the amount of each material that is exchanged

Question 13

The size and metabolic rate of an organism will affect the amount of each material that is exchanged.
Example

Answer 13

For example, organisms with a high metabolic rate:

1. Exchange more materials
2. So require a larger SA:V ratio

Question 14

The size and metabolic rate of an organism will affect the amount of each material that is exchanged.
For example, organisms with a high metabolic rate exchange more materials and so require a larger SA:V ratio.
In turn, this is reflected in what?

Answer 14

In turn, this is reflected in the type of:
1. Exchange surface
2. Transport system
that evolved to meet the requirements of each organism

Question 15

Examples of things that need to be interchanged between an organism and its environment include what?

Answer 15

Examples of things that need to be interchanged between an organism and its environment include:

1. Respiratory gases
2. Nutrients
3. Excretory products
4. Heat

Question 16

Examples of things that need to be interchanged between an organism and its environment include respiratory gases (what), nutrients, excretory products and heat?

Answer 16

Examples of things that need to be interchanged between an organism and its environment include:

1. Respiratory gases (oxygen and carbon dioxide)
2. Nutrients
3. Excretory products
4. Heat

Question 17

Examples of things that need to be interchanged between an organism and its environment include respiratory gases (oxygen and carbon dioxide), nutrients (what), excretory products and heat?

Answer 17

Examples of things that need to be interchanged between an organism and its environment include:

1. Respiratory gases (oxygen and carbon dioxide)
2. Nutrients (glucose, fatty acids, amino acids, vitamins and minerals)
3. Excretory products
4. Heat

Question 18

Examples of things that need to be interchanged between an organism and its environment include respiratory gases (oxygen and carbon dioxide), nutrients (glucose, fatty acids, amino acids, vitamins and minerals), excretory products (what) and heat?

Answer 18

Examples of things that need to be interchanged between an organism and its environment include:

1. Respiratory gases (oxygen and carbon dioxide)
2. Nutrients (glucose, fatty acids, amino acids, vitamins and minerals)
3. Excretory products (urea and carbon dioxide)
4. Heat

Question 19

Examples of things that need to be interchanged between an organism and its environment include respiratory gases (oxygen and carbon dioxide), nutrients (glucose, fatty acids, amino acids, vitamins and minerals), excretory products (urea and carbon dioxide) and heat.
Except for heat, these exchanges can take place in how many ways?

Answer 19

Except for heat, these exchanges can take place in 2 ways:
1. Passively
Or,
2. Actively

Question 20

Examples of things that need to be interchanged between an organism and its environment include respiratory gases (oxygen and carbon dioxide), nutrients (glucose, fatty acids, amino acids, vitamins and minerals), excretory products (urea and carbon dioxide) and heat.
Except for heat, these exchanges can take place in 2 ways - Passively (no what is required) or actively?

Answer 20

Except for heat, these exchanges can take place in 2 ways:
1. Passively (no metabolic energy is required)
Or,
2. Actively

Question 21

Examples of things that need to be interchanged between an organism and its environment include respiratory gases (oxygen and carbon dioxide), nutrients (glucose, fatty acids, amino acids, vitamins and minerals), excretory products (urea and carbon dioxide) and heat.
Except for heat, these exchanges can take place in 2 ways - Passively (no metabolic energy is required) or actively (what is required)?

Answer 21

Except for heat, these exchanges can take place in 2 ways:
1. Passively (no metabolic energy is required)
Or,
2. Actively (metabolic energy is required)

Question 22

Examples of things that need to be interchanged between an organism and its environment include respiratory gases (oxygen and carbon dioxide), nutrients (glucose, fatty acids, amino acids, vitamins and minerals), excretory products (urea and carbon dioxide) and heat.
Except for heat, these exchanges can take place in 2 ways - Passively (no metabolic energy is required), by what, or actively (metabolic energy is required)?

Answer 22

Except for heat, these exchanges can take place in 2 ways:
1. Passively (no metabolic energy is required), by diffusion and osmosis
Or,
2. Actively (metabolic energy is required)

Question 23

Examples of things that need to be interchanged between an organism and its environment include respiratory gases (oxygen and carbon dioxide), nutrients (glucose, fatty acids, amino acids, vitamins and minerals), excretory products (urea and carbon dioxide) and heat.
Except for heat, these exchanges can take place in 2 ways - Passively (no metabolic energy is required), by diffusion and osmosis, or actively (metabolic energy is required), by what?

Answer 23

Except for heat, these exchanges can take place in 2 ways:
1. Passively (no metabolic energy is required), by diffusion and osmosis
Or,
2. Actively (metabolic energy is required), by active transport

Question 24

In a cell, where is the lowest oxygen concentration?

Answer 24

In a cell, the lowest oxygen concentration is inside the mitochondria

Question 25

In a cell, the lowest oxygen concentration is inside the mitochondria, where what?

Answer 25

In a cell, the lowest oxygen concentration is inside the mitochondria, where oxygen is used up in respiration

Question 26

In a cell, the lowest oxygen concentration is inside the mitochondria, where oxygen is used up in respiration.
Mitochondria also contain the highest concentration of what?

Answer 26

Mitochondria also contain the highest concentration of carbon dioxide

Question 27

In a cell, the lowest oxygen concentration is inside the mitochondria, where oxygen is used up in respiration.
Mitochondria also contain the highest concentration of carbon dioxide.
What does this do?

Answer 27

This maintains the diffusion gradient for these gases:
1. In
2. Out
of the cell

Question 28

Exchange takes place at the surface of an organism, but the materials absorbed are used by the cells that mostly make up its volume.
For exchange to be effective, what must be large compared with what?

Answer 28

For exchange to be effective, the exchange surface(s) of the organism must be large compared with its volume

Question 29

Small organisms have a surface area that is large enough, compared with their volume, to allow efficient exchange across their body surface.
However, as organisms become larger, what does their volume do?

Answer 29

As organisms become larger, their volume increases at a faster rate than their surface area

Question 30

Small organisms have a surface area that is large enough, compared with their volume, to allow efficient exchange across their body surface.
However, as organisms become larger, their volume increases at a faster rate than their surface area.
Because of this, simple diffusion of substances across the outer surface can only do what?

Answer 30

Because of this, simple diffusion of substances across the outer surface can only meet the needs of relatively inactive organisms

Question 31

Small organisms have a surface area that is large enough, compared with their volume, to allow efficient exchange across their body surface.
However, as organisms become larger, their volume increases at a faster rate than their surface area.
Because of this, simple diffusion of substances across the outer surface can only meet the needs of relatively inactive organisms.
Even if the outer surface could supply enough of a substance, it would still take too long for it to do what if diffusion alone was the method of transport?

Answer 31

Even if the outer surface could supply enough of a substance, it would still take too long for it to reach the middle of the organism if diffusion alone was the method of transport

Question 32

Small organisms have a what surface area compared to their volume?

Answer 32

Small organisms have a large surface area compared to their volume

Question 33

Large organisms have a what surface area compared to their volume?

Answer 33

Large organisms have a small surface area compared to their volume

Question 34

Small organisms have a surface area that is large enough, compared with their volume, to allow efficient exchange across their body surface.
However, as organisms become larger, their volume increases at a faster rate than their surface area.
Because of this, simple diffusion of substances across the outer surface can only meet the needs of relatively inactive organisms.
Even if the outer surface could supply enough of a substance, it would still take too long for it to reach the middle of the organism if diffusion alone was the method of transport.
The solution to this is that organisms have evolved what?

Answer 34

The solution to this is that organisms have evolved one of more features:

1. A flattened shape
2. Specialised exchange surfaces with large areas

Question 35

Small organisms have a surface area that is large enough, compared with their volume, to allow efficient exchange across their body surface.
However, as organisms become larger, their volume increases at a faster rate than their surface area.
Because of this, simple diffusion of substances across the outer surface can only meet the needs of relatively inactive organisms.
Even if the outer surface could supply enough of a substance, it would still take too long for it to reach the middle of the organism if diffusion alone was the method of transport.
The solution to this is that organisms have evolved one or more features - A flattened shape, so that what, and specialised exchange surfaces with large areas?

Answer 35

The solution to this is that organisms have evolved one of more features:

1. A flattened shape, so that no cell is ever far from the surface
2. Specialised exchange surfaces with large areas

Question 36

Small organisms have a surface area that is large enough, compared with their volume, to allow efficient exchange across their body surface.
However, as organisms become larger, their volume increases at a faster rate than their surface area.
Because of this, simple diffusion of substances across the outer surface can only meet the needs of relatively inactive organisms.
Even if the outer surface could supply enough of a substance, it would still take too long for it to reach the middle of the organism if diffusion alone was the method of transport.
The solution to this is that organisms have evolved one or more features - A flattened shape, so that no cell is ever far from the surface, and specialised exchange surfaces with large areas to do what?

Answer 36

The solution to this is that organisms have evolved one of more features:

1. A flattened shape, so that no cell is ever far from the surface
2. Specialised exchange surfaces with large areas to increase the SA:V ratio

Question 37

Small organisms have a surface area that is large enough, compared with their volume, to allow efficient exchange across their body surface.
However, as organisms become larger, their volume increases at a faster rate than their surface area.
Because of this, simple diffusion of substances across the outer surface can only meet the needs of relatively inactive organisms.
Even if the outer surface could supply enough of a substance, it would still take too long for it to reach the middle of the organism if diffusion alone was the method of transport.
The solution to this is that organisms have evolved one or more features - A flattened shape, so that no cell is ever far from the surface (for example, what) and specialised exchange surfaces with large areas to increase the SA:V ratio?

Answer 37

The solution to this is that organisms have evolved one of more features:

1. A flattened shape, so that no cell is ever far from the surface (for example, a flatworm or a leaf)
2. Specialised exchange surfaces with large areas to increase the SA:V ratio

Question 38

Small organisms have a surface area that is large enough, compared with their volume, to allow efficient exchange across their body surface.
However, as organisms become larger, their volume increases at a faster rate than their surface area.
Because of this, simple diffusion of substances across the outer surface can only meet the needs of relatively inactive organisms.
Even if the outer surface could supply enough of a substance, it would still take too long for it to reach the middle of the organism if diffusion alone was the method of transport.
The solution to this is that organisms have evolved one or more features - A flattened shape, so that no cell is ever far from the surface (for example, a flatworm or a leaf) and specialised exchange surfaces with large areas to increase the SA:V ratio (for example, what)?

Answer 38

The solution to this is that organisms have evolved one of more features:

1. A flattened shape, so that no cell is ever far from the surface (for example, a flatworm or a leaf)
2. Specialised exchange surfaces with large areas to increase the SA:V ratio (for example, lungs in mammals and gills in fish

Question 39

To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:
1. A large what?

Answer 39

A large surface area relative to the volume of the organism

Question 40

To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:
1. A large surface area relative to the volume of the organism, which does what?

Answer 40

A large surface area relative to the volume of the organism, which increases the rate of exchange

Question 41

To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:

1. A large surface area relative to the volume of the organism, which increases the rate of exchange.
2. Very what?

Answer 41

Very thin

Question 42

To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:

1. A large surface area relative to the volume of the organism, which increases the rate of exchange.
2. Very thin, so that what?

Answer 42

Very thin, so that:

1. The diffusion distance is short
2. Therefore materials cross the exchange surface rapidly

Question 43

To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:

1. A large surface area relative to the volume of the organism, which increases the rate of exchange.
2. Very thin, so that the diffusion distance is short and therefore materials cross the exchange surface rapidly.
3. What to allow selected materials to cross?

Answer 43

Selectively permeable to allow selected materials to cross

Question 44

To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:

1. A large surface area relative to the volume of the organism, which increases the rate of exchange.
2. Very thin, so that the diffusion distance is short and therefore materials cross the exchange surface rapidly.
3. Selectively permeable to allow selected materials to cross.
4. Movement of what to maintain a diffusion gradient?

Answer 44

Movement of the environmental medium to maintain a diffusion gradient

Question 45

To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:

1. A large surface area relative to the volume of the organism, which increases the rate of exchange.
2. Very thin, so that the diffusion distance is short and therefore materials cross the exchange surface rapidly.
3. Selectively permeable to allow selected materials to cross.
4. Movement of the environmental medium (for example what) to maintain a diffusion gradient?

Answer 45

Movement of the environmental medium (for example air) to maintain a diffusion gradient

Question 46

To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:

1. A large surface area relative to the volume of the organism, which increases the rate of exchange.
2. Very thin, so that the diffusion distance is short and therefore materials cross the exchange surface rapidly.
3. Selectively permeable to allow selected materials to cross.
4. Movement of the environmental medium (for example air) to maintain a diffusion gradient.
5. A what system to ensure the movement of the internal medium in order to maintain a diffusion gradient?

Answer 46

A transport system to ensure the movement of the internal medium in order to maintain a diffusion gradient

Question 47

To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:

1. A large surface area relative to the volume of the organism, which increases the rate of exchange.
2. Very thin, so that the diffusion distance is short and therefore materials cross the exchange surface rapidly.
3. Selectively permeable to allow selected materials to cross.
4. Movement of the environmental medium (for example air) to maintain a diffusion gradient.
5. A transport system to ensure the movement of the internal medium (for example what) in order to maintain a diffusion gradient?

Answer 47

A transport system to ensure the movement of the internal medium (for example blood) in order to maintain a diffusion gradient

Question 48

Being thin, specialised exchange surfaces are what?

Answer 48

Being thin, specialised exchange surfaces are easily:

1. Damaged
2. Dehydrated

Question 49

Being thin, specialised exchange surfaces are easily damaged and dehydrated.
They are therefore often located where?

Answer 49

They are therefore often located inside an organism

Question 50

Being thin, specialised exchange surfaces are easily damaged and dehydrated.
They are therefore often located inside an organism.
Where an exchange surface is located inside the body, what does the organism need to have?

Answer 50

Where an exchange surface is located inside the body, the organism needs to have a means of moving the external medium over the surface

Question 51

Being thin, specialised exchange surfaces are easily damaged and dehydrated.
They are therefore often located inside an organism.
Where an exchange surface is located inside the body, the organism needs to have a means of moving the external medium over the surface.
Example

Answer 51

For example, a means of ventilating the lungs in a mammal