6.1: Exchange between organisms and their environment Flashcards
The external environment is different from the internal environment found within what?
The external environment is different from the internal environment found:
- Within an organism
- Within its cells
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?
This transfer:
- Takes place at exchange surfaces
- Always involves crossing cell plasma membranes
Tissue fluid
Tissue fluid is the environment around the cells of multicellular organisms
Tissue fluid
Tissue fluid is the environment around the cells of multicellular organisms
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?
It is this mass transport system that maintains the diffusion gradients that bring materials:
1. To
2. From
the cell-surface membranes
In a mass transport system, what do all the substances do?
In a mass transport system, all the substances move in the same direction at the same speed
In a mass transport system, all the substances move in the same direction at the same speed.
Example
For example, the:
- Mammalian circulatory system
- Vascular system of a plant
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?
Mass transport systems are just as important for the rapid removal of waste as they are for supplies
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?
Even communication from one cell to another can take place via a mass transport system
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
For example, hormones in a blood stream
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?
The greater the metabolic rate of an organism, the greater the demands on its mass transport system
The what of an organism will affect the amount of each material that is exchanged?
The:
1. Size
2. Metabolic rate
of an organism will affect the amount of each material that is exchanged
The size and metabolic rate of an organism will affect the amount of each material that is exchanged.
Example
For example, organisms with a high metabolic rate:
- Exchange more materials
- So require a larger SA:V ratio
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?
In turn, this is reflected in the type of:
1. Exchange surface
2. Transport system
that evolved to meet the requirements of each organism
Examples of things that need to be interchanged between an organism and its environment include what?
Examples of things that need to be interchanged between an organism and its environment include:
- Respiratory gases
- Nutrients
- Excretory products
- Heat
Examples of things that need to be interchanged between an organism and its environment include respiratory gases (what), nutrients, excretory products and heat?
Examples of things that need to be interchanged between an organism and its environment include:
- Respiratory gases (oxygen and carbon dioxide)
- Nutrients
- Excretory products
- Heat
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?
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
- Heat
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?
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)
- Heat
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?
Except for heat, these exchanges can take place in 2 ways:
1. Passively
Or,
2. Actively
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?
Except for heat, these exchanges can take place in 2 ways:
1. Passively (no metabolic energy is required)
Or,
2. Actively
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)?
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)
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)?
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)
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?
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
In a cell, where is the lowest oxygen concentration?
In a cell, the lowest oxygen concentration is inside the mitochondria
In a cell, the lowest oxygen concentration is inside the mitochondria, where what?
In a cell, the lowest oxygen concentration is inside the mitochondria, where oxygen is used up in respiration
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?
Mitochondria also contain the highest concentration of carbon dioxide
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?
This maintains the diffusion gradient for these gases:
1. In
2. Out
of the cell
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?
For exchange to be effective, the exchange surface(s) of the organism must be large compared with its volume
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?
As organisms become larger, their volume increases at a faster rate than their surface area
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?
Because of this, simple diffusion of substances across the outer surface can only meet the needs of relatively inactive organisms
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?
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
Small organisms have a what surface area compared to their volume?
Small organisms have a large surface area compared to their volume
Large organisms have a what surface area compared to their volume?
Large organisms have a small surface area compared to their volume
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?
The solution to this is that organisms have evolved one of more features:
- A flattened shape
- Specialised exchange surfaces with large areas
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?
The solution to this is that organisms have evolved one of more features:
- A flattened shape, so that no cell is ever far from the surface
- Specialised exchange surfaces with large areas
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?
The solution to this is that organisms have evolved one of more features:
- A flattened shape, so that no cell is ever far from the surface
- Specialised exchange surfaces with large areas to increase the SA:V ratio
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?
The solution to this is that organisms have evolved one of more features:
- A flattened shape, so that no cell is ever far from the surface (for example, a flatworm or a leaf)
- Specialised exchange surfaces with large areas to increase the SA:V ratio
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)?
The solution to this is that organisms have evolved one of more features:
- A flattened shape, so that no cell is ever far from the surface (for example, a flatworm or a leaf)
- Specialised exchange surfaces with large areas to increase the SA:V ratio (for example, lungs in mammals and gills in fish
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?
A large surface area relative to the volume of the organism
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?
A large surface area relative to the volume of the organism, which increases the rate of exchange
To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:
- A large surface area relative to the volume of the organism, which increases the rate of exchange.
- Very what?
Very thin
To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:
- A large surface area relative to the volume of the organism, which increases the rate of exchange.
- Very thin, so that what?
Very thin, so that:
- The diffusion distance is short
- Therefore materials cross the exchange surface rapidly
To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:
- A large surface area relative to the volume of the organism, which increases the rate of exchange.
- Very thin, so that the diffusion distance is short and therefore materials cross the exchange surface rapidly.
- What to allow selected materials to cross?
Selectively permeable to allow selected materials to cross
To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:
- A large surface area relative to the volume of the organism, which increases the rate of exchange.
- Very thin, so that the diffusion distance is short and therefore materials cross the exchange surface rapidly.
- Selectively permeable to allow selected materials to cross.
- Movement of what to maintain a diffusion gradient?
Movement of the environmental medium to maintain a diffusion gradient
To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:
- A large surface area relative to the volume of the organism, which increases the rate of exchange.
- Very thin, so that the diffusion distance is short and therefore materials cross the exchange surface rapidly.
- Selectively permeable to allow selected materials to cross.
- Movement of the environmental medium (for example what) to maintain a diffusion gradient?
Movement of the environmental medium (for example air) to maintain a diffusion gradient
To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:
- A large surface area relative to the volume of the organism, which increases the rate of exchange.
- Very thin, so that the diffusion distance is short and therefore materials cross the exchange surface rapidly.
- Selectively permeable to allow selected materials to cross.
- Movement of the environmental medium (for example air) to maintain a diffusion gradient.
- A what system to ensure the movement of the internal medium in order to maintain a diffusion gradient?
A transport system to ensure the movement of the internal medium in order to maintain a diffusion gradient
To allow effective transfer of materials across specialised exchange surfaces by diffusion or active transport, exchange surfaces show the following characteristics:
- A large surface area relative to the volume of the organism, which increases the rate of exchange.
- Very thin, so that the diffusion distance is short and therefore materials cross the exchange surface rapidly.
- Selectively permeable to allow selected materials to cross.
- Movement of the environmental medium (for example air) to maintain a diffusion gradient.
- A transport system to ensure the movement of the internal medium (for example what) in order to maintain a diffusion gradient?
A transport system to ensure the movement of the internal medium (for example blood) in order to maintain a diffusion gradient
Being thin, specialised exchange surfaces are what?
Being thin, specialised exchange surfaces are easily:
- Damaged
- Dehydrated
Being thin, specialised exchange surfaces are easily damaged and dehydrated.
They are therefore often located where?
They are therefore often located inside an organism
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?
Where an exchange surface is located inside the body, the organism needs to have a means of moving the external medium over the surface
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
For example, a means of ventilating the lungs in a mammal
