Unit 3 Organisms exchange with their environment Flashcards
Why are substances transported to the other tissues and cells via the tissue fluid?
The distance between the cells and the substance that are needed to diffuse are too large
What is the membrane in which substance s are transferred across within an organism?
The tissue fluid
How does the exchange between substances and the tissue fluid occur?
Once absorbed the materials are rapidly distributed to the tissue fluid ad the waste products are returned to the exchange surface for removal
During the transfer of substance what is maintained between the cell-surface membrane?
The diffusion gradients have been maintained
What are the factors that affect the transport of the materials that are diffused?
The size and metabolic rate of the organisms
Why do size and metabolic rate affect the transport of the materials within an organism?
Ann organism with a high m,etabolic rate requires more exchange of materials and therefore requires a large SA : V ratio
Give some examples of what is exchanged between the surfaces in the organism?
Useful products: Glucose, oxygen , amino acids, lipids
Waste products: Urea, ammonia, Carbon dioxide
What are the transport processes that help the exchanges?
Diffusion, osmosis and active transport
Explain the SA:V ratio between small and large organisms and how the transport systems work alongside them?
(small organism)
In small organisms - the SA:V ratio is larger enough as the SA is larger than the volume so they don’t require a transport mechanism for exchanging as there is a shorter diffusion distance between the surface of the organism and the blood
Explain the SA:V ratio between small and large organisms and how the transport systems work alongside them?
(large organism)
The large organism has a greater volume than the SA so the SA:V ratio is smaller than of the smaller organisms so it will have a higher metabolic rate and will need a larger exchange of materials.
Thi means that it requires an exchange system so that it can allow the efficient diffusion or active tranpsort materials within an organism so that it cna meet its needs
One way that the SA of a leaf can be increased?
A flattened surface so that the distance between the cell and the cell-surface membrane is shorter for the exchange of substances which makes it faster
How can large organisms have increased SA? (One way)
Large organisms have specialised exchange surface with the such as lungs in mammals and fish in gills
What are the efficiency of exchange surfaces give examples?
Large SA:V ratio = Increased rate of exchange
Thin membrane so there is a short diffusion distance and the materials can diffuse faster
Selectively permembale membrane allows specific materials to oass through
Transport medium such as air allows the maintenace of a concentratuion gradient
Transport system = enable the concnetration gradienct such as the blood
What is the direct proportion equation for diffusion?
Diffusion = k(SA x difference in conc grad) / length in diffusion path
The increase in gas exchange in other organisms conflicts what else?
The gas exchange conflicts with the conservation of water because it can evaporate
How are insects adapted for gas exchange?
Insects have an internal network of tubes called the trachea which are supported by strengthened rings to prevent them fom collapsing
How are insects adapted for gas exchange? (2)
The trachea divide into smaller tubes called the tracheoles which extend throughout all the tissues within the insect
What happens to the insects whilst they are repsiring explain the process?
The concentration of oxygen falls as they are respiring which leads to
Why are the ends of tracheoles contain water?
The muscles cells that respire carry out anaerobic respiration producing lactate which is soluble and lowers the water potential of the muscle cells this means that the volume of water that is taken from the tracheoles is at a fast rate so more air is drawn
What happens at the spiracles of insects?
Gases can leave or enter through these tiny pores on the body’s surface when spiracles are open the water can evaporate from the insect this is usually happening to prevent water loss
Describe the structure of the gill in fish?
The gills are located behind the head and are made up of gill filaments and are stacked up in a pile. To the right angles of filaments are gill lamellae which increase the SA of the gills
What is unusual about the flow of water and the flow of blood along the gill lamellae?
The flow of water and the flow of blood along the gill lamellae are in opposite directions so are in a counter-current flow
What would happen if the flow of blood and water are in the same directions?
If the flow of blood and water were in the same direction then there is less gas exchange by 80% of oxygen
Explain the counter-current exchange principle works?
The blood with the lowest concentration of oxygen meets the water with the highest concentration of oxygen so there si a diffusion gradient maintained