Topic 8- Animal Exchange And Transport Flashcards
The rate of diffusion can speed up or slow down based what factors ?
Concentration gradient
Membrane surface area
Temperature
How can concentration gradient slow or speed up the rate of diffusion ?
The concentration gradient is linked to the difference in concentration between two areas.
The bigger the difference in concentration between two areas, the greater the concentration gradient and the faster the rate of diffusion.
How can membrane surface area slow or speed up the rate of diffusion ?
The larger the surface area of the membrane that a substance is diffusing through (e.g. the membrane around a cell), the faster the rate of diffusion.
How can temperature slow or speed up the rate of diffusion ?
The higher the temperature, the faster the rate of diffusion.
What is meant when asked Surface Area to Volume Ratio ?
Small organisms normally have higher surface area to volume ratios than large organisms. This means that diffusion can happen through a large area in small organisms. This makes diffusion useful for transporting molecules through a small organism.
How is a root hair cell adapted for absorption of water and nutrients?
The large surface area of root hair cells increases the rate of diffusion.
This allows more water and nutrients to enter the plant.
Why can’t multicellular organisms just rely on diffusion?
Multicellular organisms (with more than one cell) cannot just rely on diffusion. Their cells are too far from the external environment, and so they need a transport system with specialised surfaces to exchange molecules.
What’s fick’s law ?
rate of diffusion=(surface area×concentration difference)÷thickness of membrane
What are Exchange surfaces ?
are surfaces that are adapted to maximise the efficiency of gas and solute (a substance dissolved in a liquid) exchange across them
What are the adaptations of exchange surfaces (aveoli) ?
Thin membrane
Ventilation
Large surface area
Blood supply
How is having a thin membrane an adaptation for the exchange surfaces (alveoli) ?
A thin membrane reduces the diffusion distance.
Alveoli are one cell thick
How is having ventilation an adaptation for the exchange surfaces ?
In animals, if a gas is exchanged, the surface is ventilated (through breathing) to maintain a high concentration gradient and increase the rate of exchange.
How is having a large surface area an adaptation for the exchange surfaces (alveoli) ?
A large surface area allows more of a substance to diffuse at the same time.
Alveoli create a large surface area for gas exchange in the lungs.
How is having a blood supply an adaptation for the exchange surfaces (alveoli) ?
Where substances are exchanged through blood in animals, exchange surfaces are densely packed with blood vessels:
These blood vessels replenish the blood supply to maintain a high concentration gradient by bringing in new blood as diffusion starts to even out the concentrations.
There are many capillaries around the alveoli.
How are alveoli adapted for gas exchange?
One cell thick for short diffusion distance.
Good blood supply (surrounded by many capillaries).
Create a large surface area in the lungs.
Multicellular organisms (with more than one cell) cannot just rely on diffusion. Their cells are too far from the external environment, so what do they need ?
so they need a transport system with specialised surfaces to exchange molecules.
How is the small intestine an example of a specialised exchange surface?
The small intestine is adapted for exchanging nutrients between digested food in the small intestine and the blood
How are alveoli an example of a specialised exchange surface ?
The alveoli (small air sacs in the lungs) are adapted for exchanging carbon dioxide and oxygen between the blood and air
How are gills an example of a specialised exchange surface ?
The gills are adapted for exchanging oxygen that is dissolved in water, with the carbon dioxide in a fish’s bloodstream.
How are roots an example of a specialised exchange surface ?
Roots are adapted for taking up both water and minerals from the soil around them.
How are leaves an example of a specialised exchange surface ?
Leaves are adapted for exchanging carbon dioxide and oxygen between the leaves and the surrounding air.
What is blood ?
Blood is a tissue. Tissues are groups of similar cells that act together to perform a similar function.
What is blood made up of ?
Red blood cells (erythrocytes)
White blood cells (phagocytes and lymphocytes)
Platelets
Plasma
What are the features of platelets ?
Platelets are small cell fragments that do not have a nucleus.
Platelets are responsible for triggering blood clotting at the sites of wounds