8.2 - Exchange Surfaces and SA: Volume Ratio Flashcards
What are specialised exchange surfaces?
Specialised exchange surfaces allow efficient transport of substances from one area to another, such as from outside to inside the organism.
What are the characteristics of exchange surfaces?
Exchange surfaces often have a short distance for diffusion and a large surface area.
What is the role of root hair cells in plants?
Root hair cells are specialised to take up water and nutrients from the soil due to their large surface area and thin walls.
How do the walls of nephrons in the kidney function?
The walls of the nephrons have thin walls and a large surface area to efficiently reabsorb substances like water and glucose.
What occurs in the lungs during gas exchange?
In the lungs, oxygen is transferred to the blood and carbon dioxide is transferred to the lungs across the surface of alveoli.
What are alveoli?
Alveoli are millions of air sacs in the lungs covered in tiny capillaries that facilitate gas exchange.
What is the function of villi in the small intestine?
Villi are projections in the small intestine that increase surface area for the absorption of digested food into the bloodstream.
How do fish gills facilitate gas exchange?
Fish gills allow gas exchange where oxygen diffuses into the blood and carbon dioxide diffuses into the water.
What are gill filaments and gill lamellae?
Gill filaments are plates in the gills, and gill lamellae are structures where diffusion of oxygen and carbon dioxide takes place.
What is the role of stomata in plant leaves?
Stomata allow carbon dioxide to diffuse in for photosynthesis and oxygen and water vapour to move out.
How do guard cells regulate stomata?
Guard cells change the size of the stomata based on water availability; they swell with water to make stomata larger.
Why is a large surface area important for exchange surfaces?
A large surface area allows more particles to move through, resulting in a faster rate of diffusion.
How do alveoli contribute to surface area in the lungs?
The small, spherical alveoli create a very large surface area, approximately 75m² in humans.
How do villi in the small intestine increase absorption speed?
Villi increase the surface area, allowing digested food to be absorbed into the blood faster.
What is the advantage of having a thin membrane in exchange surfaces?
A thin membrane provides a short diffusion pathway, allowing the process to occur faster.
How do alveoli and capillary walls contribute to gas exchange?
Alveoli and capillary walls are extremely thin, facilitating efficient gas exchange.
Why is an efficient blood supply important for gas exchange?
An efficient blood supply creates a steep concentration gradient, allowing diffusion to occur faster.
How do lungs maintain a steep concentration gradient?
Lungs constantly supply oxygen to the blood from alveoli capillaries, exchanging it for carbon dioxide.
How do fish maintain a steep concentration gradient in gills?
In fish, water flows in one direction while blood flows in the other, maintaining a steep concentration gradient.
What is the Surface Area to Volume Ratio?
It is the size of the surface area of the organism compared to its volume.
How is the Surface Area to Volume Ratio calculated?
By finding the volume (length x width x height) and the surface area (length x width), and writing the ratio in the smallest whole numbers.
What does a large Surface Area to Volume Ratio indicate about an organism?
The organism is less likely to require specialised exchange surfaces and a transport system because the rate of diffusion is sufficient in supplying and removing necessary gases.
How is the ratio 15 (surface area) to 5 (volume) expressed?
It is written as 3:1.
How do single-celled organisms transport molecules?
They can use diffusion to transport molecules into their body from the air due to their relatively large surface area to volume ratio.
Why is diffusion sufficient for single-celled organisms?
Due to their low metabolic demands, diffusion across the surface of the organism is sufficient enough to meet its needs.
Why can’t multicellular organisms rely on diffusion alone?
They have a small surface area to volume ratio, so they require adaptations in surfaces and organ systems for transport.
What is the surface area to volume ratio like in larger organisms?
Larger organisms often have a small surface area to volume ratio, as they have a large volume but relatively small surface area.
What is the surface area to volume ratio like in smaller organisms?
Smaller organisms have a larger surface area to volume ratio, as they have a large volume relative to their surface area.
What is the benefit of a greater surface area to volume ratio?
The greater the surface area to volume ratio, the better adapted the organism is for diffusion.
What happens if an organism increases its surface area?
It can take in more nutrients and expel more waste products more efficiently.
