PPQ's Flashcards
Tubifex worms are small, thin animals that live in water. They have no specialised gas exchange or circulatory system. The figure below shows a tubifex worm.
Name the process by which oxygen reaches the cells inside the body of a tubifex worm. (1)
Osmosis
Define diffusion. (1)
Movement of molecules or ions from a region of higher concentration to a region of lower concentration.
Define osmosis. (1)
Movement of water molecules across a selectively permeable membrane, from a region of higher water potential to a region of lower water potential.
Define active transport. (1)
Movement of molecules or ions across a membrane from a region of lower concentration to a region of higher concentration, using ATP.
Which of the following are passive processes and which are active processes? (2)
- Diffusion
- Osmosis
- Active Transport
Diffusion = Passive.
Osmosis = Passive.
Active Transport = Active.
Why is Active Transport an Active process? (1)
Because it requires the energy from ATP.
The exchange of urea in the nephron is an example of which type of process? (1)
Diffusion.
The exchange of water in root hair cells is an example of which type of process? (1)
Osmosis.
The exchange of sucrose in the companion cells of the phloem is an example of which type of process? (1)
Active transport.
The exchange of water in the air spaces of leaves is an example of which type of process? (1)
Osmosis.
The exchange of mineral ions in the root hair cell is an example of which type of process? (1)
Active transport.
The exchange of water in the nephron is an example of which type of process? (1)
Osmosis.
The exchange of glucose and a.a’s in the proximal convoluted tubule is an example of which type of process? (1)
Active transport.
The exchange of glucose and a.a’s in the ileum is an example of which type of process? (1)
Active transport.
The exchange of oxygen and carbon dioxide in the lungs is an example of which type of process? (1)
Diffusion.
The exchange of water in the lungs is an example of which type of process? (1)
Osmosis.
The exchange of oxygen and carbon dioxide in the respiring cells is an example of which type of process? (1)
Diffusion.
The exchange of oxygen and carbon dioxide in the gills is an example of which type of process? (1)
Diffusion.
The exchange of oxygen and carbon dioxide in the leaf air spaces is an example of which type of process? (1)
Diffusion.
Describe how the SA:V ratio changes as the size of an organism increases. (1)
Decreases, as volume increases more rapidly than surface area.
What is the relationship between metabolic rate and SA:V? (1)
Organisms which a higher metabolic rate (rate of respiration) tend to have a larger SA:V.
Describe two specialisations which organisms commonly have to increase the rate of diffusion. (2)
- Flattened body
- Specialised gas exchange system
Name the 5 features of a specialised exchange surface: (5)
- Large surface area relative to volume.
- Very thin surface.
- Selectively permeable.
- Movement of the environmental medium (air or water).
- Mass transport system.
Explain why most specialised exchange surfaces are internal to the body: (2)
- Surfaces are very thin and air is not a dense medium, therefore, not supported and easily damaged.
- Surfaces are a site of extensive water and heat loss, if outside the body, it would lead to dehydration.
