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Practice each question, then open the answer or worked solution.
Differentiate between diffusion and translocation in plants.
Diffusion is the movement of substances from a region of their higher concentration to a region of their lower concentration
Translocation is the bulk transport of material in solution inside plant channels.
How is facilitated diffusion different from diffusion?
Diffusion occurs through phospholipid layer and facilitated diffusion occurs through membrane proteins
Explain the mass flow hypothesis of transport in phloem
In 1930, Munch proposed the mass flow hypothesis which explains the movement of sap through the phloem. When there is a high concentration of sugar present in the source (which is where the food is prepared) then a diffusion gradient gets created between the sugar source and the sugar shrink where the sugar is stored. This is responsible for drawing water into the cells from the neighbouring xylem. When this happens, turgor pressure gets created (bidirectional movement)
Observe the diagram and answer the following;
a. Are these types of guard cells found in monocots or dicots?
b. Which of these shows a higher water content (i) or (ii)?
c. Which element plays an important role in the opening and closing of stomata?
a) These types of guard cells are found in dicots because as we know the shape is bean-shaped. Whereas for monocots, it is usually dumble-shaped.
b) Higher water content is shown in figure (i)
c) The element that plays an important role in the opening and closing of stomata is potassium ion.
Define Uniport, Symport and Antiport. Do they require energy?
1. Uniport: When a single substance moves in a single direction across a cell membrane, it is called uniport.
2. Antiport: When two substances move in the opposite direction across a cell membrane, it is called antiport.
3. Symport: When two substances move in the same direction across a cell membrane, it is called symport
They do not need energy directly.