Facilitated diffusion allows cells to:
1. achieve uphill transport without ATP energy
2. select substances for uptake
3. stop transport of hydrophilic substances
4. decrease the rate of diffusion of lipophilic substances
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Unlike a symporter and an antiporter, a uniporter:
1. is not an integral membrane protein
2. is a cell surface carbohydrate
3. is not a co-transporter
4. cannot be used for active transport
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Consider the following statements:
I. | Pure water is usually defined as having a solute potential (Ψπ)of zero. |
II. | A solution will have a lower and hence more negative water potential than that of pure water. |
III. | The more solute molecules present, the more negative the solute potential is. |
Correct statements are:
1. I and II
2. I and III
3. II and III
4. I, II and III
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Consider the following statements regarding water potential:
I. Water potential is the potential energy of water relative to pure free water (e.g., deionized water)
in reference conditions.
II. Typically, pure water at standard temperature and pressure (or other suitable reference condition) is defined as having a water potential of 0.
III. The addition of solutes to water increases its potential (makes it more negative), just as the increase in pressure lowers its potential (makes it more positive).
The correct statements are:
1. I, II and III | 2. I and II |
3. I and III | 4. II and III |
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The pressure that must be applied to a solution to prevent the inward flow of water across a semi permeable membrane is called as:
1. Hydrostatic pressure
2. Water potential
3. Osmotic pressure
4. Osmotic potential
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For imbibition to occur, affinity between the adsorbant and the liquid is:
1. not essential
2. not essential since imbitition is also a diffusion
3. not essential if occurring against the concentration gradient
4. a pre-requisite
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In the diagram given below showing the pathway of water movement in the root, A, B, C and D respectively represent:
1. | Symplastic pathway, Apoplastic pathway, Phloem and Xylem |
2. | Apoplastic pathway, Symplastic pathway, Phloem and Xylem |
3. | Symplastic pathway, Apoplastic pathway, Xylem and Phloem |
4. | Apoplastic pathway, Symplastic pathway, Xylem and Phloem |
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The movement of water through the root layers is ultimately:
1. apoplastic along the walls | 2. active transport by porins |
3. symplastic in the endodermis | 4. symplastic in the xylem |
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In the mycorrhizal symbiotic relationship, the root provides the fungus with:
1. Water | 2. Phosphorus |
3. N – containing compounds | 4. Sodium and potassium |
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The greatest contribution of root pressure in water transport in plants most likely is that it:
1. | pushes water to the top at night |
2. | pushes water to the top of the plant when the rate of transpiration is low |
3. | re-establishes the continuous chain of water molecules in the xylem |
4. | pushes water into the endodermal cells changing the transport from apoplast to symplast |
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