Q. No.Which of the following facilitates opening of stomatal aperture?
1.
Decrease in turgidity of guard cells
2.
Radial orientation of cellulose microfibrils in the cell wall of guard cells
3.
Longitudinal orientation of cellulose microfibrils in the cell wall of guard cells
4.
Contraction of outer wall of guard cells
| 1. | Both processes can happen together because the diffusion coefficient of water and CO2 is different |
| 2. | The above processes happen only during the night-time. |
| 3. | One process occurs happen only in the daytime and the other at night |
| 4. | Both processes cannot happen simultaneously |
A column of water within xylem vessels of tall trees does not break under its weight because of?
1. Dissolved sugar in water
2. Tensile strength of water
3. Lignification of xylem vessels
4. Positive root pressure
In a ring-girdled plant:
2. the root dies first
3. the shoot and root die together
4. Neither root nor shoot will die
2. Potassium influx and efflux
3. Starch hydrolysis
4. Guard cell photosynthesis
Two cells A and B are contiguous. Cell A has osmotic pressure 10 atm, turgor pressure-7 atm, and diffusion pressure deficit 3 atm. Cell B has an osmotic pressure of 8 atm, turgor pressure of 3 atm, and diffusion pressure deficit of 5 atm. The result will be:
1. Movement of water from cell B to A
2. No movement of water
3. Equilibrium between the two
4. Movement of water from cell A to B
The main difference between active and passive transport across cell membrane is :
| 1. | passive transport is non-selective whereas active transport is selective |
| 2. | passive transport requires a concentration gradient across a biological membrane whereas active transport requires energy to move solutes. |
| 3. | passive transport is confined to anionic carrier proteins whereas active transport is confined to cationic channel. |
| 4. | active transport occurs more rapidly than passive |
Which of the following is not a feature of the active transport of solutes in plants?
1. Occurs against the concentration gradient
2. Non-selective
3. Occurs through membranes
4. Requires ATP
What will be the direction of flow of water when a plant cell is placed in a Hypotonic solution?
1. Water will flow in both directions.
2. Water will flow out of the cell.
3. Water will flow into the cell.
4. No flow of water in any direction.
The translocation of organic solutes in sieve tube members is supported by:
1. root pressure and transpiration pull
2. P-proteins
3. mass flow involving a carrier and ATP
4. cytoplasmic streaming
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