Tag: absorption by roots - the processes involved

Questions Related to absorption by roots - the processes involved

Which one of the following is the most suitable medium for culture of Drosophila melanogaster ?

  1. Ripe banana

  2. Cow dung

  3. Moist bread

  4. Agar agar


Correct Option: A
Explanation:

For the culture of Drosophila melanogaster  one of the most suitable medium is ripe banana, rich in carbohydrates.

So, the correct answer is 'Ripe banana'

Osmotic pressure is higher in _______________.

  1. Xerophytes

  2. Lithophytes

  3. Halopyhtes

  4. Mesophytes


Correct Option: C
Explanation:

Because halophytes are the plants of saline habitat.

So the correct option is C.

OP of a solution can be measured by 

  1. Photometer

  2. Osmometer

  3. Calorimeter

  4. Plasmolysis


Correct Option: B
Explanation:

An osmometer is a device for measuring the osmotic strength of a solution.
Photometer is an instrument for measuring the intensity of light.

A calorimeter is an object used in the process of measuring the heat capacity. 
Plasmolysis is the contraction of the protoplast of a plant cell as a result of loss of water from the cell.
Thus, the correct answer is option (B). 

A higher plant cell covered with cutin and suberin is placed in water. After 15 minutes the cell

  1. Will be killed

  2. Size will increase

  3. Size will remain unchanged

  4. Size will decrease


Correct Option: C
Explanation:

Suberin and cutin are complex macromolecules which mainly function as a barrier to movement of water and solutes. Thus if a higher plant cell is covered with cutin and suberin and placed in water then there will not be any change in the size of the cell as cutin and suberin are hard and water repulsive substances. There will not be any exosmosis or endosmosis in such type of cell.

So the correct answer is 'Size will remain unchanged'.

In a plant cell, O.P. is equal to 

  1. T.P. - D.P.D.

  2. D.P.D - T.P.

  3. T.P. - D.P.

  4. D.P.D + T.P.


Correct Option: D
Explanation:

Here O.P. stands for osmotic pressure, D.P.D. stands for diffusion pressure deficit and T.P. stands for turgor pressure. 

Diffusion pressure deficit( DPD) is the reduction in the diffusion pressure of water in a solution over its pure state due to the presence of solutes and consequent development of turgor pressure. It is equal to the osmotic pressure of the system minus wall pressure:
$D.P.D=O.P.-W.P.(=T.P.)$

Thus the osmotic pressure is the sum of DPD and TP.
So the correct answer is 'D.P.D +T.P'.

Movement of water through semipermeable membrane produces 

  1. Wall pressure

  2. Suction pressure

  3. Osmotic pressure

  4. Turgor pressure


Correct Option: C
Explanation:
(A) Wall pressure is the pressure exerted by cell wall against turgor pressure.
(B) Suction pressure is the actual pressure by which cell absorb water.
(C) The movement of water from higher concentration to lower concentration through a semi-permeable membrane is called osmosis. The pressure required to stop osmosis is called osmotic pressure. 
(D) Turgor pressure is pressure applied against the cell wall.
So, the correct answer is 'Osmotic pressure'.

The cell becomes turgid in solution which is

  1. Hypertonic

  2. Isotonic

  3. Hypotonic

  4. None of the above


Correct Option: C
Explanation:
The cell becomes turgid in solution which is hypotonic because a hypotonic solution has more concentration of solvent molecules than the fluid inside the cell. So, the solvent molecules move inside the cell from the region of higher concentration to the lower concentration by the process of endosmosis. The cell swells and increases in size.
So, the correct answer is option C.

Water will enter a cell, if it is placed in solution less concentrated than cell sap due to

  1. Endosmosis

  2. Diffusion

  3. Imbibition

  4. Plasmolysis


Correct Option: A
Explanation:

(A) Endosmosis is the movement of solution from outside of the cell to inside the cell.

(B) Diffusion is the movement of the molecule from higher concentration to the lower concentration.
(C) Imbibition is the special diffusion where water is absorbed by solid colloids to get an increase in the volume.
(D) Plasmolysis is the process of cell getting contracted due to the loss of water from the cell.
So, the correct answer is 'Endosmosis'.

Glucose is not stored in plants due to its ability to 

  1. Decrease osmotic pressure

  2. Increase osmotic pressure

  3. Increase turgor pressure

  4. Decrease turgor pressure


Correct Option: B
Explanation:

  • Osmosis occurs only through the semi-permeable membrane. Osmosis is a gradient dependent process, osmosis is different from diffusion as it is characterized by a semi-permeable membrane.
  • Net direction and rate of osmosis depend on both pressure gradient and concentration gradient.
So, the correct answer is 'Increase osmotic pressure'.