Absorption by Roots Questions and Answers ICSE Class 10

1 Marks Questions

Question 1 : Differentiate between the following pairs on the basis of what is mentioned within bracket.

Turgor pressure and wall pressure (explain)

Answer : Turgor pressure is the pressure exerted by the protoplasm against the cell wall.

While, wall pressure is the back pressure exerted by the cell wall on the protoplasm.

Question 2 : Give biological reason why wooden frames of doors get jammed during the monsoon season.

Answer : Wooden frames of door get jammed during monsoon season due to the process of imbibition.

In this process, water is adsorbed to the surface of a hydrophilic colloids.

As wood has a strong affinity for water (hydrophilic), they adsorb or imbibe water or moisture from their surroundings and get swelled up.

Question 3 : Name the phenomenon by which living or dead plant cells absorb water by surface attraction.

Answer : Imbibition is the process by which living or dead plant cells or material adsorb water by surface attraction.

Question 4 : Give the biological term for a membrane which allows the passage of molecules selectively.

Answer : Plasma membrane is selectively permeable membrane which allows the passage of molecules selectively.

Question 5 : Briefly explain the term osmosis.

Answer : Osmosis is the process of movement of water molecules from a region of their higher concentration to a region of lower concentration through a semi-permeable membrane.

Question 6 : Give reason why potato cubes when placed in water become firm and increase in size.

Answer : Potato cubes when placed in water become firm and increase in size. This happens because water acts as a hypotonic medium, thus water enters into potato cells due to endosmosis making them firm and larger in size (turgid).

Question 7 : Explain the term turgidity.

Answer : Turgidity is the condition of a cell in which it becomes distended or bulged due to the entry of water by endosmosis.

Question 8 : Explain the term diffusion.

Answer : Diffussion is the process of movement of molecules from a region of higher concentration to a region of their lower concentration.

Question 9 : Identify and name the process of movement of molecules from a region of higher concentration to a region of lower concentration.

Answer : The process is diffusion.

Question 10 : Rewrite the completed explanation by inserting the key word in the space indicated by ‘^’.

Osmosis is the movement of water molecules from its region of higher concentration to its region of lower concentration through a ‘^’ membrane.

Answer : Osmosis is the movement of water molecules from its region of higher concentration to its region of lower concentration through a semi-permeable membrane.

Question 11 : Give the biological term of the process of mixing of two different substances/molecules.

Answer : Diffusion is the biological term for the process of mixing of two different substances/molecules.

Question 12 : Name a solution whose concentration is greater than that of a cell sap.

Answer : A solution whose concentration is greater than that of cell sap is known as hypertonic solution.

Question 13 : Give reason:

Plants begin to die when excess of soluble fertilizers are added to the soil.

Answer : Fertilisers along with soil water acts as a hypertonic solution.

This leads to exosmosis, i.e. movement of water from plant. Thus, the plants begin to die.

Question 14 : Define hypnotic solution.

Answer : Hypotonic solution is the solution that has lower solute concentration than inside the cell sap.

Question 15 : Give the biological reason why marine fish burst when thrown under tap water.

Answer : Marine fish burst when thrown under tap water because their cells exist best in hypertonic solution or salty water. When put in tap water or hypotonic solution their cell show endosmosis and thus swells and bursts.

Question 16 : Give the biological reason for the following:

On sprinkling common salt on grass growing in a lawn, the grass is killed.

Answer : Sprinkling salt makes soil hypertonic, hence grass lose water due to exosmosis and thus get killed.

Question 17 : Define the term active transport giving one example.

Answer : Active transport is the movement of molecules (or ions) from the lower concentration to higher concentration against a concentration gradient using energy in the form of ATP (Adenosine Triphosphate) , e.g., uptake of mineral ions into root cells.

Question 18 : Give one reason for the following:

Wilted lettuce leaves if kept in cold water become crisp.

Answer : Leaves of wilted lettuce are flaccid in nature due to the loss of water. When these leaves are kept in cold water, the water enters the cell making them turgid. Hence, they become crisp.

Question 19 : Marine fish when thrown under tap water bursts because of

a) Endosmosis

b) Exosmosis

c) Diffusion

d) Plasmolysis

Answer : a) Endosmosis

Question 20 : Mention the process by which water enters into root hair cell.

Answer : Osmosis is the process by which water enters into root hair cell.

Question 21 : Answer the following briefly.

Plants growing in fertilised soil are often found to wilt if the soil is not adequately watered, why?

Answer : If the soil is fertilised and not well watered, the concentration of the soil solution will be very high and water begins to move from the root hair cells to soil due to exosmosis. If this process continues for a long time plasmolysis takes place and leads to wilting of plants.

Question 22 : The space between the cell wall and plasma membrane in plasmolysed cell is filled with :

a) isotonic solution

b) hypotonic solution

c) hypertonic solution

d) water

Answer : a) Hypertonic solution.

Question 23 : Name the pressure exerted by cell contents on a plant cell wall.

Answer : Turgor pressure is the pressure exerted by cell contents on a plant cell wall.

Biology Questions and Answers ICSE Class 10 :