1 Marks Questions
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.
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.
Answer : Imbibition is the process by which living or dead plant cells or material adsorb water by surface attraction.
Answer : Plasma membrane is selectively permeable membrane which allows the passage of molecules selectively.
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.
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).
Answer : Turgidity is the condition of a cell in which it becomes distended or bulged due to the entry of water by endosmosis.
Answer : Diffussion is the process of movement of molecules from a region of higher concentration to a region of their lower concentration.
Answer : The process is diffusion.
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.
Answer : Diffusion is the biological term for the process of mixing of two different substances/molecules.
Answer : A solution whose concentration is greater than that of cell sap is known as hypertonic solution.
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.
Answer : Hypotonic solution is the solution that has lower solute concentration than inside the cell sap.
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.
Answer : Sprinkling salt makes soil hypertonic, hence grass lose water due to exosmosis and thus get killed.
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.
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.
Answer : a) Endosmosis
Answer : Osmosis is the process by which water enters into root hair cell.
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.
Answer : a) Hypertonic solution.
Answer : Turgor pressure is the pressure exerted by cell contents on a plant cell wall.