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Practice each question, then open the answer or worked solution.
Given below is a table. Fill in the gaps
| Property | Simple diffusion | Facilitated transport | Active Transport |
| i. Highly selective
ii Uphill transport iii Requires ATP |
A
B C |
Yes
D E |
F
Yes G |
A B C D E = No
F and G = Yes
Define water potential and solute potential.
Water potential (Ψw) is the sum of solute potential (Ψs) and pressure potential (Ψp): Ψw= Ψs+ Ψp.
The solute potential is also known as osmotic potential is the potential of solution that allows the water to enter the solution by diffusion or osmosis due to the presence of the solute in it.
Why is solute potential always negative? Explain yw = ys + yp
So when a solute is dissolved in water, the water potential of pure water decreases or starts assuming a negative value.
Tradescantia leaf epidermal peel was taken and
a. Placed in the salt solution for five minutes.
b. After that, it was placed in distilled water. When seen under the microscope what would be observed in a and b?
a. The cells would have shrunk when seen under the microscope because the salt solution is hypertonic causing water to move out of the cell thus leading to exosmosis.
b. After that when it was placed in distilled water, the cell regains its turgidity as it absorbs water and deplasmolysis occurs.
Differentiate between Apoplast and Symplast pathways of water movement. Which of these would need active transport?
1. Apoplast consists of non-living parts of the plant whereas symplast consists of living parts of the plant.
2. Water diffusion in apoplast occurs by passive diffusion whereas in symplast occurs by osmosis
3. Resistance is less to water movement in apoplast whereas in symplast resistance is more to water movement.
Symplast pathway of water movement requires active transport.
How does water moves within the root?
Water moves from the soil to the roots via the process of osmosis. The water potential in the soil is more than in the cytoplasm of the root hair. So water passes across the semi-permeable membrane of the root hair cell into the root via osmosis.
Give the location of the Casparian strip and explain its role in the water movement.
Casparian strips are situated in the endodermal cell walls (radial and transverse) of plant roots. It prevents movement of water from pericycle to cortex thus promoting and establishing a positive hydrostatic pressure
Differentiate between guttation and transpiration.
Transpiration is the loss of water from the plant by aerial parts of the plant in the form of water vapour whereas guttation is the loss of water from margins of leaves in the form of water droplets.
Transpiration is a necessary evil in plants. Explain.
Transpiration is the process by which plants lose water in the form of water vapour from aerial parts of the plant. When there is a huge amount of transpiration that takes place, it leads to a huge amount of water loss thus causing wilting of the plant.
Describe briefly the three physical properties of water which helps in the ascent of water in the xylem.
i) Adhesion is the attraction between water molecules and other molecules
ii) Cohesion is the force due to which molecules of water stay linked together due to hydrogen bonding in between them.
iii)Surface tension is the property of the surface of a liquid to resist an external force applied owing to the cohesive nature of the molecules of the liquid. Capillary action is a result of adhesion and cohesion.