1. Observe the figure given below: (Score 2)
a. Name the process.
b. Define the above identified process.
Facilitated diffusion (Facilitated transport).
It is the diffusion of hydrophilic substances across a membrane along the concentration gradient through some transport proteins.
1. Though transpiration results in loss of water, it has many purposes. List out any four advantages of transpiration. (Score 2)
i. Creates transpiration pull for absorption and transport of plants.
ii. Supplies water for photosynthesis.
iii. Transports minerals from the soil to all parts of the plant.
iv. Cools leaf surfaces.
v. Maintains shape and structure of plants by keeping cells turgid.
1. Observe the figure given below:
Identify the process demonstrated in the figure.
Write the role of membrane in this process. (Score 2)
Osmosis/Diffusion of water across the membrane.
Functions: Active transport and passive transport.
1. The opening and closing of stomata is aided by the peculiarities of bean shaped guard cells. Mention any two such peculiarities. (Score 2)
The inner wall of guard cells is thick and elastic.
Outer wall remains thin.
1. State any four features of facilitated diffusion. (2)
· Requires special membrane proteins.
· Highly selective.
· Transport saturates.
· Not requires ATP energy.
1. A cell when placed in a concentrated sucrose solution, shrink after few hours. Identify the physical phenomenon that leads to shrinkage of cell and justify your answer. (2)
Water molecules move out of the cell (exosmosis).
Cell membrane becomes shrink away from the cell wall.
1. The movement of water through the root layers is ultimately symplastic in the endodermis. Give a reason. (2)
This is the only way water and solutes can enter the vascular cylinder.
1. How can you differentiate active transport from facilitated diffusion? (2)
In active transport, transport proteins and energy are used.
In facilitated diffusion- transport protein only is used.
1. Define imbibition and give one example studied by you. (2)
It is a type of diffusion in which water is absorbed by solids (colloids) increasing their volume. E.g. absorption of water by seeds and dry wood.
1. Transpiration has more than one purpose in plants. Write any one purpose of transpiration in plants and list any two factors that affect this process. (2).
Transpiration creates transpiration pull for absorption of water and transport of minerals.
Factors affecting transpiration: Temperature, light, humidity, wind, number of stomata etc.