biology : class11 Root Pressure in Herbaceous Plants : Mechanism, Guttation, Importance : Root Pressure MCQ Questions and Answers
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Root Pressure in Herbaceous Plants
MCQ questions and answers.
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MCQ Questions
1. What is root pressure in herbaceous plants?
A.
The positive pressure developed in the root xylem
B.
The pressure created by leaves during photosynthesis
C.
The force that pulls water from the atmosphere
D.
The pressure produced by stem growth
Correct Answer:
The positive pressure developed in the root xylem
Explanation:
Root pressure is the positive pressure that develops in the xylem of roots when water enters the root from the soil.
2. Root pressure in herbaceous plants is mainly caused by the active absorption of which substance by root cells?
A.
Mineral ions
B.
Oxygen
C.
Carbon dioxide
D.
Starch grains
Correct Answer:
Mineral ions
Explanation:
Root cells actively absorb mineral ions into the xylem, lowering its water potential and causing water to enter by osmosis, which produces root pressure.
3. How does water enter the xylem during the development of root pressure?
A.
By osmosis
B.
By transpiration
C.
By photosynthesis
D.
By seed germination
Correct Answer:
By osmosis
Explanation:
The accumulation of mineral ions in the root xylem causes water to move into it through osmosis, contributing to root pressure.
4. Which visible phenomenon in herbaceous plants can result from root pressure?
A.
Guttation
B.
Pollination
C.
Fruit ripening
D.
Leaf fall
Correct Answer:
Guttation
Explanation:
Root pressure can force water out through special structures called hydathodes at leaf margins, producing guttation.
5. Through which structures does guttation commonly occur in herbaceous plants?
A.
Hydathodes
B.
Stomata of flowers
C.
Root hairs
D.
Lenticels of seeds
Correct Answer:
Hydathodes
Explanation:
Hydathodes are water-excreting structures usually present at the margins or tips of leaves, where guttation droplets appear.
6. When is guttation due to root pressure most likely to occur in a herbaceous plant?
A.
At night or early morning when transpiration is low
B.
At midday when transpiration is highest
C.
Only during complete soil dryness
D.
Only after the leaves have fallen
Correct Answer:
At night or early morning when transpiration is low
Explanation:
When transpiration is low, especially at night or early morning, root pressure can push water to the leaf margins and cause guttation.
7. What may be seen on the margins of leaves due to guttation in herbaceous plants?
A.
Small water droplets
B.
Dry powder particles
C.
Air bubbles
D.
Oil droplets
Correct Answer:
Small water droplets
Explanation:
Guttation produces visible droplets of xylem sap at the leaf margins or tips of herbaceous plants.
8. Which condition generally favors the development of root pressure in herbaceous plants?
A.
Moist soil and low transpiration
B.
Dry soil and strong winds
C.
Frozen soil and high temperature
D.
Very low mineral absorption by roots
Correct Answer:
Moist soil and low transpiration
Explanation:
Adequate soil water allows roots to absorb water, while low transpiration permits pressure to build up in the root xylem.
9. What is one importance of root pressure in herbaceous plants?
A.
It helps push water and minerals upward for a short distance
B.
It converts water into glucose
C.
It prevents mineral absorption by roots
D.
It stops water movement through the xylem
Correct Answer:
It helps push water and minerals upward for a short distance
Explanation:
Root pressure can assist the upward movement of water and dissolved minerals through the xylem, particularly in small herbaceous plants.
10. Why is root pressure not considered the main force for transporting water to the tops of tall plants?
A.
It is usually too weak to raise water over great heights
B.
It occurs only in dry leaves
C.
It prevents water from entering the xylem
D.
It is produced only by flowers
Correct Answer:
It is usually too weak to raise water over great heights
Explanation:
Root pressure can support water movement in herbaceous plants, but it is generally insufficient to transport water to the tops of tall plants.
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