Q1. What is the primary vascular tissue responsible for transporting water and minerals from roots to the rest of the plant?
a) Xylem
b) Phloem
c) Epidermis
d) Cortex
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Correct Answer: a) Xylem
Explanation: Xylem is the primary vascular tissue in plants responsible for conducting water and minerals from the roots to the stems and leaves. It consists of tracheids and vessels, supported by fibers, and provides structural support to the plant. Xylem transport is largely driven by transpiration and cohesion-tension forces.
Q2. Which of the following is responsible for transporting sugars and other organic compounds from leaves to other parts of the plant?
a) Xylem
b) Phloem
c) Epidermis
d) Cortex
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Correct Answer: b) Phloem
Explanation: Phloem is the vascular tissue responsible for transporting sugars, amino acids, hormones, and other organic compounds synthesized in the leaves to other parts of the plant, such as roots, stems, and developing fruits. Phloem consists of sieve tube elements, companion cells, and various specialized cells.
Q3. Which cells in the xylem are responsible for providing structural support and aiding in water transport through their interconnected hollow tubes?
a) Sieve tube elements
b) Companion cells
c) Tracheids and vessel elements
d) Parenchyma cells
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Correct Answer: c) Tracheids and vessel elements
Explanation: Tracheids and vessel elements are specialized cells in the xylem responsible for water transport. They are elongated, hollow cells with thick lignified walls that provide structural support and allow water to move through their interconnected lumens, facilitating efficient water transport from roots to leaves.
Q4. What is the process by which water and dissolved minerals move upward through the plant’s xylem vessels?
a) Translocation
b) Transpiration
c) Photosynthesis
d) Osmosis
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Correct Answer: b) Transpiration
Explanation: Transpiration is the process by which water evaporates from the aerial parts of the plant, such as leaves, and is replaced by water absorbed from the soil. This creates a negative pressure gradient that pulls water upward through the xylem vessels, facilitating the movement of water and dissolved minerals.
Q5. Which of the following is NOT a mechanism involved in the movement of water and minerals in the xylem?
a) Root pressure
b) Capillary action
c) Transpiration pull
d) Active transport
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Correct Answer: d) Active transport
Explanation: Active transport is not a mechanism involved in the movement of water and minerals in the xylem. Instead, water movement in the xylem is primarily driven by root pressure, capillary action, and transpiration pull, which operate passively without requiring energy expenditure by the plant.
Q6. What is the name of the phenomenon where water molecules adhere to each other and to the walls of the xylem vessels, aiding in the upward movement of water?
a) Root pressure
b) Cohesion
c) Transpiration
d) Translocation
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Correct Answer: b) Cohesion
Explanation: Cohesion is the phenomenon where water molecules form hydrogen bonds with each other, creating a continuous column of water in the xylem vessels. This cohesive force, along with adhesion to the walls of the vessels, helps in the upward movement of water through the plant.
Q7. Which of the following statements best describes the role of the Casparian strip in the root?
a) It regulates the movement of water and minerals into the xylem vessels.
b) It provides structural support to the root.
c) It synthesizes organic compounds for the plant.
d) It facilitates gas exchange between the root and the soil.
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Correct Answer: a) It regulates the movement of water and minerals into the xylem vessels.
Explanation: The Casparian strip is a band of impermeable lignin and suberin found in the endodermis of plant roots. It acts as a barrier that forces water and minerals to pass through the selectively permeable plasma membranes of endodermal cells before entering the xylem vessels, regulating their movement.
Q8. Which of the following is responsible for the bulk flow of sugars in the phloem, driven by a pressure gradient from source to sink?
a) Transpiration
b) Translocation
c) Transpiration pull
d) Transpiration stream
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Correct Answer: b) Translocation
Explanation: Translocation is the process by which organic compounds, particularly sugars, are transported through the phloem from source organs (such as leaves) to sink organs (such as roots, fruits, and developing tissues). It involves the bulk flow of sap driven by a pressure gradient established by active loading and unloading of solutes.
Q9. What is the name of the specialized cells in the phloem responsible for actively loading sugars into the sieve tube elements?
a) Tracheids
b) Companion cells
c) Vessel elements
d) Parenchyma cells
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Correct Answer: b) Companion cells
Explanation: Companion cells are specialized parenchyma cells found adjacent to sieve tube elements in the phloem. They are responsible for actively loading sugars, amino acids, and other organic compounds into the sieve tube elements through plasmodesmata, maintaining the osmotic pressure gradient necessary for sap flow.
Q10. What is the primary mechanism by which sugars are transported from source to sink in the phloem?
a) Osmosis
b) Active transport
c) Diffusion
d) Bulk flow
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Correct Answer: d) Bulk flow
Explanation: Bulk flow is the primary mechanism by which sugars and other organic compounds are transported from source to sink in the phloem. This process involves the mass movement of sap driven by a pressure gradient generated by differences in solute concentrations between source and sink tissues.