Q31. Which of the following statements best describes the role of the epidermis in plant roots?
a) It regulates the movement of water and minerals into the xylem.
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: d) It facilitates gas exchange between the root and the soil.
Explanation: The epidermis is the outermost layer of cells in plant roots responsible for facilitating gas exchange between the root and the soil. It contains specialized structures called root hairs that increase the surface area for absorption of water and minerals from the soil. Additionally, the epidermis serves as a protective barrier against pathogens and mechanical damage.
Q32. Which of the following structures in the plant stem is responsible for the transport of sugars and other organic compounds?
a) Xylem
b) Phloem
c) Epidermis
d) Cortex
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Correct Answer: b) Phloem
Explanation: Phloem is the vascular tissue responsible for the transport of 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. It consists of sieve tube elements, companion cells, phloem fibers, and various specialized cells involved in long-distance transport.
Q33. What is the name of the process by which water molecules move from areas of higher water potential to areas of lower water potential through a semi-permeable membrane?
a) Transpiration
b) Translocation
c) Osmosis
d) Diffusion
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Correct Answer: c) Osmosis
Explanation: Osmosis is the process by which water molecules move across a semi-permeable membrane from regions of higher water potential (lower solute concentration) to regions of lower water potential (higher solute concentration). It is a passive process driven by the concentration gradient of water molecules.
Q34. Which of the following is responsible for the absorption of water and minerals from the soil in plant roots?
a) Xylem
b) Phloem
c) Root hairs
d) Epidermis
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Correct Answer: c) Root hairs
Explanation: Root hairs are specialized structures located on the surface of plant roots responsible for the absorption of water and minerals from the soil. They increase the surface area available for absorption and facilitate the uptake of essential nutrients by the plant through osmosis and active transport processes.
Q35. What is the name of the tissue responsible for the lateral transport of organic compounds in the plant?
a) Xylem
b) Phloem
c) Epidermis
d) Cambium
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Correct Answer: d) Cambium
Explanation: Cambium is a meristematic tissue located between the xylem and phloem in vascular plants. It is responsible for secondary growth and the lateral transport of water, nutrients, and organic compounds within the plant. Cambium cells undergo cell division, producing new xylem cells toward the inside and new phloem cells toward the outside, contributing to the radial growth of stems and roots.
Q36. Which of the following is NOT a function of the vascular cambium in plants?
a) Formation of new xylem cells
b) Formation of new phloem cells
c) Transportation of water and minerals
d) Transportation of organic compounds
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Correct Answer: c) Transportation of water and minerals
Explanation: The vascular cambium is not directly involved in the transportation of water and minerals in plants. Instead, it is responsible for secondary growth and the formation of new xylem and phloem cells, contributing to the radial growth of stems and roots and the lateral transport of organic compounds.
Q37. What is the primary function of the cortex in plant stems and roots?
a) Transportation of water and minerals
b) Storage of starch and other substances
c) Synthesis of organic compounds
d) Facilitation of gas exchange
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Correct Answer: b) Storage of starch and other substances
Explanation: The cortex is a region of parenchyma cells located between the epidermis and vascular tissues in plant stems and roots. Its primary function is the storage of starch, oils, water, and other substances. The cortex also provides mechanical support and protection to the vascular tissues and facilitates lateral transport within the plant.
Q38. Which of the following statements best describes the role of the phloem in plant stems?
a) It transports water and minerals from roots to leaves.
b) It transports sugars and other organic compounds from leaves to other parts of the plant.
c) It provides structural support to the stem.
d) It facilitates gas exchange between the stem and the atmosphere.
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Correct Answer: b) It transports sugars and other organic compounds from leaves to other parts of the plant.
Explanation: The primary role of the phloem in plant stems is to transport sugars, amino acids, hormones, and other organic compounds synthesized in the leaves (source) to other parts of the plant, such as roots, stems, and developing fruits (sink). Phloem tissue consists of sieve tube elements, companion cells, phloem fibers, and various specialized cells involved in long-distance transport.
Q39. Which of the following structures in the plant stem is responsible for providing structural support and conducting water and minerals?
a) Xylem
b) Phloem
c) Epidermis
d) Cortex
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Correct Answer: a) Xylem
Explanation: Xylem is the vascular tissue responsible for conducting water and minerals from roots to the rest of the plant, including stems and leaves. It provides structural support and consists of tracheids, vessel elements, parenchyma cells, and fibers. Xylem transport is primarily driven by transpiration and cohesion-tension forces.
Q40. What is the primary function of the pericycle in plant roots?
a) Transportation of water and minerals
b) Storage of starch and other substances
c) Formation of lateral roots
d) Facilitation of gas exchange
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Correct Answer: c) Formation of lateral roots
Explanation: The pericycle is a specialized layer of cells located just inside the endodermis in plant roots. Its primary function is the formation of lateral roots, which arise from pericycle cells undergoing cell division and elongation. Lateral roots play a crucial role in anchoring the plant, increasing root surface area, and enhancing nutrient uptake.