Q21. What is the primary function of the spongy mesophyll tissue in plant leaves?
a) Gas exchange
b) Photosynthesis
c) Water storage
d) Mechanical support
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Correct Answer: a) Gas exchange
Explanation: The spongy mesophyll tissue in plant leaves is primarily responsible for gas exchange. It contains air spaces between cells, allowing for the diffusion of gases such as oxygen, carbon dioxide, and water vapor between the leaf’s interior and the external environment.
Q22. Which of the following processes involves the breakdown of glucose molecules to release energy in plant cells?
a) Photosynthesis
b) Transpiration
c) Respiration
d) Translocation
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Correct Answer: c) Respiration
Explanation: Respiration in plant cells involves the breakdown of glucose molecules in the presence of oxygen to release energy, carbon dioxide, and water. This process occurs in mitochondria and is essential for cellular activities such as growth, metabolism, and synthesis of organic molecules.
Q23. What is the term for the specialized cells in plant roots responsible for the selective uptake of minerals and water?
a) Xylem vessels
b) Phloem cells
c) Root hairs
d) Epidermal cells
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Correct Answer: c) Root hairs
Explanation: Root hairs are specialized extensions of root epidermal cells in plants. They increase the surface area for absorption and are responsible for the selective uptake of water and minerals from the soil, essential for plant growth and development.
Q24. Which of the following substances is primarily transported through the xylem in plants?
a) Sugars
b) Amino acids
c) Water and minerals
d) Plant hormones
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Correct Answer: c) Water and minerals
Explanation: The xylem in plants primarily transports water and minerals absorbed by the roots from the soil to other parts of the plant, including the leaves and stems. It also provides structural support and plays a role in the movement of signaling molecules.
Q25. What is the term for the loss of water vapor from the aerial parts of plants, primarily through stomata?
a) Transpiration
b) Guttation
c) Evaporation
d) Osmosis
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Correct Answer: a) Transpiration
Explanation: Transpiration is the process by which water vapor is lost from the aerial parts of plants, primarily through stomata on leaves and stems. It plays a crucial role in water transport, nutrient uptake, and temperature regulation in plants.
Q26. Which of the following statements about respiration in plants is true?
a) Respiration only occurs during the day
b) Respiration produces oxygen as a byproduct
c) Respiration occurs in mitochondria
d) Respiration requires sunlight energy
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Correct Answer: c) Respiration occurs in mitochondria
Explanation: Respiration in plants occurs in mitochondria, where glucose and other organic molecules are broken down in the presence of oxygen to release energy in the form of ATP. This process is essential for cellular activities and occurs continuously, day and night.
Q27. What is the primary function of lenticels in plants?
a) Gas exchange
b) Water absorption
c) Photosynthesis
d) Nutrient transport
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Correct Answer: a) Gas exchange
Explanation: Lenticels are small openings or pores on the bark of woody stems and roots in plants. They facilitate gas exchange, allowing for the diffusion of gases such as oxygen, carbon dioxide, and water vapor between the internal tissues of the plant and the external environment.
Q28. Which of the following processes involves the movement of sugars and other organic nutrients from source tissues to sink tissues in plants?
a) Transpiration
b) Respiration
c) Translocation
d) Photosynthesis
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Correct Answer: c) Translocation
Explanation: Translocation is the process by which sugars and other organic nutrients produced in source tissues (such as leaves) are transported to sink tissues (such as roots, fruits, and developing leaves) in plants through the phloem. It is essential for growth, development, and energy distribution in plants.
Q29. What is the term for the process by which excess salts and minerals are removed from the plant’s vascular system and deposited in leaves or other tissues?
a) Transpiration
b) Guttation
c) Excretion
d) Accumulation
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Correct Answer: c) Excretion
Explanation: Excretion in plants involves the removal of excess salts and minerals from the plant’s vascular system and their deposition in leaves or other tissues. This process helps regulate osmotic balance, prevent toxicity, and maintain proper nutrient levels in plant cells.
Q30. Which of the following is a specialized tissue in plant leaves responsible for photosynthesis?
a) Epidermis
b) Xylem
c) Phloem
d) Mesophyll
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Correct Answer: d) Mesophyll
Explanation: Mesophyll is a specialized tissue in plant leaves responsible for photosynthesis. It contains chloroplast-rich cells, including palisade and spongy mesophyll cells, where chlorophyll captures light energy and converts it into chemical energy in the form of glucose.