Q11. Which of the following structures in plants is responsible for the transport of organic nutrients, such as sugars, from leaves to other parts of the plant?
a) Xylem
b) Phloem
c) Stomata
d) Root hairs
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Correct Answer: b) Phloem
Explanation: Phloem is a vascular tissue in plants responsible for the transport of organic nutrients, such as sugars produced during photosynthesis, from source tissues (such as leaves) to sink tissues (such as roots, fruits, and developing leaves) through a process called translocation.
Q12. What is the term for the loss of water droplets from the tips of leaves or grass blades due to root pressure?
a) Transpiration
b) Guttation
c) Evaporation
d) Osmosis
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Correct Answer: b) Guttation
Explanation: Guttation is the process by which water droplets are expelled from the tips of leaves or grass blades of plants due to root pressure. It occurs when water uptake by roots exceeds transpirational water loss through the stomata, resulting in the accumulation and exudation of water at leaf margins.
Q13. Which of the following structures in plants is primarily responsible for gas exchange in underground tissues?
a) Lenticels
b) Stomata
c) Trichomes
d) Root hairs
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Correct Answer: a) Lenticels
Explanation: Lenticels are small pores or openings present on the bark of woody stems and roots of plants. They allow for gas exchange, primarily oxygen uptake and carbon dioxide release, in underground tissues where stomata are absent or insufficient for gas exchange.
Q14. Which of the following statements about root hairs in plants is true?
a) They are responsible for anchoring the plant in the soil
b) They absorb water and minerals from the soil
c) They produce organic nutrients through photosynthesis
d) They facilitate gas exchange in underground tissues
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Correct Answer: b) They absorb water and minerals from the soil
Explanation: Root hairs are tiny, finger-like extensions of root epidermal cells that increase the surface area for water and mineral absorption from the soil. They play a crucial role in nutrient uptake and water balance in plants.
Q15. In which part of the plant does gas exchange primarily occur during the night when stomata are closed?
a) Roots
b) Stems
c) Leaves
d) Flowers
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Correct Answer: a) Roots
Explanation: During the night when stomata are closed, gas exchange primarily occurs in the roots of plants. Lenticels and other openings on the roots facilitate the exchange of gases, allowing for oxygen uptake and carbon dioxide release in underground tissues.
Q16. Which of the following substances is primarily responsible for the movement of water from roots to leaves in plants?
a) Glucose
b) Sucrose
c) Transpiration pull
d) Root pressure
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Correct Answer: c) Transpiration pull
Explanation: Transpiration pull is the primary mechanism responsible for the movement of water from roots to leaves in plants. It occurs due to the evaporation of water from stomata on leaves, creating a negative pressure gradient that pulls water upward through the xylem.
Q17. What is the term for the opening and closing of stomata in response to environmental cues such as light intensity, humidity, and carbon dioxide levels?
a) Transpiration
b) Guttation
c) Turgor pressure
d) Stomatal regulation
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Correct Answer: d) Stomatal regulation
Explanation: Stomatal regulation refers to the opening and closing of stomata in response to environmental cues such as light intensity, humidity, and carbon dioxide levels. This process helps plants regulate gas exchange, water loss, and photosynthesis.
Q18. Which of the following substances is NOT transported through the phloem in plants?
a) Sugars
b) Amino acids
c) Water
d) Plant hormones
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Correct Answer: c) Water
Explanation: The phloem in plants primarily transports organic nutrients, such as sugars produced during photosynthesis, and other substances such as amino acids, plant hormones, and signaling molecules. Water is primarily transported through the xylem.
Q19. Which of the following statements about guard cells in plants is true?
a) They produce sugars through photosynthesis
b) They facilitate gas exchange through stomata
c) They anchor the plant in the soil
d) They store excess nutrients
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Correct Answer: b) They facilitate gas exchange through stomata
Explanation: Guard cells are specialized cells surrounding stomatal pores in the epidermis of leaves and stems in plants. They control the opening and closing of stomata, thereby regulating gas exchange, water loss, and photosynthesis in response to environmental cues.
Q20. What is the term for the process by which plants convert light energy into chemical energy stored in glucose?
a) Transpiration
b) Excretion
c) Photosynthesis
d) Respiration
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Correct Answer: c) Photosynthesis
Explanation: Photosynthesis is the process by which plants, algae, and some bacteria convert light energy from the sun into chemical energy stored in glucose and other organic molecules. It involves the uptake of carbon dioxide and release of oxygen, facilitated by chlorophyll in chloroplasts.