Q31. What is the primary function of the epidermis in plant leaves?
a) Photosynthesis
b) Gas exchange
c) Protection
d) Water absorption
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Correct Answer: c) Protection
Explanation: The epidermis is the outermost layer of cells in plant leaves, stems, and roots. Its primary function is to provide protection against physical damage, pathogens, and water loss. In leaves, it also contains specialized cells such as guard cells and trichomes.
Q32. Which of the following is a method of water uptake by plants that involves the movement of water along a water potential gradient?
a) Osmosis
b) Transpiration
c) Capillary action
d) Root pressure
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Correct Answer: d) Root pressure
Explanation: Root pressure is a method of water uptake by plants that involves the active transport of minerals into the roots, creating a positive pressure in the xylem. This pressure pushes water upward through the xylem vessels along a water potential gradient.
Q33. What is the term for the process by which plants release oxygen into the atmosphere as a byproduct of photosynthesis?
a) Respiration
b) Transpiration
c) Excretion
d) Evaporation
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Correct Answer: a) Respiration
Explanation: Respiration in plants involves the release of oxygen into the atmosphere as a byproduct of photosynthesis. During photosynthesis, plants use carbon dioxide and water to produce glucose and oxygen. The oxygen released during this process is utilized by plants and other organisms for cellular respiration.
Q34. 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.
Q35. What is the primary function of the guard cells in plant leaves?
a) Photosynthesis
b) Gas exchange
c) Water absorption
d) Nutrient transport
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Correct Answer: b) Gas exchange
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.
Q36. 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.
Q37. 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.
Q38. 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.
Q39. 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.
Q40. 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.