Question 81:
Which type of plant tissue is responsible for providing mechanical support and strength?
A) Parenchyma
B) Collenchyma
C) Sclerenchyma
D) Phloem
Answer: C) Sclerenchyma
Explanation: Sclerenchyma cells have thickened cell walls and provide mechanical support and rigidity to the plant.
Question 82:
In what part of the plant does the majority of nutrient assimilation occur?
A) Roots
B) Stems
C) Leaves
D) Flowers
Answer: C) Leaves
Explanation: Leaves are the primary site for photosynthesis and nutrient assimilation, where plants convert sunlight into energy.
Question 83:
What is the role of lignin in xylem?
A) Nutrient transport
B) Providing strength and support
C) Water absorption
D) Storage of carbohydrates
Answer: B) Providing strength and support
Explanation: Lignin is a complex organic polymer that strengthens the cell walls of xylem vessels, providing structural support to the plant.
Question 84:
Which of the following conditions would most likely cause stomatal closure?
A) High humidity
B) Low light intensity
C) Water stress
D) High temperature
Answer: C) Water stress
Explanation: Stomata close in response to water stress to minimize water loss, helping the plant conserve moisture.
Question 85:
What is the primary function of phloem parenchyma?
A) Conducting water
B) Storing and transporting nutrients
C) Providing mechanical support
D) Photosynthesis
Answer: B) Storing and transporting nutrients
Explanation: Phloem parenchyma cells are involved in the storage and transport of nutrients and play a supportive role in the phloem.
Question 86:
Which of the following processes primarily drives the upward movement of water in plants during the night?
A) Transpiration
B) Root pressure
C) Osmosis
D) Capillary action
Answer: B) Root pressure
Explanation: During the night, when transpiration is low, root pressure can push water upward through the xylem.
Question 87:
What is the main advantage of having a taproot system?
A) Increased nutrient absorption
B) Ability to reach deep water sources
C) Better stability
D) All of the above
Answer: D) All of the above
Explanation: A taproot system allows plants to access deeper water sources, enhances nutrient absorption, and provides greater stability.
Question 88:
In which plant part does the majority of transpiration occur?
A) Flowers
B) Stems
C) Roots
D) Leaves
Answer: D) Leaves
Explanation: The large surface area and abundance of stomata on leaves make them the primary site for transpiration.
Question 89:
Which of the following mechanisms is responsible for the movement of water in plants?
A) Active transport
B) Bulk flow
C) Simple diffusion
D) Facilitated diffusion
Answer: B) Bulk flow
Explanation: Bulk flow is the movement of water and solutes through xylem and phloem driven by pressure differences.
Question 90:
What do sieve tube elements lack that differentiates them from typical plant cells?
A) Nucleus
B) Cell wall
C) Cytoplasm
D) Chloroplasts
Answer: A) Nucleus
Explanation: Sieve tube elements are living cells that lack a nucleus, allowing for the efficient transport of nutrients in phloem.
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