Question 51:
Which of the following plant hormones promotes the opening of stomata?
A) Auxin
B) Ethylene
C) Cytokinins
D) Gibberellins
Answer: A) Auxin
Explanation: Auxins can influence stomatal opening by affecting the growth and turgor of guard cells, although abscisic acid primarily promotes stomatal closure.
Question 52:
The primary function of the cuticle in plant leaves is to:
A) Facilitate gas exchange
B) Protect against herbivores
C) Reduce water loss
D) Store nutrients
Answer: C) Reduce water loss
Explanation: The cuticle is a waxy layer that covers the leaf surface, minimizing water loss by reducing evaporation.
Question 53:
What role do plasmodesmata play in plant cells?
A) Water transport
B) Nutrient transport
C) Cell communication
D) Photosynthesis
Answer: C) Cell communication
Explanation: Plasmodesmata are small channels that connect adjacent plant cells, allowing for communication and transport of small molecules between them.
Question 54:
The cohesion-tension theory explains:
A) The movement of sugars in phloem
B) The movement of water in xylem
C) The uptake of nutrients by roots
D) The process of photosynthesis
Answer: B) The movement of water in xylem
Explanation: The cohesion-tension theory describes how water is pulled upward through the xylem due to the cohesive properties of water molecules and the tension created by transpiration.
Question 55:
In which plant tissue does photosynthesis primarily occur?
A) Sclerenchyma
B) Parenchyma
C) Collenchyma
D) Epidermis
Answer: B) Parenchyma
Explanation: Parenchyma cells contain chloroplasts and are primarily responsible for photosynthesis in plant tissues.
Question 56:
Which of the following conditions would lead to increased root pressure?
A) High humidity
B) Low temperature
C) Abundant soil moisture
D) All of the above
Answer: D) All of the above
Explanation: High humidity, low temperature, and abundant soil moisture can all contribute to increased root pressure, as these conditions promote water uptake by roots.
Question 57:
The function of the stomatal complex includes:
A) Water storage
B) Nutrient transport
C) Gas exchange
D) All of the above
Answer: C) Gas exchange
Explanation: The stomatal complex primarily facilitates gas exchange (CO₂ and O₂) during photosynthesis and respiration.
Question 58:
Which of the following factors can decrease the rate of photosynthesis in plants?
A) High light intensity
B) Low CO₂ concentration
C) Warm temperatures
D) Abundant water supply
Answer: B) Low CO₂ concentration
Explanation: Low concentrations of CO₂ limit the photosynthetic process, as it is a key reactant in photosynthesis.
Question 59:
What mechanism allows for the upward movement of water in plants against gravity?
A) Diffusion
B) Osmosis
C) Cohesion and adhesion
D) Root pressure
Answer: C) Cohesion and adhesion
Explanation: The upward movement of water in plants is facilitated by cohesion (water molecules sticking to each other) and adhesion (water molecules sticking to the walls of the xylem).
Question 60:
In plants, the term “source” refers to:
A) A site of water uptake
B) A site of sugar production
C) A site of nutrient storage
D) A site of gas exchange
Answer: B) A site of sugar production
Explanation: In phloem transport, a “source” is any part of the plant that produces sugars, such as leaves during photosynthesis.
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