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Multiple Choice
Which of the following conditions will result in the fastest transport through the xylem in a tree, assuming adequate water supply in the roots?
A
Positive pressure potential in the xylem
B
Positive pressure potential in the mesophyll
C
Negative pressure potential in the guard cells
D
Phloem transport being in the opposite direction from the xylem transport
E
Negative pressure potential in the leaf mesophyll
Verified step by step guidance
1
Understand the role of xylem: Xylem is responsible for the transport of water and minerals from the roots to the leaves of a plant. This process is primarily driven by transpiration, which creates a negative pressure potential.
Identify the factors affecting xylem transport: The speed of water transport through the xylem is influenced by pressure potential, which can be positive or negative. Negative pressure potential, often referred to as tension, is crucial for pulling water upwards.
Analyze the options: Positive pressure potential in the xylem or mesophyll would not enhance the upward movement of water, as it would not create the necessary tension. Negative pressure potential in the guard cells is unrelated to xylem transport.
Consider the correct condition: Negative pressure potential in the leaf mesophyll is essential for efficient water transport. It is created by the evaporation of water from the leaf surfaces during transpiration, which pulls water up through the xylem.
Conclude with the correct choice: The condition that results in the fastest transport through the xylem, given adequate water supply, is the negative pressure potential in the leaf mesophyll, as it maximizes the tension needed for water movement.