The Question is from neet-botany , and it was created by the author D VINOD

Question

The primary mechanism for xylem sap ascent in tall trees is transpiration pull. However, root pressure plays a minor role. Which statement BEST describes the limited contribution of root pressure to overall xylem sap ascent in tall trees?

D VINOD · Accepted Answer

## CORE INFORMATION
✓ **Answer**: D
## CONCEPT FRAMEWORK
 **Primary Concept**: Plant water transport and the forces involved (transpiration pull and root pressure).
 **Related Topics**: Xylem structure and function, water potential, osmosis.
 **Prerequisites**: Understanding of basic fluid dynamics and pressure gradients.
## SOLUTION PATHWAY
**Given Information**:
  The primary mechanism for xylem sap ascent is transpiration pull.
  Root pressure plays a minor role.
  We need to identify the best explanation for the limited contribution of root pressure.
**Method & Steps**:
 1. Analyze each option to determine its validity in explaining the limited role of root pressure.
  Reasoning: Root pressure is generated by osmosis in the roots, pushing water upwards. However, this pressure is relatively low and countered by gravity.
 2. Evaluate the limitations of root pressure in tall trees.
  Working: Consider the height of the water column and the force of gravity.  Also consider that root pressure is not a continuous force.
  Key Point: The height to which a column of water can be pushed by a given pressure is limited by gravity.  The higher the tree, the greater the gravitational force opposing the root pressure.
 3. Determine which option best reflects the limitations of root pressure.
  Result: Option D accurately describes the limitation: root pressure can only push water a limited height due to the opposing force of gravity and the relatively low pressure generated.
  Verification: Options A, B, and C are incorrect because they either exaggerate the effect of root pressure or introduce irrelevant factors.
 ## OPTION ANALYSIS
A :x: Root pressure doesn't generate excessive pressure; it's relatively low.  Damage to xylem is typically caused by other factors.
B :x: While root pressure is more active at night, it still contributes minimally during the day.
 C :x: Root surface area to volume ratio is related to water uptake, but doesn't directly explain the limited height root pressure can push water against gravity.
D ✓: This option correctly identifies the primary limitation of root pressure: the opposing force of gravity and the low pressure generated.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing root pressure with transpiration pull as the main force for water ascent in tall trees:  Remember that transpiration pull is the dominant force.
  2.Overestimating the magnitude of root pressure: Root pressure is a relatively weak force compared to transpiration pull.
 **Quick Tips**:
  1.Think about the physics of pushing water against gravity – pressure needs to overcome the weight of the water column.
  2.Remember that transpiration pull is a much stronger force driven by evaporation from leaves.

D VINOD · Answer

Root pressure generates excessive pressure that could damage the delicate xylem tissues in tall trees.

D VINOD · Answer

Root pressure is only active during the night and therefore cannot contribute to daytime transpiration.

D VINOD · Answer

Tall trees have a significantly lower root surface area to volume ratio, minimizing the contribution of root pressure.

D VINOD · Answer

The correct Option is "Root pressure can only push water a limited height due to the opposing force of gravity and the relatively low pressure generated."

NEET Botany MCQs

Select Chapter

Question Tags

Question Tags

NEET Subjects

Our Bots

Company