The Question is from neet-botany , and it was created by the author K SURESH KUMAR

Question

Which type of molecule is LEAST likely to cross a cell membrane by simple diffusion?

K SURESH KUMAR · Accepted Answer

## CORE INFORMATION
✓ **Answer**: C
## CONCEPT FRAMEWORK
 **Primary Concept**: Cell membrane permeability and simple diffusion
 **Related Topics**: Hydrophobicity, polarity, molecular size, membrane transport
 **Prerequisites**: Understanding of cell membrane structure (phospholipid bilayer), properties of polar and nonpolar molecules.
## SOLUTION PATHWAY
**Given Information**:
  The question asks about the molecule LEAST likely to cross a cell membrane by simple diffusion.
  Simple diffusion is the passive movement of molecules across a membrane from an area of high concentration to an area of low concentration.
**Method & Steps**:
 1. Consider the properties of the cell membrane:
  Reasoning: The cell membrane is primarily composed of a phospholipid bilayer, which has a hydrophobic (water-fearing) core and hydrophilic (water-loving) heads.  Small, nonpolar molecules can easily pass through this hydrophobic core because they are not repelled by it.
  Formula/Rule: None directly applicable; this is a conceptual understanding problem.
 2. Analyze the effect of molecule size and polarity:
  Working: Larger molecules have a harder time squeezing through the membrane's tight spaces. Polar molecules are repelled by the hydrophobic core and require assistance to cross (e.g., facilitated diffusion or active transport).
  Key Point: The combination of large size and polarity creates the greatest barrier to simple diffusion.
 3. Determine the least likely molecule to cross by simple diffusion:
  Result: A large, polar molecule is least likely to cross by simple diffusion due to its size and its interaction with the hydrophobic core of the membrane. 
  Verification: The other options represent molecules that can more easily pass through the membrane by simple diffusion.
 ## OPTION ANALYSIS
A :x: Small, nonpolar molecules readily diffuse across the membrane.
B :x: Small, polar molecules can diffuse, but less easily than nonpolar molecules.
C ✓: Large, polar molecules are too large and too polar to easily diffuse across the hydrophobic core of the membrane.
D :x: Small, uncharged molecules are generally able to diffuse across the membrane.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Overlooking the importance of both size and polarity: Students might focus only on one factor and incorrectly choose a smaller or less polar molecule as the least likely to diffuse.
  2.Confusing simple diffusion with other transport methods: Simple diffusion does not require energy or transporter proteins. 
 **Quick Tips**:
  1.Remember “like dissolves like”: Nonpolar molecules pass easily through the nonpolar core of the membrane.
  2.Visualize the cell membrane: Imagine the hydrophobic core as a barrier that repels polar molecules.

K SURESH KUMAR · Answer

Small, nonpolar molecule

K SURESH KUMAR · Answer

Small, polar molecule

K SURESH KUMAR · Answer

The correct Option is "Large, polar molecule"

K SURESH KUMAR · Answer

Small, uncharged molecule

NEET Botany MCQs

Select Chapter

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

NEET Subjects

Our Bots

Company