The Question is from neet-zoology human-reproduction fertilisation-and-implantation, and it was created by the author A SUBRAMANYAM

Question

During fertilization, the cortical reaction primarily prevents:

A SUBRAMANYAM · Accepted Answer

## CORE INFORMATION
✓ **Answer**: C
## CONCEPT FRAMEWORK
 **Primary Concept**: Fertilization and prevention of polyspermy
 **Related Topics**:  Cortical granules, zona pellucida, acrosomal reaction, sperm capacitation
 **Prerequisites**: Basic understanding of fertilization process
## SOLUTION PATHWAY
**Given Information**:
  The question asks about the primary function of the cortical reaction during fertilization.
  No specific numerical data is given.
**Method & Steps**:
 1. Understand the cortical reaction.
  Reasoning: The cortical reaction is a crucial process that occurs in the egg cell after fertilization.  It involves the release of cortical granules from the egg's cytoplasm.
  Formula/Rule: N/A
 2. Identify the effect of cortical granules release.
  Working: The released cortical granules contain enzymes that modify the zona pellucida (the outer layer of the egg) and the egg cell membrane.  These modifications prevent further sperm from binding and penetrating the egg.
  Key Point: The primary purpose is to block polyspermy (fertilization by multiple sperm).
 3. Determine the primary prevention.
  Result: The cortical reaction primarily prevents polyspermy.
  Verification: The other options are not directly prevented by the cortical reaction. The acrosome reaction happens before the sperm reaches the egg, sperm capacitation occurs before fertilization, and zona pellucida degradation is a consequence, not a prevention, of the cortical reaction.
 ## OPTION ANALYSIS
A :x: The acrosome reaction is the process by which the sperm releases enzymes to penetrate the zona pellucida. It happens *before* the cortical reaction.
B :x: Sperm capacitation is a process that prepares the sperm for fertilization. It occurs *before* the cortical reaction.
C ✓: Polyspermy, the fertilization of an egg by multiple sperm, is directly prevented by the cortical reaction. The alterations to the zona pellucida and egg membrane made by the cortical granules prevent additional sperm from entering.
D :x: Zona pellucida degradation is a *result* of the cortical reaction, not something it directly prevents.  The enzymes released break down parts of the zona pellucida as part of the block to polyspermy.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing the cortical reaction with the acrosomal reaction: Remember that the acrosomal reaction is what allows the sperm to penetrate the egg, while the cortical reaction prevents further sperm from entering.
  2.Thinking the cortical reaction prevents fertilization: The cortical reaction prevents *polyspermy*, not fertilization itself. Fertilization still occurs, but only with one sperm.
 **Quick Tips**:
  1.Remember that the cortical reaction is the egg's defense mechanism against polyspermy.
  2.Cortical granules = prevention of polyspermy

A SUBRAMANYAM · Answer

Acrosome reaction

A SUBRAMANYAM · Answer

Sperm capacitation

A SUBRAMANYAM · Answer

The correct Option is "Polyspermy"

A SUBRAMANYAM · Answer

Zona pellucida degradation

NEET Zoology Human Reproduction Fertilisation And Implantation MCQs

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