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Question #45564
The Question
During an in vitro fertilization (IVF) protocol, a slight thermal deviation in the laboratory incubator alters the cleavage kinetics of a developing embryo. Although the embryo morphologically reaches the 8-blastomere stage and is transferred via ZIFT (Zygote Intra-Fallopian Transfer), the procedure fails. Which of the following best explains the primary physiological basis for this failure?
Options
- A.
The altered metabolic rate creates a developmental asynchrony between the embryo's cleavage chronology and the specific biochemical micro-environment of the fallopian tube.
- B.
The thermal deviation induces premature hatching of the blastocyst, rendering the embryo strictly eligible for Intra-Uterine Transfer (IUT) instead of ZIFT.
- C.
The altered temperature coefficient (Q10) permanently arrests further cleavage, preventing the 8-blastomere embryo from transitioning into a morula.
- D.
The thermal stress inhibits the immediate secretion of human chorionic gonadotropin (hCG) by the blastomeres, leading to premature regression of the corpus luteum.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
ZIFT|IUT|Thermal Tolerance Ranges
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the morphological cell count rules for ART (<=8 for ZIFT, >8 for IUT) but fail to recognize the underlying physiological requirement of 'kinetic synchrony' between the embryo and the maternal micro-environment.
The trap options exploit chronological misconceptions, such as placing blastocyst hatching or hCG secretion at the 8-blastomere stage.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Reproductive Health - Class 12 |
| Concept | ZIFT vs IUT |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |