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PCAT Biological Processes – In Vitro Fertilization

  • by Sam
  • Jan 23, 2018
  • PCAT Question of the Day

Embryos generated from In Vitro Fertilization should have roughly 8 cells after 72 hours. What is the time required for the number of cells in the blastomere to double?

A) 9 hours

B) 24 hours

C) 36 hours

D) 72 hours

Click for Explanation

Cells in blastomeres double on a relatively constant time period. Starting with 1 cell, the number of cells increases to 2, 4, and 8 with three doubling times. With 8 cells at 72 hours, a time of 24 hours is required for the number of cells in the blastomere to double.

A) 9 hours, incorrect, This answer is 72 hours divided by 8 and does not reflect a constant doubling time.

B) 24 hours, correct.

C) 36 hours, incorrect, This answer choice is 72 hours divided by 2.

D) 72 hours, incorrect, The number of cells in the blastomere has doubled 3 times by 72 hours.

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