A fertilized egg divides into 8 cells after 18 hours. Assuming exponential division with no cell death, how many cells will be present after 30 hours?
Answer
32
The correct answer is 32 — Hence 32 cells will be present at 30 hours.
Step-by-step solution
- Start with 1 cell at time 0.
- After 18 hours the cell number is 8, indicating 3 divisions.
- Thus each division cycle lasts 6 hours (18h ÷ 3).
- From 18h to 30h is 12 hours, i.e., 2 division cycles.
- Each cycle doubles the cell count: 8 → 16 → 32.
- Hence 32 cells will be present at 30 hours.
Common mistake: Treating cell growth linearly instead of exponentially
Concept tested: Cell division timing
Published · How this solution was prepared and checked
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