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GATE 2026 BT – Question 63

Plant, Animal and Microbial Biotechnology · Animals: Culture media and growth conditions, preservation, anchorage dependent and independent culture, growth kinetics, carrier culture · 2 marks · Numerical answer

In the process of generating a clonal mammalian cell line, a single cell was seeded in a well of a cell culture plate. After the first 48 hours, one of the progeny cells underwent apoptosis due to a new mutation. If the doubling time of the cells is 24 hours and no more cell death occurs, the total number of cells after a total of 7 days from seeding will be ______. (answer in integer)

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Correct answer: 96

Explanation

In 48 hours (two doublings) one cell becomes 4. One of them dies, leaving 3. The remaining 5 days is 120 hours, which is 5 doublings, so there are $3 \times 2^5 = 96$ cells.