Question

A bacterium divides after every $35$ minutes. If a culture containing $ 10^{5} $ cells per mL is grown, then cell concentration per mL after $175$ minutes will be

• A. $ 175\times 10^{5} $
• B. $ 125\times 10^{5} $
• C. $ 48\times 10^{5} $
• D. $ 32\times 10^{5} $

Answer 1

Answer: (D)

Bacteria generally divides by binary fission, in this one cell divide to produce two cells.
$1 \times 10^{5}$ cell $\longrightarrow {\longrightarrow _{\text {stdiv. }}} \times 10^{5} \underset{\text { 2nddiv. }}{\longrightarrow } 4 \times 10^{5} \underset{\text { 3rddiv. }}{\longrightarrow } 8 \times 10^{5} \underset{\text { 4thdiv. }}{\longrightarrow } 16 \times 10^{5}$ $\underset{\text { 5thdiv. }}{\longrightarrow } 32 \times 10^{5}$
So, cell concentration per $mL$ after $175$ minutes will be $32 \times 10^{5}$.