Figure 2 shows colonies of bacteria growing on an agar plate - Edexcel - GCSE Biology Combined Science - Question 2 - 2023 - Paper 1

To determine the number of bacteria after five hours, we first need to calculate the number of reproduction cycles in that timeframe.

Five hours is equal to 300 minutes. Since each reproduction cycle takes 30 minutes:

$ext{Number of cycles} = \frac{300 \text{ minutes}}{30 \text{ minutes/cycle}} = 10 \text{ cycles}$

Starting with one bacterium, the number of bacteria doubles with each cycle:

$N = N_0 \times 2^n$

Where:

• $N_0 = 1$ (initial bacterium)
• $n = 10$ (number of cycles)

Thus:

$N = 1 \times 2^{10} = 1024$

Therefore, after five hours, there will be 1024 bacteria in the colony.