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Each colony starts as one bacterium - Edexcel - GCSE Biology - Question 3 - 2023 - Paper 1
Question 3
Each colony starts as one bacterium. Every time bacteria reproduce, the number of bacteria in each colony doubles. (a) Calculate the number of bacteria in a colony... show full transcript
Worked Solution & Example Answer:Each colony starts as one bacterium - Edexcel - GCSE Biology - Question 3 - 2023 - Paper 1
Step 1
Calculate the number of bacteria in a colony after five hours
Answer
To find the number of bacteria after five hours, we first determine how many 30-minute intervals are in five hours:
5 hours = 5 × 60 minutes = 300 minutes 300 minutes / 30 minutes per interval = 10 intervals.
The number of bacteria doubles with each interval, starting with 1 bacterium:
Number of bacteria = 1 × 2^{10} = 1024.
So, there would be 1024 bacteria after five hours.
Step 2
Explain why antibiotics can be used to treat bacterial infections
Answer
Antibiotics are effective against bacterial infections because they target specific features of bacterial cells. They can:
- Inhibit cell wall synthesis, causing bacteria to burst.
- Interfere with protein synthesis, disrupting essential functions.
- Affect the synthesis of nucleic acids, preventing bacterial replication.
By specifically targeting bacterial systems, antibiotics can eliminate the bacteria without harming human cells.
Step 3
Calculate the magnification of this drawing
Answer
To calculate the magnification, we use the formula:
Magnification = (Size of drawing) / (Actual size of object)
Here, the size of the drawing is 80 mm, and the actual size of the bacterium is 0.005 mm:
Magnification = 80 mm / 0.005 mm = 16000.
Thus, the magnification of the drawing is 16000 times.