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Figure 10 shows colonies of bacteria growing on an agar plate - Edexcel - GCSE Biology Combined Science - Question 6 - 2023 - Paper 1
Question 6
Figure 10 shows colonies of bacteria growing on an agar plate. Each colony starts as one bacterium. Every time bacteria reproduce, the number of bacteria in each c... show full transcript
Worked Solution & Example Answer:Figure 10 shows colonies of bacteria growing on an agar plate - Edexcel - GCSE Biology Combined Science - Question 6 - 2023 - Paper 1
Step 1
Calculate the number of bacteria in a colony after five hours:
Answer
To find the number of bacteria after a specific time, we will use the formula for exponential growth:
Number of bacteria = Initial number of bacteria × 2^(n)
Where:
- The initial number of bacteria = 1 (since every colony starts from one bacterium)
- n = (total time in minutes / time for one division) = (300 minutes / 30 minutes) = 10
Thus, the calculation will be:
Number of bacteria = 1 × 2^{10} = 1024
So, after five hours, there will be 1024 bacteria in the colony.
Step 2
Step 3
Explain why antibiotics can be used to treat bacterial infections:
Answer
Antibiotics are effective against bacterial infections because they inhibit critical processes in bacteria. They can disrupt cell wall synthesis, interfering with bacterial growth and reproduction. However, antibiotics do not affect human cells, allowing them to target bacteria specifically without harming the host.
Step 4
Calculate the magnification of this drawing:
Answer
Magnification can be calculated using the formula:
Magnification = Size of the image / Actual size of the object
In this case:
- Size of the image = 80 mm
- Actual size of the rod-shaped bacterium = 0.005 mm
Thus, the calculation will be:
Magnification = 80 mm / 0.005 mm = 16,000
The magnification of the drawing is 16,000.
Step 5
Describe the similarities and differences of a bacterial cell and a plant cell:
Answer
Similarities:
- Both have a cell membrane that encases the cell contents.
- Both have ribosomes, which are involved in protein synthesis.
- Both contain cytoplasm, where cellular processes occur.
- Both types of cells have DNA as their genetic material.
Differences:
- Bacterial cells possess chromosomal DNA that is often circular and not enclosed within a nucleus, while plant cells have linear DNA organized into chromosomes inside a nucleus.
- Bacterial cells may have flagella for movement, whereas plant cells do not.
- Bacterial cells are generally smaller in size compared to plant cells.
- Plant cells are eukaryotic (have a defined nucleus), while bacterial cells are prokaryotic (do not have a defined nucleus).