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Figure 17 shows colonies of bacteria growing on an agar plate - Edexcel - GCSE Biology - Question 9 - 2023 - Paper 1

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Figure 17 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 17 shows colonies of bacteria growing on an agar plate - Edexcel - GCSE Biology - Question 9 - 2023 - Paper 1

Step 1

Calculate the number of bacteria in a colony after five hours

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Answer

To find the number of bacteria in a colony after five hours, we need to determine how many times the bacteria double in that duration.

  1. Convert 5 hours to minutes: 5exthours=5imes60=300extminutes5 ext{ hours} = 5 imes 60 = 300 ext{ minutes}

  2. Since the bacteria reproduce every 30 minutes, we divide the total time by 30: 300extminutes\/30extminutes=10extdoublingcycles300 ext{ minutes} \/ 30 ext{ minutes} = 10 ext{ doubling cycles}

  3. Each cycle doubles the number of bacteria, starting from 1: extNumberofbacteria=210=1024 ext{Number of bacteria} = 2^{10} = 1024

Thus, the number of bacteria in the colony after five hours is 1024.

Step 2

Explain why antibiotics can be used to treat bacterial infections

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Answer

Antibiotics can be used to treat bacterial infections because they specifically target bacterial cells and their processes without affecting human cells. For example:

  • Antibiotics like penicillin interfere with the synthesis of the bacterial cell wall, leading to the lysis or death of the bacteria.
  • They can also inhibit protein synthesis within bacteria, which is critical for their growth and reproduction. This selective targeting allows antibiotics to effectively eliminate pathogens causing infections.

Step 3

Calculate the magnification of this drawing

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Answer

To calculate the magnification, we use the following formula:

Magnification=Length in drawingActual length\text{Magnification} = \frac{\text{Length in drawing}}{\text{Actual length}}

Substituting in the values: [ \text{Magnification} = \frac{80 \text{ mm}}{0.005 \text{ mm}} = 16000 ]\n Thus, the magnification of the drawing is 16000.

Step 4

Describe the similarities and differences of a bacterial cell and a plant cell

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Answer

Similarities:

  1. Both bacterial and plant cells have a cell membrane that protects the cell and controls the movement of substances in and out.
  2. They both contain genetic material (DNA) that controls the functions of the cell.

Differences:

  1. Structure: Bacterial cells are generally smaller and simpler, lacking a nucleus, while plant cells are larger and more complex with a defined nucleus.
  2. Cell wall composition: Bacterial cell walls are made of peptidoglycan, whereas plant cell walls are made of cellulose.
  3. Organelles: Plant cells contain chloroplasts for photosynthesis, while bacterial cells do not possess membrane-bound organelles.
  4. Reproduction: Bacteria often reproduce asexually through binary fission, while plant cells can reproduce both sexually and asexually.

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