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Cells are the basic units of all forms of life - AQA - GCSE Biology Combined Science - Question 4 - 2020 - Paper 1
Question 4
Cells are the basic units of all forms of life. 1. A bacterial cell is smaller (than a plant cell). 2. A bacterial cell does not have chloroplasts (plant cells do).... show full transcript
Worked Solution & Example Answer:Cells are the basic units of all forms of life - AQA - GCSE Biology Combined Science - Question 4 - 2020 - Paper 1
Step 1
Describe four differences between a bacterial cell and a plant cell.
Answer
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A bacterial cell is generally smaller than a plant cell, making it easier to multiply rapidly.
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Bacterial cells do not contain chloroplasts, which are present in plant cells and are essential for photosynthesis.
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The genetic material in bacterial cells is not enclosed in a nucleus; instead, it floats freely in the cytoplasm, whereas plant cells have their DNA within a defined nucleus.
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Bacterial cells may possess a flagellum for movement, while plant cells do not have this feature.
Step 2
Gonorrhoea is a bacterial disease. A new vaccine is being developed against gonorrhoea. Describe how a vaccine would work to prevent gonorrhoea.
Answer
A vaccine for gonorrhoea would typically contain inactivated or weakened forms of the gonorrhoea bacteria. When administered, this triggers the immune system to recognize these pathogens.
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White blood cells are stimulated to produce antibodies, which help identify and neutralize the bacteria if they're encountered in the future.
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Additionally, some memory cells are formed, ensuring a quick and robust response upon re-exposure to the gonorrhoea bacteria.
Step 3
Explain how vaccinating chickens reduces the number of cases of salmonella food poisoning.
Answer
Vaccination of chickens against Salmonella decreases the likelihood that these chickens will carry the bacteria. As a result, fewer bacteria/pathogens will be transmitted to humans through food consumption.
This reduces the instances of food poisoning caused by salmonella, as the bacteria is less likely to be ingested in contaminated chicken or eggs.
Step 4
Give one way that the spread of salmonella food poisoning from one human to another is controlled. Do not refer to vaccination in your answer.
Answer
One effective method to control the spread of salmonella food poisoning is through good hygiene practices, such as washing hands before preparing food and after using the toilet.
Step 5
The number of cases of salmonella food poisoning is usually higher in summer than in winter. Suggest one reason why.
Answer
One reason for the higher number of salmonella cases in summer could be warmer weather, which allows bacteria to reproduce and increase their activity more rapidly than in colder weather.