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Clostridium tetani is a bacterium that can be found in soil - Edexcel - GCSE Biology Combined Science - Question 6 - 2019 - Paper 1
Question 6
Clostridium tetani is a bacterium that can be found in soil. It causes the infection tetanus. Children are vaccinated against tetanus. Explain why these children d... show full transcript
Worked Solution & Example Answer:Clostridium tetani is a bacterium that can be found in soil - Edexcel - GCSE Biology Combined Science - Question 6 - 2019 - Paper 1
Step 1
Explain why these children do not get tetanus if the bacteria enter their body through a cut in the skin.
Answer
Children do not get tetanus from Clostridium tetani due to vaccination. The vaccine contains either inactive or dead bacteria that carry antigens, prompting the immune system to recognize and respond to the bacteria. This exposure leads to the production of memory lymphocytes, which can quickly produce antibodies upon encountering the actual bacterium. Therefore, if Clostridium tetani enters through a cut, the immune response is immediate, preventing the infection.
Step 2
Explain how these bacteria have become resistant to Colistin.
Answer
Bacteria develop resistance to colistin through various mechanisms such as genetic mutations or the acquisition of resistance genes from other bacteria. These changes can modify the bacterial cell membrane, preventing colistin from entering effectively or altering the binding sites that colistin targets. As a result, these bacteria survive in the presence of the antibiotic, leading to increased resistance over time.
Step 3
Explain how information from Figure 8 provides evidence for human evolution.
Answer
The layers of rock depicted in Figure 8 indicate a chronological sequence of tool use, where different stone tools were found in distinct layers. This stratification suggests that as hominins evolved, their tools and technologies progressed over time. Tools from earlier layers may indicate more primitive techniques, while those in the upper layers reflect advanced craftsmanship. Thus, the findings suggest a timeline of human evolution concerning the development of tool-making skills.