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9 (a) Clostridium tetani is a bacterium that can be found in soil - Edexcel - GCSE Biology - Question 9 - 2019 - Paper 1
Question 9
9 (a) Clostridium tetani is a bacterium that can be found in soil. It causes the infection tetanus. Children are vaccinated against tetanus. Explain why these childr... show full transcript
Worked Solution & Example Answer:9 (a) Clostridium tetani is a bacterium that can be found in soil - Edexcel - GCSE Biology - Question 9 - 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 who are vaccinated against tetanus develop antibodies in response to the vaccine. These antibodies are part of the immune system and provide protection against the toxin produced by Clostridium tetani. When the bacteria enter through a cut, the immune system is able to recognize and neutralize the toxin before it can cause harm, preventing the onset of tetanus.
Step 2
Explain how these bacteria have become resistant to Colistin.
Answer
Bacteria can become resistant to Colistin through several mechanisms. One common method is through genetic mutations that alter the target site of the antibiotic, rendering it ineffective. Additionally, bacteria may acquire resistance genes from other resistant bacteria through horizontal gene transfer. Overuse and misuse of antibiotics in healthcare and agricultural settings also contribute to the selection pressure that leads to the survival of resistant strains.
Step 3
Explain how information from Figure 15 provides evidence for human evolution.
Answer
Figure 15 shows three stone tools found in different layers of rock, with each layer representing a different time period. The stratigraphy indicates a chronological sequence of tool use, suggesting that earlier tools (tool C) are simpler and less advanced compared to more recent tools (tool A). This progression in tool complexity reflects the cognitive and cultural development of early humans, supporting the theory of human evolution. Furthermore, the presence of these tools in dated layers provides a timeline for human technological advancements, illustrating how early humans adapted to their environments over time.