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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 ch... 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 immunity due to the presence of antibodies. The vaccine introduces a harmless component of the tetanus toxin, prompting the immune system to produce specific antibodies. If the bacteria enter the body through a cut, these antibodies are already present and can neutralize the toxin produced by Clostridium tetani, preventing the onset of the disease.
Step 2
Explain how these bacteria have become resistant to Colistin.
Answer
Bacteria can develop resistance to Colistin through several mechanisms, including genetic mutations and horizontal gene transfer. Mutations may alter the target site of the antibiotic, reducing its effectiveness. Additionally, bacteria can acquire resistance genes from other species through plasmids or transposons, allowing them to survive in the presence of Colistin. Overuse and misuse of antibiotics in medicine and agriculture also contribute to the selection pressure that favors resistant strains.
Step 3
Explain how information from Figure 15 provides evidence for human evolution.
Answer
Figure 15 illustrates the different layers of rock in which three stone tools (tools A, B, and C) are found. The vertical arrangement of these tools supports the idea of chronological development. Tool A, found in the upper layer, represents the most recent technological advancement, while Tool C, located deeper, indicates an earlier stage of human tool-making. This stratification suggests a timeline of human evolution, demonstrating how tool use has progressed over time, reflecting cognitive and technological advancements in early humans.