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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
Vaccination provides immunity against tetanus. When children are vaccinated, they receive a dose of a weakened or inactivated form of the tetanus toxin. This stimulates their immune system to produce specific antibodies and memory cells against the pathogen. In the event that Clostridium tetani bacteria enter through a cut, these pre-existing antibodies can quickly neutralize the toxin before it causes harm, thanks to the immune memory. Thus, children do not develop tetanus due to this protective immune response.
Step 2
Explain how these bacteria have become resistant to Colistin.
Answer
Bacteria can become resistant to Colistin through various mechanisms. One common method is the mutation of genes that encode for the target protein of the antibiotic, leading to reduced binding efficacy. Additionally, bacteria may acquire resistance through horizontal gene transfer, obtaining plasmids that contain resistance genes from other resistant bacteria. This can happen through transformation, transduction, or conjugation. The use and overuse of antibiotics also exert selective pressure on bacterial populations, allowing those with resistance traits to survive and proliferate.
Step 3
Explain how information from Figure 15 provides evidence for human evolution.
Answer
Figure 15 illustrates the concept of stratigraphy, where different tools are found in various layers of rock. The position of these tools in the geological layers indicates the chronological order of their use. Tool A, found in the uppermost layer, was used more recently, while tool C, located in a deeper layer, represents an earlier stage of human tool-making. This sequence suggests a progression in technology and cognitive development over time, providing evidence for the evolutionary advancement of humans. The morphology of these tools can also reflect changes in human behavior and the adaptation to different environments.