Photo AI
Rabies is a disease caused by a virus that affects mammals - HSC - SSCE Biology - Question 25 - 2016 - Paper 1
Question 25
Rabies is a disease caused by a virus that affects mammals. In 1880 Louis Pasteur investigated dogs that were suffering from rabies in order to find the cause. He b... show full transcript
Worked Solution & Example Answer:Rabies is a disease caused by a virus that affects mammals - HSC - SSCE Biology - Question 25 - 2016 - Paper 1
Step 1
Why was Pasteur NOT able to observe the rabies virus?
Answer
Light microscopes were not powerful enough to observe viruses, which are extremely small in size. The limitations of light microscopy mean that objects smaller than approximately 200 nanometers cannot be clearly visualized, and since the rabies virus falls below this threshold, Pasteur was unable to observe it directly.
Step 2
Explain why Pasteur needed to identify and culture the microorganism in order to meet the scientific standards for establishing the cause of rabies.
Answer
Pasteur needed to identify the microorganism to ensure the causative agent of rabies was accurately established. Following Koch's postulates, the microorganism must be shown to cause disease when introduced to a healthy host. Culturing the microorganism would allow Pasteur to demonstrate that the specific agent could be isolated and identified in the saliva of infected dogs. By introducing the microorganism into a healthy animal and observing the development of disease, he could confirm its role as the causative agent of rabies.