Here, you will find the summary and questions and answers of NBSE class 10 Alternative English chapter 2 Man Against Virus. Additional questions and solutions will be added later. However, these notes should be used only for references. These materials should be modified/changed as per the needs.
SUMMARY: As a biologist, Louis Pasteur had discovered the vaccine for anthrax and chicken cholera. He was interested in preparing a vaccine against rabies as well since it caused an extremely painful death in human beings bitten by rabies-infected dogs. He conducted a series of experiments, to locate the germ that caused rabies in animals. He presumed they were in the saliva of mad animals since people who were beaten by them got rabies. He injected the saliva of rabies-infected animals but found that they did not always get rabies. He and his assistant, Roux tried to locate the germ in the blood of infected animals since germs generally live in the blood but they were not successful there either. At last, the symptoms of rabies gave them a clue. Initially, the rabies-infected dog foamed in the mouth and bit people. But later it became paralyzed and eventually died. The paralysis meant that the nervous system of the dog was also affected.
Pasteur and Roux looked for tire germ in the brain and spinal cord of rabies-infected animals and found it living in the inner region of the brain known as the medulla. They tested the microbe by injecting it directly into the brain of a healthy rabbit. It developed rabies. Through experiments, they also found out that the germs in the rabbits in the lab were stronger than those in mad street-dogs. They developed weakened strains of the germ in the medulla of the brain and used it as a vaccine to help animals and human beings build immunity against rabies.
I. Choose the correct Option
1.What is the meaning of the phrase ‘confound it’?
Answer: a. To be confused or perplexed
2. vaccine: protect:: ______
Answer: c. oil : lubricate
3. Pasteur’s discovery that the rabies microbe lives in the nervous system was
Answer: c. Both
4. Why did Pasteur release the crazed dog’s saliva into a sterile test-tube?
Answer: a. He did not want to mix the rabies microbes with other germs.
5. How did Pasteur weaken the rabies microbe?
Answer: d. By letting the infected medulla sit in a sterile solution for several days.
II. Read the lines and answer the questions that follow:
1. Pasteur had never been able to forget the horror of that moment.
a. What had horrified Pasteur?
b. Why had the person suffering the horror done so willingly?
c. What did witnessing this moment make Pasteur resolve in the future?
Answer: a. The moans of the villager and the hiss of the blacksmith’s red-hot iron burn the skin of a person who was bitten by a rabid infected wolf had horrified Pasteur.
b. The person suffering the horror had done so willingly because he was bitten by a rabid carrying mad wolf and at that time this method was believed to be the cure and an escape from death.
c. Witnessing the horror left a lasting impact on Pasteur. It strengthened his determination to find a cure for rabies that was not so painful.
2. ‘The sooner it gets there, the sooner it has an effect.’
a. What do ‘it’ and ‘there’ refer to?
b. How did Pasteur and Roux help ‘it’ get ‘there’ sooner?
c. Why is it the sooner, the more effective?
Answer: a. Here ‘it’ refers to the rabies virus and ‘there’ refers to the brain.
b. Pasteur and Roux help ‘it’ get ‘there’ sooner by injecting the virus straight into the brain of a healthy rabbit.
c. The sooner it gets there, the sooner it has an effect because the rabies virus lives in the brain, so by injecting the virus directly into the brain of a rabbit Pasteur and Roux were able to get the necessary results quickly.
III. Answer these questions briefly.
1. Why were Pasteur’s assistants shocked to see him sucking saliva of a mad dog into a tube?
Answer: Pasteur’s assistants were shocked to see him sucking saliva of a mad dog into a tube because if he had sucked too hard he would have gotten the saliva into his mouth which contained the virus rabies. At that time there was no perfect cure for rabies and he was taking a great risk by sucking like that.
2. Why was Pasteur studying samples of saliva from rabid animals?
Answer: Pasteur was studying samples of saliva from rabid animals as he was trying to develop a vaccine against rabies. He was looking for the rabies microbe in the saliva and trying to isolate it to study the microbes and eventually develop vaccine.
3. How did Pasteur make the vaccine against rabies?
Answer: Pasteur was able to develop the vaccine against rabies after much toiling, perseverance, and persistence. He was determined to find a less painful method to prevent death from rabies. He started studying the saliva samples of rabies infected animals. He knew somewhere in the saliva was the microbe he was looking for. When after injecting the saliva into healthy animals they found that not every animal was getting infected and the blood was having no effect, they concluded that the virus must be living in the brain and spinal cord and affecting the nervous system as the animals infected with rabies gets paralyzed eventually. They took brain samples of an infected animal and injected them under the skins of healthy animals. Though it took time, many of the animals developed rabies. After that, they injected more brain samples directly into the brains of healthy rabbits and the rabbits quickly developed the disease.
Then they tested the strength of the germ, by noting how quickly a rabbit developed rabies after the germ was injected into its brain. They found that strength varied depending on what kind of animal it had been living in. Germs from the laboratory rabbits were more virulent than germs taken from stray mad dogs. They decided to use the most virulent kind in trying to make a vaccine. The next move was to try weakening the germ. As they could not see it or find a way of growing it outside the brain, they had to work with infected brains. The germ seemed to favour a region of the brain called medulla, so they used samples from there. Roux put these into a sterile solution which he then closed. As days went by, the pieces of medulla shrivelled. They grind up the pieces of the brain samples and inject them into healthy animals. When they did this, the animals appeared to get rabies, but instead of getting really sick, they rapidly recovered. Then they tested the strength of the virus by injecting them into healthy animals depending on how long the samples had been dried and shrivelled. They found that a piece of medulla fourteen days old was harmless and perfect for the vaccine and thereby the vaccine was made.
IV. Going Beyond
1. ‘…stop not till your goal is reached.’ Apply this statement to describe Pasteur as a biologist with a purpose.
Answer: Pasteur was a remarkable biologist, and it wasn’t only because of him being a gifted person, but because he was determined and persistent.
He was focused on finding a way to prevent the death from rabies without much pain, and for this, he spent countless hours experimenting and brainstorming. When a method failed, he tried to get the results using another way. No amount of setbacks or disappointments could hold him back as he continued to keep his perseverance and goal of finding a vaccine, which he eventually did. Pasteur wasn’t just another biologist, he was someone with a purpose.
His story assures us that if you stop not till your goal is reached, no goal is too far.
2. How do you feel about experimenting with animals to find cures for illnesses?
Answer: I don’t feel very comfortable that animals are being used to find cures for illnesses as they have lives too and their lives matter. Most of us would say it’s a sacrifice we need to make for a greater goal, and at this juncture of our story, it seems like a valid point. But there should be ways to find cures for illnesses without testing on animals and more research should be done in these ways. Maybe we are not doing more research on finding an alternative because animals are viewed as a cheap and easy solution and that just displays out lack of empathy and insensitivity towards the other forms of lives.
3. Discuss in class: What according to you is success? What do you think are the qualities one needs to be successful? Use two examples to substantiate your points.
Answer: Do it yourself