ADDITIONAL QUESTIONS AND ANSWERS:
1. Name the following:
(a) The type of drugs that kills bacteria without damaging human cells.
Ans: Antibiotics
(b) The vector that spreads rabies.
Ans: Dogs
(c) Organisms against which it is difficult to develop a drug.
Ans: Viruses
(d) Organisms that use the machinery of human cells for their life processes.
Ans: Viruses.
(e) Any two diseases caused by worms.
Ans: Intestinal worm infections and elephantiasis
(f) Any two common vectors.
Ans: Mosquitoes, houseflies.
(g) The body mechanism that fights against infection.
Ans: Immune System.
(h) (i) An acute and (ii) a chronic disease
Ans:
(i) Acute disease- cough and cold (ii) Chronic disease-Elephantiasis
(i) Any two:
(i) infectious (ii) non-infectious diseases.
Ans:
(i) Infectious diseases -Tuberculosis, Typhoid
(ii)Non-infectious diseases – High blood pressure, cancer, diabetes
(j) The categories of organisms that act as infectious agents.
Ans: Viruses, bacteria, fungi, protozoa and multicellular organisms like worms.
(k) Any two diseases caused by
(i) Viruses
Ans: Common cold, influenza, dengue fever, AIDS.
(ii) Bacteria
Ans: Typhoid, cholera, tuberculosis, anthrax.
(iii) Fungi
Ans: Skin diseases like ringworm and eczema
(iv) Protozoan microbes
Ans: Malaria, kala azar
(v) Worms
Ans: Intestinal worm infection and elephantiasis.
(vi) Sexual contact.
Ans: Syphilis and AIDS.
(l) Any two common vectors.
Ans: Mosquitoes, houseflies.
(m) The disease which spreads though blood transfusion.
Ans: HIV-AIDS
(n). The types of diseases on the basis of their duration.
Ans: On the basis of their duration the diseases are classified as acute diseases and chronic diseases.
(o). The modes by which infectious diseases spread.
Ans: Infectious diseases spread (i) through air and are called air-borne diseases (ii) through water and are called water-borne diseases (iii) through physical contact and (iv) by vectors.
(p). The ways by which AIDS spreads.
Ans: By sexual contact with an infected person. Blood to blood contact with an infected person as in the case of a blood transfusion. Infected mothers to the baby through breastfeeding or to the new born child during pregnancy.
(q). The preventive measure to be taken against airborne diseases.
Ans: The preventive measure to be taken against airborne diseases would be to avoid overcrowded living conditions.
(r). The preventive measure to be taken against water-borne diseases.
Ans: Water-borne diseases can be prevented by consuming safe drinking water i.e. to boil the water before drinking.
(s). The principles of treatment of an infectious disease.
Ans: (i) To reduce the effects of the disease like inflammation, pain, fever, and so on.(ii) To kill the cause of the disease by killing the microbes-administering appropriate drugs.
Answer the following:
1. What is health.
Ans: Health is a state of being well enough, to function well physically mentally and socially
2. When do we say that a person suffers from a disease.
Ans: A person is said to suffer from a disease when the functioning or the appearance of one or more of his systems changes for the worse.
3. Good economic conditions and jobs are factors necessary for good health. Justify
Ans: It is because good and nutritious food is necessary to ensure good health and food can be earned by doing work.
4. Why is public cleanliness important for individual health ?
Ans: Public cleanliness ensures that vectors that carry disease are eliminated. Hence it ensures
individual health.
5. Give an example to show that public cleanliness is essential for individual health.
Ans: If, in a village, town or city, the people do not dispose off the garbage properly i.e. throw it by the roadside instead of dumping it in the garbage bin, it will be a cause for many diseases and an individual may suffer from it along with others.
6. A disease-free person need not necessarily be healthy. Explain with an example.
Ans: A healthy person should be able to function well physically, mentally and socially. Example: a dancer should be able to stretch his body into graceful positions. He should be able to bring out the best in him. If he is not able to do it then we may say that he is not healthy, though there are no symptoms of any disease or he is disease-free.
7. What do you mean by symptoms of a disease ?
Ans: Symptoms of a disease are the things we feel as being wrong
8. What are the symptoms of common cold ?
Ans: The symptoms of common cold are headache, sneezing, and so on.
9. When is a disease said to be acute.
Ans: The diseases which last for very short period are acute diseases.
10. When is a disease said to be chronic.
Ans: The disease which lasts for a very long period is said to be a chronic disease.
11. How does an acute disease differ from a chronic disease.
Ans: The diseases which last for a very short period are acute diseases while those which last for a long time are chronic diseases.
12. Why do acute diseases have no major effect on general health.
Ans: An acute disease has no major effect on general health because the disease lasts for a few days.
13. Chronic diseases have a major effect on the general health of a person. Why ?
Ans: When a person suffers from a chronic disease, there is a poor functioning of some organs or the system of the body for a long time, sometimes for a lifetime. Therefore chronic diseases affects the general health of the person.
14. What are infectious diseases ?
Ans: Diseases, whose immediate cause is the microbes, are called infectious diseases.
15. Why are infectious diseases called communicable diseases ?
Ans: Infectious diseases are called communicable diseases because the microbes causing the diseases move from an affected person to healthy.
16. Why is bed rest essential for a person suffering from an infectious ?
Ans: When a person takes bed rest his energy is saved. Thus more energy is persons and affect them disease available to the body to fight the disease. Therefore it takes less time for healing.
17. The majority of Indian children are immune to hepatitis A. Why ?
Ans: Hepatitis A viruses are transmitted through water. Indian children are exposed to this virus through water. Therefore by the time they are five years old they develop an immunity against it.
18. Why should water be boiled before drinking ?
Ans: When water is boiled the disease-producing microbes present in it are killed.
19. How does cholera spread through water ?
Ans: The excreta of the person suffering from cholera, which is passed out in the open, gets mixed up with drinking water and thus enters new hosts through drinking water.
20. What are vectors ?
Ans: Vectors are the animals which carry infecting agents from a sick person to a potential host.
21. How can the diseases spread by vectors be prevented ?
Ans: The diseases spread by vectors can be prevented by eliminating vectors. This can be achieved by keeping the environment clean of animals.
22. In many species of mosquitoes, the females bite and suck the blood.
Ans: The female mosquitoes of some species need highly nutritious food in the form of blood in order to be able to lay mature eggs for reproduction. So they bite animal and suck their blood.
23. Complete the second pair:
(i) Pneumonia: air-borne :: syphilis: ……………
(ii) Anthrax: Protozoa :: HIV: …………..
(iii) Rabies: dogs:: Japanese encephalitis: ……………
(iv) Jaundice: liver:: Malaria:………………
Ans: (i) Physical (sexual) contact (ii) Virus
(iii) Mosquitoes (iv) liver and then red blood corpuscles.
24. Why is there inflammation in the infected area.
Ans: The immune system of the body recruits and engages many cells in the infected area to fight and kill the disease-producing microbes. There is inflammation due to the recruitment of immune cells in the infected area.
25. Sometimes there is swelling and pain in the infected area. Why.
Ans: The immune system of our body recruits many cells in the infected area to fight and kill the disease-producing microbes. Therefore there is inflammation due to the recruitment of immune cells in the infected area which causes swelling and pain.
26. What is an antibiotic.
Ans: Antibiotic is a drug that blocks the life processes of microbes without affecting the life processes of human cells.
27. How does an antibiotic kill bacteria.
Ans: Antibiotics block the bacterial synthesis pathways which are important to the life processes of bacteria and thus kills them.
28. How does penicillin kill bacteria.
Ans: Penicillin blocks the bacterial processes that build the cell wall. So they are unable to build the cell wall.
29. A drug effective against one member is also effective against other members of the group of bacteria. Give a reason.
Ans: The members of the bacteria group have many common life processes. A drug which is devised to block one of these life processes of a bacterium works against the others because of the similarity of life processes. Therefore a drug effective against one member is also effective against other members of the group.
30. Antibiotics cause no harm to the human body even though they kill bacteria. Why.
Ans: Antibiotics block certain life processes of bacteria and kill them. Human cells have altogether different life processes. Therefore antibiotics cause no harm to human cells.
31. What are the ways of disease spread ?
Ans: Diseases can be spread in four ways: Air, water, physical contact , vectors.
32. Why is making of anti-viral drugs more difficult than making anti-bacterial drugs.
Ans: Many life processes are similar in bacteria and therefore the drugs effective against one member are also effective against other members of the group. But viruses do not have specific life processes of their own. They use the mechanism of human cells for their life processes. Since their life processes are not specific it is difficult to develop drugs against them.
33. Antibiotics are not effective against viral infection. Why.
Ans: Antibiotics work against the pathways of the life processes of bacteria. Viruses do not have specific life processes. Hence antibiotics are not effective against viral infections.
34. Why are antibiotics ineffective against common cold.
Ans: Common cold is a viral infection. Antibiotics cannot work against a virus.
35. A person having a strong immune system does not easily suffer from infectious diseases. Give a reason.
Ans: It is because the immune system of the body fights the diseases bacterial infection and not against a viral infection producing microbes and kills them before the infection assumes a major proportion
36. What is the principle of vaccination.
Ans: The immune system develops a memory for a particular infection or microbe from the mimic of that infection introduced in the body Subsequently when the infecting microbe enters the body, the immune system works against it very vigorously and destroys it
37. A nurse in a hospital has to attend to patients with infectious diseases. What precautions does she take to avoid contracting the diseases direct contact with the patient.
Ans: She uses a mask to avoid infections through air and gloves to avoid. She takes vaccines against different infectious diseases
38. Explain the principle of immunization.
Ans: Whenever an infectious microbe enters the body, the immune system fights against it and kills it. lt specifically remembers the microbes. If the same microbe or its close relatives happen to enter the body again, the immune system now fights more vigorously than the first time and eliminates it more quickly.
39. In HIV- AIDS infection even a small cold can develop into severe pneumonia. Give a reason.
Ans: HIV virus damages the immune system and its function. Therefore the efficiency of the immune system of an HIV-AlDS infected person decreases. As a result the body cannot fight off even minor infections like the common cold. Thus a common cold can develop into pneumonia.
40. Why should hepatitis A vaccine not be given to Indian children.
Ans: Hepatitis A viruses are transmitted through water. Indian children are exposed to this virus through water and become immune to it by the time they are five years of age. Therefore hepatitis A vaccine need not be given to Indian children.
41. Why do airborne diseases like pneumonia and tuberculosis affect the lungs.
Ans: In case of most of the airborne diseases, the disease producing microbes enter through the nose and affect the major organs of the respiratory system like the lungs
51. Write two points to distinguish between:
(a) Acute and chronic diseases.
Ans:
|
Acute diseases
|
Chronic diseases
|
|
Acute diseases last for a short period of time.
|
Chronic diseases last for a longer period, may be even a lifetime. |
| Acute diseases have no drastic effects on the general health |
Chronic diseases have drastic effect on the general health |
(b) Infectious and Non-infectious diseases.
Ans:
|
Infectious diseases
|
Non-Infectious diseases
|
| Infectious diseases are caused due to microbes or micro-organisms. | The cause of non-infectious diseases is internal. |
| Infectious diseases are communicable ie. they spreadfrom an affected person to others | Non-infectious diseases are not communicable diseases. |
(c) Viruses and Bacteria.
Ans:
|
Viruses
|
Bacteria
|
| Viruses live in host cells. | Bacteria do not live in host cells. |
| The life processes are not similar in viruses. | Many life processes are similar in bacteria. |
| The drug effective against one member is not effective against the other members of the group | The drug effective against one member is effective against the other members of the group |
42. Many diseases are spread through vectors.
(i) What are vectors.
Ans: Vectors are the animals which carry infecting agents from a sick person to a potential host.
(ii) How can the diseases spread by vectors be prevented ?
Ans: The diseases spread by vectors can be prevented by eliminating the vectors. This can be achieved by keeping the environment clean
43. Tuberculosis is an air-borne disease.
(i) When is a disease said to be an air-borne disease.
Ans: A disease in which the disease producing microbes or viruses spread through air is called an air-borne disease
(ii) Which organs are usually targets of these organisms causing air-borne diseases. Give reason.
Ans: The target organs are the organs of the respiratory system because the air containing these organisms enter the respiratory system through the nose and go to the lungs
44. Cholera is water-borne disease.
(i) Why is cholera a water-borne disease ?
Ans: Microbes of cholera enter the digestive system through drinking water contaminated by the excreta of a person suffering from cholera.
(ii) How can such diseases be prevented ?
Ans: Such diseases can be prevented by using safe drinking water i.e. water in which all disease producing microbes are destroyed.
45. The Government of India has undertaken the Pulse Polio programme of immunisation.
(i) Why is polio a chronic disease ?
Ans: Polio is a chronic disease because there is a lifetime of poor functioning of the organs of the body of a polio-stricken individual
(ii) What is immunisation ?
Ans: Immunisation is to prepare the immune system of a body to fight efficiently against disease producing microbes through vaccination.
46. In Goa, the Government has provided toilets (Sulabh Shauchalaya) to many rural houses. Also the number of villages getting drinking water through pipelines is increasing.
(i) Why are toilets provided to rural areas ?
Ans: Toilets are provided in rural areas because it is a practice in rural areas to defecate in the open from where the infectious microbes like that of cholera get into drinking water resulting in the spread of the disease. Also vectors like houseflies sit on the excreta and transfer the microbes to the food.
(ii) Why is drinking water supplied through pipelines to more and more villages ?
Ans: The water supplied through pipelines is treated to kill microbes which spread diseases. Also, when water is supplied through closed pipelines, there is little chance of water contamination
(iii) How is drinking water from wells made safe for drinking ?
Ans: By adding disinfectants like bleaching powder and potassium permanganate.
47. George was frequently sneezing and had mild fever. The teacher, on noticing, advised him to go home. Rakesh, Irfan and Balu were sitting near George. After a couple of days, Rakesh and Irfan developed similar symptoms i.e. sneezing and fever. But Balu was not affected. He was alright.
(i) What disease could George be suffering from ?
Ans: Common cold or influenza.
(ii) Why did the teacher advise George to go home ?
Ans: George needed rest for a speedy recovery. Further, cold or influenza is an infectious disease and may spread to other students. Therefore the teacher advised him to go home.
(iii) Would you advise George to take antibiotics. Justify your .
Ans: No. Because common cold is a viral infection and antibiotics do not work against viral infections.
(iv) Why were only Rakesh and Irfan affected but not Balu ?
Ans: It is because the immunity of Balu is stronger than that of Rakesh and Irfan.