Science Chapter 5 - Why Do We Fall Ill
Page No 308:Short Answer Questions
Question 1:
Differentiate between healthy and disease free.
Answer:
| Healthy | Disease-free |
| It refers to a state of complete well-being (physical, social and mental). | It refers to a state of absence of discomfort in any part of the body. |
| Besides an individual, it also depends upon the physical and socio-environmental factors. | It depends only on the individual. |
| Performance of a healthy person is very high because of high energy. | Performance of a disease-free person depends upon the environment and personal behaviour. |
Question 2:
Name the health problems subsequent to a disaster.
Answer:
Health problems subsequent to a disaster include infectious diseases such as diarrhoea, cholera, and typhoid. Disasters also lead to diseases caused by deficiency of nutrients because of the unavailability of proper food.
Question 3:
What provisions are made by local authorities to provide clean drinking water?
Answer:
Following are some provisions made by local authorities to provide clean drinking water:
(a) Ensuring routine checks on water leakage in the tanks
(b) Treating the water with chlorine if the water gets unhygienic for drinking
Question 4:
What provisions are made by local authorities for solid waste management?
Answer:
Following are some provisions made by local authorities for solid waste management:
(a) Collecting the waste on a regular basis for its proper degradation
(b) Cleaning the local area regularly to collect the solid waste at one place
Question 5:
Distinguish between symptoms and signs of a disease.
Answer:
| Symptoms of a disease | Signs of a disease |
| Symptoms of a disease indicate the presence of a disease. | These indicate the presence of a specific disease. |
| They are a collective indication of a number of diseases. | They are specific for different diseases. |
Question 6:
Write down the causal organisms of the following diseases :
Tuberculosis, Kala-azar, Malaria, Measles, Athlete's foot, Cholera.Answer:
Tuberculosis is caused by Mycobacterium tuberculosis.
Kala-azar is caused by Leishmania.
Malaria is caused by Plasmodium.
Measles is caused by Paramyxovirus.
Athlete's foot is caused by Trichophyton.
Cholera is caused by Vibrio cholerae.
Question 7:
Mention two means of physical contacts by which AIDS does not spread.
Answer:
Following are the two means of physical contact by which AIDS does not spread:
(i) It does not spread by shaking hands with the infected person.
(ii) It does not spread by sitting or talking with the infected person.
Question 8:
Differentiate between carrier and vector.
Answer:
| Vector | Carrier |
| A vector is an organism that passes on a disease without getting infected. | A carrier is an organism that itself does not have any symptoms of a disease, but the pathogen lives in its body and is passed on to others. |
|
A vector may act as an intermediate host for the completion of part of the life cycle of the pathogen. |
A carrier may or may not be needed by the pathogen to complete its life cycle. |
| Pathogen inhabits a vector usually for a short period of time. | The carrier state may carry the pathogen for a short or long duration (temporary or transient carrier or chronic carrier). |
| Example- Mosquito with malarial parasite | Example- A human with HIV virus but not AIDS or a human with pathogen Salmonella typhi but not typhoid |
Question 9:
Write short note on organ-specific and tissue-specific manifestations of disease.
Answer:
Organ-specific manifestation of a disease:
It refers to those types of diseases in which the pathogen infects a specific organ of an individual.
Example: In tuberculosis, the lungs of an individual are targeted.
Tissue-specific manifestation of a disease:
It refers to those types of diseases in which the pathogen infects a specific tissue of an individual.
Example: The HIV virus targets the tissue and cells of an individual, thereby decreasing the immunity.
Question 10:
Explain how does the body react after the entry of microbe in the body.
Answer:
After the entry of microbes in the body, the immune system of the body gets activated and starts releasing antibodies against the microbes. The immune system comprises several WBCs that fight against the microbes. These cells kill the microbes before they cause much harm to the body.
Question 11:
Why a person suffering from AIDS cannot fight even very small infections?
Answer:
A person suffering from AIDS cannot fight even the minute infections because his/her immune system or self-defence gets weakened. The HIV virus attacks the WBCs of the host and reduces the immunity. Hence, a person suffering from AIDS usually dies of secondary infections as he/she cannot fight even minor infections.
Question 12:
"We can treat an infectious disease by killing microbe". Justify the statement with suitable examples.
Answer:
"We can treat an infectious disease by killing microbes".
An infectious disease is caused by pathogens such as bacteria, protozoa, fungi, worm and viruses. When these pathogens enter a body, they result in a certain dysfunction in the body. Such symptoms can be treated by taking medicines; however, medicines do not necessarily remove the pathogens.
To treat an infectious disease, the microbes have to be killed by taking medicines that either kill the microbes or block the microbial synthetic pathways without affecting the host cellular pathways.
Question 13:
"Prevention is better than cure". Explain.
Answer:
Prevention is better than cure because of the following reasons:
(a) Curing a disease takes time and the person suffering from a disease has to cut off his work and daily routines to get complete rest.
(b) A person once infected serves as a medium of spreading the disease to others.
(c) Once a person gets infected, his or her body gets affected and he or she may never recover completely.
Question 14:
Explain how does vaccine work?
Answer:
A vaccine is a small quantity of a weakened antigen that is injected into the body of an individual. Once the antigen gets into the body of a healthy person, his/her body synthesises antibodies against the antigen. Once the body encounters an infectious antigen, it develops a memory; and when that antigen enters that body again, a large amount of antibodies is secreted by the body to destroy the antigen. Hence, it prevents the disease from occurring.
Question 15:
Name any three diseases of human beings caused by bacteria and three diseases caused by virus.
Answer:
The following three diseases in human beings are caused by bacteria:
(a) Cholera
(b) Tuberculosis
(c) Typhoid
The following three diseases in human beings are caused by viruses:
(a) Influenza
(b) Dengue fever
(c) AIDS
Question 16:
How does dehydration set in during diarrhoea?
Answer:
Dehydration sets in during diarrhoea because of excessive loss of water from the body tissues via discharge of semisolid or fluid faeces and vomiting. Dehydration may lead to the death of infants. Hence, the doctor tries to prevent dehydration from occurring during diarrhoea by advising liquid diet to the patient to compensate for the loss of water along with antibiotic treatment.
Question 17:
In a cluster of hutments, many people are suffering from malaria. Mention the unhygienic conditions that must be prevailing in that locality. How does a doctor confirm malaria?
Answer:
The unhygienic conditions prevailing in a locality where people suffer from malaria are as follows:
(i) Stagnant water at various places, due to which mosquitoes continue breeding
(ii) No use of insect repellents and mosquito nets by the people
Doctors confirm malaria by taking blood test of the infected individuals.
Question 18:
Explain the methods of prevention of malaria.
Answer:
Malaria can be prevented by adopting the following measures:
(i) Using insect repellents to avoid mosquito bites
(ii) Sprinkling kerosene oil on large open water bodies
(iii) Introducing Gambusia in water bodies, as it feeds on mosquito larvae
(iv) Spraying insecticides to kill adult mosquitoes
Question 19:
It was diagnosed that the body of a patient has lost its power of fighting any infection. Name the disease he is suffering from. What type of microbe is responsible for this disease and how does it spread from one person to the other.
Answer:
He is suffering from AIDS (acquired immunodeficiency syndrome). The microbe that is responsible for the disease is the retrovirus human immunodeficiency virus (HIV).
It spreads from one person to another by the following ways:
(a) Unprotected sexual contact with the infected person
(b) Transfusion of blood contaminated by HIV
(c) Use of injected needles or unsterilised needles
(d) From an infected mother to her child during pregnancy
Question 20:
Define diarrhoea. Give an account of occurrence, symptoms, prevention and control of this ailment.
Answer:
Diarrhoea refers to an abnormal and frequent discharge of semisolid or fluid faeces. It is caused by bacteria.
It is caused by infections via contaminated food, drinks, clothes, etc.
The symptoms include discharge of semisolid or fluid faeces, vomiting, abdominal cramps and decreased appetite. It can be prevented by improving hygiene.
It can be cured by giving antibiotic treatment to the patient.
Question 21:
Why is rabies is called hydrophobia? Explain.
Answer:
Rabies is also referred to as hydrophobia because the person suffering from this disease develops a fear of water. The person finds difficulty even in drinking water.
Question 22:
Write short note on Pulse Polio Programme.
Answer:
Pulse Polio Immunisation Programme (PPIP):
It was conducted in December 1995 for the first time to eradicate polio from India. In this programme, a dose (0.5 mL) of oral polio vaccine (OPV) is given to a child at different ages (1.5, 2.5 and 3.5 months), along with a booster dose given at 1.5 years of age (now up to 5 years of age). The vaccine helps to develop antibodies against the polio virus in the intestine and blood of the child. The days on which PPIP is conducted in the country are fixed and are known as national immunisation days (NIDS).
Page No 308:Long Answer Questions
Question 1:
Describe community issues that influence health.
Answer:
Health of a person can be influenced by the following community issues:
(i) Unsafe drinking water:
If the water is not treated properly and consumed with infectious agents in it, it can cause various infectious diseases. Hence, it is the responsibility of the local authorities of a community to keep a check so that every home gets safe drinking water.
(ii) Increase of garbage on the roads:
People throw garbage on roads and make the place dirty and unhygienic. Because of this, many parasite carriers grow in such environment. If the roads in a locality are kept uncleaned, it can cause increase in the number of diseases and other health issues. The local authorities should make facilities for proper garbage disposal and waste management so as to provide a better and healthy environment for the people.
Question 2:
Explain various modes of transmission of infectious diseases.
Answer:
Following are the modes of transmittance of infectious diseases:
(i) Air- Certain microbes travel in air and are inhaled by human beings, causing various infectious diseases such as common cold, pneumonia and tuberculosis.
(ii) Water- Infectious diseases spread via water when the stool of an infected person gets mixed in drinking water of a locality. Cholera is an example of water-borne diseases.
(iii) Sexual contact- Some infectious diseases such as syphilis and AIDS spread via sexual contact between a normal person and an infected person.
(iv) Vectors- Many animals are the carriers of various pathogens that cause infectious diseases and behave as vectors. Malaria is an example of such disease, in which female mosquito is the vector of the malaria-causing parasite.
Question 3:
Explain the general ways of preventing infection.
Answer:
General ways of preventing infection:
(i) Increasing personal hygiene
(ii) Avoiding exposure to air-borne pathogens by inhabiting in a less crowded place
(iii) Consuming safe drinking water and food to prevent water and food-borne diseases
(iv) Keeping the surroundings clean in order to prevent vector-borne diseases
(v) Taking proper vaccines at appropriate time or age
(v) Using protective measures during sexual contact to eliminate the risk of sexually-transmitted pathogens
Question 4:
Write short note on principle of treatment.
Answer:
An infectious disease can be treated by the following two ways:
(i) Reducing the effect of the disease-
In this method, medicine is given to the infected person for reducing the symptoms of the disease such as for bringing down fever or reducing pain. This practice is more focussed on healing the symptoms of the disease rather than preventing the disease. Although one can get rid of the body discomforts by using this method, the actual disease persists in the body.
(ii) Killing the microbe or pathogen that has caused the disease-
In this method, the treatment is more focussed on removing the pathogen from the body rather than just lowering the symptoms of the disease. Although it usually takes more time than the previous method, it is more beneficial to the health.
Microbes can be killed in two ways:
(a) By consuming drugs that kill microbes specifically and does not harm the host body
(b) By consuming drugs that block the essential biochemical processes of the microbe without harming the host cellular pathways: For this, antibiotics are given to the patient.
Question 5:
Write short notes on
(a) AIDS;(b) Malaria.
Answer:
(a) AIDS:
AIDS stands for acquired immunodeficiency syndrome, which is caused by a retrovirus known as human immunodeficiency virus. HIV infects the host body by attacking the WBCs, thereby weakening the body's self defence or immune system.
AIDS is transmitted from one person to another by the following modes:
(i) Unprotected sexual contact with the infected person
(ii) Transfusion of blood contaminated by HIV
(iii) Use of unsterilised needles for injections
(iv) From an infected mother to her child during pregnancy
Prevention of AIDS:
(i) Avoiding sexual contact with an unknown person
(ii) Using sterilised needles for injections
(iii) Screening the blood for HIV before transfusing it to some other person
So far, there is no medicine to treat AIDS.
(b) Malaria:
Malaria is an infectious disease that is caused by Plasmodium. It spreads by the bite of a female Anopheles mosquito that carries the malarial parasite. Malarial infection spreads in stagnant water bodies because the female mosquito breeds in such places. It causes headache, nausea, muscular pain and high fever in the infected person. Malarial parasite attack is of 6‒10 hours of duration with three stages, i.e., cold stage (extreme cold and shivering), hot stage (high fever) and sweating stage ( profuse sweating).
Malaria can be prevented by the following ways:
(i) Using insect repellents to avoid mosquito bites
(ii) Sprinkling kerosene oil on large water bodies
(iii) Introducing Gambusia in water bodies, as it feeds on mosquito larvae
(iv) Spraying insecticides to kill adult mosquitoes
Quinine is a drug that is used to treat a person suffering from malaria.
Question 6:
Describe certain bacterial diseases of human beings.
Answer:
Certain bacterial diseases of human beings are as follows:
1. Tuberculosis-
It is caused by the bacterium Mycobacterium tuberculosis, which infects all parts of the body by secreting a toxin called tuberculin. Symptoms of this disease include sickness, loss of appetite and weight, fever and night sweats.
It can be prevented by immunisation with BCG (Bacillus Calmette‒Guerin), which gives immunity for 3‒5 years.
2. Cholera-
It is caused by the bacterium Vibrio cholerae, which is transmitted by flies, contaminated food and water when there is poor sanitation. Symptoms of cholera include watery diarrhoea, vomiting, loss of weight and muscular cramps.
It can be prevented by improving personal hygiene and sanitation conditions in the community. Tetracycline is an antibiotic that kills the bacteria.
3. Typhoid-
It is caused by Salmonella typhi, which affects the human intestine. It spreads via contaminated food and water through houseflies. Symptoms of typhoid are headache and high fever that maximise during afternoons in the first and second weeks.
It can be prevented by TAB vaccination, which provides immunity for three years.
4. Diarrhoea-
It is caused by various bacteria that spread via contaminated food, water, hands, clothes, utensils, etc.
It is marked by frequent discharge of fluid faeces, vomiting and loss of appetite. In some cases, dehydration occurs due to rapid loss of water from the body.
It can be prevented by increasing personal and community hygiene.
Certain antibiotics are given for curing diarrhoea.
5. Peptic ulcers:
It is caused by the bacterium Helicobacter pylori, which causes painful bleeding within the stomach and the duodenum. It can be cured by the antibiotic amoxicillin.
Question 7:
Give an account of some important viral diseases of human beings.
Answer:
Some viral diseases of human beings are as follows:
1. Influenza:
It is caused by Myxovirus influenza, which travels in air and is transmitted from one person to another via sneezing, talking or coughing. Symptoms of influenza are discharge from the nose, sneezing, headaches, coughing and muscular pain.
It can be prevented by avoiding contact with the infected person.
2. Jaundice/Hepatitis:
It is caused by viral infection of HAV (in case of hepatitis A) and HBV (in case hepatitis B).
HAV spreads via ingestion of contaminated food, water and milk, whereas HAB spreads by infected blood and from the mother to her babies. Hepatitis A causes symptoms such as high temperature, headache, fatigue, discharge of dark yellow urine and appearance of rashes on the body.
Main symptoms of Hepatitis B include progressive liver disease, chronic active hepatitis and hepatocellular carcinoma.
Hepatitis A can be prevented by improving personal hygiene.
Hepatitis B vaccine can prevent the disease.
3. Rabies:
It is caused by Lyssavirus, which spreads via the bite of an infected dog. It causes high fever, painful muscle contraction, restlessness, excessive salivation and hydrophobia.
It can be prevented by immunisation of stray dogs. To treat rabies, Pasteur's treatment is given to the patient.
4. AIDS:
It is caused by a retrovirus known as human immuno-deficiency virus. HIV infects the host body by attacking at the WBCs, thereby weakening the body's self defence or immune system.
AIDS is transmitted from one person to another by the following methods:
(i) Unprotected sexual contact with the infected person
(ii) Transfusion of blood contaminated by HIV
Prevention of AIDS:
(i) Avoiding sexual contact with an unknown person
(ii) Using sterilised needles for injections
5. Polio:
It is caused by polio virus, which enters the body via food and water. It destroys motor nerve cells of the spinal cord responsible for muscle control.
Its symptoms include fever, vomiting, muscular pain and tingling sensation in limbs; these ultimately lead to paralysis.
Polio can be prevented by giving a child oral polio vaccine.
Question 8:
Write short notes on
(a) Tuberculosis;(b) Polio.
Answer:
(a) Tuberculosis:
It is an infectious disease caused by the bacterium Mycobacterium tuberculosis. This bacterium secretes a toxin called tuberculin and infects parts of the body such as limbs, lymph glands and bones.
Symptoms of the disease include sickness, loss of appetite and weight, fever and night sweats. There are two specific sites of tuberculosis infection:
(i) Lung or pulmonary TB: In this, the person suffers from fever and cough and produces blood-stained sputum. It may even destroy large areas of the lungs.
(ii) Lymph gland TB: It is characterised by the swelling and tenderness of the lymph glands, often in the legs.
It can be prevented by immunisation with BCG (Bacillus Calmette‒Guerin), which gives immunity for 3‒5 years.
Tuberculosis can be cured by six essential drugs: rifampicin, INH, streptomycin, pyrazinamide, ethambutol and thioacetozone.
(b) Polio:
It is a disease of the nervous system caused by polio virus. The virus enters the body via food and water and destroys motor nerve cells of the spinal cord responsible for muscle control. Hence, the muscles of a person suffering from polio cannot carry out normal functions.
The disease is characterised by fever, vomiting, muscular pain and tingling sensation in limbs; these ultimately lead to paralysis.
Polio can be prevented by giving a child oral polio vaccine (OPV), which provides immunity against the polio virus.
Children below the age of five are given OPV on specific days, all over the country. Such days are known as national immunisation days (NIDS).