Disease and Hygiene

Malaria is caused by

1. Bacteria
2. Protozoan
3. Fungi
4. virus

Answer

Protozoan

Reason — Malaria is caused by protozoan Plasmodium which enters the human body through the bite of a female Anopheles mosquito.
Bacteria cause diseases like typhoid, cholera. Fungi cause ringworm, athlete’s foot. Virus cause diseases like dengue, flu.

Deficiency of vitamin C causes

1. Night blindness
2. Scurvy
3. Anaemia
4. Polio

Answer

Scurvy

Reason — Deficiency of vitamin C causes Scurvy (swollen bleeding gums).
Night blindness is caused by deficiency of Vitamin A. Anaemia is caused by deficiency of iron (in most cases). Polio is caused by a virus (poliovirus).

Hay fever and asthma are

1. Deficiency diseases
2. Genetic diseases
3. Organic diseases
4. Allergic diseases

Answer

Allergic diseases

Reason — Hay fever and asthma are allergic diseases because both diseases are caused by unpredictable reaction of the body to a particular substance.
Deficiency diseases occur when the body lacks essential nutrients. Genetic diseases are caused by abnormalities in genes or chromosomes and are often inherited from parents. Organic disease is a term used for diseases that involve structural or physical damage to organs or tissues.

Which one of the following is a genetic disease?

1. Scurvy
2. Leukemia
3. Goitre
4. Haemophilia

Answer

Haemophilia

Reason — Haemophilia is a genetic disease because it is inherited from parent to child.
Scurvy is caused by vitamin C deficiency. Leukemia is a type of blood cancer. Goitre is caused by iodine deficiency.

Which one of the following is a degenerative disease?

1. Thalassemia
2. Beri-beri
3. Cataract
4. Diabetes

Answer

Cataract

Reason — Cataract is a degenerative disease because it is a age related eye disease which affects older person.
Thalassemia is a genetic blood disorder. Beri-beri is caused by vitamin B₁ deficiency. Diabetes is mainly a metabolic/endocrine disorder.

Pellagra is caused by the deficiency of

1. Vit. B₃
2. Vit. B₁
3. Vit. C
4. Vit. D

Answer

Vit. B₃

Reason — Pellagra is caused by the deficiency of Vit. B₃ (Niacin).
Vit. B₁ deficiency causes beriberi. Vit. C deficiency causes scurvy. Vitamin D deficiency causes rickets.

Deficiency of Iodine in one's food can cause

1. Beri-beri
2. Goitre
3. Scurvy
4. Pellagra

Answer

Goitre

Reason — Deficiency of Iodine causes Goitre.
Beri-beri is caused by deficiency of Vitamin B1. Scurvy is caused by deficiency of Vitamin C. Pellagra is caused by deficiency of Vitamin B3.

Which one of the following vitamin deficiency diseases can be cured by eating a diet which includes carrot, yellow fruits, vegetables, butter, milk, fish?

1. Beri-beri
2. Dermatitis
3. Night blindness
4. Scurvy

Answer

Night blindness

Reason — Night blindness is caused by deficiency of Vitamin A. Sources of Vitamin A are carrot, yellow fruits, vegetables, butter, milk, fish.
Beri-beri is caused by deficiency of Vitamin B1. Dermatitis is commonly linked with deficiency of Vitamin B3 or other B vitamins. Scurvy is caused by deficiency of Vitamin C

Which one of the following is a communicable disease?

1. Measles
2. Cancer
3. Heart stroke
4. Allergy

Answer

Measles

Reason — Measles is a communicable disease because it is spread by direct contact with an infected person.
Cancer is non-communicable disease. Heart stroke is non-communicable condition related to blood circulation. Allergy is immune reaction, not infectious and not communicable.

The infamous COVID-19 was a contagious disease spread by :

1. Bacteria
2. Protozoa
3. Viruses
4. Worms

Answer

Viruses

Reason — The contagious disease COVID-19 was spread by viruses.
Bacteria cause diseases like tuberculosis and cholera. Protozoa cause diseases like malaria. Worms cause diseases like filariasis and roundworm infection.

Which of the following is a lung disease caused by bacteria ?

1. Rabies
2. Pneumonia
3. Malaria
4. Cholera

Answer

Pneumonia

Reason — Pneumonia is a disease of the lungs caused by a bacteria.
Rabies is caused by a virus. Malaria is caused by a protozoan (Plasmodium). Cholera is caused by bacteria, but it affects the intestines.

Kwashiorkor disease is caused due to the deficiency of :

1. Proteins
2. Proteins and fats
3. Carbohydrates
4. Carbohydrates and proteins

Answer

Proteins

Reason — Kwashiorkor is a form of malnutrition primarily caused by a lack of protein in the diet.
Carbohydrates deficiency mainly causes energy shortage. Deficiency of proteins, carbohydrates and fats together causes marasmus.

Which of the following is a specific symptom of the disease — scurvy ?

1. Skin inflammation
2. Bleeding gums
3. Drying of cornea
4. Bones turning soft

Answer

Bleeding gums

Reason — Scurvy is caused by a severe lack of Vitamin C, which is crucial for healthy gums. This deficiency leads to swollen, bleeding gums.
Skin inflammation is common in pellagra/dermatitis. Drying of cornea is due to Vitamin A deficiency. Bones turning soft is due to Vitamin D deficiency (rickets/osteomalacia).

Swelling in the neck is a symptom of :

1. Anaemia
2. Mumps
3. Goitre
4. Rabies

Answer

Goitre

Reason — Goitre is caused due to deficiency of Iodine.
Anaemia causes weakness and pale skin. Mumps causes swelling near the cheeks/jaw due to salivary gland infection, not typical thyroid neck swelling. Rabies affects the nervous system.

Which of the following is not a disease spread by the bite of a mosquito ?

1. Dengue
2. Typhoid
3. Elephantiasis
4. Malaria

Answer

Typhoid

Reason — Typhoid is a bacterial infection spread through contaminated food and water, not mosquito bites. Its symptoms are continuous fever.
Dengue fever is spread by Aedes mosquitoes. Elephantiasis is spread by female Culex mosquitoes. Malaria is spread by female Anopheles mosquitoes.

Assertion: Genetic diseases like haemophilia and thalassemia are transmitted from mothers to newly born babies if the mother herself is suffering from the same disease.

Reason: Father's chromosomes do not play any role in the transmission of genetic diseases from him to the newly born babies.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

A is false but R is true.

Reason — A is false as genetic diseases like haemophilia and thalassemia are not transmitted only from mothers. They are inherited through genes from both parents, depending on whether the disease is sex-linked (like haemophilia on the X chromosome) or autosomal (like thalassemia).
R is true because in sex-linked genetic diseases like haemophilia, the father’s chromosomes may not directly pass the disease to sons, but they still contribute to inheritance (especially daughters as carriers). So the statement that father’s chromosomes do not play a role is considered partially true in simplified school biology explanations.

Therefore, A is false but R is true is the correct option.

Assertion: Nightblindness is a kind of deficiency disease in which a person is not able to see during the night even if the room is well illuminated.

Reason: The person suffering from nightblindness should eat plenty of yellow fruits like carrots, papayas, etc. to meet the required demand of vitamin-A needed by the body.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both A and R are true and R is the correct explanation of A.

Reason — A is true as night blindness is a deficiency disease in which a person cannot see properly in dim light or at night due to lack of vision adaptation.
R is true as night blindness is caused by deficiency of Vitamin A. Foods like carrots, papayas, and other yellow/orange fruits and vegetables are rich in Vitamin A.

Therefore, Both A and R are true and R is the correct explanation of A is the correct option.

Assertion: Mumps is a viral disease in which parotid glands swell and become painful. It is a communicable disease.

Reason: The mumps virus infects the salivary glands, causing inflammation of the tissue.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both A and R are true and R is the correct explanation of A.

Reason — A is true as mumps is a viral infectious (communicable) disease that causes swelling and pain in the parotid salivary glands.
R is true as the mumps virus infects the salivary glands, leading to inflammation and swelling.

Therefore, Both A and R are true and R is the correct explanation of A is the correct option.

Assertion: The disease malaria is caused by a parasite - Plasmodium which enters the human body through the bite of a female Anopheles mosquito.

Reason: Plasmodium is a parasite which completes its life-cycle in two hosts - Anopheles mosquitoes and human beings.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both A and R are true and R is the correct explanation of A.

Reason — A is true as malaria is caused by the parasite Plasmodium, which enters the human body through the bite of an infected female Anopheles mosquito.
R is true as Plasmodium completes its life cycle in two hosts - Anopheles mosquitoes and human beings.

Therefore, Both A and R are true and R is the correct explanation of A is the correct option.

Fill in the blanks by selecting suitable words given below:

(goitre, insulin, rickets, iron, proteins)

(a) Anaemia is caused due to the deficiency of ...............
(b) Deficiency of Vit.D causes ............... in children.
(c) Deficiency of iodine in the diet may cause ...............
(d) Kwashiorkor is caused due to the deficiency of ...............

Answer

(a) Iron
(b) Rickets
(c) Goitre
(d) Proteins

Find the odd one out:

(a) Typhoid, cholera, jaundice, tuberculosis, tetanus.
(b) Cold, malaria, measles, mumps.
(c) Scurvy, rickets, polio, pellagra, nightblindness.
(d) Proteins, carbohydrates, fats, minerals, cancer.

Answer

(a) Jaundice
Reason — Jaundice is caused by a virus while others are bacterial diseases.

(b) Malaria
Reason — Malaria is caused by a protozoan while others are viral diseases.

(c) Polio
Reason — Polio is a viral disease while others are vitamin deficiency diseases.

(d) Cancer
Reason — Cancer is a disease while others are food components.

Match the terms given in column A with those of column B :

Answer

Fill in the blanks in the following table:

Answer

Name the following:

(a) A bacterial disease caused due to contaminated water.
(b) A disease caused due to Plasmodium.
(c) A disease caused due to the bite of female Culex mosquito.
(d) A viral disease spread by the bite of a dog.
(e) Two diseases caused due to the deficiency of protein in the diet of a child.
(f) Any three water-borne disease.
(g) Two common eye infections
(h) Two stimulants harmful for human consumption
(i) Two diseases that are spread via contaminated food and water
(j) Two diseases caused by protozoans
(k) Two communicable diseases

Answer

(a) Cholera
(b) Malaria
(c) Elephantiasis
(d) Rabies/Hydrophobia
(e) Kwashiorkor and Marasmus
(f) Typhoid, Cholera, Jaundice
(g) Trachoma and Conjunctivitis
(h) Tobacco and Alcohol
(i) Typhoid and Cholera
(j) Malaria and Amoebiasis
(k) Viral fever and Chicken pox

Write the technical names of the following vitamins :
(i) Vitamin A
(ii) Vitamin B₁
(iii) Vitamin B₃
(iv) Vitamin C
(v) Vitamin D

Answer

(i) Vitamin A — Retinol
(ii) Vitamin B₁ — Thiamine
(iii) Vitamin B₃ — Niacin
(iv) Vitamin C — Ascorbic acid
(v) Vitamin D — Calciferol

Identify the disease with the help of the clues given below :

(i) Highly swollen legs
(ii) Locked jaws due to painful contractions of the jaw and neck muscles
(iii) Vomiting and watery stools
(iv) Diarrhoea, stool mixed with mucus and blood
(v) Chills, high temperature, profuse sweating.

Answer

(i) Filariasis (Elephantiasis)
(ii) Tetanus
(iii) Cholera
(iv) Amoebiasis
(v) Malaria

Give two examples of each :

(i) Metabolic diseases
(ii) Genetic diseases
(iii) Allergies
(iv) Dietary deficiency diseases
(v) Cancer

Answer

(i) Two examples of Metabolic diseases are — diabetes, and kidney stones.

(ii) Two examples of Genetic diseases are — Haemophilia, and thalassemia.

(iii) Two examples of Allergies are — Hay fever and Asthma.

(iv) Two examples of Dietary deficiency diseases are — Beri-Beri and Scurvy.

(v) Two examples of Cancer are — Breast cancer, and Leukemia.

Write 'True' and 'False' against each of the following statements :

(i) Malaria is an infectious disease.
(ii) Rickets is caused due to the deficiency of vitamin A.
(iii) Viruses carry germs from garbage and sewage.
(iv) Filarial germs are transmitted by the bite of female Culex mosquito.
(v) Nightblindness is the disease in which people are not able to see at night even if light is available.

Answer

(i) True
Reason — Malaria is a disease caused by a protozoan transmitted by mosquito bites, making it an infectious disease.

(ii) False
Reason — Rickets is caused due to the deficiency of vitamin D.

(iii) False
Reason — Houseflies, not viruses carry germs from garbage and sewage. Viruses infect cells and replicate within them.

(iv) True
Reason — Filarial germs are transmitted by the bite of female Culex mosquito.

(v) True
Reason — Nightblindness is the Vitamin A deficiency disease in which people are not able to see at night even if light is available.

Define the terms given below :
(i) Health
(ii) Disease
(iii) Pathogen
(iv) Allergen
(v) Hygiene

Answer

(i) Health — Health is defined as a state of complete physical, mental and social well-being, and not merely an absence of disease or infirmity.

(ii) Disease — Any physical or functional change in the body from a normal state which causes discomfort or disability is called a disease.

(iii) Pathogen — Pathogens are disease-causing germs (microorganisms) that have the potential to cause infectious diseases. For example, viruses, bacteria, protozoans etc.

(iv) Allergen — Allergens are substances that can trigger an unpredictable allergic reaction in individuals.

(v) Hygiene — Hygiene is defined as science and practice of maintaining good health.

Write short notes (1-2 sentences) on each of the following:

1. Disease
2. Pathogen
3. Allergy

Answer

1. Disease — Any physical or functional change in the body from a normal state which causes discomfort or disability is called a disease. Disease is a departure from normal health through structural or functional disorder of the body.

2. Pathogen — Micro-organisms which cause communicable diseases are called pathogens. These germs are transmitted through various agencies like air, insect bites, rodents, contaminated food or water, etc. Pathogens may be different kinds of bacteria, viruses, fungi, protozoa or worms.

3. Allergy — Allergy is an unpredictable reaction of the body to a particular substance called allergen. A few common allergens are dust, spores, pollens, certain clothes, particular medicines, cosmetics, etc. Asthma, Eczema, Diarrhoea, Vomiting, Nausea, etc. are some of the common allergic reactions.

What is a non-communicable disease?

Answer

The diseases which are caused either due to improper functioning of the body organs or due to the deficiency of certain minerals and vitamins in the body are known as non-communicable diseases. These diseases are not caused by any germ, therefore these diseases cannot spread from one person to another (i.e., they are non-transmissible). Examples — rickets, diabetes, heart diseases, etc.

What is a deficiency disease?

Answer

A disease which is caused due to the deficiency of certain nutrients, vitamins and minerals in the diet is called a deficiency disease. Example - Anaemia, Goitre.

What are communicable diseases?

Answer

The diseases that can easily spread from an infected person to a healthy person through disease causing germs called pathogens are called communicable diseases.

Biting nails should be strictly avoided. Give reason.

Answer

Dirt and many disease causing pathogens get accumulated under the nails. It is difficult to remove them even if we wash our hands frequently. Biting nails may cause these pathogens to enter into our body through our mouth causing various diseases. Hence, biting nails should be strictly avoided.

Regular exercise and proper rest is a must. Give reason.

Answer

Regular exercise keeps the body muscles active. It helps in the normal functioning of the heart and lungs and also in better circulation of blood. Proper rest helps the body repair, regenerate and recover.

Children eating more fast foods tend to suffer from obesity (overweight). Comment.

Answer

Fast foods are rich in fats and carbohydrates and deficient in vitamins. Eating more fast foods results in the accumulation of fat in the body of children making them suffer from obesity.

How can you control the spreading of diseases by mosquitoes and houseflies?

Answer

We can control spreading of diseases by mosquitoes and houseflies by using repellents, throwing garbage in covered bins, avoiding stagnation of water and covering all the drains prevent breeding of mosquitoes.

Public hygiene is equally important as personal hygiene. Give reasons.

Answer

Maintaining public hygiene prevents the spread of communicable diseases like Malaria, Dengue, Cholera, Diarrhoea, etc. Maintaining a clean environment controls the breeding of mosquitoes, houseflies and other pathogens. Hence, public hygiene is equally important as personal hygiene for good health and preventing diseases.

Given below is a crossword puzzle. Read the clues across and clues down, and fill up the blank squares. Check your performance with the correct solutions given at the end of the chapter.

Clues down

1. Germs or germ - substances introduced into the body to prevent occurrence of an infectious disease.

2. A disease caused by an infected dog that affects the central nervous system.

3. A disease in which the eyes, the skin and the urine turn yellow.

4. The disease pertussis is popularly known as whooping ...............

Clues across

1. Category of pathogen that causes diseases like common cold and mumps.

5. This is the vaccine for preventing tuberculosis.

6. An organ usually affected by tuberculosis.

7. Jumbled spelling of one of the most common insect which visits our exposed foods and contaminates them.

8. Cover this part of your body by a handkerchief while sneezing to prevent droplet infection to others.

9. These may readily grow in your hair, if you do not wash it regularly.

10. A disease that weakens body's defence system against infections.

Answer

The solved cross word puzzle is shown below:

Describe the ways in which communicable diseases are transmitted through various indirect methods.

Answer

Indirect method of transmission of communicable disease are:

1. From items used by the infected person — Touching and sharing items like towels, handkerchiefs, combs, utensils, etc. of an infected person may spread the disease to a healthy person.
2. Contaminated food and water — Houseflies carry germs from garbage and sewage and deposit them on food. Contamination of drinking water even with little amount of faeces or dung can cause a number of diseases.
3. Droplets through air — The droplets coming out when a person infected with common cold, TB, etc. sneezes or coughs, transmit the disease causing germs through the air spreading the disease to more people.
4. Vectors or carriers — Houseflies, mosquitoes, rodents, etc. also carry disease causing germs.

List 3 ways by which you should keep your environment clean.

Answer

Three ways to keep the environment clean are:

1. Maintain a clean environment to prevent the spreading of diseases due to the breeding of mosquitoes, houseflies and pathogens.
2. Garbage should be kept in covered bins so that flies do not breed on it.
3. There should be proper sewer lines connected to sewage treatment plants.

Distinguish between Elephantiasis and Malaria on the basis of the mode of transmission.

Answer

Differences between Elephantiasis and Malaria on the basis of the mode of transmission:

Distinguish between Jaundice and Tuberculosis on the basis of the affected organs.

Answer

Differences between Jaundice and Tuberculosis on the basis of the affected organs:

Distinguish between Rickets and Smallpox on the basis of the characteristic symptoms.

Answer

Differences between Rickets and Smallpox on the basis of the characteristic symptoms:

Distinguish between Anaemia and Goitre on the basis of the deficient mineral.

Answer

Differences between Anaemia and Goitre on the basis of the deficient mineral:

Distinguish between Metabolic diseases and Mental illness on the basis of the one example of each.

Answer

Differences between Metabolic diseases and Mental illness on the basis of the one example of each:

Students of class 6 were excited about their upcoming sports day and had been practising hard all week. But just two days before the event, five students from one team fell sick with cough and cold. They were sneezing and feeling tired. The teacher suspected that the illness could spread to the rest of the class, so she decided to keep them isolated from others and eventually sent them home. Answer the following questions:

(i) What do you mean by "communicable diseases" ?

(ii) Mention the kind of pathogen that causes cough and cold.

(iii) What is the main mode of transmission of the above pathogen?

(iv) Give two examples of non-communicable diseases.

Answer

(i) Communicable diseases are diseases that can easily spread from an infected person to a healthy person through disease-causing germs called pathogens.

(ii) Cough and cold are caused by virus.

(iii) It spreads through water droplets introduced into the air during sneezing and coughing.

(iv) Two examples of non-communicable diseases are diabetes and cancer.