Class 6 · Concise Biology · Chapter Practice
Disease and Hygiene
Learn communicable diseases, deficiency disorders, pathogens, vitamins and healthy habits through interactive questions and activities.
15MCQs
4Assertion–Reason
30+Written answers
8FAQs
01
Fast learning
Quick Revision Notes
Pathogen
A disease-causing microorganism or agent, such as a bacterium, virus, fungus or protozoan.
Communicable
A disease that can spread through air, food, water, contact, droplets or disease-carrying vectors.
Non-communicable
A disease that does not spread from one person to another, such as diabetes or a deficiency disease.
Deficiency disease
An illness caused by a long-term shortage of an essential nutrient, vitamin or mineral.
Interactive habit tracker
Build a hygiene shield
Tick each healthy habit and complete the shield.
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02
Test yourself
Multiple Choice Questions
Select one option for every question, then press Check my score.
Score: — / 15
Question 1(i)
Malaria is caused by:
Explanation: Malaria is caused by the protozoan parasite Plasmodium, transmitted through the bite of an infected female Anopheles mosquito.
Question 1(ii)
Deficiency of Vitamin C causes:
Explanation: Scurvy results from Vitamin C deficiency and may cause swollen or bleeding gums.
Question 1(iii)
Hay fever and asthma are:
Explanation: Both can occur when the body reacts strongly to particular allergens.
Question 1(iv)
Which one is a genetic disease?
Explanation: Haemophilia is an inherited bleeding disorder caused by changes in genes involved in blood clotting.
Question 1(v)
Which one is commonly classified as a degenerative disease?
Explanation: Cataract commonly develops with age and causes clouding of the eye lens.
Question 1(vi)
Pellagra is caused by deficiency of:
Explanation: Pellagra is caused by deficiency of Vitamin B3, also called niacin.
Question 1(vii)
Iodine deficiency can cause:
Explanation: Iodine is needed for thyroid hormone production. Its deficiency can enlarge the thyroid gland and cause goitre.
Question 1(viii)
A diet rich in carrots, yellow fruits, vegetables, butter, milk and fish can help prevent:
Explanation: These foods can supply Vitamin A, whose deficiency is associated with night blindness.
Question 1(ix)
Which one is a communicable disease?
Explanation: Measles is an infectious viral disease that spreads mainly through respiratory droplets and airborne particles.
Question 1(x)
COVID-19 is caused by:
Explanation: COVID-19 is caused by SARS-CoV-2, which is a virus.
Question 1(xi)
Which option is a lung disease that may be caused by bacteria?
Explanation: Pneumonia affects the lungs and may be bacterial, viral or fungal. Among these options, pneumonia is correct.
Question 1(xii)
Kwashiorkor is mainly caused by deficiency of:
Explanation: Kwashiorkor is a severe form of malnutrition mainly associated with inadequate protein intake.
Question 1(xiii)
A specific symptom of scurvy is:
Explanation: Vitamin C deficiency weakens connective tissues and can cause swollen or bleeding gums.
Question 1(xiv)
Swelling in the front of the neck is a typical symptom of:
Explanation: Goitre is enlargement of the thyroid gland, often linked with iodine deficiency.
Question 1(xv)
Which disease is not spread by a mosquito bite?
Explanation: Typhoid usually spreads through food or water contaminated with Salmonella Typhi.
03
Reason carefully
Assertion–Reason Questions
Read both statements before selecting an option.
Score: — / 4
Question 2(i)
Assertion: Genetic diseases such as haemophilia and thalassemia are transmitted only from mothers who have the disease.
Reason: A father's chromosomes do not play any role in transmitting genetic diseases to children.
Explanation: Both statements are false. Children inherit chromosomes from both parents. Haemophilia is usually X-linked, while thalassemia is generally inherited through autosomal genes. The original option set omitted the scientifically correct choice, so it has been added here.
Question 2(ii)
Assertion: Night blindness is a deficiency disease in which a person has difficulty seeing in dim light or darkness.
Reason: A person with Vitamin A deficiency should eat Vitamin A-rich foods such as carrots, papayas and other yellow or orange fruits and vegetables.
Explanation: Night blindness is associated with Vitamin A deficiency, and Vitamin A-rich foods help meet the body's requirement.
Question 2(iii)
Assertion: Mumps is a communicable viral disease in which the parotid glands swell and become painful.
Reason: The mumps virus infects salivary glands and causes inflammation.
Explanation: The mumps virus can infect the parotid salivary glands, producing swelling and pain.
Question 2(iv)
Assertion: Malaria is caused by Plasmodium, which enters the human body through the bite of an infected female Anopheles mosquito.
Reason: Plasmodium completes its life cycle in two hosts—humans and Anopheles mosquitoes.
Explanation: Both statements are true. The two-host life cycle explains why infected female Anopheles mosquitoes transmit the parasite to humans.
04
Recall and connect
Fill in the Blanks, Odd One Out and Matching
Question 3
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 and explanation
(a) Iron
(b) Rickets
(c) Goitre
(d) Proteins
Find the odd one out
Question 4
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 and explanation
(a) Jaundice
Reason — Jaundice is the odd one out because it is a sign of an underlying condition and is not itself classified as a bacterial disease; the other four are commonly taught as 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 following
Question 5
Match the terms given in column A with those of column B :
Column A Column B
(i) Cancer (a) Asthma
(ii) Allergies (b) Sunburn
(iii) Hydrophobia (c) Lead poisoning
(iv) Physical agent (d) Leukemia
(v) Chemical agent (e) Rabies
Answer and explanation
Column A Column B
(i) Cancer (d) Leukemia
(ii) Allergies (a) Asthma
(iii) Hydrophobia (e) Rabies
(iv) Physical agent (b) Sunburn
(v) Chemical agent (c) Lead poisoning
Fill in the blanks in the following table
Question 6
Fill in the blanks in the following table:
Vitamin Name of the deficiency diseases Source of vitamin
(a) Vitamin A ............... ...............
(b) ............... Beri-Beri ...............
(c) Ascorbic acid ............... ...............
(d) ............... Rickets (in childhood) bones turn soft ...............
Answer and explanation
Vitamin Name of the
deficiency diseases Source of vitamin
(a) Vitamin A Nightblindness, drying of cornea Carrot, yellow fruits, vegetables, butter, fish, milk.
(b) Vitamin B1 Beri-beri Whole grains, eggs, nuts, legumes, yeast.
(c) Ascorbic acid Scurvy
(bleeding gums) Citrus fruits, tomatoes, germinating seeds.
(d) Vitamin D Rickets (in childhood)
bones turn soft Egg yolk, fish liver oil, sunlight, milk, butter.
05
Write precisely
Short Answer Questions
Question 1
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 harmful substances commonly consumed by people
(i) Two diseases that are spread via contaminated food and water
(j) Two diseases caused by protozoans
(k) Two communicable diseases
Answer and explanation
(a) Cholera
(b) Malaria
(c) Elephantiasis
(d) Rabies/Hydrophobia
(e) Kwashiorkor and Marasmus
(f) Typhoid, Cholera, Hepatitis A
(g) Trachoma and Conjunctivitis
(h) Tobacco and Alcohol
(i) Typhoid and Cholera
(j) Malaria and Amoebiasis
(k) Viral fever and Chicken pox
Question 2
Write the technical names of the following vitamins :
(i) Vitamin A
(ii) Vitamin B1
(iii) Vitamin B3
(iv) Vitamin C
(v) Vitamin D
Answer and explanation
(i) Vitamin A — Retinol
(ii) Vitamin B1 — Thiamine
(iii) Vitamin B3 — Niacin
(iv) Vitamin C — Ascorbic acid
(v) Vitamin D — Calciferol
Question 3
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 and explanation
(i) Filariasis (Elephantiasis)
(ii) Tetanus
(iii) Cholera
(iv) Amoebiasis
(v) Malaria
Question 4
Give two examples of each :
(i) Metabolic diseases
(ii) Genetic diseases
(iii) Allergies
(iv) Dietary deficiency diseases
(v) Cancer
Answer and explanation
(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.
Question 5
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) Night blindness is a condition in which a person has difficulty seeing in dim light or darkness.
Answer and explanation
(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 — Night blindness is linked with Vitamin A deficiency and causes difficulty seeing in dim light or darkness.
Question 6
Define the terms given below :
(i) Health
(ii) Disease
(iii) Pathogen
(iv) Allergen
(v) Hygiene
Answer and explanation
(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.
Question 7
Write short notes (1-2 sentences) on each of the following:
Disease
Pathogen
Allergy
Answer and explanation
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.
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.
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.
Question 8(a)
What is a non-communicable disease?
Answer and explanation
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.
Question 8(b)
What is a deficiency disease?
Answer and explanation
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.
Question 8(c)
What are communicable diseases?
Answer and explanation
The diseases that can easily spread from an infected person to a healthy person through disease causing germs called pathogens are called communicable diseases.
Question 8(d)
Biting nails should be strictly avoided. Give reason.
Answer and explanation
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.
Question 8(e)
Regular exercise and proper rest is a must. Give reason.
Answer and explanation
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.
Question 8(f)
Children eating more fast foods tend to suffer from obesity (overweight). Comment.
Answer and explanation
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.
Question 8(g)
How can you control the spreading of diseases by mosquitoes and houseflies?
Answer and explanation
We can control diseases spread by mosquitoes and houseflies by using repellents, placing garbage in covered bins, preventing water stagnation, and keeping drains covered and clean.
Question 8(h)
Public hygiene is equally important as personal hygiene. Give reasons.
Answer and explanation
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.
Question 9 · Crossword
Read the clues and complete the crossword puzzle.
Clues down
- Germs or germ-substances introduced into the body to prevent an infectious disease.
- A disease caused by an infected dog that affects the central nervous system.
- A condition in which the eyes, skin and urine may turn yellow.
- Pertussis is popularly known as whooping ______.
Clues across
- Category of pathogen that causes common cold and mumps.
- Vaccine used to help prevent tuberculosis.
- An organ commonly affected by tuberculosis.
- Jumbled spelling of the common insect that contaminates exposed food.
- Cover this body part with a handkerchief while sneezing.
- These may grow in unwashed hair.
- A disease that weakens the body's defence system against infections.
Solved crossword
Likely entries: Vaccine, Rabies, Jaundice, Cough, Virus, BCG, Lungs, Housefly, Mouth, Lice and AIDS.
06
Explain in detail
Long Answer Questions
Question 1
Describe the ways in which communicable diseases are transmitted through various indirect methods.
Answer and explanation
Indirect method of transmission of communicable disease are:
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.
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.
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.
Vectors or carriers — Houseflies, mosquitoes, rodents, etc. also carry disease causing germs.
Question 2
List 3 ways by which you should keep your environment clean.
Answer and explanation
Three ways to keep the environment clean are:
Maintain a clean environment to prevent the spreading of diseases due to the breeding of mosquitoes, houseflies and pathogens.
Garbage should be kept in covered bins so that flies do not breed on it.
There should be proper sewer lines connected to sewage treatment plants.
Question 3(i)
Distinguish between Elephantiasis and Malaria on the basis of the mode of transmission.
Answer and explanation
Differences between Elephantiasis and Malaria on the basis of the mode of transmission:
Elephantiasis Malaria
Elephantiasis spreads by the bite of female Culex mosquito. Malaria spreads by the bite of female Anopheles mosquito.
Question 3(ii)
Distinguish between Jaundice and Tuberculosis on the basis of the affected organs.
Answer and explanation
Differences between Jaundice and Tuberculosis on the basis of the affected organs:
Jaundice Tuberculosis
Jaundice primarily affects the liver. It causes yellowing of the skin and eyes. Tuberculosis primarily affects the lungs, although other parts of the body may also be affected.
Question 3(iii)
Distinguish between Rickets and Smallpox on the basis of the characteristic symptoms.
Answer and explanation
Differences between Rickets and Smallpox on the basis of the characteristic symptoms:
Rickets Smallpox
Rickets primarily affects bone development. Bones turn soft due to which children may have bow-shaped limbs. Smallpox is a serious disease which is marked by small pustules all over the body.
Question 3(iv)
Distinguish between Anaemia and Goitre on the basis of the deficient mineral.
Answer and explanation
Differences between Anaemia and Goitre on the basis of the deficient mineral:
Anaemia Goitre
Anaemia is caused by deficiency of Iron. Goitre is caused by deficiency of Iodine.
Question 3(v)
Distinguish between Metabolic diseases and Mental illness on the basis of the one example of each.
Answer and explanation
Differences between Metabolic diseases and Mental illness on the basis of the one example of each:
Metabolic diseases Mental illness
One example of Metabolic diseases is Diabetes. One example of Mental illness is Depression.
07
Apply your knowledge
Case Study Question
Question 1
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 and explanation
(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 common cold are usually caused by viruses.
(iii) It spreads mainly through respiratory droplets released during sneezing and coughing.
(iv) Two examples of non-communicable diseases are diabetes and cancer.
08
Common doubts
Frequently Asked Questions
What are communicable diseases?
Communicable diseases are illnesses that can spread from an infected person or source to another person through pathogens, air, water, food, contact or vectors.
What causes malaria?
Malaria is caused by Plasmodium parasites and is transmitted to humans through the bite of an infected female Anopheles mosquito.
Which vitamin deficiency causes scurvy?
Scurvy is caused by a deficiency of Vitamin C, also called ascorbic acid.
Which deficiency causes rickets in children?
Rickets is mainly caused by Vitamin D deficiency, which affects normal bone mineralisation.
Why does iodine deficiency cause goitre?
Iodine is needed to make thyroid hormones. A long-term deficiency can enlarge the thyroid gland and produce goitre.
What is the difference between a pathogen and an allergen?
A pathogen is a disease-causing organism or agent, while an allergen is a substance that triggers an allergic reaction in a sensitive person.
How can mosquito-borne diseases be prevented?
Prevent water stagnation, keep drains and containers covered, use mosquito nets or repellents, and maintain clean surroundings.
What does hygiene mean?
Hygiene is the science and practice of maintaining health through cleanliness and healthy habits.
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