CBSE Class 9 Science Why do we fall ill Sure Shot Questions Set 01

CBSE Class 9 Science Why do we fall ill Sure Shot Questions A. There are many more useful educational material which the students can download in pdf format and use them for studies. Study material like concept maps, important and sure shot question banks, quick to learn flash cards, flow charts, mind maps, teacher notes, important formulas, past examinations question bank, important concepts taught by teachers. Students can download these useful educational material free and use them to get better marks in examinations.  Also refer to other worksheets for the same chapter and other subjects too. Use them for better understanding of the subjects.

ASSIGNMENT QUESTIONS SET – 1

CHAPTER – 13

WHY DO WE FALL ILL

Multiple choice questions

Which one of the following is an infectious disease?

1. diphtheria
2. diabetes
3. hypertension
4. cancer

Answer: (a) diphtheria

Elephantiasis can have a

1. short-term effect on our health
2. no effect on our health
3. long-term effect on our health
4. sometimes a bad effect on our health

Answer: (c) long-term effect on our health

The Ascaris worm lives in which part of the human body?

1. kidneys
2. liver
3. small intestine
4. large intestine

Answer: (c) small intestine

Microbes which enter the body through the nose most likely affect

1. liver
2. heart
3. brain
4. lungs

Answer: (d) lungs

Which of the following is a viral infection?

1. Diphtheria
2. Influenza
3. Cholera
4. Typhoid

Answer: (b) Influenza

The HIV virus, when active in the body, mainly attacks

1. lungs
2. liver
3. immunity
4. nerves

Answer: (c) immunity

An organism which carries pathogens is termed

1. host
2. vector
3. parasite
4. predator

Answer: (b) vector

Diseases which are always present in a certain location are called

1. epidemic diseases
2. endemic diseases
3. acute diseases
4. chronic diseases

Answer: (b) endemic diseases

DPT vaccines are administered to develop immunity against

1. tetanus
2. diphtheria
3. pertussis
4. all of these

Answer: (d) all of these

Anti-viral drugs are difficult to make because viruses

1. live outside the host cells
2. live inside the host cells
3. live in consumed food particles
4. live in the blood stream

Answer: (b) live inside the host cells

The BCG vaccine is used to develop immunity against

1. jaundice
2. polio
3. influenza
4. tuberculosis

Answer: (d) tuberculosis

Which of the following is a communicable disease?

1. Rickets
2. Scurvy
3. Marasmus
4. Cholera

Answer: (d) Cholera

The causative organism for malaria is a

1. bacterium
2. protozoan
3. virus
4. fungus

Answer: (b) protozoan

Vaccination helps in controlling diseases because

1. it develops resistance against the pathogen attack
2. it kills the pathogens causing disease
3. it blocks the food supplied to pathogens
4. it does not allow pathogens to multiply in hosts

Answer: (a) it develops resistance against the pathogen attack

ORS is given in

1. diarrhoea
2. measles
3. typhoid
4. tetanus

Answer: (a) diarrhoea

Which of the following is an example of a nutritional deficiency disease?

1. Hypertension
2. Rickets
3. Diabetes
4. Gastroenteritis

Answer: (b) Rickets

Short and long answer questions

Define health. What do you interpret when we say a person is in good health?

Answer: Health is a state of complete physical, mental and social well-being. A person in good health is free from disease and is physically fit, mentally happy and balanced, and gets on well with the people around him or her.

State any two conditions essential for good health.

Answer: A balanced diet and a clean environment (clean surroundings, safe water). Regular exercise, enough sleep and good economic and social conditions also help.

What are the three dimensions of health? Are they interrelated?

Answer: The three dimensions are physical, mental and social health. Yes, they are interrelated: a problem in one affects the others.

The kidneys of a person do not filter urine properly. How does it affect the physical, mental and social dimensions of that person?

Answer: Physically, waste products stay in the body and the person falls sick and feels weak. Mentally, the person feels worried and depressed. Socially, the person cannot take part in work and social activities and may need frequent hospital visits.

State any two conditions essential for being free of disease.

Answer: Clean surroundings and personal hygiene, and a balanced diet along with immunisation against diseases.

Are the answers to the previous two questions (conditions for good health and for being free of disease) necessarily the same or different? Why?

Answer: They are not necessarily the same. Good health needs a balanced diet, exercise, mental peace and a good social environment, while being free of disease mainly needs hygiene, clean surroundings and protection from germs. Good health includes being free of disease, but a person who is free of disease may not be in good health.

What is a balanced diet?

Answer: A diet that contains all the nutrients (carbohydrates, proteins, fats, vitamins, minerals and water) in the right amounts, along with roughage, is called a balanced diet.

A hefty boy of 12 years often picks fights with others. Do you think he is in good health? Explain your answer.

Answer: No. He may be physically strong, but he is not mentally and socially healthy because he cannot get on well with others. Health means physical, mental and social well-being together.

How do you define 'disease'?

Answer: Disease means a lack of ease. It is a condition in which the proper working of one or more organs of the body is disturbed and the person feels uneasy.

State and explain in brief the four major factors which are the causes of disease.

Answer: 1. Infectious agents (pathogens): viruses, bacteria, fungi, protozoa and worms.
2. Genetic (inherited) causes: defects in genes passed on from parents.
3. Nutritional causes: deficiency or excess of nutrients.
4. Environmental causes: pollution, unsafe water, poor living conditions and lifestyle.

Is there any difference between 'being healthy' and 'disease free'?

Answer: Yes. Being disease free only means that a person has no disease, whereas being healthy means complete physical, mental and social well-being.

How do we identify a disease?

Answer: By its symptoms and signs. Symptoms are what the patient feels (headache, cough, loose motions) and signs are what the doctor finds on examination or tests (fever, rash, blood test results).

What is the difference between symptoms and signs of a disease?

Answer: Symptoms are the effects that the patient feels and tells (for example pain, nausea). Signs are the effects that the doctor observes or measures by examination or tests (for example high temperature, a swollen gland).

List any three reasons why you would think that you are sick and ought to see a doctor. If only one of these symptoms were present, would you still go to the doctor? Why or why not?

Answer: Three reasons: continuing high fever, repeated vomiting or loose motions, and persistent cough or severe pain. If only one mild symptom is present for a short time, I may wait and rest because it may be minor. If it is severe or does not go away, I would still go to the doctor, because a single symptom can be a sign of a serious disease.

Based on duration or persistence, how are diseases categorised?

Answer: As acute diseases and chronic diseases.

Give examples of acute diseases.

Answer: Common cold, cough, typhoid, cholera and influenza.

Give four examples of chronic diseases.

Answer: Tuberculosis, elephantiasis, cancer and arthritis. (Diabetes is also a chronic disease.)

Differentiate between acute diseases and chronic diseases.

Answer: Acute diseases last for a short time and usually do not cause long-term ill effects (for example common cold). Chronic diseases last for a long time, even for the whole life, and have a drastic effect on health (for example tuberculosis).

What are congenital diseases? Give two examples of such diseases.

Answer: Diseases which a person has from birth, due to genetic abnormalities, are congenital diseases. Examples: haemophilia and colour blindness (also Down syndrome).

Name a disease which was earlier considered to be chronic but can now be treated in a short duration.

Answer: Tuberculosis (and, in the same way, some cases of leprosy), since modern drugs cure them in a few months.

A baby is not able to tell her/his caretakers that she/he is sick. What would help us to find out (a) that the baby is sick? (b) what the sickness is?

Answer: (a) Signs like crying continuously, not feeding, fever, being dull or not playing, and changes in sleep show that the baby is sick.
(b) A doctor can find out the sickness from the signs and from tests such as a temperature check, examination and blood tests.

What are acquired diseases?

Answer: Diseases which a person gets after birth, from an infection or because of lifestyle or nutrition, are acquired diseases. They are of two types: infectious (for example malaria) and non-infectious (for example diabetes).

Write a few common signs and symptoms of a disease if the brain is affected.

Answer: Headache, vomiting, loss of consciousness, fits, fever, stiff neck and weakness or paralysis.

List any two differences between infectious and non-infectious diseases. Write one example of each.

Answer: 1. Infectious diseases are caused by pathogens, while non-infectious diseases are not caused by pathogens.
2. Infectious diseases spread from one person to another, while non-infectious diseases do not spread.
Example of infectious disease: cholera. Example of non-infectious disease: cancer (or diabetes).

What are infectious agents? What are the different infectious agents?

Answer: Organisms that cause infectious diseases are infectious agents or pathogens. They are viruses, bacteria, fungi, protozoa and worms.

What is the 'germ theory of disease'? Who proposed it?

Answer: The germ theory says that many diseases are caused by microorganisms (germs). It was proposed by Louis Pasteur (and developed by Robert Koch).

What are Koch's postulates?

Answer: They are the rules to prove that a particular microbe causes a particular disease: the microbe must be found in every case of the disease; it must be isolated and grown in pure culture; the culture must cause the same disease when injected into a healthy host; and the same microbe must be found again in the diseased host.

List the diseases caused by viruses.

Answer: Common cold, influenza, dengue fever, AIDS, polio, rabies, chikungunya and hepatitis (jaundice).

Give three examples of bacterial diseases.

Answer: Typhoid, cholera, tuberculosis, anthrax and tetanus (any three).

Give examples of fungal diseases.

Answer: Ringworm, athlete's foot and other skin infections.

List three diseases caused by protozoans.

Answer: Malaria, kala-azar and sleeping sickness.

Name the pathogen that causes peptic ulcer.

Answer: The bacterium Helicobacter pylori.

List the diseases caused by worms.

Answer: Elephantiasis (filariasis) and diseases caused by intestinal worms such as roundworm (ascariasis) and tapeworm.

Name the protozoan pathogen that causes kala-azar.

Answer: Leishmania.

Name the microbe which causes acne.

Answer: A bacterium, Propionibacterium acnes.

What is the scientific name of the roundworm? Where do we commonly find it in the human body? Name the disease caused by it.

Answer: Its scientific name is Ascaris lumbricoides. It is found in the small intestine. It causes ascariasis (intestinal worm infection).

Why is it important that we think of these categories of infectious agents?

Answer: Organisms in one category have similar biological features, so the same medicine works on all of them. Antibiotics work on bacteria but not on viruses, so knowing the category helps us choose the right treatment.

How do antibiotics (say, penicillin) work on bacteria but not on human beings?

Answer: Bacteria make a cell wall around themselves, and penicillin blocks the pathway that builds the cell wall, so the bacteria die. Human cells do not have a cell wall, so penicillin does not harm us.

Define antibiotic. Explain how it is able to control bacterial infections but not viral infections.

Answer: An antibiotic is a medicine that kills bacteria or stops them from growing. It blocks a biochemical pathway that is important for the bacteria. Viruses do not have these pathways of their own and live inside the host cells, so antibiotics do not work on them.

Explain why antibiotics are more effective in curing bacterial diseases than viral diseases.

Answer: Bacteria have their own life processes and cell-wall synthesis, which antibiotics block. Viruses do not have their own metabolic pathways and enter the host cell, so antibiotics cannot affect them.

Why is taking an antibiotic not effective in the common cold?

Answer: The common cold is caused by a virus, and antibiotics do not act on viruses.

Give two examples of bacterial antibiotics.

Answer: Penicillin and streptomycin (also tetracycline).

Give an example of a fungal antibiotic.

Answer: Penicillin (obtained from the fungus Penicillium).

Why are we normally advised to take bland and nourishing food when we are sick?

Answer: When we are sick the digestion is weak, and bland food is easy to digest. Nourishing food provides the energy and nutrients that the body needs to fight the infection and recover.

What are the different means by which infectious diseases are spread?

Answer: Through air (cough, sneeze), water, food, direct contact (touch), sexual contact, blood, and through vectors such as mosquitoes and houseflies. Diseases can also spread from mother to child.

If a person has a persistent cough and breathlessness, most likely which of the following organs is affected?

1. Liver
2. Heart
3. Brain
4. Lungs

Answer: (d) Lungs. (The question as printed in the source had no options; this is the likely list.)

What is the alternate name of brain fever? Which vector is responsible for this disease?

Answer: Japanese encephalitis (viral). The vector is the Culex mosquito.

Name the vector which causes malaria.

Answer: The female Anopheles mosquito.

Name the vector which causes dengue, chikungunya and yellow fever.

Answer: The Aedes mosquito.

Name the vector that can cause sleeping sickness.

Answer: The tsetse fly.

Name the diseases that can spread through the housefly.

Answer: Cholera, typhoid, dysentery and diarrhoea.

Name the vectors which can cause rabies.

Answer: Rabies is spread by the bite of infected animals such as dogs, cats and monkeys, so these animals act as the carriers.

A doctor/nurse/health worker is exposed to more sick people than others in the community. How does she/he avoid getting sick?

Answer: By following hygiene and safety measures such as washing hands, wearing masks, gloves and gowns, and by being immunised against diseases such as hepatitis.

What precautions can you take in your school to reduce the incidence of infectious diseases?

Answer: Keep the classroom and surroundings clean, make sure drinking water is safe, wash hands before eating and after using the toilet, do not let water collect and breed mosquitoes, cover the mouth while coughing or sneezing, and stay at home when sick.

What do you mean by immunity?

Answer: Immunity is the ability of the body to resist and fight the attack of disease-causing germs.

What is immunisation?

Answer: Immunisation (vaccination) is the process of giving a vaccine, which has dead or weakened germs, so that the body builds immunity against a particular disease.

What is an antigen?

Answer: An antigen is a foreign substance (such as a part of a germ) which makes the body produce antibodies.

What are antibodies?

Answer: Antibodies are proteins made by the white blood cells that attach to antigens and destroy the germs.

What is colostrum? Why is mother's milk strongly advised for newborns?

Answer: Colostrum is the first yellowish milk produced after childbirth. It is rich in antibodies, which give the baby protection from infections, and the milk is also easily digestible and nutritious.

What are the immunisation programmes available at the nearest health centre in your locality? Which of these diseases are the major health problems in your area?

Answer: This depends on the locality. In general, health centres give vaccines against tuberculosis (BCG), diphtheria, pertussis and tetanus (DPT), polio, measles, hepatitis B and others. The major health problems of the area should be written from your own observation.

What are epidemic and endemic diseases?

Answer: An epidemic is a disease that spreads rapidly to many people in an area at the same time (for example cholera or influenza). An endemic disease is one that is always present in a particular area or population (for example malaria in some regions).

Which organ is affected if a person is suffering from jaundice?

Answer: The liver.

What do you mean by phagocytosis?

Answer: Phagocytosis is the process by which white blood cells (phagocytes) engulf and destroy germs.

Why is it not necessary to give the Hepatitis A vaccine to children?

Answer: In many places most children get a mild hepatitis A infection early in life, which gives them lasting immunity naturally, so the vaccine is not needed for all.

What are the basic principles involved in the medical treatment of diseases?

Answer: There are two ways: to reduce the effect of the disease (treat the symptoms, such as giving medicine for fever or pain and rest), and to kill the cause of the disease (for example giving antibiotics to kill bacteria).

Why is it advisable to breastfeed the baby for the first few weeks? Why is colostrum good for infants?

Answer: The mother's milk is the best and most complete food for the baby. Colostrum contains antibodies that protect the baby from infections and helps the baby's immunity to develop.

How do skin, hair and saliva form the first line of defence against diseases?

Answer: The skin forms a barrier that does not let germs enter the body. The hair in the nose traps dust and germs. Saliva contains a chemical (lysozyme) which kills germs entering through the mouth.

(a) diptheria

(b) diabetes

(c) hypertension

(d) cancer

2. Elephantiasis disease can have

(a) kidneys

(b) liver

(a) liver

(b) heart

(c) brain

(c) Cholera

(d) Typhoid

(a) lungs

(b) liver

(c) parasite

(d) predator

(a) Tetanaus

(b) Diptheria

(c) Pertussis

(a) jaundice

(b) polio

(c) influenza

(a) Rickets

(b) Scurvy

(c) Marasmus

(c) virus

(d) fungi

(b) measeles

(c) typhoid

(c) Diabetes

(d) Gastroenteritis

72. What is immunisation?

73. What is antigen?

74. What are antibodies?

75. What is colostrum? Why is mothers milk strongly advised to new borns?

82. Why it is advisable to breast feed the baby for first few several weeks? Why Colostrum is good for infants?

83. How do Skin, Hairs, Saliva form the first line of defense against diseases?