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NCERT Solutions for Class 9 Science Chapter 13
Class 9 Science – Biology – Why do we fall Ill
Important Questions with Answers – Class 9 Biology
- Question 1:
- (a) State any two conditions essential for good health.
- (b) State any two conditions essential for disease free.
- (c) Are the answers to the above question necessarily the same or different? Why?
- Answer 1:
- (a) For Good Health:
- (i) All organs should function properly.
- (ii) The person should have proper physical and social environment.
- (b) For Disease free:
- (i) Proper nutrition or balanced diet is essential.
- (ii) Proper habits of keeping body and environment clean.
- (c)The answers to both the questions are same because we can remain healthy only when we are disease free, our physical and social environment is healthy. Our all body organs function properly.
- Question 2:
What is an antibiotic? Give one an example.
- Answer 2:
The drugs which are obtained from micro-organism and used to kill or suppress the multiplication of micro-organism are called antibiotics, e.g. tetracycline, penicillin, chloramphenicol, streptomycin, etc.
- Question 3:
Why are overcrowded and poorly ventilated areas are a major factor in spread of air borne diseases?
- Answer 3:
When an infected person sneeze or cough, little droplets are thrown in air which enter body of a healthy person who gets infection. Poorly ventilated areas do not get fresh air and lack of oxygen may cause breathing problems.
- Question 4:
Explain giving reasons
- (a) Balanced diet is necessary for maintaining healthy body.
- (b) Health of an organism depends upon the surrounding environment conditions.
- (c) Our surrounding area should be free of stagnant water.
- (d) Social harmony and good economic conditions are necessary for good health.
- Answer 4:
- (a) It will provides nutrition to all parts of the body which is essential for their proper functioning, e.g. lack of vitamin A leads to night blindness, vitamin C deficiency leads to scurvy, vitamin D deficiency leads to rickets.
- (b) If surrounding are not clean chances of infections are high, House fly spreads many diseases.
- (c) On stagnant water mosquito breads which spreads malaria.
- (d) Good economic condition help to get proper and regular meal. Social harmony leads to peace and happiness. Social disharmony leads to stress, hypertension and depression.
- Question 5:
What is immunisation?
- Answer 5:
It is production of immunity by artificial means by producing antibodies through vaccination.
- Question 6:
Why is it difficult to make anti viral drugs than antibacterial drug?
- Answer 6:
It is because virus use host machinery and do not have their biological processes.
- Question 7:
Why is AIDS consider to be a Syndrome and not a disease?
- Answer 7:
Syndrome is a group of symptoms, or signs, physical and biological which have common causes. It reduces immunity of the body to fight against infections. HIV that causes AIDS damages T4 helper cells. As a result, small cold leads to pneumonia.
- Question 8:
How can doctor pin point a particular disease?
- Answer 8:
Doctor carries out physical examination, blood test, urine test. Based on symptoms and on the basis of test reports, he can pin point the particular disease e.g., blood test shows a person is suffering from malaria or dengue or chikengunia or typhoid.
- Question 9:
Write the symptoms when the following organs are targeted by microbes:
(a) Lungs (b) Liver (c) Brain
- Answer 9:
(a) It leads to cough and breathing.
(b) Fever, vomiting, loss of appetite, yellow urine, yellow skin.
(c) Headache, vomiting and unconsciousness.
- Question 10:
A baby is not able to tell her/his caretaker that she/he is sick. What would help us to find out
(a) that the baby is sick?
(b) what is the sickness?
- Answer 10:
(a) The baby keeps on crying even if he is fed. His body temperature rises up, eyes start watering, vomits, has loose motions.
(b) He should be taken to a child specialist. He will conduct some tests and for symptoms he would find the cause and treatment of the sickness.