NCERT Class-9 Science Solutions: Chapter 13-Why Do We Fall Ill Part 3 (For CBSE, ICSE, IAS, NET, NRA 2023)
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Question 17:
Viruses, which cause hepatitis, are transmitted through
- Air
- Water
- Food
- Personal contact
Answer: B
Question 18:
Vectors can be defined as
- Animals carry the infecting agents from sick person to another healthy person
- Microorganisms which cause many diseases
- Infected person
- Diseased plants
Answer: A
Short Answer Questions
Question 19:
Give two examples for each of the following
- Acute diseases
- Chronic diseases
- Infectious diseases
- Non-infectious diseases
Answer:
(A) Acute diseases:
Viral fever, Flu
(B) Chronic diseases:
Elephantiasis, Tuberculosis (TB)
(C) Infectious diseases:
Small pox, Chicken pox
(D) Non-infectious diseases:
Diabetes, Goiter
Question 20:
- Name two diseases caused by Protozoans
- What are their causal organisms?
Answer:
Sleeping sickness caused by Trypanosoma/Malaria by plasmodium
Kala-azar caused by Leishmania
Question 21:
- Which bacterium causes peptic ulcers?
- Who discovered the above pathogen for the first time?
Answer:
Helicobacter pylori bacterium causes peptic ulcers.
Marshall and Warren discovered the pathogen for the first time
Question 22:
What is an antibiotic? Give two examples
Answer:
Antibiotic is a chemical substance that kill bacteria, secreted by microorganisms which can kill the pathogens.
Examples, Penicillin and Streptomycin
Question 23:
Fill in the blanks
- Pneumonia is an example of … disease.
- Many skin diseases are caused by …
- Antibiotics commonly block biochemical pathways important for the growth of …
- Living organisms carrying the infecting agents from one person to another are called …
Answer:
- Pneumonia is an example of communicable disease.
- Many skin diseases are caused by fungi
- Antibiotics commonly block biochemical pathways important for the growth of bacteria.
- Living organisms carrying the infecting agents from one person to another are called vector.