9th Class (CBSE) Science: Why Do We Fall Ill

Question: Define health.

Answer: Health means a state of physical, mental and social well-being.

Question: Define disease.

Answer: Disease means being uncomfortable.

Question: What do you mean by symptoms of disease?

Answer: Symptoms of disease are the signs of a disease which indicates the presence of a particular disease.

Question: What are acute diseases?

Answer: Those diseases which last for very short period of time are called acute diseases. Example, headache and cold.

Question: What are chronic diseases?

Answer: The diseases which last for very long period of time are called chronic disease Example, tuberculosis and jaundice.

Question: What are pathogens?

Answer: The disease causing microbes are called pathogens. Example, bacteria, virus, fungi, worms.

Question: What are vectors?

Answer: The organisms that spread or carry pathogens from one place to another, from infected person to healthy person is called vector. Example, mosquito, housefly etc.

Question: What are infectious diseases?

Answer: Diseases which can spread from one person to another and microbes are the immediate cause for these diseases are called infectious diseases. Example, typhoid

Question: What are non-infectious diseases?

Answer: Diseases which do not spread from one person to another is called non-infectious diseases. Example, cancer.

Question: Name any one disease caused due to genetic abnormality.

Answer: Haemophilia.

Question: Name two diseases caused by protozoa.

Answer: Malaria and amoebiasis.

Question: Name two diseases caused due to bacteria.

Answer: Tuberculosis, typhoid.

Question: Name two disease caused due to virus.

Answer: Polio, chickenpox.

Question: Name two disease caused by fungi.

Answer: Scabies and skin infection.

Question: What are antibiotics?

Answer: Antibiotics are drugs that block the biochemical pathways important for bacteria. These are used to cure diseases caused due to bacteria.

Question: Give the full form of AIDS.

Answer: AIDS – Acquired Immunodeficiency Syndrome (Syndrome means collection of symptoms).

Question: Name the pathogen that causes sleeping sickness.

Answer: The protozoan → Trypanosoma.

Question: Name the organism that causes kala-azar.

Answer: Leishmania.

Question: Name two air-borne diseases.

Answer: Common cold, cough, tuberculosis.

Question: Name two diseases that are organ specific.

Answer:

1. Jaundice – liver
2. Tuberculosis – lungs

Question: Which virus causes AIDS?

Answer: HIV virus causes AIDS
HIV – Human Immuno Deficiency Virus.

Question: State any two conditions for good health

Answer: Two conditions essential for good health are:

1. State of physical, mental and social well-being.
2. Better surroundings or environment.

Question: State any two conditions essential for being free of disease.

Answer: The two conditions essential for being free of disease are:

1. Personal and domestic hygiene
2. Clean environment and surroundings

Question: Are the answers to the above questions necessarily the same or different? Why?

Answer: The answer to the above questions are different because a person may be free of disease but his mental, social or economical health may not be good.