Answer: Option A. -> True
:
A
Some diseases persist for only a very short period, and these are called acute diseases. E.g. common cold, appendicitis, etc. Symptoms of other diseases prolong for several years or even a lifetime. These are called chronic diseases. E.g. elephantiasis,AIDS, etc.

Answer: Option B. -> False
:
B
Our body has a special mechanism to fight against infectious pathogens. This property is called immunity. The immune system consists of certain immune cells which produce allergies, reactions or antibodies against antigens (foreign particles) entering our body. The process of resistance against diseases is called immunization.

Answer: Option B. -> lungs
:
B
Microbes in the air enters into a person while breathing. The microbes are taken into the lungs, which is the primary place of infection. The examples of air-borne diseases arecommon cold, pneumonia and tuberculosis.

Answer: Option B. -> shaking hands
:
B

HIV spread only through body fluids of an infected person. These fluids are blood, semen, pre-seminal fluids, rectal fluids, vaginal fluids and breast milk.

Answer: Option B. -> Diphtheria
:
B and D

Infectious diseases are caused by certain microorganisms called pathogens and leads to infections. These can be spread from one person to another and hence they are also called communicable diseases.  Diphtheria is an infectious disease spread by direct physical contact or breathing the aerosolized secretions of infected individuals. Kala-azar can be spread from person to person by the bite of an infected sandfly.

Answer: Option B. -> lungs
:
B
Microbes in the air enters into a person while breathing. The microbes are taken into the lungs, which is the primary place of infection. The examples of air-borne diseases are common cold, pneumonia and tuberculosis.

Answer: Option B. -> False
:
B
Tuberculosis is a deadly disease of the respiratory tract. It spreads from an infected person to a healthy person via pathogen-containing tiny air droplets which are released by an infected person while coughing or sneezing.

Answer: Option B. -> False
:
B
Our body has a special mechanism to fight against infectious pathogens. This property is called immunity. The immune system consists of certain immune cells which produce allergies, reactions or antibodies against antigens (foreign particles) entering our body. The process of resistance against diseases is called immunization.

Answer: Option A. -> Small pox
:
A
Edward Jenner discovered the vaccine for smallpox in 1798. Working in an agricultural community, Jenner knew that milkmaids never caught smallpox. However, they inevitably caught cowpox. Jenner speculated that exposure to cowpox produced immunity against smallpox and even encountered locals who claimed to have deliberately infected themselves to provoke such a response. Jenner injected an eight-year-old boy with pus from cowpox blisters on the hands of a milkmaid and the boy developed immunity against smallpox.

Answer: Option D. -> Cancer
:
D
Chronic diseases are those diseases which last for a long period of time and weaken the body by attacking the immune system. Cancer is an example of chronic disease. A cancer patient may suffer for many years to a lifetime in worse conditions.