When a microorganism invades a host, a definite sequence of events usually occur leading to infection and disease, causing suffering to the host. This process is called pathogenesis. Once a microorganism overcomes the defense system of the host, development of the disease follows a certain sequence of events as shown in the graph. Study the graph given below for the sequence of events leading to appearance of a disease and answer the questions that follow:

(a) In which period, according to the graph there are maximum chances of a person transmitting a disease / infection and why?
(b) Study the graph and write what is an incubation period. Name a sexually transmitted disease that can be easily transmitted during this period. Name the specific type of lymphocytes that are attacked by the pathogen of this disease.
OR
(b) Draw a schematic labelled diagram of an antibody.
(c) In which period, the number of immune cells forming antibodies will be the highest in a person suffering from pneumonia ?
Name the immune cells that produce antibodies.

Solution

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