Human Health & Disease Test - 4

• The antibody recognizes a small portion of the antigen called the antigenic determinant or epitope .
• Each antibody recognizes and binds to a specific antigen in a lock and key type model .
• The variable regions, which make up the two identical antigen-binding sites, are different in each specific type of antibody, giving these sites specific shapes that fit certain antigenic epitopes.
• The remainder of the molecule consists of light and heavy chain constant regions where these amino acid sequences vary little from antibody to antibody.

• Antigen-binding site:

  
  Hence the correct option is 'A '

• The production of  antibodies  by plasma cells in response to an antigen is  called active immunity.
• Active immunity refers to the immune response that occurs when the body is exposed to a pathogen or foreign substance and produces its own antibodies in response. This type of immunity can be obtained naturally, such as through infection, or artificially, through vaccination. 
• Innate immunity is the body 's first line of defense against pathogens and is present from birth. 
• Acquired immunity refers to the immune response that develops over time in response to exposure to various pathogens and foreign substances.
• Passive immunity, on the other hand, occurs when pre-formed antibodies are transferred from one individual to another, such as through maternal antibodies passed from mother to baby during breastfeeding.

Hence the correct option is 'D '

• Antibodies are produced  by specialized white blood  cells  called  B lymphocytes  (or  B cells ). When an antigen binds to the  B -cell  surface, it stimulates the  B cell  to divide and mature into a group of identical  cells  called a clone.
• B cells, also known as B lymphocytes are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system by secreting antibodies. B-cells  bind to an antigen, receive help from a cognate helper T cell and differentiate into a plasma cell that secretes large amounts of antibodies.

Hence the correct option is 'B '
 

The thymus reduces in size with age and becomes very small by the time puberty is attained.
This phenomenon is primarily due to changes in the thymus 's function andtissue composition as an individual matures.

Hence the correct option is 'D '

Chikungunya virus is most often spread to people by Aedes aegypti and Aedes albopictus mosquitoes. These are the same mosquitoes that transmit dengue virus.

• Mosquitoes become infected when they feed on a person already infected with the virus.
• Infected Mosquitoes can then spread the virus to other people through bites.

Hence the correct option is 'B '

• Snake antivenom is a medication made up of antibodies used to treat snake bites by venomous snakes. It is a type of antivenom.It contains antibodies.
• It is a biological product that typically consists of venom neutralizing antibodies derived from a host animal, such as a horse or sheep.
• The host animal  is hyperimmunized to one or more snake venoms, a process which creates an immunological response that produces large numbers of neutralizing antibodies against various components (toxins) of the venom.
• The antibodies are then collected from the host animal, and further processed into snake antivenom for the treatment of envenomation.

Hence the correct option is 'D '

• Sporozoites enter the female Anopheles mosquito when they bite an infected person where these sporozoite fertilise and multiply in the stomach wall of the female Anopheles and stored in the salivary gland of mosquito till it is again transferred to the human body by a mosquito bite.
•  After entering the human body the sporozoites reach the liver cells, where they multiply. This is followed by their attack on red blood cells resulting in their rupture. The ruptured RBCs release a toxin called  hemozoin, which is responsible for high recurring fever, chills and shivering.
• Life cycle of malarial parasite in Female Anopheles mosquito:

Hence the correct option is 'C '

 

• Microorganisms that cause disease are collectively called pathogens .
• Pathogens cause disease either by disrupting the body 's normal processes and/or stimulating the immune system to produce a defensive response, resulting in high fever, inflammation and other symptoms.

Hence the correct option is 'B '

Infectious diseases are transmitted from one person to another by droplet infection, direct contact with infected persons, animal bite, contact with soil or by transplacental transmission.

Answer: Option D.

Solution: Malaria is caused by Plasmodium parasites, not a virus. The statement in R is true as the disease is indeed transmitted by the bite of infected Anopheles mosquitoes, making A false and R true.

​​​​​​​Lymphocytes are  a unit of the immune system.

• Lymphocytes are one of several different types of white blood cells.
• Lymphocytes are of two types B cells and T cells.

1. When a macrophage engulfs organisms, B cells (humoral immunity) release antibodies which cause the destruction of bacteria.
2. The T cells (cell-mediated immunity) destroy the infectious organisms by killing the body cells that are affected.

Hence  the correct option is 'C '

Sickle-cell anaemia is a congenital disease. Congenital diseases are contracted before birth due to chromosomal abnormalities or gene mutations or defect in development. Goitre and Kwashiorkor are caused due to deficiency of an essential element while Rheumatoid Arthritis is an autoimmune disease.

• Acquired Immune Deficiency Syndrome or AIDS is a set of symptoms caused by the  HIV  virus.
• It is in fact, the most advanced stage of infection caused by  HIV .
• This disease modifies and corrupts the immune system , making people susceptible to infections and diseases.

Hence the correct option is 'B '

The function of IgE antibody as mediators in allergic reactions of Type I is explained by their ability to interact both with antigen and with receptor molecules on the membrane of blood basophils and tissue mast cells. It is essential for type I hypersensitivity, which occurs as allergic asthma, rhinitis, and other allergic disorders. It also plays a key role in allergic reactions to anaphylactic medicines, bee stings, and antigen preparations used in immunotherapy tolerance.

Hence the correct option is 'B ' 

Widal Test is used for diagnosis of Typhiod. Widal Test is used for diagnosis of Typhiod.

1.ESR is done to check out the concentration of Erythrocytes in blood.

2. PCR is done to amplify the amount of DNA molecules.

3.Widal test is a serological test for typhoid or enteric fever.

4. ELISA is done in AIDS.

Hence the correct option is 'C '