Recent widespread incidences of dengue and chikungunya in many parts of India are linked to which mosquito vector?

[Human-Health-and-Disease] [class-xii ]

• *Anopheles* mosquitoes
• *Culex* mosquitoes
• *Aedes* mosquitoes
• Houseflies
Correct Option: C  [ *Aedes* mosquitoes ]

Remark: Widespread incidences of the vector-borne (*Aedes* mosquitoes) diseases like dengue and chikungunya have been noted.

The ability of the host to fight disease-causing organisms, conferred by the immune system, is called:

[Human-Health-and-Disease] [class-xii ]

• Vaccination
• Memory response
• Immunity
• Metastasis
Correct Option: C  [ Immunity ]

Remark: This overall ability of the host to fight the disease-causing organisms, conferred by the immune system is called immunity.

Innate immunity is characterized by being:

[Human-Health-and-Disease] [class-xii ]

• Pathogen specific and having memory
• Non-specific and present at the time of birth
• Acquired during a lifetime
• Mediated by antibodies alone
Correct Option: B  [ Non-specific and present at the time of birth ]

Remark: Innate immunity is non-specific type of defence, that is present at the time of birth.

Which component is an example of a physical barrier in innate immunity?

[Human-Health-and-Disease] [class-xii ]

• Acid in the stomach
• Interferons
• Skin on our body
• Natural killer cells
Correct Option: C  [ Skin on our body ]

Remark: Skin on our body is the main physical barrier preventing entry of micro-organisms.

Which of the following secretions acts as a physiological barrier preventing microbial growth?

[Human-Health-and-Disease] [class-xii ]

• Antibodies
• Mucus coating of epithelium
• Saliva in the mouth
• Cytokines
Correct Option: C  [ Saliva in the mouth ]

Remark: Acid in the stomach, saliva in the mouth, tears from eyes—all prevent microbial growth.

Which types of cells are classified as cellular barriers capable of phagocytosis?

[Human-Health-and-Disease] [class-xii ]

• B-lymphocytes and T-lymphocytes
• Erythrocytes and platelets
• PMNL-neutrophils, monocytes, and Natural Killer cells
• Mast cells and Basophils
Correct Option: C  [ PMNL-neutrophils, monocytes, and Natural Killer cells ]

Remark: Certain types of leukocytes like PMNL-neutrophils, monocytes and natural killer cells can phagocytose and destroy microbes.

Virus-infected cells secrete proteins called interferons. These belong to which barrier category?

[Human-Health-and-Disease] [class-xii ]

• Physical barriers
• Physiological barriers
• Cellular barriers
• Cytokine barriers
Correct Option: D  [ Cytokine barriers ]

Remark: Virus-infected cells secrete proteins called interferons which are categorized as cytokine barriers.

The second, highly intensified response elicited upon subsequent encounter with the same pathogen is called:

[Human-Health-and-Disease] [class-xii ]

• Primary response
• Innate response
• Secondary or anamnestic response
• Passive response
Correct Option: C  [ Secondary or anamnestic response ]

Remark: Subsequent encounter with the same pathogen elicits a highly intensified secondary or anamnestic response.

The primary and secondary immune responses are carried out with the help of two special types of lymphocytes: T-lymphocytes and:

[Human-Health-and-Disease] [class-xii ]

• Macrophages
• PMNL-neutrophils
• B-lymphocytes
• Mast cells
Correct Option: C  [ B-lymphocytes ]

Remark: The responses are carried out with the help of B-lymphocytes and T-lymphocytes.

The proteins produced by B-lymphocytes in response to pathogens are called:

[Human-Health-and-Disease] [class-xii ]

• Interferons
• Carcinogens
• Antibodies
• Allergens
Correct Option: C  [ Antibodies ]

Remark: The B-lymphocytes produce an army of proteins called antibodies to fight pathogens.