Lymphoid tissue located within the lining of the major tracts (respiratory, digestive, urogenital) is called:

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

• Thymus associated lymphoid tissue (TALT)
• Spleen Associated Lymphoid Tissue (SALT)
• Mucosa-Associated Lymphoid Tissue (MALT)
• Peyer's Patches (PP)
Correct Option: C  [ Mucosa-Associated Lymphoid Tissue (MALT) ]

Remark: Lymphoid tissue located within the lining of the major tracts is called mucosa-associated lymphoid tissue (MALT).

MALT constitutes about what percentage of the total lymphoid tissue in the human body?

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

• 10 per cent
• 25 per cent
• 50 per cent
• 75 per cent
Correct Option: C  [ 50 per cent ]

Remark: MALT constitutes about 50 per cent of the lymphoid tissue in human body.

The word 'Syndrome' in Acquired Immuno Deficiency Syndrome (AIDS) means:

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

• An infectious disease
• A fatal condition
• A group of symptoms
• A congenital deficiency
Correct Option: C  [ A group of symptoms ]

Remark: ‘‘Syndrome’’ means a group of symptoms.

AIDS is caused by Human Immuno deficiency Virus (HIV), which is a member of which viral group?

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

• Adenovirus
• Rhino virus
• Retrovirus
• Oncogenic virus
Correct Option: C  [ Retrovirus ]

Remark: HIV is a member of a group of viruses called retrovirus.

Which route of transmission is NOT generally associated with HIV infection?

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

• Sexual contact with infected person
• Transfusion of contaminated blood
• Sharing infected needles
• Inhaling aerosols from infected person
Correct Option: D  [ Inhaling aerosols from infected person ]

Remark: HIV is transmitted via body fluids, through sexual contact, blood transfusion, sharing needles, or mother to child via placenta. It is not spread by mere touch or physical contact.

The time-lag between HIV infection and the appearance of AIDS symptoms typically varies from:

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

• A few days to one week
• One to three years
• A few months to many years (usually 5-10 years)
• More than 20 years
Correct Option: C  [ A few months to many years (usually 5-10 years) ]

Remark: There is always a time-lag between the infection and appearance of AIDS symptoms. This period may vary from a few months to many years (usually 5-10 years).

In the lifecycle of HIV, the enzyme reverse transcriptase helps the viral RNA genome to replicate and form:

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

• New RNA genomes
• Viral proteins
• Viral DNA
• Progeny viruses directly
Correct Option: C  [ Viral DNA ]

Remark: RNA genome of the virus replicates to form viral DNA with the help of the enzyme reverse transcriptase.

Which host cells continue to produce virus and act like an "HIV factory"?

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

• Helper T-lymphocytes
• B-lymphocytes
• Macrophages
• Erythrocytes
Correct Option: C  [ Macrophages ]

Remark: The macrophages continue to produce virus and in this way acts like a HIV factory.

The progressive decrease in the number of which specific immune cell leads to immunodeficiency in an AIDS patient?

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

• B-lymphocytes
• Helper T-lymphocytes (Tᵤ)
• Natural killer cells
• Monocytes
Correct Option: B  [ Helper T-lymphocytes (Tᵤ) ]

Remark: The progeny viruses attack other helper T-lymphocytes, leading to a progressive decrease in their number.

Due to immunodeficiency, AIDS patients frequently suffer from infections caused by bacteria, especially:

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

• Salmonella typhi
• Streptococcus pneumoniae
• Mycobacterium
• Haemophilus influenzae
Correct Option: C  [ Mycobacterium ]

Remark: The person suffers from infections due to bacteria especially Mycobacterium, viruses, fungi and even parasites like Toxoplasma.