Consider statements about human immunity: 1. Skin acts as a physical barrier. 2. White blood cells fight infections. 3. Antibiotics are effective against viruses. Which are correct? MCQ with Answer and Explanation

Question

Consider statements about human immunity: 1. Skin acts as a physical barrier. 2. White blood cells fight infections. 3. Antibiotics are effective against viruses. Which are correct?

A. 2 and 3 only

B. 1 and 2 only

C. 1, 2 and 3

D. 1 and 3 only

Answer: Option B

Solution (By JKSSB Mock Tests)

The skin and mucous membranes form the first line of defense (innate immunity), acting as physical barriers that prevent pathogens from entering the body. White blood cells (leukocytes), including phagocytes and lymphocytes, are the cellular components of the immune system that identify, attack, and destroy pathogens. Antibiotics are drugs designed to kill or inhibit the growth of bacteria; they are completely ineffective against viruses, which lack the cellular machinery targeted by antibiotics. Thus, statements 1 and 2 are correct.

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Question #1

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The animal that lays eggs and has a beak but no teeth is:

A. Kangaroo

B. Whale

C. Platypus

D. Bat

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Correct Answer: Option C

Explanation:
The platypus is a monotreme (egg-laying mammal) with a duck-like beak, no teeth, and webbed feet. Bats and whales are placental mammals, kangaroo is a marsupial. Platypus is found in Australia.

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Question #2

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The process of physical and chemical breakdown of food into absorbable form is:

A. Digestion

B. Absorption

C. Assimilation

D. Egestion

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Correct Answer: Option A

Explanation:
Digestion converts complex, insoluble food molecules into simple, soluble forms that can be absorbed. It involves mechanical action (chewing, churning) and enzymatic hydrolysis. Absorption is the uptake of nutrients, assimilation is incorporation into body tissues, egestion is elimination of undigested waste.

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Question #3

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Which of the following is a viral disease that primarily attacks the immune system, specifically the CD4+ T helper cells?

A. Hepatitis B

B. HIV (AIDS)

C. Herpes Simplex

D. Influenza

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Correct Answer: Option B

Explanation:
Human Immunodeficiency Virus (HIV), the causative agent of Acquired Immunodeficiency Syndrome (AIDS), is a retrovirus that specifically targets and destroys CD4+ T helper cells, which are crucial for coordinating the adaptive immune response. As the CD4+ count drops, the immune system becomes severely compromised, leading to opportunistic infections and certain cancers. Hepatitis B targets the liver, Herpes causes lesions, and Influenza targets the respiratory tract.

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