The functional unit of the human lung is the: MCQ with Answer and Explanation

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The functional unit of the human lung is the:

A. Nephron

B. Alveolus

C. Villus

D. Neuron

Answer: Option B

Solution (By JKExamLibrary)

Alveoli are tiny air sacs surrounded by capillaries where gas exchange (O₂ and CO₂) occurs. Nephrons are kidney units, neurons nerve cells, villi intestinal projections. The lungs contain millions of alveoli to maximize surface area.

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Question #1

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Consider statements about five kingdom classification: 1. Monera includes all prokaryotes. 2. Protista includes unicellular eukaryotes. 3. Fungi are photosynthetic autotrophs. Which are correct?

A. 1 and 3 only

B. 2 and 3 only

C. 1, 2 and 3

D. 1 and 2 only

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Correct Answer: Option D

Explanation:
R.H. Whittaker's five kingdom classification places all prokaryotic organisms in Kingdom Monera and unicellular eukaryotes in Kingdom Protista. Fungi are a distinct kingdom characterized by heterotrophic nutrition, primarily saprophytic or parasitic, and possess chitinous cell walls. They are not photosynthetic autotrophs. Therefore, statements 1 and 2 are correct, while 3 is incorrect.

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Question #2

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The nephron structure that measures the concentration of sodium chloride in the filtrate and regulates GFR is the:

A. Proximal convoluted tubule

B. Juxtaglomerular apparatus

C. Collecting duct

D. Bowman's capsule

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Correct Answer: Option B

Explanation:
The juxtaglomerular apparatus (JGA) is formed by the macula densa cells of the distal tubule and granular cells of the afferent arteriole. It detects NaCl concentration in the filtrate and releases renin, which regulates GFR and systemic blood pressure via the renin-angiotensin-aldosterone system. Bowman's capsule collects filtrate, PCT reabsorbs, collecting duct concentrates urine.

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Question #3

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Consider the following statements about mitosis:
1. It produces diploid cells.
2. It is involved in growth and repair.
3. It reduces chromosome number by half.
Which of the above is/are correct?

A. 1 and 2 only

B. 1, 2, and 3

C. 1 and 3 only

D. 2 and 3 only

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Correct Answer: Option A

Explanation:
Mitosis yields two identical diploid cells, important for growth/repair. Meiosis halves chromosome number. So 3 is incorrect.

This question belongs to: Science Biology

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