The primary muscle of breathing is the: MCQ with Answer and Explanation

The primary muscle of breathing is the:
A. Pectoral muscles
B. Intercostal muscles
C. Abdominal muscles
D. Diaphragm
Answer: Option D
Solution (By JKExamLibrary)
The diaphragm is a dome-shaped skeletal muscle that contracts during inspiration, flattening and increasing thoracic volume. The external intercostal muscles assist.

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Practice More Biology Questions

Question #1
The part of the seed that contains stored food for the embryo is the:
A. Radicle
B. Cotyledon
C. Plumule
D. Seed coat

Correct Answer: Option B


Explanation:
Cotyledons are seed leaves that store food (starch, proteins, lipids) for the developing embryo and may become photosynthetic after germination. Monocots have one, dicots two. Radicle is root, plumule shoot, seed coat protects.

This question belongs to: Science Biology
Question #2
Consider statements about viruses: 1. They possess both DNA and RNA. 2. They are obligate intracellular parasites. 3. They can be crystallized. Which are correct?
A. 2 and 3 only
B. 1 and 2 only
C. 1 and 3 only
D. 1, 2 and 3

Correct Answer: Option A


Explanation:
Viruses are unique entities containing either DNA or RNA, never both simultaneously, enclosed in a protein capsid. They are obligate intracellular parasites, requiring a host cell's machinery to replicate. Despite being biological entities, they can be crystallized like chemicals, as demonstrated by W.M. Stanley with TMV. Thus, statements 2 and 3 are correct.

This question belongs to: Science Biology
Question #3
The structure that prevents food from entering the nasal cavity during swallowing is the:
A. Tongue
B. Epiglottis
C. Soft palate (uvula)
D. Pharynx

Correct Answer: Option C


Explanation:
The soft palate, including the uvula, elevates during swallowing to close off the nasopharynx, preventing food from entering the nasal passages. The epiglottis closes the larynx, the tongue pushes food.

This question belongs to: Science Biology