GRE Subject Test: Biology : Understanding Respiratory Structures

Study concepts, example questions & explanations for GRE Subject Test: Biology

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Example Questions

Example Question #11 : Respiratory System

Before it enters the lungs, air must pass through which of the following structures?

Possible Answers:

The pharynx

Nephrons

Alveoli

The esophagus

Correct answer:

The pharynx

Explanation:

After entering the nose and mouth, air is passed into the pharynx. It then travels to the larynx, which houses the vocal cords, before entering the trachea. The trachea transports the air into the thoracic cavity before branching into the primary bronchi. The right bronchus carries air to the right lung; the left bronchus carries air to the left lung. Of the given answer options, air only passes through the pharynx before entering the lungs.

Alveoli are found in the lungs and the primary site of gas exchange; however, the question specifies a structure before the air enters the lungs. The esophagus transports food, and is not involved in respiration. Nephrons are the function units of the excretory system, and are located in the kidneys.

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