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Do Frogs Have Lungs — Reading Comprehension

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"This comprehensive reading passage explains the fascinating respiratory system of frogs and other amphibians. It details the dual methods of respiration: using simple lungs for positive-pressure breathing on land and relying on highly permeable skin for cutaneous respiration in water or for supplementary oxygen. The passage introduces key scientific concepts like buccal pumping and gas diffusion, aligning with NGSS standards for middle school life science (LS1.A: Structure and Function). It provides clear, factual explanations, relatable examples, and a fun fact to engage students. The content is designed to enhance students' understanding of biological adaptations, how an organism's structure relates to its function, and the unique challenges faced by animals living in both aquatic and terrestrial environments."

CONTENT PREVIEW

Frogs, like other amphibians, have a fascinating and complex respiratory system that allows them to live both on land and in water. Unlike fish that use gills or mammals that rely solely on lungs, frogs have multiple ways to breathe. This dual-life capability is a key characteristic of their class, Amphibia, which means "double life." The primary organs for breathing on land are the lungs, but they are quite different from the lungs of mammals.

A frog's lungs are relatively small and simple sac-like structures with less surface area than human lungs. To breathe air, a frog performs a process called buccal pumping. It lowers the floor of its mouth, which draws air in through its nostrils. Then, it closes its nostrils and raises the floor of its mouth, forcing the air down its trachea into its lungs. This is a positive-pressure breathing method, unlike the negative-pressure breathing used by humans, where we create a vacuum to pull air in.

In addition to their lungs, frogs also use their moist skin to breathe. This process is known as cutaneous respiration. Their skin is highly permeable and contains a dense network of tiny blood vessels right below the surface. Oxygen from the surrounding water or air can diffuse directly across the skin and into the bloodstream, while carbon dioxide diffuses out. This is why it is crucial for a frog's skin to remain moist. If it dries out, gas exchange cannot occur effectively, and the frog could suffocate.

When underwater, cutaneous respiration is the frog's primary method of getting oxygen. On land, it supplements the oxygen taken in by the lungs, especially during periods of low activity. Some frogs, like the Titicaca water frog, have a large amount of loose, wrinkly skin that increases their surface area for cutaneous respiration. They can stay underwater for extended periods, relying almost entirely on their skin for oxygen. The combination of lungs for air breathing and skin for aquatic or supplementary respiration is what makes the frog's respiratory system so unique.

Fun Fact: The Bornean flat-headed frog is the only known frog species without lungs. It relies entirely on its skin for all its respiratory needs.

What is the primary method a frog uses to breathe when it is on land?

GillsCutaneous respirationLungsBuccal pumping

How is a frog's breathing process different from a human's?

Frogs use negative-pressure breathing.Frogs use buccal pumping to force air in.Humans use their skin to breathe.Frogs breathe only through their nostrils.

What is the name of the process by which a frog breathes through its skin?

Pulmonary respirationDiffusional exchangeCutaneous respirationBuccal pumping

Why is it important for a frog's skin to remain moist?

To prevent it from catching a cold.To help it absorb more water.To allow for effective gas exchange.To make it more slippery for predators.

Which of the following best describes the structure of a frog's lungs?

Large and highly complexSimple, sac-like structuresSimilar to fish gillsA dense network of blood vessels

According to the passage, what happens to a frog's skin if it dries out?

It becomes less permeable.Gas exchange becomes less effective.It develops a protective layer.The frog starts to breathe faster.

What is the main idea of this reading passage?

Frogs are unique amphibians.Frogs can only breathe with their lungs.Frogs have a versatile respiratory system.The skin is a frog's most important organ.

Based on the passage, if a scientist discovered a new frog species that spent its entire life in a dry desert environment, which respiratory system would it most likely rely on?

Entirely cutaneous respiration.A highly developed lung system.A gill system for water absorption.An increased reliance on buccal pumping for skin breathing.