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How do Amphibians Breathe? — Reading Comprehension

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This comprehensive science passage, suitable for middle school students, explores the fascinating topic of amphibian respiration. It delves into the different breathing methods amphibians use throughout their life cycle, from gill-breathing tadpoles to adult frogs and salamanders that utilize lungs and cutaneous respiration. The content aligns with NGSS standards related to life science and organism adaptations, providing a solid foundation for understanding biological systems. Key vocabulary is highlighted, and real-world connections are drawn to make the content engaging and relevant. The passage is designed to support self-study and classroom instruction, offering a clear and factual explanation of this unique biological process.

CONTENT PREVIEW

Amphibians are fascinating vertebrates that occupy a unique place in the animal kingdom, transitioning between aquatic and terrestrial environments throughout their lives. A key aspect of this dual lifestyle is their remarkable ability to breathe in multiple ways, adapting to their surroundings. Unlike humans who rely solely on lungs, amphibians employ a variety of methods for gas exchange, including using their lungs, gills, and even their skin. This adaptability allows them to thrive in a wide range of habitats, from underwater ponds to damp forests.

The breathing methods of amphibians change dramatically as they grow. When they are young, amphibians like tadpoles live exclusively in water and breathe using gills. Similar to fish, these gills are feather-like structures located on the sides of their bodies that extract dissolved oxygen from the water. As they undergo metamorphosis, their body changes. They lose their gills and develop lungs, which are essential for breathing air on land. This transformation is a critical step in their life cycle, allowing them to leave the water and begin their adult lives.

Once they become adults, most amphibians primarily use their lungs to breathe, but this isn't their only method. A unique and crucial form of respiration for them is cutaneous respiration, or breathing through their skin. Their skin is thin, moist, and contains many blood vessels close to the surface, which allows oxygen to be absorbed directly into the bloodstream. This method is so effective that some amphibians, such as lungless salamanders, rely on it entirely. For this reason, amphibians must always keep their skin moist to prevent it from drying out, as dry skin cannot facilitate gas exchange.

The combination of pulmonary respiration (breathing with lungs) and cutaneous respiration makes amphibians highly adaptable. When submerged in water, they can absorb oxygen through their skin. On land, they use their lungs, often supplemented by their skin, especially in humid conditions. This dual-breathing system is a perfect example of how living organisms evolve to suit their environment.

Fun Fact: The Lake Titicaca frog, also known as the "scrotum frog" because of its wrinkled skin folds, has an exceptionally large surface area for cutaneous respiration, allowing it to breathe entirely through its skin in the cold, oxygen-poor waters of Lake Titicaca.

Which of the following is NOT a method of respiration used by amphibians?

LungsGillsNaresSkin

What is the primary method of respiration for a young tadpole living in water?

LungsGillsCutaneous respirationBuccal pumping

What must an amphibian do to ensure its skin can be used for gas exchange?

Keep its skin moistBask in the sunShed its skin regularlyHarden its skin

What is the main idea of this reading passage?

Amphibians are a unique type of fish.Amphibians must live in water their entire lives.Amphibians have evolved multiple ways to breathe.Amphibians are the only animals with lungs.

The passage states that adult amphibians often use their lungs, but their skin can supplement this process. This suggests that cutaneous respiration is most effective in which type of environment?

Hot and dryCold and windyHumid and dampFreezing and icy

Which term is used to describe the process of an amphibian breathing through its skin?

MetamorphosisPulmonary respirationCutaneous respirationGas exchange

What happens to the gills of a tadpole during metamorphosis?

They grow larger and more complex.They are lost as the amphibian develops lungs.They are used for both water and air breathing.They become a part of the amphibian's circulatory system.

Which of the following statements best describes the function of lungs in adult amphibians?

They are the only respiratory organ used by adult amphibians.They are used exclusively for breathing underwater.They are the primary organ for breathing on land.They are not as important as the skin for breathing.