Question

Frog lungs have a lower surface area for gas exchange than mammalian lungs. How do frogs compensate for this difference? a. Frog tissue absorbs more oxygen from the blood than mammalian tissue does. b. Frogs breathe more quickly than mammals. e. Frogs also obtain oxygen via diffusion across the skin. d. Frog lung tissue has a greater density of capillary beds than mammalian lung tissue.

Short answer

Frogs compensate for their lower lung surface area by obtaining oxygen through diffusion across the skin (Option C). This process, known as cutaneous respiration, allows frogs to obtain the necessary oxygen without relying solely on their lungs.

Step-by-step solution

Option A

Frog tissue absorbs more oxygen from the blood than mammalian tissue does. This option is not correct since it does not directly address the problem of lower surface area for gas exchange in frogs.

Option B

Frogs breathe more quickly than mammals. This option is also not correct, as faster breathing does not necessarily address the issue of reduced surface area for gas exchange in frog lungs.

Option C

Frogs also obtain oxygen via diffusion across the skin. This option is the correct answer. Frogs compensate for their lower lung surface area by obtaining additional oxygen through their skin. This process, known as cutaneous respiration, allows frogs to obtain the necessary oxygen without relying solely on their lungs.

Option D

Frog lung tissue has a greater density of capillary beds than mammalian lung tissue. Although this might contribute to better oxygen uptake in frogs, it does not explain how frogs compensate for their lower lung surface area compared to mammals. Thus, this option is not the correct answer. In conclusion, frogs compensate for their lower lung surface area by obtaining oxygen through diffusion across the skin (Option C).

Key concepts

Cutaneous Respiration

Amphibians, like frogs, have a unique ability to breathe through their skin, a process called cutaneous respiration. This capability is essential for their survival, as it supplements the oxygen exchange that occurs in their lungs. In cutaneous respiration:

• Oxygen diffuses directly through the skin into the bloodstream.
• Carbon dioxide is expelled in the opposite direction, leaving the body.

This method of respiration is particularly useful in aquatic environments or during periods of inactivity when lung ventilation is reduced. Frogs often keep their skin moist, which is necessary for efficient gas diffusion. This moist condition creates a favorable environment for cutaneous gas exchange to occur. By utilizing their skin as a respiratory surface, frogs effectively compensate for their lungs' limitations in surface area.

Gas Exchange

Gas exchange is a vital process that facilitates the absorption of oxygen and the release of carbon dioxide. In amphibians, like frogs, this exchange takes place in both the lungs and across the skin:

• Through their lungs, frogs inhale air, which provides oxygen to the blood.
• Simultaneously, respiration through the skin allows for additional oxygen uptake and carbon dioxide removal.

Together, these methods ensure that frogs receive adequate oxygen for their metabolic needs. Cutaneous respiration is a particularly adaptive feature for frogs when they are submerged in water, as it allows them to continue exchanging gases without relying solely on their lungs. This adaptability in gas exchange mechanisms is what enables frogs to thrive in a variety of environments.

Anatomy of Frog Lungs

Frog lungs are structurally different from those of mammals, and understanding their anatomy helps to explain how frogs manage respiration. Here are some key aspects of frog lung anatomy:

• Frog lungs are simpler, sac-like structures with a smaller surface area compared to mammalian lungs.
• The internal surface of frog lungs is lined with folds, which increase the surface area available for gas exchange, yet not to the extent seen in more complex mammalian lungs.
• This limited surface area means that frogs must employ supplementary respiration through other means, such as their skin.

Frog lungs also play an essential role during periods of high activity, providing rapid oxygenation when needed. However, for many everyday activities, the combination of lung and skin respiration suffices to meet their oxygen demands. The simplicity of frog lungs is offset by their reliance on cutaneous respiration, highlighting the unique anatomical adaptations frogs possess for maintaining effective gas exchange.