Frog lungs have a smaller 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.
c. Frogs also obtain oxygen via diffusion across the skin.
d. Frog lung tissue has a greater density of capillary beds than mammalian lung tissue.

Verified step by step guidance

1. Understand the problem: Frogs have smaller lung surface areas compared to mammals, which affects their ability to exchange gases efficiently through their lungs alone.
2. Consider the options provided: Each option suggests a different mechanism by which frogs might compensate for their smaller lung surface area.
3. Evaluate option c: Frogs also obtain oxygen via diffusion across the skin. This is a known adaptation in amphibians, where cutaneous respiration allows them to absorb oxygen directly through their skin, supplementing lung respiration.
4. Compare option c with other options: While options a, b, and d suggest different physiological adaptations, option c is unique to amphibians and is a well-documented method of respiration.
5. Conclude that option c is the most plausible mechanism: Frogs use cutaneous respiration to compensate for their smaller lung surface area, allowing them to efficiently exchange gases through their skin.

Key Concepts

Cutaneous Respiration

Cutaneous respiration is the process by which some animals, including frogs, exchange gases through their skin. This adaptation allows frogs to absorb oxygen directly from the environment, compensating for the smaller surface area of their lungs. The skin must remain moist to facilitate this gas exchange, which is why frogs are often found in humid environments.

Surface Area to Volume Ratio

The surface area to volume ratio is a critical factor in the efficiency of gas exchange. Frogs have a smaller lung surface area compared to mammals, which limits their ability to exchange gases through the lungs alone. By utilizing their skin for respiration, frogs increase their effective surface area for gas exchange, allowing them to meet their metabolic needs.

Adaptations in Amphibians

Amphibians, like frogs, have evolved various adaptations to survive in diverse environments. These include the ability to respire through both lungs and skin, known as bimodal respiration. This dual system allows them to thrive in both aquatic and terrestrial habitats, providing flexibility in oxygen acquisition depending on environmental conditions.