Question

Presence of gills in the tadpole of frog indicates that

• A. fish were amphibious in the past
• B. fish evolved from frog-like ancestors
• C. frogs will have gills in future
• D. frogs evolved from gilled ancestors.

Answer 1

The Correct Option is D

The question concerns the presence of gills in the tadpole stage of frogs, which provides important insights into their evolutionary history. Let's analyze the information and options to understand why the presence of gills in tadpoles indicates that "frogs evolved from gilled ancestors."

1. Understanding Metamorphosis in Frogs: Frogs undergo a process called metamorphosis, in which their early life stage (tadpoles) is aquatic and possesses gills for breathing underwater. As they mature, they lose their gills and develop lungs for breathing air.
2. Evolutionary Implications: The presence of gills in tadpoles suggests that at some point in their evolutionary history, frogs or their ancestors were entirely aquatic and relied on gills for respiration. This is indicative of their evolutionary roots linking back to aquatic ancestors.
3. Analyzing Options:
   • Option 1: "Fish were amphibious in the past" is incorrect as it does not relate to the frog's evolutionary history; rather, it suggests a characteristic about fish.
   • Option 2: "Fish evolved from frog-like ancestors" is incorrect because fish are believed to be more primitive and did not evolve from amphibians like frogs. Instead, fish appeared earlier in the evolutionary timeline.
   • Option 3: "Frogs will have gills in future" is a misinterpretation; evolution doesn't predict a return to previous anatomical features like gills once they are entirely adapted for terrestrial life with lungs.
   • Option 4: "Frogs evolved from gilled ancestors" correctly illustrates that the presence of gills is a vestigial reminder of their evolutionary past, where their predecessors were aquatic and possessed gills.
4. Conclusion: The most accurate choice is "frogs evolved from gilled ancestors," as it directly reflects how the structure and function of tadpole gills trace back to when their ancestors were fully aquatic, breathing through gills.

This analysis explains the reasoning behind the correct answer, linking biological evolution and developmental biology to understand metamorphosis in frogs and their ancestral traits.