Choose the INCORRECT statement.

Correct option is D

The correct answer is (d) Frogs have four-chambered heart.

• Crocodiles (a) do have a four-chambered heart, which is unique among reptiles.

• Birds (b) also have a four-chambered heart, similar to mammals, which helps in the efficient separation of oxygenated and deoxygenated blood, making them capable of high metabolic activity required for flight.

• Fishes (c) have a two-chambered heart, where the heart has only one atrium and one ventricle. This is simpler than that of other vertebrates.

• Frogs (d), however, have a three-chambered heart: two atria and one ventricle. The blood in their heart is not completely separated into oxygenated and deoxygenated, unlike in four-chambered hearts.

Why other options are correct:

• (a) Crocodiles have four-chambered heart: This is a true statement. Crocodiles are unique among reptiles in having a four-chambered heart, which is similar to birds and mammals.

• (b) Birds have four-chambered heart: This is also correct. Birds have a four-chambered heart that helps maintain high efficiency in oxygenating their blood, crucial for their high-energy lifestyle.

• (c) Fishes have two-chambered heart: This is correct as well. Fish have a simple two-chambered heart that circulates blood in a single loop, as they do not require as much metabolic energy as birds or mammals.

Information Booster:

• Three-chambered heart is typically found in amphibians (e.g., frogs) and reptiles (e.g., snakes), though some reptiles like crocodiles have evolved to have a four-chambered heart.

• The four-chambered heart in mammals, birds, and some reptiles allows for complete separation of oxygenated and deoxygenated blood, which supports higher metabolic demands.

• Frogs having a three-chambered heart means there is partial mixing of oxygenated and deoxygenated blood in the single ventricle, which is less efficient than a fully separated circulatory system.