CAPF AC 2022 Q15: Science & Technology – Biology
Which one of the following animals has a four-chambered heart?
- (a) King cobra
- (b) Turtle
- (c) Chameleon
- (d) Crocodile
Answer: (d) Crocodile
Explanation
The reptile with a four-chambered heart
How to think: all four animals are reptiles.
Most reptiles have a three-chambered heart.
Crocodiles are the exception with four chambers.
| Group | Chambers of the heart | Examples |
|---|---|---|
| Fishes | 2 | Shark, rohu |
| Amphibians | 3 | Frog, salamander |
| Most reptiles | 3 | King cobra, turtle, chameleon |
| Crocodilians | 4 | Crocodile, alligator, gharial |
| Birds and mammals | 4 | Pigeon, human |
Why four chambers help: oxygen-rich and oxygen-poor blood do not mix.
This gives a better supply of oxygen to the body.
Answer: (d) Crocodile.
Why each option is right or wrong
- (a) Incorrect. The king cobra is a snake with a three-chambered heart.
- (b) Incorrect. The turtle has a three-chambered heart.
- (c) Incorrect. The chameleon is a lizard with a three-chambered heart.
- (d) CORRECT. The crocodile has a four-chambered heart, like birds and mammals.
Key point
Heart chambers: fishes 2, amphibians 3, reptiles 3 (crocodiles 4), birds and mammals 4. NCERT Class XI: all reptiles have a three-chambered heart except crocodiles.
Remember
Crocodile: the reptile with four heart chambers.
Common mistakes
- Assuming all reptiles have a three-chambered heart without exception.
- Thinking a turtle has four chambers because it lives long.
- Mixing up amphibians and reptiles when recalling the number of chambers.
Exam tip
Educated guess: three of the four are ordinary reptiles (a snake, a turtle, a lizard). The crocodile is the famous exception, being the closest living relative of birds.
Sources
- NCERT Class XI Biology — Animal Kingdom (Reptilia) and Body Fluids and Circulation
- NCERT Class X Science — Life Processes (transportation in human beings and other animals)