info@jobexams.pk

MCQ Detailed View

Explore the question in detail with explanation, related questions, and community discussions.

1 BIOLOGY MCQS

Which animal has three hearts?

  • Crow
  • Dolphin
  • Octopus
  • None of these
Correct Answer: C. Octopus

Detailed Explanation

The octopus is a fascinating marine creature known for its intelligence, flexibility, and unique circulatory system. One of its most remarkable features is that it has three separate hearts instead of one, unlike most animals.


How the Octopus’s Three Hearts Work:


1️⃣ Two Branchial Hearts: These hearts are located near the gills. Each branchial heart pumps blood through one of the two gills, where it gets oxygenated.
2️⃣ One Systemic Heart: This main heart then pumps the oxygen-rich blood from the gills to the rest of the body, supplying energy to muscles and organs.


This three-heart system ensures efficient oxygen transport in water environments, where oxygen levels can be lower than in air.


Unique Fact About Octopus Hearts:


When an octopus swims, its systemic heart temporarily stops beating, which is why octopuses prefer crawling along the sea floor instead of continuous swimming—they tire out quickly due to reduced blood circulation while swimming.


Why Other Options Are Incorrect:




  • Crow: Like most birds and mammals, it has only one heart with four chambers.




  • Dolphin: As a mammal, it also has one heart with four chambers, similar to humans.




  • None of these: Incorrect, because the octopus (Option 3) is scientifically known to have three hearts.




Key Biological Facts:




  • Octopus blood is blue due to a copper-based protein called hemocyanin, which works better than iron-based hemoglobin in cold, low-oxygen waters.




  • Having three hearts allows better blood flow to maintain high activity levels under water pressure.




  • Other animals, like some species of squid, also share this three-heart trait.




Thus, among the given options, the correct answer is:


✅ Octopus — the only listed animal with three functioning hearts.

Discussion

Thank you for your comment! Our admin will review it soon.
No comments yet. Be the first to comment!

Leave a Comment