Chapter 32, Problem 6STP

Summary Introduction

Introduction:

Earlier it was believed that birds are glorified from reptiles as both birds and reptiles lay eggs outside the water. Later they were compared as mammals as they have a four chambered heart with double circulation.

Answer to Problem 6STP

Correct answer:

The correct answer is option (c) birds have a large cerebrum to coordinate movement and balance.

Explanation of Solution

Explanation/justification for the correct answer:

Option (c) the cerebellum helps in the motor movement and balancing. The demands of flight and complex control of movements are fulfilled by the cerebrum in birds.

Explanation for incorrect answer:

Option (a) birds do not have a large medulla that controls their vision as they have the best vision among vertebrates which is controlled by the large optic lobes that processes the complex signals. The hindbrain consists of the medulla that acts as a junction between the brain and the spinal cord.

Option (b) cerebellum is a small brain with its two hemispheres and a complex folded surface. They help in the regulation of movement, balance cardiac, muscular activity, speech and respiratory. Cerebellum after receiving the information from the sensory systems helps in regulating motor movements. So cerebellum controls respiration but not digestion.

Option (d) Bird’s brain has a small cerebral cortex similar to that of a human brain. Some bird species do have good cognitive abilities too. Cerebellum plays a major role in maintaining the balance, movement and strength of flight. Cerebral cortex does not control flight.

Conclusion

Birds have a large cerebrum to coordinate movement and balance while in a flight.