Zoology

Chromosomes are classified based on the position of the centromere:

• Metacentric Chromosome: The centromere is located at the center, dividing the chromosome into two equal arms.
• Sub-metacentric Chromosome: The centromere is slightly away from the middle, resulting in one arm being slightly longer than the other.
• Acrocentric Chromosome: The centromere is located close to one end, producing a very short arm and a long arm.
• Telocentric Chromosome: The centromere is at the very end, forming a single arm.

In sub-metacentric chromosomes, the arms are unequal due to the centromere being slightly off-center.

The vertebral column is divided into the following regions in sequence from the skull:

• Cervical (B): The first seven vertebrae starting from the skull, labeled , support the neck.
• Thoracic (A): The next twelve vertebrae, labeled , are located in the upper back and connect to the ribs.
• Lumbar (D): The five larger vertebrae, labeled , are in the lower back and bear the body’s weight.
• Sacral (C): A group of fused vertebrae located at the base of the spine.

Hence, the correct sequence is Cervical, Thoracic, Lumbar, and Sacral.