Question

Secondary constriction is also called as

• A. Nucleo-chromosome
• B. Nucleolar organizer
• C. SAT chromosome
  
• D. None of the above

Answer 1

The correct option is B Nucleolar organizer

Secondary constrictions are narrow areas and are of two types: joints and Nucleolar Organizing Region (NOR). Joints are areas involved in breaking and fusion of chromosome segments. NOR or nucleolar organizer region is secondary constriction capable of forming nucleolus in interphase. Satellite or trabant is knob-like part distal to NOR. The chromosomes with trabant are called SAT chromosomes. The satellite does not take stain/stains poorly.

So, the correct answer is 'Nucleolar organizer'