Some chromosomes have non-staining secondary constrictions at a constant location. This gives the appearance of a small fragment called the ......

The given diagram shows the types of chromosomes (labelled as $A, B, C$ and $D$) based on the position of the centromere. Which one is the correct option for the labelled chromosomes $A, B, C$ and $D$?

$L-$ shaped chromosomes are called

Where is the satellite found?

The structure of the nuclear envelope is helpful in ...... .

Two sister chromatids are held together at the chromosome by which of the following structures?