Centromere is part of

The pore size of the nuclear membrane is approximately:

When the centromere is present slightly away from the middle of the chromosome,the chromosome is called $:-$

The genomic content of the nucleus is constant for a given species,whereas the extrachromosomal $DNA$ is found to be variable among the members of a population. Explain.

$DNA$ is primarily found in:

Robert Brown is well known for the discovery of . . . . . . .