Chromosomes are made up of

Which of the following is mismatched?

In which of the following organisms is the given structure $NOT$ found?

Which of the following are used to define the karyotype of a species?
$1$. The number of chromosomes
$2$. The chromosome length
$3$. The positions of the centromeres

The pore size of the nuclear membrane is approximately:

The study of the nucleus is called .....