Which of the following statement is not correct with respect to the chromosomes?

Chromosomes are straight, rod-like, coiled or thread-like in structure.

Chromosomes range from 0.5 to 30 microns in length and from 0.2 to 3 microns in diameter.

Each Chromosome has a centromere, which holds together the two chromatids.

There is a variable number of chromosomes in each cell.

There are two types of chromosomes found in the human body - Autosomes and Allosomes.