Which of the following accurately describes a typical human karyotype?
a. 2 sex chromosomes and 44 autosomal chromosomes are pictured.
b. 23 pairs of chromosomes are arranged from smallest to largest.
c. 46 pairs of chromosomes are arranged from largest to smallest.
d. 22 pairs of sex chromosomes and 1 pair of autosomal chromosomes are pictured.

The answer is B.

A typical human karyotype has 23 types of chromosomes arranged from smallest to largest. In males and females 22 of these chromosomes look exactly the same and they are called autosomes. The 23rd pair of chromosomes is the sex chromosome which differentiates males from females. Females have 2 copies of the x chromosome. Males have a copy of both x and y chromosome to make the 23rd pair. 

Chromosomes can also have abnormalities that result to different conditions and identifiable traits. A most common chromosomal abnormality is the condition called Down Syndrome, where chromosome 21 has a third copy because of an abnormal cell division.