What does a karyotype display?

A karyotype provides a visual representation of an organism's chromosomes, showing their number and structural characteristics. It is essentially a photograph of the chromosomes arranged in pairs according to size and shape, and it helps in identifying chromosomal abnormalities, such as aneuploidy (an abnormal number of chromosomes) or structural changes in the chromosomes. Karyotyping is a crucial technique in genetics and cytogenetics for analyzing chromosomal abnormalities in health and disease.

In contrast, the other options describe different aspects of genetic information. The genetic sequence refers to the specific order of nucleotides in DNA, which is not visible in a karyotype. Phenotypic traits are the observable characteristics that result from the interaction of genetics and the environment, which also cannot be directly inferred from a karyotype. Lastly, gene expression involves the process of translating DNA information into proteins, which is not represented in the structure of chromosomes displayed in a karyotype. Thus, the correct understanding of a karyotype centers on its role in displaying the number and appearance of chromosomes within a cell's nucleus.