What is a karyotype?

• A. A representation of alleles
• B. A photographic representation of all chromosomes in a cell
• C. A process of gene expression
• D. A collection of traits in an organism

Answer: (B)

A karyotype is defined as a photographic representation of all chromosomes in a cell, typically organized and displayed in a systematic way. This visual arrangement allows for the identification and analysis of an organism's chromosomal characteristics, such as number, size, shape, and any potential chromosomal abnormalities. Karyotyping is often used in genetic studies and clinical settings to diagnose genetic disorders or to evaluate chromosomal structure.

The other options presented do not accurately define a karyotype. While alleles are related to genetic expression, a karyotype does not represent alleles but rather the physical chromosomes themselves. Additionally, a process of gene expression would pertain to how genes are activated and translated into proteins, which is distinct from what a karyotype illustrates. Finally, a collection of traits pertains to phenotypes and characteristics of an organism rather than the chromosomal analysis provided by a karyotype. Thus, the correct choice captures the essence of what a karyotype represents in the field of genetics.