The fact that about 80% of mouse genes have a corresponding gene in the human genome suggests what about mammalian genomes?

• A. Humans and mice share many identical genes
• B. Humans have far more genes than mice
• C. All mouse genes have a human counterpart
• D. Mouse genes are completely different from human genes

Answer: (A)

The main idea here is that mammalian genomes share a large portion of their gene content. If about 80% of mouse genes have a corresponding human gene, it means there is substantial overlap in the genes present in both species, reflecting their close evolutionary relationship and the conservation of many basic biological functions. This shared gene set is what lets scientists use mice as models to study human biology, since many genes likely play similar roles in both.

It’s important to note that not every mouse gene will have a human counterpart, and the genes aren’t necessarily identical in sequence or regulation. There are species-specific genes and variations in copy number or regulatory elements. But the substantial overlap supports the idea that humans and mice share many similar genes.