Q: Embryos usually don't survive if they have extra or too few of these genetic units?


Read this paragraph and choose the correct option from the provided answers:

Outside of chromosome 21 and the sex chromosomes, most embryos with extra chromosomes do not usually survive. Because chromosomes carry many, many genes, a disruption of a chromosome can cause severe problems with the development of a fetus. Individuals with one (or more) fewer chromosome usually don't survive either. Can you explain why?.

 Choices:

- phenotypes

- genes

- ribosomes

- chromosomes


A:
chromosomes