Sex Determination, Linkage and Blood Groups
Genetics · Sex Determination and Linkage
Syllabus tag: KCSE | Biology | Form 4 | Topic 1 Genetics
Lesson objectives
By the end of this topic, you should be able to:
- Explain sex determination in humans using sex chromosomes.
- Explain linkage and how crossing over breaks it.
- Work problems on sex-linked characteristics.
- Explain the inheritance of the ABO blood groups and multiple alleles.
Summary
Sex is determined by the sex chromosomes: females are XX and males XY. Since the mother can give only X, the father determines the sex of the child. Genes on the same chromosome are linked and inherited together unless separated by crossing over. Genes on the X chromosome give sex-linked conditions, which affect males far more often.