Mendelian Inheritance

Syllabus tag: KCSE | Biology | Form 4 | Topic 1 Genetics

Lesson objectives

By the end of this topic, you should be able to:

• Define the terms used in genetics and use correct symbols.
• Work monohybrid crosses and predict ratios.
• Explain the test cross and incomplete dominance.
• Work dihybrid crosses and state Mendel's laws.

Summary

A characteristic is controlled by a pair of alleles, one from each parent. A dominant allele shows whenever present; a recessive allele shows only when both are recessive. Crossing two heterozygotes gives the 3:1 monohybrid ratio. A test cross with the recessive reveals whether a dominant individual is homozygous or heterozygous.