Genetics: Mendelian inheritance — KCSE Biology

KCSE Biology · 79 practice questions · 4 syllabus objectives

25 easy35 medium19 hard

What You'll Learn

Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.

State Mendel's laws of inheritance

Solve genetics problems using Punnett squares for monohybrid crosses

Explain sex determination and sex-linked traits

Genetics: Mendelian inheritance

Sample Questions

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1
easySHORT ANSWER3 marks

State Mendel's law of independent assortment and give one example to illustrate it. (3 marks)

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Part (a) — 3 marks
Law of Segregation: the two alleles of a gene separate during gamete formation so each gamete carries only one allele (1 mk)
Law of Independent Assortment: alleles of different genes are distributed to gametes independently of one another (applies to genes on different chromosomes) (1 mk)
Example for each — e.g. Segregation: Tt parent → T or t gametes; Independent Assortment: TtYy → TY, Ty, tY, ty gametes in equal proportions (1 mk)
2
easySHORT ANSWER2 marks

Name the genetic disorder described below and state its mode of inheritance. "The blood of affected individuals fails to clot normally due to absence of a clotting factor; the condition is far more common in males than females" (2 marks)

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Part (a) — 2 marks
Correct name of the genetic disorder (1 mk)
Correct mode of inheritance stated (1 mk)
3
easySHORT ANSWER3 marks

State Mendel's law of independent assortment and give one example to illustrate each law. (3 marks)

View Marking Scheme
Part (a) — 3 marks
Law of Segregation: the two alleles of a gene separate during gamete formation so each gamete carries only one allele (1 mk)
Law of Independent Assortment: alleles of different genes are distributed to gametes independently of one another (applies to genes on different chromosomes) (1 mk)
Example for each — e.g. Segregation: Tt parent → T or t gametes; Independent Assortment: TtYy → TY, Ty, tY, ty gametes in equal proportions (1 mk)
4

Name the genetic disorder described below and state its mode of inheritance. "Affected individuals lack melanin pigment in skin, hair, and eyes; they are highly sensitive to sunlight and are at increased risk of skin cancer" (2 marks)

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