Three pairs of genes with two alleles each A1 and A 2, B1 and B2 , and C 1 and C

Question

Three pairs of genes with two alleles each A1 and A2, B1 and B2 , and C1 and C2 control the height of a plant. The alleles of these genes have an additive relationship: each copy of alleles A1 , B1 , and C 1 contributes 6 cm to plant height, and each copy of alleles A 2, B2 , and C2 contributes 3 cm.

A) What is the expected height of plants with the homozygous genotype A1B1C1 ? (answer is not 18cm - can someone show me how to work this)

B) What is the expected height of plants with the homozygous genotype A2B2C2 ?

C) What height is expected in the F1 progeny of a cross between A1 A1 B1 B1C1 C1 and A2 A2 B2 B2 C2 C2 ?

D) What is the expected height of a plant with the genotype A1 A2 B2 B2C1 C2 ?

E) Identify all possible genotypes for plants with an expected height of 33 cm

F) Identify the number of different phenotypes (expected plant heights) that are possible with these three genes.

A1 A1 B1 B1C1 C2 A2 A2 B2 B2C1 C2 A1 A2 B2 B2C1 C2 A1 A1 B1 B2C1 C1 A1 A2 B1 B2C2 C2 A1 A2 B1 B2C1 C2 A1 A2 B1 B1C1 C1 None of all above.

Explanation / Answer

Here knowning the dominant and recessive pattern of the alleles would be more important to detemine the height.

A) A1B1C1 homozygous means A1B1C1A1B1C1=36

B) A2B2C2 homozygous means A2B2C2A2B2C2= 18

C) F1= A1A2B1B2C1C2=27cm

D) Height of A1 A2 B2 B2C1 C2=24cm

E) Expected genotype for plant height 33cm=A1A1B1B1C1C2, A1A1B1B2C1C1, A1A2B1B1C1C1

F) The different phenotypes (expected plant heights in Cm) that are possible with these three genes: 36, 18, 27, 24, 33.

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