EasyBiologyHigh School (11–12)Heredity and Evolution › Principles of Inheritance and VariationConceptualAPA-LevelIB
Name the pattern for each of these statements: incomplete dominance, codominance, pleiotropy…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Name the pattern for each of these statements: incomplete dominance, codominance, pleiotropy, multiple alleles or polygenic inheritance.
- A person with the genotype has both antigens on the red cells.
- A single mutation in the gene for one enzyme causes mental retardation and also pale skin and hair.
- A gene for coat colour in a population has four different alleles.
- Adult height depends on many genes, and each one adds a little.
- Red-flowered and white-flowered plants give pink flowers in the F1.
Need a reminder? The key ideaShow
In incomplete dominance the heterozygote is intermediate, and the F2 ratio is 1 : 2 : 1 for the phenotype too. The ABO gene has the alleles , and i. and are codominant, and both are dominant over i. In polygenic inheritance each dominant allele adds one unit, and the classes follow the binomial numbers.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Both alleles show in full. This is codominance.
Step 2. (b) One gene has several effects. This is pleiotropy.
Step 3. (c) A population has more than two alleles of one gene. This is multiple alleles. Each person still has only two of them.
Step 4. (d) Many genes shape one trait. This is polygenic inheritance.
Step 5. (e) The heterozygote is in between the two parents. This is incomplete dominance.
Answer: (a) codominance; (b) pleiotropy; (c) multiple alleles; (d) polygenic inheritance; (e) incomplete dominance.
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