AP Biology · Unit 5: Heredity
5.4 Non-Mendelian Genetics
In short
You must understand various deviations from Mendel's model, including genetic linkage, codominance, incomplete dominance, sex-linked traits, pleiotropy, and non-nuclear inheritance. You are expected to know how to calculate map distance (map units) for linked genes based on segregation probabilities.
Last updated
What else do you need to know about Non-Mendelian Genetics?
For sex-linked traits, you should recognize that they reside on sex chromosomes (e.g., X or Y), are inherited at higher rates in XY individuals than XX individuals, and can be predicted using pedigrees. You must also understand that non-nuclear inheritance (mitochondrial and chloroplast DNA) is typically maternally inherited in both animals (via the egg) and plants (via the ovule). The topic includes understanding different sex determination systems as illustrative examples (e.g., ZW in birds, haplodiploidy in bees).
Can you do these?
- I can explain how linked genes, codominance, and incomplete dominance deviate from Mendelian ratios and calculate map distance between linked genes.
- I can predict the pattern of inheritance for sex-linked traits using data such as pedigrees.
- I can describe pleiotropy as a single gene resulting in multiple traits that do not segregate independently.
- I can explain how non-nuclear inheritance of chloroplast and mitochondrial DNA occurs maternally and does not follow Mendelian rules.
How is Non-Mendelian Genetics tested on the exam?
Assessment frequently involves quantitative analysis, such as performing chi-square hypothesis testing to determine if observed phenotypic ratios statistically differ from predicted Mendelian ratios. You may be required to perform mathematical calculations including means, rates, ratios, and percentages. Questions often present pedigree data to test predictions of genotypes and phenotypes for sex-linked or maternally inherited traits. A common requirement is calculating genetic map distances from linkage data. You should be careful not to apply independent assortment to linked genes or pleiotropic effects.
Free practice questions with full explanations, and instant marking of your free-response answers.
Non-Mendelian Genetics: common questions
What do you need to know about Non-Mendelian Genetics for AP Biology?
You must understand various deviations from Mendel's model, including genetic linkage, codominance, incomplete dominance, sex-linked traits, pleiotropy, and non-nuclear inheritance. You are expected to know how to calculate map distance (map units) for linked genes based on segregation probabilities.
How is Non-Mendelian Genetics tested on the AP Biology exam?
Assessment frequently involves quantitative analysis, such as performing chi-square hypothesis testing to determine if observed phenotypic ratios statistically differ from predicted Mendelian ratios. You may be required to perform mathematical calculations including means, rates, ratios, and percentages.
How do I know I have mastered Non-Mendelian Genetics?
Check you can do each of these: explain how linked genes, codominance, and incomplete dominance deviate from Mendelian ratios and calculate map distance between linked genes; predict the pattern of inheritance for sex-linked traits using data such as pedigrees; describe pleiotropy as a single gene resulting in multiple traits that do not segregate independently; explain how non-nuclear inheritance of chloroplast and mitochondrial DNA occurs maternally and does not follow Mendelian rules.
Where does Non-Mendelian Genetics fit in AP Biology?
Non-Mendelian Genetics is topic 5.4 in Unit 5: Heredity of AP Biology.
Want help mastering this topic?
Work through Non-Mendelian Genetics one-on-one with an AP Guru tutor.
Book a free demo class