Questions and Answers
Define polygenic inheritance.
Polygenic inheritance is when two or more genes affect the expression of one trait.
Explain how polygenic inheritance contributes to continuous variation.
When multiple genes control the expression of a phenotype, many possible phenotypes can exist, leading to continuous variation.
Explain how human skin colour is an example of polygenic inheritance.
People's skin colour varies dramatically due to multiple genes affecting the intensity of the pigments in the skin.
Explain how human height is an example of polygenic inheritance.
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Study Notes
Polygenic Inheritance
- Polygenic inheritance involves two or more genes influencing the expression of a single trait.
Continuous Variation
- Traits influenced by a single gene typically result in limited phenotypes, focusing on dominant or recessive traits.
- Co-dominance introduces additional potential phenotypes, expanding variation.
- In polygenic inheritance, multiple genes contribute to one phenotype, leading to a greater number of possible phenotypes.
- As the number of genes affecting a trait increases, it becomes more challenging to deduce genotype solely from phenotype observations.
- Each additional gene contributes an additive effect, enhancing phenotype diversity, a phenomenon known as continuous variation.
- With an increased number of controlling genes, the distribution of phenotypes tends to approximate a normal distribution.
Human Skin Colour
- Skin colour exhibits substantial diversity both globally among different races and within the same race.
- Multiple genes regulate the intensity of skin pigments, resulting in varied skin tones.
Human Height
- Height shows considerable variation among individuals, which is influenced by both environmental and genetic factors.
- It exemplifies continuous variation, as heights across populations demonstrate a wide range rather than fixed categories.
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Description
This quiz focuses on the concept of polygenic inheritance in biology. You'll learn about the definition of polygenic inheritance and how it leads to continuous variation in traits. Test your understanding of genetics with these flashcards.
