Questions and Answers
What color offspring do snapdragon flowers produce when red and white flowers are crossed?
Pink (RW) offspring.
What type of flower color results from crossing red and white four o'clock plants?
Pink (RW) flowers.
Which coat color results from crossing a chestnut horse and a cremello horse?
Palomino (Cc) offspring.
When red and white cattle are bred, what is the resulting phenotype of the offspring?
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If woolly mammoths had incomplete dominance for hair traits, what might a cross between hairy and hairless individuals yield?
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What color feathers do chickens produce when black feathers are crossed with white feathers?
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Study Notes
Incomplete Dominance
Example Organisms
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Snapdragon Flowers (Antirrhinum majus)
- Color inheritance: Red (RR) and white (WW) flowers produce pink (RW) offspring.
- Demonstrates blending of traits.
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Four O'Clock Plants (Mirabilis jalapa)
- Flower color inheritance: Red (RR) and white (WW) plants yield pink (RW) flowers.
- Exhibits the same blending pattern as snapdragons.
-
Horses
- Coat color inheritance: A cross between a chestnut horse (CC) and a cremello horse (cc) can produce palomino offspring (Cc).
- Shows blending of coat colors.
-
Cattle
- Coat color inheritance: A red (RR) and white (WW) parent can produce roan (RW) offspring, which have a mix of red and white hairs.
- Example of incomplete dominance in livestock.
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Woolly Mammoths
- Hypothetical genetic model: If woolly mammoths had incomplete dominance for hair traits, a cross between hairy (HH) and hairless (hh) could yield intermediate fur density (Hh).
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Feather Color in Chickens
- Inheritance of feather color can show incomplete dominance, such as black (BB) and white (WW) producing blue (BW) feathers.
Key Concepts
- Incomplete dominance occurs when the phenotype of heterozygotes is an intermediate mix of the two homozygous phenotypes.
- It differs from complete dominance, where one allele completely masks the other.
Incomplete Dominance
- Incomplete dominance leads to offspring exhibiting a blended phenotype from two parent traits.
- Distinct from complete dominance, where one allele fully masks the effect of another.
Example Organisms
-
Snapdragon Flowers (Antirrhinum majus):
- A cross between red (RR) and white (WW) flowers produces pink (RW) flowers, illustrating the blending of traits.
-
Four O'Clock Plants (Mirabilis jalapa):
- Similar to snapdragons, these plants show that a red (RR) and white (WW) cross results in pink (RW) flowers.
-
Horses:
- Mating a chestnut horse (CC) with a cremello horse (cc) can result in palomino offspring (Cc), demonstrating blending in coat color.
-
Cattle:
- A red (RR) and white (WW) parent produces roan (RW) offspring, displaying a mix of red and white hairs.
-
Woolly Mammoths:
- Hypothetically, if incomplete dominance existed for hair traits, crossing hairy (HH) with hairless (hh) could yield intermediate fur density (Hh).
-
Feather Color in Chickens:
- Black (BB) and white (WW) feathers can produce blue (BW) feathers, showcasing incomplete dominance in their feather color traits.
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Description
Explore the fascinating concept of incomplete dominance through various examples, including snapdragon flowers and horses. This quiz covers inheritance patterns that result in blending traits and showcases real-life organisms that exhibit this genetic phenomenon. Test your understanding of how these traits manifest in different species!
