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Which of the following statements incorrectly illustrates incomplete dominance?
Select one:
a. Tall plants crossed with short plants produce medium height plants.
b. Dark brown fur crossed with white fur produces yellow fur.
c. A black horse crossed with a white horse produces a mixture of white and black hair in a horse.
d. Red flowers crossed with white flowers produce pink flowers

5 months ago

Answered By Arsalan Q

The phrasing of this question is what I imagine is tricky for you. Incomplete dominance is defined as a mix of the dominant and recessive allele. Its often described as "half way" between the two phenotypic expressions. The most common example of incomplete dominance in human beings is wavy hair, it's halfway between the dominant curly hair and the recessive straight hair. With that in mind, the answer to this question is whichever offspring is not a mix of the two parents.

a) this is definitely incomplete dominance, halway between short and tall is medium, so this option checks out

b) Half way between dark brown and white should theoretically be light brown not yellow, so this option is a candidate for our right answer as it doesnt look like incomplete dominance, rather a sepreat heterozygous expression

c) The word "mixture" makes this sound oddly like co-dominance, where both the dominant and recessive alleles are fully expressed which is different from incomplete dominance. However that simply may be a result of the way the question is phrased, and it's in fcat trying to convey that it is actually grey hair and is a halway between the two phenotypes.

d) red and white mixed together produce pink, the halfway expression. This is for sure incomplete dominance

In context of the question (specifcally options a and d) it makes it seem like the question is challenging our ability to reaosn this out with logic. A and D are incomplete because short+tall=medium and red+white=pink. through logic brown+white doesnt equal yellow. 

Therefore by logic option b seemes to be the right answer as it incorrectly displays incomplete dominance