If a trait is simple and genetically inherited, then: -The trait is not determin

Question

If a trait is simple and genetically inherited, then:

-The trait is not determined by enviornmental factors

-Two distinct phenotypes are observed

-One allele is dominant and one allele is recessive. Two parents with recessive phenotypes will produce offspring with the recessive phenotype

-Identical twins express the same phenotype

Do these traits follow simple Mendelian Laws?

2. Tongue Rolling

Claim: Tongue rolling is a simple, two-allele inherited trait, and the allele for rolling (R) is dominant over the nonrolling allele (r).

Analyze the following information to support or refute the claim

a) Values complied from a number of studies reveal that the tongue rolling phenotype occurs in 65-82% of individuals. (10/12 people could roll their tongue in my class)

b) Some individuals can slightly lift the edges of their tongue but cannot completely roll it.

c) Another study revealed that tongue rolling can be learned. Many children cannot roll their tongues when first asked, but develop the ability over time.

d) A study conducted by Philip Matlock in 1940 examined the tongue rolling ability of 33 pairs of identical twins. Eighteen pairs of twins were capable of rolling their tongues, and eight pairs of twins were not. In seven pairs, one identical twin could perform tongue rolling, but the other could not.

Explanation / Answer

tongue rolling is a Mendelian trait, i.e, dominant and recessive alleles have been identified. however, its inheritance is not much understood.

in most of the cases, dominant trait (rolling tongue) is observed. however, studies have shown that people who were not able to roll their tongue at first, were able to roll after a few attempts. the role of recessiveness stands controversial in such cases.

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