Question

Plss help Due today! 40 points and brainliest to best answer!! Help Plzzz!
1) Identify the trait that you believe to be dominant for each of the features surveyed. Explain your reasoning.

2) What recessive features do you exhibit? Do you have any relatives who exhibit those same features?

3) In the family you surveyed, what features did the offspring share with one or both parents? Were there any features that the offspring exhibited that were not exhibited by either parent?

4) How is it possible for an offspring to exhibit a recessive trait if neither parent exhibited that recessive trait? What must be true about the parents’ genes for this to occur?

5) Are there any results in your data that surprised you?

6) It is possible that a recessive trait in a survey such as this one may have a greater total number than its dominant counterpart. Explain how that might happen in an investigation like this.

7) How might surveying a different number of people or different population of people possibly change the percentages that you calculated?

Use the info in the fallowing images to answer these questions plss.

Answer 1

The proposed traits exhibit mostly complete dominance and one of them incomplete dominance. Free earlobe, hair on the knuckle, widow's peak, curly hair and cleft on the chin are the dominant traits.

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1)

Features:

• Earlobe (Free or attached) ⇒ controlled by a single diallelic gene expressing complete dominance

Free is dominant // Attached is recessive

• Hair on the knuckle (yes or no) ⇒ controlled by a five-allelic single gene.

Presence of hair is dominant // Absence of hair is recessive

• Hairline ( Widow's peak or straight) ⇒ Coded by a single diallelic gene.

Widow's peak is dominant // Straight line is recessive

• Hair texture (Straight or curly) ⇒ Coded by a single diallelic gene, expressing incomplete dominance.

Curly is dominant // Straight is recessive // Wavy hair is the intermediate phenotype

• Chin shape (Cleft or no cleft) ⇒ Coded by a single diallelic gene

The cleft is dominant // No cleft is recessive

2)

Recessive traits :

• Absence of hair in the knuckle

• No cleft in the chin

Mother, sister, and brother with no hair on the knuckle.

Mother, father, sister, and brother with no cleft in the chin

3)

Surveyed family composed of mother, father, two sisters and a boy.

• Earlobe (Free or attached)

Mother and father with free earlobe

Their three children have free earlobes

The offspring share the trait with both parents.

• Hair on knuckle

Father with hair and mother with no hair on the knuckle

Their three children do not have hair on their knuckles

The offspring share the trait with the mother but not with the father.

• Hairline

Mother and father exhibiting the widow's peak

The three children have widow's peak

The offspring share the trait with both parents.

• Hair texture (Straight or curly)

Mother and father have curly hair

Two daughters have curly hair

Son has wavy hair

The sisters share the trait with both parents, but the boy does not.

• Chin shape (Cleft or no cleft)

Mother and father with no cleft on the chin

Children with no cleft on the chin

The offspring share the trait with both parents.

4)

If a recessive trait appears only in one of the children but no parent expresses it, it means that the mother and the father must be heter0zyg0us and that the gene coding for the trait expresses complete dominance.

Let us picture the cross:

Parentals) Pp x Pp

Gametes) P p P p

Punnett square)        P         p

                      P         PP       Pp

                      p          Pp      pp

F1) 3/4 of the progeny will express the dominant trait (PP + Pp)

     1/4 of the progeny will express the recessive trait (pp)

So even when both parents are expressing the dominant trait, their children can express the recessive trait.

5)

Yes. Most of the traits are coded by diallelic single genes expressing complete dominance. But hair texture shows incomplete dominance, with a third phenotype different from the ones expressed by h0m0zyg0us individuals.

Also, hair on the knuckles exhibits graduation of the phenotype. Individuals that express the dominant trait and have hair on knuckles may have short thin hair, thick long hair, and many intermedia phenotypes. This is because the gene coding for this trait is 5-allelic.

6)

Yes, it is possible. Two reasons can explain this,

1- Because in the population the frequency of the recessive genotype is higher than the frequency of the h0m0zyg0us dominant and heter0zyg0us genotypes.

This could be because the recessive genotype improves the fitness of individuals, so its frequency is increasing in the population.

Or because of Mating systems ⇒ Endogamia or mating with individuals exhibiting similar genotype/phenotype.

2- By random chances. Sampled individuals could exhibit recessive traits by chance.

7)

Sampling a higher or lower number of individuals in the population will affect the results.

• Sampling a small number of individuals can not reflect what is actually happening in the population. There are high chances of sampling individuals of the same genotype and phenotype.

• Sampling many individuals will provide more reliable information about the population under study. There are high chances of getting individuals to express all possible genotypes and phenotypes.

• Sampling individuals from another population might include genes that were not present in the first population. It might increase diversity and heterogeneity.

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