Genetics: Part II - Practice Quiz (English)

Passing of parents' DNA in genes that code for proteins/traits to their offspring in the next generation.

• Meiosis

• Genetics

• Heredity

• Variation

Answer explanation

Heredity refers to the passing of genetic information from parents to offspring, which includes DNA that codes for proteins and traits. This process is fundamental to the inheritance of characteristics in the next generation.

In pedigrees, what do shaded shapes represent?

• Individuals without the trait

• Individuals with the trait

• Carriers of the trait

• Deceased individuals

Answer explanation

In pedigrees, shaded shapes represent individuals with the trait being studied. This visual representation helps identify who expresses the trait in a family lineage.

What is this diagram called?

• Karyotype

• Pedigree

• Punnett Square

• Dihybrid Cross

• None of the above

Answer explanation

The diagram is called a pedigree, which is used to show the inheritance of traits across generations in a family. It helps track genetic conditions and relationships, distinguishing it from karyotypes and Punnett squares.

1. People with Type AB blood have two dominant alleles, I^A and I^B. Since the two alleles are equally dominant, they are called _______________ alleles.

• polygenic

• incomplete

• codominant

• sex linked

Answer explanation

People with Type AB blood express both I^A and I^B alleles equally, which means neither allele masks the other. This characteristic is known as codominance, where both traits are fully expressed.

Looking at this pedigree, how many family members have the trait?

• None

• Three males

• Three females

• Six males and females

Answer explanation

The pedigree shows three males with the trait, confirming the correct answer is 'Three males'. The other options do not accurately represent the individuals with the trait in the pedigree.

In pedigrees, what do squares represent?

• Parents

• Females

• Males

• Children

Answer explanation

In pedigrees, squares represent males, while circles represent females. Therefore, the correct answer is that squares indicate male individuals in the family tree.

Females with a recessive sex-linked trait or disorder will have which genotype/s?

• X^DX^d or X^dX^d

• X^DX^D or X^DX^d

• X^DX^D or X^dX^d

• Only X^dX^d

• Only X^DX^D

Answer explanation

Females with a recessive sex-linked trait must have two copies of the recessive allele. Therefore, the only genotype they can have is X^dX^d, making this the correct choice.

Fathers can pass sex linked disorders and traits to their:

• Daughters only

• Sons only

• Sons and daughters

• Neither sons nor daughters

Answer explanation

Fathers pass X-linked traits to their daughters because daughters inherit one X chromosome from their father. Sons inherit their father's Y chromosome, not the X, so they do not receive these traits.

Hemophilia is more common in males than in females because ____________________________.

• fathers can only pass the allele for hemophilia to their sons

• mothers cannot pass the allele for hemophilia to their daughters

• the allele for hemophilia is dominant and located on the Y chromosome

• the allele for hemophilia is recessive and located on the X chromosome

Answer explanation

Hemophilia is more common in males because the allele is recessive and located on the X chromosome. Males have only one X chromosome, so if they inherit the allele, they will express the condition, unlike females who have two X chromosomes.

If a woman is a carrier for a sex linked recessive trait of hemophilia and her husband has hemophilia, which of the following statements is true?

• 100% of sons will have hemophilia

• 100% of daughters will have hemophilia

• 50% of daughters and 50% of sons have hemophilia

• 100% of sons have hemophilia and 100% of daughters are carriers

Answer explanation

The woman, being a carrier, can pass on the hemophilia allele to her children. Sons inherit the Y chromosome from their father, so 50% will have hemophilia. Daughters inherit one X chromosome from each parent, making 50% carriers and 50% affected.