Genetic Inheritance

In the case of mitochondrial inheritance, if a woman with a mitochondrial disorder has children, what percentage of her children are expected to inherit the disorder?

• 0%

• 25%

• 50%

• 100%

Answer explanation

Mitochondrial disorders are passed down from the mother to all her children, resulting in 100% of her children inheriting the disorder.

What is the expected phenotype ratio in the offspring when two individuals heterozygous for a codominant trait mate?

• 1:2:1

• 3:1

• 9:3:3:1

• 1:1

Answer explanation

When two individuals heterozygous for a codominant trait mate, the expected phenotype ratio in the offspring is 1:2:1, representing the genotypes of homozygous dominant, heterozygous, and homozygous recessive, respectively.

An individual with two different alleles for a specific trait is said to be: (a)    

• homozygous

• heterozygous

• homogeneous

• heterogeneous

Answer explanation

An individual with two different alleles for a specific trait is said to be heterozygous.

How many males are shown in this pedigree? (a)  

• 8

• 5

• 2

• 16

Answer explanation

There are 8 males shown in the pedigree. This is determined by counting the number of male symbols in the pedigree diagram.

In this pedigree, (a)   can be carriers of colorblindness and not have it.

• Just males

• Just females

• Both genders

Answer explanation

Only females can be carriers of colorblindness and not have it, as they inherit the trait on the X chromosome and can have one normal X chromosome to compensate.

Cystic Fibrosis is a recessive trait. A heterozygous genotype (Cc) will show the phenotype (a)   .

• CC

• Cc

• cc

• Normal (unaffected or carrier)

• Cystic Fibrosis (affected)

Answer explanation

A heterozygous genotype (Cc) for Cystic Fibrosis will show the Normal (unaffected or carrier) phenotype as it is a recessive trait.

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

A woman with an X-linked dominant disorder has children with a man who does not have the disorder. The probability that their son will inherit the disorder is (a)   .

• 0%

• 25%

• 50%

• 100%

Answer explanation

The son has a 50% chance of inheriting the X-linked dominant disorder from the mother, as he will receive either her affected X chromosome or the father's Y chromosome.

Tags

NGSS.HS-LS3-1

In X-linked recessive inheritance, a healthy woman (carrier) and a healthy man have a child. What is the probability that their daughter will be a carrier of the X-linked recessive trait?

• 0%

• 25%

• 50%

• 100%

Answer explanation

The daughter has a 50% chance of inheriting the X-linked recessive trait from her carrier mother, making her a carrier as well.

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-3

A child inherits a mitochondrial disorder. Which parent is most likely to have passed on this disorder?

• The father

• The mother

• Both parents equally

• It is impossible to determine

Answer explanation

The mother is most likely to have passed on the mitochondrial disorder because mitochondria are inherited exclusively from the mother.

In a pedigree chart, a square represents (a)   .

• A female affected by the trait in q

• A male affected by the trait in que

• A female carrier of the trait in qu

• A male carrier of the trait in ques

Answer explanation

In a pedigree chart, a square represents a male affected by the trait.