Question 1

Which statement best describes the difference between genotype and phenotype?

Accepted Answer

Genotype is an individual's complete set of alleles, while phenotype is the observable physical and functional traits resulting from those alleles and environmental influences.

Question 2

A woman who is heterozygous for the MC1R gene (Ff) marries a man who is homozygous recessive (ff) for freckles. What is the probability that their child will have freckles?

Accepted Answer

$\frac{1}{2}$

Question 3

Which of the following best explains why individuals with sickle cell trait (Hb	extsuperscript{A}Hb	extsuperscript{S}) are less likely to die from malaria?

Accepted Answer

They produce both normal and sickle hemoglobin, which provides some protection against malaria without causing severe anemia.

Question 4

Which genetic principle states that the alleles of different genes are distributed to gametes independently during meiosis?

Accepted Answer

Law of independent assortment

Question 5

A man with genotype X	extsuperscript{h}Y (hemophilia) and a woman who is a carrier (X	extsuperscript{H}X	extsuperscript{h}) have a child. What is the probability that their son will have hemophilia?

Accepted Answer

$\frac{1}{2}$

Question 6

Which of the following is an example of incomplete dominance?

Accepted Answer

Wavy hair resulting from one straight hair allele and one curly hair allele.

Question 7

A child is born with Down syndrome. Which chromosomal abnormality is responsible for this condition?

Accepted Answer

Trisomy 21

Question 8

Which of the following best describes polygenic inheritance?

Accepted Answer

Multiple genes contribute to a trait, resulting in a continuous range of phenotypes.

Question 9

A couple, both heterozygous for the cystic fibrosis gene (Ff), are expecting a child. What is the probability that their child will have cystic fibrosis?

Accepted Answer

$\frac{1}{4}$

Question 10

Which of the following is true regarding dominant alleles?

Accepted Answer

Dominant alleles are expressed in the phenotype even if only one copy is present.

Question 11

Which scenario best illustrates the concept of epigenetic inheritance?

Accepted Answer

Environmental factors cause methylation of DNA, altering gene expression without changing the DNA sequence.

Question 12

A male with Klinefelter syndrome has which chromosomal composition?

Accepted Answer

XXY

Question 13

Which of the following is a real-world example of a disease caused by a dominant-lethal allele?

Accepted Answer

Huntington disease

Question 14

If a father is homozygous dominant for the ability to taste PTC (TT) and the mother is homozygous recessive (tt), what will be the genotype and phenotype of their children?

Accepted Answer

All children will be Tt and able to taste PTC.

Question 15

Which of the following best explains why linked alleles may not always be inherited together?

Accepted Answer

Crossing over during meiosis can shuffle alleles that are far apart on the same chromosome, reducing the likelihood they are inherited together.

Question 16

A woman who is a carrier for hemophilia (X	extsuperscript{H}X	extsuperscript{h}) and a man with normal blood clotting (X	extsuperscript{H}Y) have a daughter. What is the probability that their daughter will be a carrier?

Accepted Answer

$\frac{1}{2}$

Question 17

Which of the following is NOT a characteristic of autosomes?

Accepted Answer

They are the sex chromosomes (X and Y).

Question 18

Which genetic disorder is caused by a deletion on chromosome 5?

Accepted Answer

Cri-du-chat syndrome

Question 19

Which of the following best describes codominance?

Accepted Answer

Both alleles in a heterozygote are fully expressed in the phenotype.

Question 20

A child with phenylketonuria (PKU) must limit phenylalanine in their diet. What is the genetic basis for this disease?

Accepted Answer

It is caused by a recessive allele inherited from both parents.

Genetics and Inheritance: Human Biology Chapter 19 Study Notes

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