Question 1

Which of the following best describes the difference between genotype and phenotype?

Accepted Answer

Genotype refers to the genetic makeup, while phenotype refers to the observable traits.

Question 2

In Mendel’s experiments, what is the expected phenotypic ratio in the F2 generation for a monohybrid cross between two heterozygous individuals ($Tt 	imes Tt$) where $T$ is dominant over $t$?

Accepted Answer

$3:1$

Question 3

Which principle states that alleles of different genes assort independently of one another during gamete formation?

Accepted Answer

Law of Independent Assortment

Question 4

A couple, both carriers for cystic fibrosis ($Ff$), want to know the probability that their child will inherit cystic fibrosis. What is the probability, using the Punnett square?

Accepted Answer

$\frac{1}{4}$

Question 5

Which of the following is an example of codominance?

Accepted Answer

A person with AB blood type expressing both A and B antigens

Question 6

If two parents are both heterozygous for two traits ($RrYy$), what is the probability that their offspring will be homozygous recessive for both traits ($rryy$)? Use the multiplication rule.

Accepted Answer

$\frac{1}{16}$

Question 7

Which term describes a single gene affecting multiple, seemingly unrelated traits?

Accepted Answer

Pleiotropy

Question 8

A pedigree shows a trait that skips generations and affects males and females equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal recessive

Question 9

Which of the following best explains incomplete dominance?

Accepted Answer

The heterozygote shows a phenotype intermediate between the two homozygotes.

Question 10

A genetic counselor is analyzing a family history for Huntington’s disease, which is autosomal dominant. If one parent is heterozygous ($Hh$) and the other is homozygous recessive ($hh$), what is the probability their child will inherit Huntington’s disease?

Accepted Answer

$\frac{1}{2}$

Question 11

Which of the following is a real-world example of polygenic inheritance?

Accepted Answer

Human skin color

Question 12

A testcross is performed between a pea plant with unknown genotype and a homozygous recessive plant. If all offspring show the dominant phenotype, what is the genotype of the unknown parent?

Accepted Answer

Homozygous dominant

Question 13

Which genetic principle is illustrated when a person with sickle-cell trait (heterozygous) is resistant to malaria?

Accepted Answer

Pleiotropy

Question 14

If a couple, both with genotype $AaBb$, have a child, what is the probability that the child will have at least one dominant allele for both genes?

Accepted Answer

$\frac{9}{16}$

Question 15

Which of the following procedures is used to sample fetal cells for genetic testing during pregnancy?

Accepted Answer

Amniocentesis

Question 16

A man with blood type $O$ marries a woman with blood type $AB$. What are the possible blood types of their children?

Accepted Answer

A and B only

Question 17

Which of the following is NOT a multifactorial disorder?

Accepted Answer

Cystic fibrosis

Question 18

If a trait is controlled by multiple genes and shows a continuous range of phenotypes, which inheritance pattern does it follow?

Accepted Answer

Polygenic inheritance

Question 19

Which of the following best describes the addition rule in genetics?

Accepted Answer

The probability that two mutually exclusive events will occur is the sum of their individual probabilities.

Question 20

A woman is a carrier for sickle-cell anemia ($Ss$) and her partner is also a carrier ($Ss$). What is the probability that their child will be homozygous dominant ($SS$)?

Accepted Answer

$\frac{1}{4}$

Genetics I: Mendel and the Gene Idea – Study Notes

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