Question 1

Which of the following best describes Mendel's law of segregation?

Accepted Answer

Two alleles for a heritable character separate during gamete formation and end up in different gametes.

Question 2

In Mendel's pea plant experiments, what phenotypic ratio did he observe in the F2 generation when crossing two heterozygous purple-flowered plants ($$Pp 	imes Pp$$)?

Accepted Answer

$$3:1$$

Question 3

A testcross is performed between a plant with a dominant phenotype and a homozygous recessive plant. If any offspring display the recessive phenotype, what can you conclude about the genotype of the parent with the dominant phenotype?

Accepted Answer

It must be heterozygous.

Question 4

Which of the following is an example of incomplete dominance?

Accepted Answer

A cross between red ($$CRCR) $$and white ($$CWCW) $$snapdragons produces pink ($$CRCW) $$flowers.

Question 5

Which of the following best illustrates the concept of pleiotropy?

Accepted Answer

A single gene mutation causing blindness, liver failure, and heart attack in sickle-cell disease.

Question 6

In a dihybrid cross between two heterozygous pea plants ($$YyRr 	imes YyRr$$), what is the expected phenotypic ratio for the offspring if the genes assort independently?

Accepted Answer

$$9:3:3:1$$

Question 7

Which of the following statements about alleles is correct?

Accepted Answer

Alleles are different forms of a gene found at the same locus on homologous chromosomes.

Question 8

A woman with blood type A ($$IAi) $$and a man with blood type B ($$IBi) $$have a child. Which of the following blood types is NOT possible for their child?

Accepted Answer

Type C

Question 9

Which of the following best describes polygenic inheritance?

Accepted Answer

Multiple genes contribute additively to a single phenotypic trait, such as human height.

Question 10

In Labrador retrievers, coat color is determined by two genes. One gene determines the pigment color (B = black, b = brown), and another gene determines whether pigment is deposited (E = pigment, e = no pigment). What is the expected phenotypic ratio in the offspring of two $$BbEe$$ dogs?

Accepted Answer

$$9$$ black : $$3$$ brown : $$4$$ yellow

Question 11

A man with achondroplasia (a dominant disorder, genotype $$Dd) $$and a woman with normal stature ($$dd) $$have children. What is the probability that their child will have normal stature?

Accepted Answer

$$0.5$$

Question 12

Which of the following is an example of codominance?

Accepted Answer

A person with blood type AB expresses both A and B antigens on their red blood cells.

Question 13

If two carriers for albinism ($$Aa 	imes Aa) $$have a child, what is the probability that the child will be phenotypically normal but a carrier?

Accepted Answer

$$1/2$$

Question 14

Which of the following best explains why Mendel chose pea plants for his experiments?

Accepted Answer

Pea plants have many distinct, heritable characters and can self-pollinate or be cross-pollinated.

Question 15

A gene has three alleles in the population: $$IA$$, $$IB$$, and $$i. $$Which human trait is determined by these alleles?

Accepted Answer

Blood type (ABO system)

Question 16

Which of the following scenarios best demonstrates the law of independent assortment?

Accepted Answer

A plant with round yellow seeds ($$RrYy) $$produces gametes with all possible combinations of alleles ($$RY$$, $$Ry$$, $$rY$$, $$ry).$$

Question 17

Which of the following is NOT a reason why humans are poor subjects for genetic research compared to pea plants?

Accepted Answer

Humans have only one allele for each gene.

Question 18

A woman with genotype $$IAIB$$ and a man with genotype $$ii$$ have children. What are the possible blood types of their children?

Accepted Answer

A and B

Question 19

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

Accepted Answer

Genotype is the genetic makeup, while phenotype is the observable characteristics.

Question 20

A couple, both carriers for cystic fibrosis (an autosomal recessive disorder), are expecting a child. What is the probability that their child will have cystic fibrosis?

Accepted Answer

$$1/4$$

CH 14- Mendel and the Gene Idea: Patterns of Inheritance

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