Q: A cross between two heterozygous pea plants for seed shape (Rr x Rr) results in what probability of producing a homozygous dominant (RR) offspring? Use the multiplication rule.

$$\frac{1}{2} \times \frac{1}{2} = \frac{1}{4}$$

Question 1

Which of the following best explains why Mendel's use of the garden pea (Pisum sativum) was crucial for his experiments on inheritance?

Accepted Answer

Peas produce many offspring, have easily distinguishable traits, and allow controlled matings.

Question 2

A cross between two heterozygous pea plants for seed shape (Rr x Rr) results in what probability of producing a homozygous dominant (RR) offspring? Use the multiplication rule.

Accepted Answer

$$\frac{1}{2} 	imes \frac{1}{2} = \frac{1}{4}$$

Question 3

Which statement best describes the Principle of Segregation as observed by Mendel?

Accepted Answer

Each gamete receives only one allele for each gene, restoring diploidy upon fertilization.

Question 4

In a dihybrid cross between two plants heterozygous for both seed shape (Rr) and seed color (Yy), what is the expected phenotypic ratio in the F2 generation, assuming independent assortment?

Accepted Answer

9:3:3:1

Question 5

A woman who is a carrier for red-green color blindness (an X-linked recessive trait) has children with a man who has normal vision. What is the probability that their son will be color blind?

Accepted Answer

$$\frac{1}{2}$$

Question 6

Which of the following scenarios demonstrates pleiotropy?

Accepted Answer

A single gene mutation causes both long limbs and heart defects in Marfan syndrome.

Question 7

If two genes are located close together on the same chromosome, which of the following is most likely to occur?

Accepted Answer

They will be inherited together more often than not due to genetic linkage.

Question 8

A geneticist observes that the recombination frequency between two genes is 12%. What is the map distance between these genes?

Accepted Answer

$$12$$ map units

Question 9

Which of the following best describes codominance?

Accepted Answer

Both alleles are fully expressed in the heterozygote, as seen in AB blood type.

Question 10

A pedigree shows a trait that appears in every generation and is present in both males and females. Which inheritance pattern is most likely?

Accepted Answer

Autosomal dominant

Question 11

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

Accepted Answer

Type A or Type B

Question 12

Which of the following is an example of a quantitative trait?

Accepted Answer

Human height, which shows continuous variation and a bell-shaped distribution

Question 13

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

Accepted Answer

Homozygous dominant

Question 14

Which of the following best explains why X-linked recessive traits are more commonly expressed in males than females?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will be expressed.

Question 15

A child is born with phenylketonuria (PKU), a genetic disorder. Which of the following best describes how environmental intervention can prevent the symptoms of PKU?

Accepted Answer

A low-phenylalanine diet prevents the buildup of phenylalanine, avoiding nervous system damage.

Question 16

If a gene exhibits incomplete dominance, what phenotype will a heterozygote display?

Accepted Answer

An intermediate phenotype between the two homozygotes

Question 17

Which of the following best describes the concept of expressivity?

Accepted Answer

The degree to which a genotype is expressed in an individual, which can vary among individuals with the same genotype.

Question 18

A woman with polydactyly (an autosomal dominant trait) and a man without the trait have a child without polydactyly. What is the most likely genotype of the woman?

Accepted Answer

Heterozygous

Question 19

Which of the following is true regarding the chromosome theory of inheritance?

Accepted Answer

Genes are located on chromosomes, and their behavior during meiosis explains inheritance patterns.

Question 20

A cross between a red-flowered and a white-flowered four o'clock plant produces all pink-flowered offspring. What type of inheritance is this an example of?

Accepted Answer

Incomplete dominance

Mendel and the Gene: Patterns and Mechanisms of Inheritance

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