Question 1

Which of the following statements best explains why Mendel's experiments with pea plants disproved the blending hypothesis of inheritance?

Accepted Answer

The F₂ generation showed a 3:1 ratio of dominant to recessive traits, indicating traits are inherited as discrete units.

Question 2

A true-breeding purple-flowered pea plant (PP) is crossed with a true-breeding white-flowered plant (pp). What is the expected genotype and phenotype ratio of the F₂ generation after self-pollinating the F₁ plants?

Accepted Answer

Genotype ratio 1:2:1 (PP:Pp:pp); Phenotype ratio 3:1 (purple:white)

Question 3

Which law states that alleles for different traits segregate independently during gamete formation, and under what condition does this law not apply?

Accepted Answer

Law of Independent Assortment; does not apply if genes are close together on the same chromosome

Question 4

In a dihybrid cross between two heterozygous pea plants (YyRr x YyRr), what is the probability of obtaining an offspring with yellow round seeds (dominant for both traits)? Use the multiplication rule.

Accepted Answer

$$\frac{9}{16}$$

Question 5

A test cross is performed between a pea plant with purple flowers of unknown genotype and a white-flowered plant (pp). If all offspring have purple flowers, what is the genotype of the purple-flowered parent?

Accepted Answer

Homozygous dominant (PP)

Question 6

Which inheritance pattern is illustrated when a heterozygote expresses a phenotype intermediate between the two homozygotes, such as pink flowers from red and white parents?

Accepted Answer

Incomplete dominance

Question 7

A person with genotype $$I^A I^B$$ for the ABO blood group will have which blood type, and what inheritance pattern does this illustrate?

Accepted Answer

Type AB; codominance

Question 8

Which genetic phenomenon is described when a single gene affects multiple, seemingly unrelated traits, such as the gene for sickle-cell anemia?

Accepted Answer

Pleiotropy

Question 9

In Labrador retrievers, one gene determines pigment color (B = black, b = brown), and another gene (E/e) determines whether pigment is deposited. What is the phenotype of a dog with genotype bbEe?

Accepted Answer

Brown coat

Question 10

Human height is influenced by many genes, each contributing a small effect. What is this type of inheritance called?

Accepted Answer

Polygenic inheritance

Question 11

A hydrangea plant with the same genotype produces blue flowers in acidic soil and pink flowers in alkaline soil. What does this example illustrate?

Accepted Answer

Environmental influence on phenotype

Question 12

Refer to the second pedigree (with Josh and Ada). If Ada is a carrier (Ww) for an autosomal recessive disorder and Josh is unaffected but has affected siblings, what is the probability that Josh is a carrier?

Accepted Answer

$$\frac{2}{3}$$

Question 13

Given that Ada is Ww and Josh has a $$\frac{2}{3}$$ chance of being a carrier (Ww), what is the probability that their child will have the disease (ww)?

Accepted Answer

$$\frac{1}{6}$$

Question 14

Which of the following best describes the inheritance pattern of a disorder that appears in both males and females, skips generations, and is more likely to appear when parents are related?

Accepted Answer

Autosomal recessive

Question 15

A pedigree shows a rare disorder present in every generation, affecting both males and females, and two affected parents have an unaffected child. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 16

Which genetic test involves sampling amniotic fluid to detect chromosomal abnormalities in a fetus?

Accepted Answer

Amniocentesis

Question 17

A couple, both carriers for cystic fibrosis (an autosomal recessive disorder), want to know the probability that their child will be unaffected. What is the probability?

Accepted Answer

$$\frac{3}{4}$$

Question 18

Which of the following is an example of a multifactorial disorder?

Accepted Answer

Heart disease

Question 19

If a genetic counselor uses a Punnett square to predict the probability of a child inheriting a certain trait, which rule of probability is used when calculating the chance of a specific genotype from independent events?

Accepted Answer

Multiplication rule

Question 20

Which of the following best describes a carrier for a recessive genetic disorder?

Accepted Answer

Heterozygous individual who does not show the disorder but can pass the allele to offspring

Genetics & Inheritance: Mendelian and Non-Mendelian Patterns

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