Question 1

Which of the following best describes Mendel's particulate theory of inheritance?

Accepted Answer

Traits are inherited as discrete units that do not blend, but are passed intact from one generation to the next.

Question 2

In Mendel's experiments with pea plants, why was it important that he used 'true breeding' (homozygous) plants for his parental (P) generation crosses?

Accepted Answer

It ensured that each parent would only contribute one type of allele for the trait being studied, making inheritance patterns easier to interpret.

Question 3

A pea plant with genotype $$Tt ($$where $$T is $$tall and $$t is $$short) is crossed with another $$Tt$$ plant. What is the expected phenotypic ratio of tall to short offspring?

Accepted Answer

3 tall : 1 short

Question 4

Which of the following statements about dominant and recessive alleles is correct?

Accepted Answer

A dominant allele codes for a functional protein that masks the effect of a recessive allele, which often represents a loss of function.

Question 5

If two parents are both heterozygous for albinism ($$Aa$$), where $$A is $$normal pigmentation and $$a is $$albinism, what is the probability that their child will have albinism?

Accepted Answer

$$\displaystyle \frac{1}{4}$$

Question 6

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

Accepted Answer

During gamete formation, the two alleles for a trait separate so that each gamete receives only one allele.

Question 7

A test cross is performed between a pea plant with an unknown genotype for yellow seeds (dominant trait) and a plant with green seeds (recessive trait). If all offspring have yellow seeds, what is the genotype of the unknown parent?

Accepted Answer

Homozygous dominant ($$YY)$$

Question 8

In a dihybrid cross between two guinea pigs heterozygous for both coat color ($$B = $$black, $$b = $$brown) and fur length ($$S = $$short, $$s = $$long), what is the expected phenotypic ratio for the offspring?

Accepted Answer

9 black short : 3 black long : 3 brown short : 1 brown long

Question 9

Which of the following scenarios demonstrates Mendel's law of independent assortment?

Accepted Answer

A cross between plants differing in two traits produces offspring with new combinations of those traits not found in the parents.

Question 10

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

Accepted Answer

Genotype refers to the genetic makeup (alleles) of an organism, while phenotype refers to the observable physical traits.

Question 11

A plant with genotype $$Pp ($$purple flowers) is crossed with a plant with genotype $$pp ($$white flowers). What percentage of the offspring are expected to have purple flowers?

Accepted Answer

$$50\%$$

Question 12

Why did Mendel's choice of pea plants make his experiments on inheritance more successful than if he had used mice?

Accepted Answer

Pea plants have simple, easily distinguishable traits controlled by single genes, making inheritance patterns easier to track.

Question 13

During meiosis, which event explains why only one allele for each trait is present in a gamete?

Accepted Answer

Homologous chromosomes separate during meiosis I.

Question 14

A woman and her partner are both carriers for a recessive genetic disorder. What is the probability that their first child will be unaffected (either carrier or non-carrier)?

Accepted Answer

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

Question 15

If a plant is heterozygous for two traits ($$RrYy) $$and self-fertilizes, what fraction of the offspring will be homozygous recessive for both traits?

Accepted Answer

$$\displaystyle \frac{1}{16}$$

Question 16

Which of the following is an example of a monohybrid cross?

Accepted Answer

Crossing two pea plants that differ only in flower color.

Question 17

A man with genotype $$Aa$$ and a woman with genotype $$aa$$ have a child. What is the probability that the child will be a carrier (heterozygous) for the trait?

Accepted Answer

$$50\%$$

Question 18

Which of the following best explains why a recessive trait can 'skip' a generation and reappear in the next?

Accepted Answer

The recessive allele can be carried in a heterozygous individual without being expressed, and two carriers can produce a homozygous recessive offspring.

Question 19

In a Punnett square for a cross between two heterozygous individuals ($$Yy x$$ $$Yy$$), what is the expected genotypic ratio among the offspring?

Accepted Answer

1 homozygous dominant : 2 heterozygous : 1 homozygous recessive

Mendelian Genetics: Patterns of Inheritance and Fundamental Laws

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