Q: A woman and her partner are both heterozygous for the gene causing albinism ($$Aa). $$They want to know the probability that their first two children will both have normal pigmentation. What is the probability?

$$\left(\frac{3}{4}\right) \times \left(\frac{3}{4}\right) = \frac{9}{16}$$

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

$$3:1$$

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 $$A is $$the dominant normal pigment allele and $$a is $$the recessive albinism allele, what is the probability that their child will have albinism?

Accepted Answer

$$25\%$$

Question 6

Mendel's law of segregation is best explained by which event during meiosis?

Accepted Answer

The separation of homologous chromosomes during meiosis I.

Question 7

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

Accepted Answer

$$YY$$

Question 8

In a dihybrid cross between two heterozygous guinea pigs ($$BbSs$$), where $$B is $$black coat, $$b is $$brown coat, $$S is $$short hair, and $$s is $$long hair, what is the expected phenotypic ratio for the F2 generation?

Accepted Answer

$$9:3:3:1$$

Question 9

Which of the following best illustrates Mendel's law of independent assortment?

Accepted Answer

A plant can inherit a tall stem and either green or yellow pods, independent of each other.

Question 10

If a plant with genotype $$Pp ($$purple flowers, where $$P is $$dominant and $$p is $$recessive) is self-crossed, what is the expected genotypic ratio among the offspring?

Accepted Answer

$$1\ PP : 2\ Pp : 1\ pp$$

Question 11

A woman and her partner are both heterozygous for the gene causing albinism ($$Aa). $$They want to know the probability that their first two children will both have normal pigmentation. What is the probability?

Accepted Answer

$$\left(\frac{3}{4}ight) 	imes \left(\frac{3}{4}ight) = \frac{9}{16}$$

Question 12

Which of the following is an example of a phenotype?

Accepted Answer

A pea plant has white flowers.

Question 13

Why did Mendel's use of pea plants (Pisum sativum) contribute to the success of his experiments?

Accepted Answer

Pea plants have easily distinguishable traits, short generation times, and can be both self- and cross-pollinated.

Question 14

A man with genotype $$Aa ($$normal pigmentation) and a woman with genotype $$aa ($$albinism) have a child. What is the probability that the child will have albinism?

Accepted Answer

$$50\%$$

Question 15

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

Accepted Answer

Genotype is the genetic makeup (alleles) of an organism, while phenotype is the observable physical trait.

Question 16

In a dihybrid cross, what is the probability that an offspring will be homozygous recessive for both traits if both parents are heterozygous for both traits ($$AaBb 	imes AaBb$$)?

Accepted Answer

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

Question 17

A plant breeder wants to determine if a tall pea plant is homozygous dominant ($$TT) or $$heterozygous ($$Tt). $$Which cross should they perform and what result would confirm homozygosity?

Accepted Answer

Cross with a homozygous recessive ($$tt) $$plant; if all offspring are tall, the parent is $$TT.$$

Question 18

Which of the following real-world scenarios best demonstrates the law of independent assortment?

Accepted Answer

A child inherits brown eyes and attached earlobes, while their sibling inherits blue eyes and free earlobes.

Question 19

If a plant with genotype $$Yy ($$yellow seeds) is crossed with a plant with genotype $$yy ($$green seeds), what percentage of the offspring are expected to have yellow seeds?

Accepted Answer

$$50\%$$

Question 20

Which of the following best explains why recessive traits can reappear in later generations after being absent in the parental generation?

Accepted Answer

Recessive alleles can be carried in a heterozygous state and only expressed when an individual is homozygous recessive.

Mendelian Genetics: Patterns of Inheritance and Fundamental Laws

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