Q: Which equation represents the probability of obtaining an offspring with genotype $$YYRR$$ from a dihybrid cross ($$YyRr \times YyRr$$)?

$$\frac{1}{4} \times \frac{1}{4} = \frac{1}{16}$$

Q: A couple each has a sibling with a recessively inherited disease. What is the probability that their child will have the disease, assuming both are carriers?

$$\frac{2}{3} \times \frac{2}{3} \times \frac{1}{4} = \frac{1}{9}$$

Question 1

Which principle did Mendel's experiments with garden peas disprove, and what did he propose instead?

Accepted Answer

The blending hypothesis; Mendel proposed the particulate hypothesis.

Question 2

In Mendel’s pea plant experiments, what is the expected phenotypic ratio in the F2 generation when crossing two heterozygous plants for flower color?

Accepted Answer

3 purple : 1 white

Question 3

If a pea plant with genotype $$PP is $$crossed with a plant with genotype $$pp$$, what will be the genotype of all F1 offspring?

Accepted Answer

All will be $$Pp$$

Question 4

What is the purpose of a testcross in genetics?

Accepted Answer

To determine the genotype of an individual with a dominant phenotype

Question 5

According to Mendel’s law of segregation, what happens to alleles during gamete formation?

Accepted Answer

The two alleles for a heritable character separate and end up in different gametes

Question 6

A dihybrid cross between two heterozygous pea plants ($$YyRr 	imes YyRr) $$produces what phenotypic ratio in the F2 generation?

Accepted Answer

$$9:3:3:1$$

Question 7

Which equation represents the probability of obtaining an offspring with genotype $$YYRR$$ from a dihybrid cross ($$YyRr 	imes YyRr$$)?

Accepted Answer

$$\frac{1}{4} 	imes \frac{1}{4} = \frac{1}{16}$$

Question 8

Which term describes an organism with two identical alleles for a gene?

Accepted Answer

Homozygote

Question 9

In incomplete dominance, what is the expected phenotype of the F1 generation when crossing a red snapdragon ($$RR) $$with a white snapdragon ($$rr$$)?

Accepted Answer

All F1 will be pink

Question 10

Which of the following best explains why dominant alleles are not necessarily more common in a population?

Accepted Answer

Dominance does not determine allele frequency; other factors like mutation and selection affect frequency

Question 11

Which genetic principle is illustrated when the probability of two independent events occurring together is calculated by multiplying their individual probabilities?

Accepted Answer

Multiplication rule

Question 12

A couple each has a sibling with a recessively inherited disease. What is the probability that their child will have the disease, assuming both are carriers?

Accepted Answer

$$\frac{2}{3} 	imes \frac{2}{3} 	imes \frac{1}{4} = \frac{1}{9}$$

Question 13

Which term describes a gene that affects multiple phenotypic traits, such as the symptoms seen in sickle-cell disease?

Accepted Answer

Pleiotropy

Question 14

In Labrador retrievers, coat color is determined by two genes. If two black labs with genotype $$BbEe$$ are crossed, what is the expected phenotypic ratio?

Accepted Answer

9 black : 3 chocolate : 4 yellow

Question 15

Which inheritance pattern is indicated when a trait shows a continuous range of phenotypes, such as human height?

Accepted Answer

Polygenic inheritance

Question 16

What is the effect of environmental factors on the phenotype of an organism with a given genotype?

Accepted Answer

Environmental factors can broaden the phenotypic range, especially for polygenic traits

Question 17

Which technique is used to visually assess fetal health and detect genetic disorders during pregnancy?

Accepted Answer

Ultrasound

Question 18

What is the genotype of a carrier for a recessively inherited disorder?

Accepted Answer

Heterozygous ($$Aa)$$

Question 19

Which law states that alleles for different genes assort independently during gamete formation?

Accepted Answer

Law of independent assortment

Question 20

If a genetic disorder is caused by a dominant allele, what is the likelihood that a child will inherit the disorder if one parent is heterozygous and the other is homozygous recessive?

Accepted Answer

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

Mendelian Genetics: Principles of Heredity and Patterns of Inheritance

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