Question 1

In a dihybrid test cross between an individual heterozygous for two genes (AaBb) and a homozygous recessive individual (aabb), what is the expected phenotypic ratio if the genes assort independently?

Accepted Answer

1:1:1:1

Question 2

Which of the following best describes the Law of Segregation?

Accepted Answer

Homologous chromosomes separate during Anaphase I of Meiosis, reducing ploidy from $$2N to$$ $$N$$

Question 3

A pedigree shows a trait appearing in every generation and affecting both males and females equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 4

Cystic Fibrosis is caused by a recessive allele. If two heterozygous parents have a child, what is the probability that the child will be affected?

Accepted Answer

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

Question 5

In a monohybrid cross between two heterozygotes ($$Aa 	imes Aa$$), what is the expected genotypic ratio among the offspring?

Accepted Answer

1:2:1

Question 6

A gene exhibits pleiotropy. Which of the following best describes this phenomenon?

Accepted Answer

A single gene affects multiple, seemingly unrelated phenotypic traits

Question 7

In a cross involving recessive lethality, what is the expected phenotypic ratio among the offspring?

Accepted Answer

2:1

Question 8

Which stage of meiosis is responsible for increasing genetic diversity through crossing over?

Accepted Answer

Prophase I

Question 9

If a gene pair exhibits recessive epistasis, what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

9:3:4

Question 10

A researcher observes a deviation from the expected 1:1:1:1 ratio in a dihybrid test cross. What is the most likely explanation?

Accepted Answer

The gene loci are linked

Question 11

How many different gametes can an individual with genotype $$AaBbCc$$ produce, assuming independent assortment?

Accepted Answer

$$2^3 = 8$

Question 12

Which of the following best describes the function of the synaptonemal complex during meiosis?

Accepted Answer

It facilitates the pairing and recombination of homologous chromosomes

Question 13

A woman with Turner Syndrome has which karyotype?

Accepted Answer

45,X

Question 14

Which of the following is true about Barr bodies?

Accepted Answer

They are inactivated X chromosomes found in cells with more than one X chromosome

Question 15

In a Chi-square test, how is the degrees of freedom ($$df) $$calculated for a genetic cross with $$n$$ phenotypic classes?

Accepted Answer

$$df = n - 1$$

Question 16

A male with Klinefelter Syndrome will have which genotype?

Accepted Answer

47,XXY

Question 17

Which event distinguishes Meiosis I from Mitosis?

Accepted Answer

Homologous chromosomes pair and separate, while sister chromatids remain together

Question 18

If the recombinant frequency between two genes is 50%, what does this indicate about their chromosomal location?

Accepted Answer

They are either on different chromosomes or far apart on the same chromosome

Question 19

Which gene is crucial for male sex determination in humans?

Accepted Answer

SRY gene

Question 20

A cross between two purple-flowered plants produces a 9:7 ratio of purple to white flowers in the F2 generation. What genetic phenomenon does this illustrate?

Accepted Answer

Reciprocal recessive epistasis

Genetics Exam 1 Review: Mendelian Inheritance, Chromosome Behavior, and Genetic Mapping

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