Question 1

Which of the following best explains why Mendel chose pea plants for his experiments on heredity?

Accepted Answer

Pea plants have easily distinguishable traits and can be cross-pollinated or self-pollinated.

Question 2

According to the chromosome theory of inheritance, what is the relationship between genes and chromosomes?

Accepted Answer

Genes are located at specific loci on chromosomes, and chromosomes are the vehicles of genetic inheritance.

Question 3

In Mendel’s experiments, what is the expected phenotypic ratio in the F2 generation when crossing two heterozygous pea plants for a single trait?

Accepted Answer

$$3:1$$

Question 4

Which of the following statements about X-linked recessive disorders is correct?

Accepted Answer

Males only need one copy of the recessive allele to express the disorder.

Question 5

A woman who is heterozygous for the X-linked gene for color blindness (X$$^NX$^n) $$has children with a man who has normal vision (X$$^NY). $$What is the probability that their son will be color blind?

Accepted Answer

$$0.25$$

Question 6

Which process is responsible for the production of recombinant phenotypes in offspring of a dihybrid cross involving linked genes?

Accepted Answer

Crossing over between homologous chromosomes during prophase I

Question 7

If two genes are located far apart on the same chromosome, what is the expected recombination frequency between them?

Accepted Answer

$$50\%$$

Question 8

A male with Klinefelter syndrome has which of the following karyotypes?

Accepted Answer

$$XXY$$

Question 9

Which of the following best describes the phenomenon of X inactivation in female mammals?

Accepted Answer

One X chromosome in each cell is randomly inactivated, forming a Barr body.

Question 10

A child is born with cri du chat syndrome, which is caused by:

Accepted Answer

A deletion in chromosome 5

Question 11

Which of the following is an example of a non-Mendelian inheritance pattern?

Accepted Answer

Genomic imprinting, where gene expression depends on the parent of origin

Question 12

A plant with genotype $$YyRr is $$test-crossed with a plant with genotype $$yyrr. If $$the genes are unlinked, what is the expected phenotypic ratio among the offspring?

Accepted Answer

$$1:1:1:1$$

Question 13

Which of the following statements about mitochondrial inheritance is correct?

Accepted Answer

Mitochondrial genes are inherited only from the mother.

Question 14

Which event during meiosis is responsible for the law of independent assortment?

Accepted Answer

Random orientation of homologous chromosome pairs during metaphase I

Question 15

A genetic map is constructed using recombination frequencies. If two genes have a recombination frequency of $$12\%$$, how many map units apart are they?

Accepted Answer

$$12$$ map units

Question 16

Which of the following best describes aneuploidy?

Accepted Answer

A condition in which an organism has an abnormal number of a particular chromosome

Question 17

Which of the following is a likely consequence of a translocation between chromosomes 9 and 22 in humans?

Accepted Answer

Chronic myelogenous leukemia (CML)

Question 18

If a female is heterozygous for an X-linked gene and X inactivation occurs, what is the expected phenotype?

Accepted Answer

She may display a mosaic phenotype, expressing both alleles in different cells.

Question 19

Which of the following best explains why linked genes do not always show perfect linkage in offspring?

Accepted Answer

Crossing over during meiosis can separate linked genes, resulting in recombinants.

Question 20

Which of the following is an example of polyploidy?

Accepted Answer

A plant species with four complete sets of chromosomes ($$4n)$$

Chromosomal Basis of Inheritance and Exceptions to Mendelian Genetics

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