Principles of Inheritance and Variation
Test 4

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following traits in pea plants was NOT studied by Mendel?

Seed color
Pod shape
Leaf venation
Flower position
3

Mendel studied traits such as seed color, pod shape, and flower position but not leaf venation.

Which type of mutation occurs when a single base substitution results in a premature stop codon?

Missense mutation
Nonsense mutation
Silent mutation
Frameshift mutation
2

A nonsense mutation introduces a premature stop codon, leading to an incomplete and nonfunctional protein.

Which of the following statements about Mendelian inheritance is incorrect?

Mendel proposed the Law of Segregation and Law of Independent Assortment.
A monohybrid cross produces a 3:1 phenotypic ratio in the F2 generation.
Dihybrid crosses result in a 9:3:3:1 phenotypic ratio.
Mendel's laws apply only to plants and not to animals.
4

Mendel’s laws apply to all sexually reproducing organisms, not just plants.

Which of the following genetic disorders is incorrectly matched with its cause?

Down’s syndrome - Trisomy 21
Turner’s syndrome - 45, XO
Klinefelter’s syndrome - 47, XYY
Patau syndrome - Trisomy 13
3

Klinefelter’s syndrome is caused by the XXY karyotype, not XYY.

Which of the following statements about Mendelian inheritance is incorrect?

Mendel's experiments were conducted on pea plants.
The Law of Dominance explains why heterozygous individuals express the dominant trait.
Dihybrid crosses do not follow the Law of Independent Assortment.
The Law of Segregation states that allele pairs separate during gamete formation.
3

The Law of Independent Assortment applies to dihybrid crosses unless genes are linked.

Which genetic disorder is caused by trisomy of chromosome 21?

Turner’s syndrome
Klinefelter’s syndrome
Down’s syndrome
Edward’s syndrome
3

Down’s syndrome is caused by trisomy of chromosome 21, leading to developmental and cognitive impairments.

Which of the following best describes a test cross?

A cross between two homozygous individuals
A cross between an individual of unknown genotype and a homozygous recessive individual
A cross between two heterozygous individuals
A cross between two recessive individuals
2

A test cross is used to determine the genotype of an organism by crossing it with a homozygous recessive individual.

Which of the following represents a heterozygous genotype for a Mendelian trait?

AA
aa
Aa
AAA
3

A heterozygous genotype contains two different alleles, such as Aa.

Which of the following is an example of a chromosomal disorder caused by trisomy?

Turner’s syndrome
Sickle-cell anemia
Down’s syndrome
Phenylketonuria
3

Down’s syndrome is caused by trisomy of chromosome 21, leading to developmental and cognitive impairments.

Which law of inheritance states that alleles segregate independently during gamete formation?

Law of Dominance
Law of Segregation
Law of Independent Assortment
Hardy-Weinberg Law
3

The Law of Independent Assortment states that different gene pairs assort independently during gamete formation.

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