Principles of Inheritance and Variation
Test 3

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following laws was proposed by Gregor Mendel based on his pea plant experiments?

Law of Evolution
Law of Segregation
Law of Independent Mutation
Law of Genetic Drift
2

Mendel proposed the Law of Segregation, stating that alleles separate independently during gamete formation.

What is the probability of a female child being born in humans?

100%
75%
50%
25%
3

The probability of having a female child is 50% since fertilization is equally likely to occur with an X or Y sperm.

Which scientist developed the Punnett square to predict genetic crosses?

Gregor Mendel
Reginald C. Punnett
Thomas Hunt Morgan
Walter Sutton
2

Reginald C. Punnett developed the Punnett square as a graphical representation to predict genetic outcomes.

Which concept explains the inheritance of two genes located on different chromosomes?

Linkage
Law of Independent Assortment
Pleiotropy
Epistasis
2

The Law of Independent Assortment states that genes located on different chromosomes assort independently during gamete formation.

Which of the following statements about Turner’s syndrome is correct?

It is caused by trisomy of chromosome 21.
Individuals have a 47, XXY chromosome composition.
Affected individuals have only one X chromosome (45, XO).
It affects only males.
3

Turner’s syndrome is caused by monosomy of the X chromosome, leading to a 45, XO genotype.

Which of the following statements about the Law of Segregation is incorrect?

It states that allele pairs separate during gamete formation.
It explains why recessive traits can reappear in later generations.
It applies only to genes on the same chromosome.
It is one of Mendel’s fundamental principles of inheritance.
3

The Law of Segregation applies to all genes, not just those on the same chromosome.

Which of the following statements about genetic disorders is correct?

Down’s syndrome is caused by trisomy of chromosome 18.
Sickle-cell anemia is caused by a mutation in the β-globin gene.
Klinefelter’s syndrome is caused by monosomy of the Y chromosome.
Hemophilia is an autosomal dominant disorder.
2

Sickle-cell anemia is caused by a single base mutation in the β-globin gene, leading to abnormal hemoglobin.

Who proposed the Chromosomal Theory of Inheritance?

Mendel and Morgan
Sutton and Boveri
Watson and Crick
Henking and Sturtevant
2

Sutton and Boveri proposed the Chromosomal Theory of Inheritance, linking genes to chromosomes.

Which type of inheritance is observed when a single gene influences multiple traits?

Polygenic inheritance
Incomplete dominance
Co-dominance
Pleiotropy
4

Pleiotropy occurs when a single gene affects multiple phenotypic traits, such as in phenylketonuria.

Which of the following best describes polygenic inheritance?

A single gene controls multiple traits
Multiple genes influence a single trait
One gene completely masks another gene
A single mutation affects multiple systems
2

Polygenic inheritance occurs when multiple genes contribute to a single phenotype, as seen in human height and skin color.

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