ESTUDYR
ILLINOIS COSMETOLOGY STATE BOARD 2025 UPDATED EXAM
WITH MOST TESTED QUESTIONS AND ANSWERS | GRADED A+
| ASSURED SUCCESS WITH DETAILED RATIONALES
1. How many bivalents form during prophase of meiosis I in the primary oocyte of the gray wolf (Canis
lupus), which has 78 chromosomes in its diploid cells?
A. 39
B. 78
C. 156
D. 26
Answer: A. 39
Rationale: A bivalent is a pair of homologous chromosomes. Since the gray wolf has 78 chromosomes
(2n = 78), there are 39 homologous pairs, forming 39 bivalents during prophase I of meiosis.
2. In meiosis, homologous chromosomes pair and crossover during ________, and bivalents line up on
the equatorial plate of the cell during ________.
A. Prophase I, Metaphase I
B. Metaphase I, Metaphase II
C. Prophase II, Metaphase II
D. Anaphase I, Anaphase II
Answer: A. Prophase I, Metaphase I
Rationale: Homologous chromosomes pair and crossover during prophase I, and bivalents align on the
equatorial plate during metaphase I.
3. In a cross of AABB x aabb, how frequent are the individuals displaying the dominant trait for both
genes in the F1 offspring?
A. 100%
B. 75%
C. 50%
D. 25%
Answer: A. 100%
Rationale: All F1 offspring will have the genotype AaBb, displaying the dominant traits for both genes.
,ESTUDYR
4. The phenomenon in which a single gene is responsible for both salty sweat on the skin and thick
mucus in the lungs is described as:
A. Codominance
B. Pleiotropy
C. Epistasis
D. Incomplete dominance
Answer: B. Pleiotropy
Rationale: Pleiotropy occurs when a single gene influences multiple phenotypic traits.
5. Two white-flowered daffodil mutants produce yellow-flowered F1 progeny. The two white-
flowered mutants complement one another because:
A. They have mutations in two different genes of the same biochemical pathway
B. They have mutations in the same gene
C. They are both homozygous recessive
D. They are both heterozygous
Answer: A. They have mutations in two different genes of the same biochemical pathway
Rationale: Complementation occurs when two mutations in different genes restore the wild-type
phenotype in the F1 generation.
6. In maize, a cross of two white-seeded plants produces all purple-seeded F1 progeny. When two
purple-seeded F1 plants are crossed, the F2 population segregates 9 purple:7 white. What type of
inheritance is this?
A. Complementary gene action
B. Codominance
C. Incomplete dominance
D. Epistasis
Answer: A. Complementary gene action
Rationale: A 9:7 ratio in the F2 generation indicates complementary gene action, where two genes
interact to produce a single trait.
7. The pedigree below shows the inheritance of a genetic disease in a human family. How is this
disease inherited?
,ESTUDYR
A. X-linked dominant
B. Autosomal recessive
C. Autosomal dominant
D. X-linked recessive
Answer: A. X-linked dominant
Rationale: X-linked dominant inheritance is characterized by affected mothers passing the trait to all
their sons and daughters, and affected fathers passing the trait only to their daughters.
8. Genes that show recombination between them 50% of the time:
A. Are not linked, may be on different chromosomes, or may be far apart on the same chromosome
B. Are tightly linked
C. Are always on the same chromosome
D. Are always on different chromosomes
Answer: A. Are not linked, may be on different chromosomes, or may be far apart on the same
chromosome
Rationale: A 50% recombination frequency indicates independent assortment, which occurs when genes
are not linked or are far apart on the same chromosome.
9. When genes are ____________, the number of parental genes is significantly higher than the
number of recombinant types in the test cross progeny.
A. Tightly linked on the same chromosome
B. On different chromosomes
C. Far apart on the same chromosome
D. Not linked
Answer: A. Tightly linked on the same chromosome
Rationale: Tightly linked genes have fewer crossovers, resulting in more parental types than
recombinants.
10. Gregor Mendel reported that flower color and seed color traits assorted independently because:
A. The two genes are far apart on the same chromosome
B. The two genes are on different chromosomes
C. The two genes are tightly linked
D. The two genes are codominant
, ESTUDYR
Answer: A. The two genes are far apart on the same chromosome
Rationale: Genes far apart on the same chromosome assort independently due to frequent crossovers.
11. Genes Q and P are linked and 20 map units apart. In the cross Qp/qP x qp/qp, what fraction of the
progeny will be QP/qp?
A. 10%
B. 20%
C. 40%
D. 80%
Answer: A. 10%
Rationale: The recombination frequency is 20%, so 10% of the progeny will be QP/qp (half of the
recombinants).
12. Familial Down syndrome is a result of which of the following?
A. Translocation
B. Nondisjunction
C. Deletion
D. Inversion
Answer: A. Translocation
Rationale: Familial Down syndrome is caused by a translocation involving chromosome 21.
13. A grasshopper with a chromosomal abnormality shows a dicentric bridge in primary
spermatocytes. Which chromosome pair belongs to this grasshopper?
A. A B C D ● E F G H I J K L A B C D ● E F K J I H G L
B. A B C D ● E F G H I J K L A B C D ● E F G H I J K L
C. A B C D ● E F G H I J K L A B C D ● E F G H I J K L
D. A B C D ● E F G H I J K L A B C D ● E F G H I J K L
Answer: A. A B C D ● E F G H I J K L A B C D ● E F K J I H G L
Rationale: The dicentric bridge indicates an inversion, which is shown in the first option.
14. Which of the following describes an organism whose genome contains a haploid set (n) of
chromosomes from one species plus a haploid set (n) of chromosomes from another species?
ILLINOIS COSMETOLOGY STATE BOARD 2025 UPDATED EXAM
WITH MOST TESTED QUESTIONS AND ANSWERS | GRADED A+
| ASSURED SUCCESS WITH DETAILED RATIONALES
1. How many bivalents form during prophase of meiosis I in the primary oocyte of the gray wolf (Canis
lupus), which has 78 chromosomes in its diploid cells?
A. 39
B. 78
C. 156
D. 26
Answer: A. 39
Rationale: A bivalent is a pair of homologous chromosomes. Since the gray wolf has 78 chromosomes
(2n = 78), there are 39 homologous pairs, forming 39 bivalents during prophase I of meiosis.
2. In meiosis, homologous chromosomes pair and crossover during ________, and bivalents line up on
the equatorial plate of the cell during ________.
A. Prophase I, Metaphase I
B. Metaphase I, Metaphase II
C. Prophase II, Metaphase II
D. Anaphase I, Anaphase II
Answer: A. Prophase I, Metaphase I
Rationale: Homologous chromosomes pair and crossover during prophase I, and bivalents align on the
equatorial plate during metaphase I.
3. In a cross of AABB x aabb, how frequent are the individuals displaying the dominant trait for both
genes in the F1 offspring?
A. 100%
B. 75%
C. 50%
D. 25%
Answer: A. 100%
Rationale: All F1 offspring will have the genotype AaBb, displaying the dominant traits for both genes.
,ESTUDYR
4. The phenomenon in which a single gene is responsible for both salty sweat on the skin and thick
mucus in the lungs is described as:
A. Codominance
B. Pleiotropy
C. Epistasis
D. Incomplete dominance
Answer: B. Pleiotropy
Rationale: Pleiotropy occurs when a single gene influences multiple phenotypic traits.
5. Two white-flowered daffodil mutants produce yellow-flowered F1 progeny. The two white-
flowered mutants complement one another because:
A. They have mutations in two different genes of the same biochemical pathway
B. They have mutations in the same gene
C. They are both homozygous recessive
D. They are both heterozygous
Answer: A. They have mutations in two different genes of the same biochemical pathway
Rationale: Complementation occurs when two mutations in different genes restore the wild-type
phenotype in the F1 generation.
6. In maize, a cross of two white-seeded plants produces all purple-seeded F1 progeny. When two
purple-seeded F1 plants are crossed, the F2 population segregates 9 purple:7 white. What type of
inheritance is this?
A. Complementary gene action
B. Codominance
C. Incomplete dominance
D. Epistasis
Answer: A. Complementary gene action
Rationale: A 9:7 ratio in the F2 generation indicates complementary gene action, where two genes
interact to produce a single trait.
7. The pedigree below shows the inheritance of a genetic disease in a human family. How is this
disease inherited?
,ESTUDYR
A. X-linked dominant
B. Autosomal recessive
C. Autosomal dominant
D. X-linked recessive
Answer: A. X-linked dominant
Rationale: X-linked dominant inheritance is characterized by affected mothers passing the trait to all
their sons and daughters, and affected fathers passing the trait only to their daughters.
8. Genes that show recombination between them 50% of the time:
A. Are not linked, may be on different chromosomes, or may be far apart on the same chromosome
B. Are tightly linked
C. Are always on the same chromosome
D. Are always on different chromosomes
Answer: A. Are not linked, may be on different chromosomes, or may be far apart on the same
chromosome
Rationale: A 50% recombination frequency indicates independent assortment, which occurs when genes
are not linked or are far apart on the same chromosome.
9. When genes are ____________, the number of parental genes is significantly higher than the
number of recombinant types in the test cross progeny.
A. Tightly linked on the same chromosome
B. On different chromosomes
C. Far apart on the same chromosome
D. Not linked
Answer: A. Tightly linked on the same chromosome
Rationale: Tightly linked genes have fewer crossovers, resulting in more parental types than
recombinants.
10. Gregor Mendel reported that flower color and seed color traits assorted independently because:
A. The two genes are far apart on the same chromosome
B. The two genes are on different chromosomes
C. The two genes are tightly linked
D. The two genes are codominant
, ESTUDYR
Answer: A. The two genes are far apart on the same chromosome
Rationale: Genes far apart on the same chromosome assort independently due to frequent crossovers.
11. Genes Q and P are linked and 20 map units apart. In the cross Qp/qP x qp/qp, what fraction of the
progeny will be QP/qp?
A. 10%
B. 20%
C. 40%
D. 80%
Answer: A. 10%
Rationale: The recombination frequency is 20%, so 10% of the progeny will be QP/qp (half of the
recombinants).
12. Familial Down syndrome is a result of which of the following?
A. Translocation
B. Nondisjunction
C. Deletion
D. Inversion
Answer: A. Translocation
Rationale: Familial Down syndrome is caused by a translocation involving chromosome 21.
13. A grasshopper with a chromosomal abnormality shows a dicentric bridge in primary
spermatocytes. Which chromosome pair belongs to this grasshopper?
A. A B C D ● E F G H I J K L A B C D ● E F K J I H G L
B. A B C D ● E F G H I J K L A B C D ● E F G H I J K L
C. A B C D ● E F G H I J K L A B C D ● E F G H I J K L
D. A B C D ● E F G H I J K L A B C D ● E F G H I J K L
Answer: A. A B C D ● E F G H I J K L A B C D ● E F K J I H G L
Rationale: The dicentric bridge indicates an inversion, which is shown in the first option.
14. Which of the following describes an organism whose genome contains a haploid set (n) of
chromosomes from one species plus a haploid set (n) of chromosomes from another species?
