Question 1

Which of the following best describes the alternation of generations in plants?

Accepted Answer

A diploid multicellular form alternates with a haploid multicellular form during the life cycle.

Question 2

In mosses, which structure is the dominant, visible form and what is its ploidy?

Accepted Answer

The gametophyte, which is haploid ($$n)$$

Question 3

During oogenesis in animals, why does only one of the four resulting cells become a functional egg?

Accepted Answer

Because only one cell receives most of the cytoplasm, providing nutrients for the developing embryo.

Question 4

Which of the following best explains the difference between spermatogenesis and oogenesis?

Accepted Answer

Spermatogenesis produces four functional sperm cells, while oogenesis produces one functional egg and three polar bodies.

Question 5

A karyotype of a human cell shows three copies of chromosome 21. What condition does this indicate, and what is the term for this chromosomal abnormality?

Accepted Answer

Down syndrome; trisomy

Question 6

Which of the following scenarios is most likely to result in aneuploidy in a human zygote?

Accepted Answer

Non-disjunction during meiosis in either the egg or sperm cell formation

Question 7

If non-disjunction occurs during meiosis I in oogenesis, what is the expected outcome after fertilization?

Accepted Answer

All resulting zygotes will be either monosomic or trisomic for the affected chromosome.

Question 8

Which chromosomal abnormality is characterized by the presence of only one X chromosome (monosomy X) and what syndrome does it cause?

Accepted Answer

Turner syndrome

Question 9

A patient is diagnosed with Klinefelter syndrome. Which karyotype would you expect to find in this individual?

Accepted Answer

$$47,XXY$$

Question 10

Which of the following best explains why aneuploidy of sex chromosomes is less likely to be fatal than aneuploidy of autosomes?

Accepted Answer

Sex chromosomes affect fewer essential body systems than autosomes.

Question 11

A geneticist observes a chromosome with a segment that has been flipped in orientation but remains in the same location. What type of chromosomal structural change is this?

Accepted Answer

Inversion

Question 12

Which chromosomal structural change is most likely responsible for the Philadelphia chromosome found in chronic myeloid leukemia?

Accepted Answer

Translocation between chromosomes 9 and 22

Question 13

A child is born with a high-pitched cry, short stature, and depigmentation in the iris. Genetic testing reveals a deletion at the end of chromosome 7. What syndrome does this child most likely have?

Accepted Answer

Williams syndrome

Question 14

Which of the following best describes the process and result of fertilization in animals?

Accepted Answer

Fusion of haploid gametes to form a diploid zygote ($$n + n = 2n)$$

Question 15

Which of the following is a real-world example of a translocation syndrome that results in a congenital heart defect due to improper separation of oxygenated and deoxygenated blood?

Accepted Answer

Alagille syndrome

Question 16

If a person has a deletion of the SRY gene on the Y chromosome, what is the most likely phenotypic outcome?

Accepted Answer

Development of female characteristics despite the presence of a Y chromosome

Question 17

Which of the following best describes the difference between autosomal and sex chromosome non-disjunction in terms of viability?

Accepted Answer

Autosomal non-disjunction is more likely to be fatal than sex chromosome non-disjunction.

Question 18

A karyotype shows a chromosome with two copies of a gene segment in a row. What type of chromosomal mutation is this?

Accepted Answer

Duplication

Question 19

Which of the following is NOT a possible outcome of non-disjunction during meiosis II?

Accepted Answer

All gametes are aneuploid.

Question 20

Which of the following best explains why individuals with Down syndrome often have heart defects?

Accepted Answer

They have low muscle tone, which includes cardiac muscle, leading to improper heart function.

Chromosomal Basis of Inheritance and Disorders: Life Cycles, Meiosis, and Chromosome Abnormalities

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