Question 1

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

Accepted Answer

A life cycle in which a haploid multicellular gametophyte alternates with a diploid multicellular sporophyte.

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 cells produced by meiosis become a functional egg?

Accepted Answer

Because the egg needs to retain most of the cytoplasm to provide nutrients for the developing embryo.

Question 4

Which of the following statements about meiosis and fertilization in animals is correct?

Accepted Answer

Meiosis produces haploid gametes, and fertilization restores the diploid number in the zygote.

Question 5

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

Accepted Answer

Down syndrome; trisomy.

Question 6

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

Accepted Answer

Sex chromosome aneuploidy affects fewer essential body systems compared to autosomal aneuploidy.

Question 7

A woman is found to have only one X chromosome (karyotype: $$45, X). $$Which syndrome does she have, and what is a likely physical characteristic?

Accepted Answer

Turner syndrome; short stature and lack of secondary sexual development.

Question 8

Which chromosomal abnormality is caused by a translocation between chromosomes 9 and 22, resulting in a 'Philadelphia chromosome'?

Accepted Answer

Chronic myeloid leukemia.

Question 9

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

Accepted Answer

Two zygotes with trisomy and two with monosomy.

Question 10

Which of the following is an example of a deletion syndrome, and what is a key feature of this syndrome?

Accepted Answer

Williams syndrome; loss of the elastin gene on chromosome 7 leading to distinctive facial features.

Question 11

A male individual has a karyotype of $$47, XXY. $$Which syndrome does he have, and what is a possible consequence?

Accepted Answer

Klinefelter syndrome; possible infertility and delayed secondary sexual development.

Question 12

Which of the following best describes the difference between deletion and duplication chromosomal mutations?

Accepted Answer

Deletion removes a segment of a chromosome, while duplication repeats a segment within the same chromosome.

Question 13

A patient is diagnosed with tetralogy of Fallot due to a chromosomal abnormality. Which type of chromosomal mutation is most likely responsible?

Accepted Answer

Translocation between chromosomes 2 and 20.

Question 14

Which of the following scenarios would most likely result in a normal (euploid) zygote after fertilization?

Accepted Answer

Both gametes have the correct number of chromosomes.

Question 15

Which gene is responsible for male sex determination, and what happens if it is deleted from the Y chromosome?

Accepted Answer

The SRY gene; deletion results in female development even if a Y chromosome is present.

Question 16

Which of the following best describes the process of inversion in chromosomal structure?

Accepted Answer

A segment of a chromosome breaks off, flips, and reattaches in the reverse orientation.

Question 17

Which of the following is a real-world consequence of improper chromosome separation during meiosis in humans?

Accepted Answer

Increased risk of genetic disorders such as Down syndrome and Turner syndrome.

Question 18

If a chromosomal segment from chromosome 1 is exchanged with a segment from chromosome 2, what type of mutation has occurred?

Accepted Answer

Translocation.

Question 19

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

Accepted Answer

Trisomy 21 leads to low muscle tone, including cardiac muscle, affecting heart function.

Question 20

Which of the following is true regarding the formation of polar bodies during oogenesis?

Accepted Answer

Polar bodies are byproducts of meiosis that do not develop into eggs.

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

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