Question

Consider the following statements: (i) There is a change in a subset of chromosome is called Aneuploidy. (ii) Aneuploidy is the deletion or addition of a few chromosome from the original genome. (iii) Aneuploidy due to failure of segregation of chromatids during cell division. (iv) Down's syndrome - Trisomy of chromosome - 22 (v) Klinefellen syndrome - Trisomy of chromosome - X How many statement/s is or are wrong?

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

Answer: (B)

2

Answer 2

The question asks us to identify the number of incorrect statements among the given five statements related to aneuploidy and genetic disorders.

Let's analyze each statement:

• (i) There is a change in a subset of chromosome is called Aneuploidy.
  Aneuploidy refers to a change in the number of whole chromosomes (e.g., gain or loss of one or more individual chromosomes). It does not refer to a structural change within a chromosome (like a deletion or duplication of a segment), which would be a type of chromosomal aberration but not aneuploidy. The phrase "change in a subset of chromosome" is ambiguous but often implies a structural change within a chromosome. Therefore, this statement is considered wrong because it is imprecise and can be misinterpreted as referring to structural changes, which are distinct from aneuploidy.

• (ii) Aneuploidy is the deletion or addition of a few chromosome from the original genome.
  This statement accurately defines aneuploidy. It refers to the gain or loss of one or more individual chromosomes (e.g., Trisomy, Monosomy). This statement is correct.

• (iii) Aneuploidy due to failure of segregation of chromatids during cell division.
  Aneuploidy primarily results from non-disjunction, which is the failure of homologous chromosomes to separate during meiosis I or sister chromatids to separate during meiosis II (or mitosis). This leads to gametes with an abnormal number of chromosomes, and subsequent fertilization results in an aneuploid zygote. This statement is correct.

• (iv) Down's syndrome - Trisomy of chromosome - 22
  Down's syndrome is caused by the presence of an extra copy of chromosome 21 (Trisomy 21), not chromosome 22. This statement is wrong.

• (v) Klinefellen syndrome - Trisomy of chromosome - X
  Klinefelter syndrome is a genetic condition in males caused by the presence of an extra X chromosome, resulting in a XXY genotype. This is indeed a form of Trisomy involving the X chromosome. This statement is correct. (Note: The spelling is Klinefelter, but the biological concept is correct).

Based on the analysis, the wrong statements are (i) and (iv). Therefore, there are 2 wrong statements.