The genetic condition in human males characterized by the sex chromosome complement XXY is known as:
Klinefelter's syndrome is an aneuploidy (change in chromosome number) in males with the karyotype 47,XXY.
Question 142 of 519
📘 CLASS XII
Which chromosomal disorder involves the absence of one X chromosome, resulting in the sex chromosome complement XO?
Turner's syndrome is an aneuploidy in females where one X chromosome is missing, leading to the karyotype 45,X.
Question 143 of 519
📘 CLASS XII
Aneuploidy, which is a change in a subset of chromosome numbers, is primarily caused by which error during cell division?
Aneuploidy (having an abnormal number of chromosomes, like trisomy or monosomy) is most often due to non-disjunction—the failure of homologous chromosomes or sister chromatids to separate during meiosis or mitosis.
Question 144 of 519
📘 CLASS XII
What is the primary purpose of a pedigree analysis?
Pedigree analysis uses standardized symbols to track a specific trait or disorder through multiple generations of a family, helping to suggest the mode of inheritance (e.g., autosomal dominant, X-linked recessive).
Question 145 of 519
📘 CLASS XII
The total number of chromosomes in an individual with Down's syndrome is:
A normal human has 46 chromosomes (2n=46). Down's syndrome (Trisomy 21) means there is an extra copy of chromosome 21, resulting in 46+1=47 chromosomes.
Question 146 of 519
📘 CLASS XII
Sex determination in human beings is based on which combination of chromosomes?
Humans have an XX-XY system. Males are heterogametic (XY) and females are homogametic (XX). The male's sperm determines the sex of the offspring.
Question 147 of 519
📘 CLASS XII
Which of the following is a symptom associated with Klinefelter's syndrome (47,XXY)?
Males with Klinefelter's syndrome often exhibit reduced secondary sexual characteristics, infertility (small testes), and breast development (gynecomastia).
Question 148 of 519
📘 CLASS XII
Which of the following is an example of an autosomal genetic disorder (mentioned or implied by the text's focus)?
Down's syndrome (Trisomy 21) is a disorder of an autosome (non-sex chromosome). Turner's and Klinefelter's are sex-chromosomal disorders, and Hemophilia is X-linked.
Question 149 of 519
📘 CLASS XII
Polyploidy is defined as a change in the entire set of chromosomes. In which group is polyploidy most commonly observed?
While polyploidy is lethal or causes severe issues in most animals, it is common and often advantageous in plants, leading to increased vigor and larger fruits/flowers.
Question 150 of 519
📘 CLASS XII
Which of the following characteristics is typically associated with Turner's syndrome (45,X)?
Turner's syndrome affects females, leading to rudimentary sexual development, including underdeveloped ovaries and consequent infertility.
