The question asks to identify the characteristic feature of Turner syndrome, which is represented by the karyotype (45, X0). This notation indicates the total number of chromosomes and the composition of the sex chromosomes. We need to understand what each part of the notation signifies and relate it to the given options.
Correct Option: C) Monosomy of X chromosome in females. The karyotype (45, X0) signifies that there are 45 chromosomes in total, with one X chromosome and no second sex chromosome. This is a condition where one of the X chromosomes is missing, leading to monosomy of the X chromosome, and it occurs in phenotypic females.
The question asks to identify the karyotype associated with Klinefelter syndrome. This requires knowledge of common chromosomal abnormalities and their corresponding genetic notations.
Correct Option: A) 47, XXY is the correct karyotype for Klinefelter syndrome, characterized by the presence of an extra X chromosome in a male.
The question asks to identify an example of co-dominance from the given options. Co-dominance is a genetic phenomenon where both alleles in a heterozygote are fully expressed, resulting in offspring with a phenotype that is neither dominant nor recessive, but rather a combination of both parental phenotypes.
Correct Option: C) AB blood group in ABO system — In the ABO blood group system, alleles \(I^A\) and \(I^B\) are co-dominant. An individual with genotype \(I^A I^B\) expresses both A and B antigens on their red blood cells, resulting in the AB blood group. Both traits are fully expressed simultaneously.
This question tests understanding of incomplete dominance, a deviation from Mendelian genetics. In incomplete dominance, neither allele is completely dominant over the other, leading to a blended phenotype in the heterozygote.
A) Pink flowers — In incomplete dominance, the F1 hybrid resulting from a cross between homozygous red (RR) and homozygous white (rr) parents will have a heterozygous genotype (Rr). This genotype expresses a phenotype that is an intermediate blend of the two parental traits, which in this case is pink flowers.
The question asks to identify the scientists who proposed the DNA double helix model. This requires knowledge of key historical discoveries in molecular biology.
James Watson and Francis Crick are credited with proposing the double helix structure of DNA in 1953, based on X-ray diffraction data primarily obtained by Rosalind Franklin and Maurice Wilkins, and chemical analysis by Erwin Chargaff.
B) Watson and Crick — James Watson and Francis Crick published their groundbreaking model of the DNA double helix in 1953 in the journal Nature. Their model described DNA as a double helix with two polynucleotide strands coiled around a central axis, held together by hydrogen bonds between complementary base pairs (A-T and G-C).
The question asks about the type of bond that holds the two strands of a DNA double helix together. Understanding the basic structure of DNA and the chemical interactions involved is key to answering this question.
A) Hydrogen bonds between complementary bases. This is correct because hydrogen bonds form between complementary nitrogenous bases (A with T, and G with C) on opposite strands, holding the two DNA strands together in a double helix structure.