Question

Match LIST-I with LIST-II
\begin{tabularx}{0.9\textwidth}{|l|X|l|X|} \hline \multicolumn{2}{|c|}{LIST-I} & \multicolumn{2}{c|}{LIST-II}
\multicolumn{2}{|c|}{Law/Principle/Gene interaction} & \multicolumn{2}{c|}{Genes distribution/Ratio}
\hline A. & Law of segregation & I. & 12:3:1
B. & Principle of independent assortment & II. & Genes are distributed without mixing.
C. & Complementary gene interaction & III. & Genes on different chromosomes are distributed independently during meiosis.
D. & Dominant epistasis & IV. & 9:7
\hline \end{tabularx}
Choose the most appropriate answer from the options given below:

• A. A - II, B - III, C - IV, D - I
• B. A - I, B - III, C - II, D - IV
• C. A - II, B - I, C - IV, D - III
• D. A - III, B - IV, C - I, D - II

Hint:

For matching questions involving genetic ratios, it's highly beneficial to memorize the key dihybrid cross ratios:

\textbf{9:3:3:1} - Standard Independent Assortment
\textbf{9:7} - Complementary Genes
\textbf{12:3:1} - Dominant Epistasis
\textbf{9:3:4} - Recessive Epistasis
\textbf{15:1} - Duplicate Dominant Genes \end{itemize}

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
This question requires matching fundamental genetic principles and types of gene interactions with their correct descriptions or characteristic phenotypic ratios.

Step 2: Detailed Matching:
- A. Law of Segregation: This Mendelian law states that the two alleles of a gene segregate (separate) from each other during gamete formation, so that each gamete receives only one allele. This implies that the alleles do not blend or mix. Thus, A matches with II.
- B. Principle of Independent Assortment: This law states that alleles of genes located on different (non-homologous) chromosomes are inherited independently of one another. This is accurately described as genes on different chromosomes are distributed independently during meiosis. Thus, B matches with III.
- C. Complementary Gene Interaction: This is a form of non-allelic interaction where two genes work together to produce a single trait. The dominant allele of both genes is required for the expression of the dominant phenotype. A dihybrid cross involving complementary genes yields a phenotypic ratio of 9:7. Thus, C matches with IV.
- D. Dominant Epistasis: This occurs when a dominant allele at one gene locus masks the expression of alleles at a second locus. A dihybrid cross involving dominant epistasis results in a characteristic phenotypic ratio of 12:3:1. Thus, D matches with I.

Step 3: Final Answer:
The correct set of matches is A-II, B-III, C-IV, D-I. This corresponds to option (A).