Question

Match List I with List II regarding patterns of inheritance:  

List I	List II
A. Incomplete dominance  B. Co-dominance  C. Pleiotropy  D. Polygenic inheritance	I. Human skin colour  II. Inheritance of flower colour in Antirrhinum sp.  III. Phenylketonuria disease in humans  IV. ABO blood groups

Choose the correct answer from the options given below:

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

Hint:

\textbf{P}leiotropy = \textbf{1} Gene $\rightarrow$ \textbf{Many} Effects. \textbf{P}olygenic = \textbf{Many} Genes $\rightarrow$ \textbf{1} Effect. Don't flip these two!

Answer 1

The Correct Option is A

Step 1: Understanding the Question
The task is to match different non-Mendelian inheritance patterns with their classic biological examples. These patterns describe how alleles interact to produce phenotypes in ways that go beyond simple "dominant vs. recessive" rules. Step 2: Key Formula or Approach
Define each genetic term: - Incomplete: Blended phenotype. - Co-dominance: Both alleles expressed. - Pleiotropy: One gene, many effects. - Polygenic: Many genes, one effect. Step 3: Detailed Explanation
A. Incomplete dominance: This occurs when the heterozygote shows a "blended" trait. In {Antirrhinum} (snapdragon), Red + White = Pink flowers. Thus, A matches with II.
B. Co-dominance: This occurs when both alleles are fully and separately expressed. In human ABO blood groups, $I^A$ and $I^B$ alleles both show up together in AB blood. Thus, B matches with IV.
C. Pleiotropy: This is when a single gene mutation causes multiple symptoms or phenotypic changes. Phenylketonuria (PKU) affects mental health, skin pigment, and more. Thus, C matches with III.
D. Polygenic inheritance: This is when a trait (like skin color or height) is controlled by the additive effect of several different genes. Thus, D matches with I.
Step 4: Final Answer
The correct sequence is A-II, B-IV, C-III, D-I. This corresponds to option (A).