Mendel's Laws of Inheritance MCQs
Practice Mendel's Laws of Inheritance multiple-choice questions from Heredity (Class 10 Science) - tap an answer for instant feedback and a step-by-step solution. Practice the full set free on the RankByte app.
Mendel's Laws of InheritanceQuiz - Solve & Score
Q1. In a dihybrid cross, two pea plants heterozygous for both seed shape and seed colour (RrYy) are crossed. What is the ratio of phenotypes in the F2 generation?
- A.9 : 3 : 3 : 1
- B.3 : 1
- C.1 : 1
- D.9 : 7
Answer: A. 9 : 3 : 3 : 1
Spot-the-setup - a typical biology numerical. The data on the table: 2. We are after What is the ratio of phenotypes in the F2 generation?. Pick the chapter relation that contains every given quantity and the unknown; rearrange for the unknown. Common-sense check: When two plants heterozygous for two traits (RrYy × RrYy) are crossed, the two gene pairs assort independently. Lock in option A) 9 : 3 : 3 : 1. Trap-watch: option B) '3 : 1' doesn't hold - 3:1 is the ratio for a monohybrid (single-trait) cross, not a dihybrid one; option C) '1 : 1' misses the point - 1:1 is a test-cross ratio, not the F2 dihybrid ratio.
Q2. Consider the following statements about Mendel's work: (I) Monohybrid F2 phenotypic ratio is 3:1. (II) Dihybrid F2 phenotypic ratio is 9:3:3:1. (III) F1 plants show the recessive trait. Which of the above statement(s) is/are correct?
- A.None of these
- B.Only III
- C.Only I
- D.Only I and II
Answer: D. Only I and II
Given 2, 3, 1, 2, 9, asked for the unknown. By hence the answer = Only I and II. Mendel's monohybrid cross TT x tt -> F1 all Tt (tall). Thus option D) Only I and II. Others fail: option A) 'None of these' doesn't hold - Re-check each statement individually; option B) 'Only III' misses the point - Re-check each statement individually.
Q3. The phenotypic ratio 9:3:3:1 contains how many distinct phenotypes?
- A.four
- B.nine
- C.two
- D.three
Answer: A. four
Quick parse - a typical biology numerical. The data on the table: 9, 3, 3, 1. We are after how many distinct phenotypes?. Tool of choice - hence the answer = four. Rearrange it for the unknown before substituting. Common-sense check: Mendel's monohybrid cross TT x tt -> F1 all Tt (tall). Lock in option A) four. Trap-watch: option B) 'nine' doesn't hold - There are four distinct phenotypes, not nine; option C) 'two' fails since 9:3:3:1 has four phenotypic classes.
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