Principles of Inheritance and Variation

Topics in this chapter

• Mendelian Inheritance and Crosses
• Non-Mendelian Inheritance Patterns
• Linkage, Recombination and Mapping
• Chromosomal Basis and Disorders
• Sex Determination and X-Linkage
• Pedigrees and Mendelian Disorders

Cheat sheet

Practice questions

1. Question 1Q-BB1492

   A cross between a red-flowered snapdragon (Antirrhinum majus) and a white-flowered snapdragon yielded pink flowers in the F1 generation. When F1 plants were selfed, the F2 generation showed phenotypic and genotypic ratios respectively as:

   1. A.3:1 and 1:2:1
   2. B.1:2:1 and 1:2:1
   3. C.1:2:1 and 3:1
   4. D.2:1:1 and 1:2:1
   See the answer and solution
2. Question 2Q-4629DE

   Which of the following conditions correctly describes the chromosomal aberration responsible for Down's syndrome?

   1. A.Monosomy of sex chromosomes (45, X)
   2. B.Trisomy of chromosome 21
   3. C.Trisomy of sex chromosomes (47, XXY)
   4. D.Deletion of the short arm of chromosome 5
   See the answer and solution
3. Question 3Q-D11538

   In a dihybrid cross involving two linked genes, the frequency of recombinant types is generally:

   1. A.Equal to the frequency of parental types
   2. B.Always 50%
   3. C.Significantly less than 50%
   4. D.Greater than 50%
   See the answer and solution
4. Question 4Q-ACDCB8

   ABO blood grouping in humans is an example of which of the following genetic phenomena?

   1. A.Multiple allelism and incomplete dominance
   2. B.Co-dominance and multiple allelism
   3. C.Polygenic inheritance and co-dominance
   4. D.Epistasis and multiple allelism
   See the answer and solution
5. Question 5Q-3AF913

   A true-breeding tall plant is crossed with a true-breeding dwarf plant. The F2 generation is self-pollinated. Out of 1000 individuals in the F2 generation, how many are expected to be heterozygous tall?

   1. A.250
   2. B.500
   3. C.750
   4. D.1000
   See the answer and solution