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1.4 Dihybrid Crosses, Gametes & Probability — Test 1
Q1. In a dihybrid cross between true-breeding parents, the F2 phenotypic ratio is:✓ 9:3:3:1
Q2. A dihybrid (AaBb) is crossed with a homozygous recessive (aabb). The phenotypic ratio of the progeny is:✓ 1:1:1:1
Q3. In a Mendelian dihybrid cross, F1 AaBb is selfed. The proportion of F2 with genotype AaBb is:✓ 4/16
Q4. Two plants heterozygous for both traits (AaBb × AaBb) are crossed. The fraction of offspring with genotype Aabb is:✓ 1/8
Q5. If a plant of genotype AaBb is self-fertilized (genes unlinked), the probability of producing AABB is:✓ 1/16
Q6. The frequency of AABB individuals from a mating of two AaBb individuals is:✓ 1/16
Q7. How many genetically different gametes can an individual of genotype AaBbCCDdEE produce (independent assortment)?✓ 8
Q8. How many different gametes can be produced by an individual of genotype Gg Hh Ii Jj?✓ 16
Q9. A diploid organism heterozygous at two loci can produce how many types of gametes?✓ 4
Q10. Which genotype would produce the largest variety of gametes by independent assortment?✓ Aa Bb CC Dd
Q11. When a male and female, both AaBbCcDd, are crossed, the proportion of progeny that are AaBbccDd is:✓ 1/128
Q12. From a cross AABbccDd × aaBBccDD, the probability of an AaBbccDd progeny is:✓ 3/32
Q13. A dihybrid genetic cross fundamentally demonstrates which Mendelian principle?✓ Independent assortment
Q14. The source of Mendelian recombination (new combinations of parental traits) is:✓ Independent assortment
Q15. In a dihybrid F2, the fraction showing both recessive phenotypes (aabb) is:✓ 1/16
Q16. Two true-breeding pea stocks are crossed: purple-axial × white-terminal; all F1 are purple-axial. Of 1000 F2, the approximate number that are purple-terminal (assuming independent assortment) is:✓ 185
Q17. In a cross, F2 plants segregate as 300 tall : 100 short. A tall plant is picked at random and selfed. Which is most likely true?✓ It can produce both tall and short plants
Q18. Which laws of Mendel state that gametes are never hybrids (each carries only one allele of a pair)?✓ Law of segregation
Q19. A monohybrid F2 shows 3 dominant : 1 recessive. If a dominant F2 individual is chosen at random, the probability it is heterozygous is:✓ 2/3
Q20. Match each cross/quantity with its correct value and select the option.✓ A-ii, B-i, C-iv, D-iii