Tiêu đề 4 Principles of inheritance n variation - Complete Questions n Answers - Topic wise.pdf ✅

© www.bankofbiology.com All rights reserved. 02  Answer a. First Law (Law of Dominance) • Characters are controlled by discrete units called factors. • Factors occur in pairs. • In a dissimilar pair of factors, one member of the pair dominates (dominant) the other (recessive). Second Law (Law of Segregation): “During gamete formation, the factors (alleles) of a character pair present in parents segregate from each other such that a gamete receives only one of the 2 factors”. b. Yes. I agree. For example, the third statement in the First Law is not always true because the cases such as incomplete dominance and codominance do not obey this rule. 10. Match the following: (Score: 2) A B a) Monohybrid phenotypic ratio 9:3:3:1 b) Monohybrid genotypic ratio 3:1 c) Monohybrid test cross ratio 1:2:1 d) Dihybrid phenotypic ratio 1:1  Answer A B a) Monohybrid phenotypic ratio 3:1 b) Monohybrid genotypic ratio 1:2:1 c) Monohybrid test cross ratio 1:1 d) Dihybrid phenotypic ratio 9:3:3:1 INHERITANCE OF TWO GENES 11. A cross between two parents differing in 2 pairs of contrasting characters is called .................. (Score: 1)  Answer: Dihybrid cross 12. In pea plant, the gene for yellow seed colour is dominant over green and round seed shape is dominant over wrinkled. Write the four types of gametes formed in a heterozygous pea plant with yellow and round seeds (YyRr). (Score: 2)  Answer YR, Yr, yR, yr 13. Work of a student is given below. (Score: 3) a. From the above give an example for genotype & phenotype. (1) b. Complete the work using Punnett square and find out the phenotypic ratio in the F2 generation. (2)  Answer a. Genotype: E.g., RRYY or RrYy or rryy. Phenotype: E.g., Round yellow or wrinkled green. b. F2 generation: 14. A diploid organism is heterozygous for 4 loci, how many types of gametes can be produced? (NCERT question) (Score: 2)  Answer If an organism is heterozygous at 4 loci (e.g. Aa, Bb, Cc, Dd), 24 = 16 types of gametes can be produced. But, if all the loci are linked, then 2 gametes are produced. 15. Two heterozygous parents are crossed. If the two loci are linked what would be the distribution of phenotypic features in F1 generation for a dihybrid cross? (NCERT question) (Score: 2)  Answer Consider the genotypes of two heterozygous parents are AaBb. If the 2 loci are linked, then it will produce only 2 types of gametes, i.e., AB & ab. Parents: AaBb X AaBb Gametes: F1: AABB AaBb AaBb aabb 16. The following table shows the F2 generation of a dihybrid cross. Identify the Phenotype with homozygous recessive genotype. Find out A: B: C: D. (Score: 2) No. Phenotype No. of offspring (F2 gen.) 1 A 21 2 B 7 3 C 63 4 D 21 AB ab AB ab