CHAPTER 4: GENETIC INHERITANCE

1 BIO TWO SDS| SESI 2021/2022 1 |KMPk CHAPTER 4: GENETIC INHERITANCE LEARNING OUTCOME Mendelian genetics: Monohybrid and Dihybrid a) Define the terminologies used in GENETIC INHERITANCE : allele, gene, locus, genotype, phenotype, homozygous, heterozygous, dominant, recessive, self-cross and test cross. b) State the characteristics of Mendel s pea plants. c) State Mendel s first law (Law of Segregation). d) Construct GENETIC diagram on the monohybrid cross and include the genotypic ratio (1:2:1) and phenotypic ratio (3:1) of F2 generation. e) Construct GENETIC diagram on Mendelian monohybrid test cross and include the genotypic ratio (1:1) and phenotypic ratio (1:1). f) State Mendel s second law (Law of Independent Assortment).

2 G) Construct GENETIC diagram on the dihybrid cross and include only phenotypic ratio (9:3:3:1) of F2 generation using Punnett square. h) Construct GENETIC diagram on Mendelian dihybrid test cross and include phenotypic ratio (1:1:1:1) of F2 generation using Punnett square. Deviations from the Mendelian INHERITANCE a) Explain briefly types of INHERITANCE that deviate from Mendelian: Codominant alleles, incomplete dominant alleles, multiple alleles, linked genes, sex-linked genes and polygenes. i. Codominant alleles: Construct GENETIC diagram to show codominant alleles using human MN blood group and include phenotypic ratio and genotypic ratio (1:2:1) ii. Incomplete dominant allele: Construct GENETIC diagram to show incomplete dominant alleles and include phenotypic ratio (1:2:1) and genotypic ratio by using Antirrhinum sp.

3 Iii. Multiple allele: Construct GENETIC diagram to show multiple alleles using human ABO blood group. iv. Linked genes: Illustrate the effects of linked genes with crossing over on the dihybrid test cross ratio. v. Sex-linked genes: Construct GENETIC diagram to show sex-linked genes using haemophilia. vi. Polygenes/ Polygenic INHERITANCE : Explain polygenes/ polygenic INHERITANCE using human skin colour GENETIC mapping. a) Define GENETIC mapping. b) Calculate the GENETIC distance (map unit) between genes using the given recombinant data. BIO TWO SDS| SESI 2021/2022 2 |KMPk c) Identify the position or order of genes along a chromosome based on recombinant data. MULTIPLE CHOICE QUESTIONS 1. Why did Mendel choose to work with the garden pea plant?

4 A. Because the pea plant is easy to work with. B. Because pea plants are fast growing. C. Because the pea plant has a number of characteristics, each with only two forms. D. All of the above 2. In Mendel's first experiment A. the F1 displayed all purple-flowered plants. B. the F1 displayed all white-flowered plants. C. the F2 displayed all purple-flowered plants. D. the F2 displayed half purple-flowered and half white-flowered plants. 3. The law of independent assortment states that A. two factors of the same characteristic separate into different gametes. B. there are dominant and recessive factors. C. factors controlling different characteristics are inherited independently of each other.

5 D. there are two factors that control INHERITANCE . 4. A plant with purple flowers is allowed to self-pollinate. Generations after generations, it produces purple flowers. This is an example of A. hybridization B. Incomplete dominance C. True-breeding D. polygenetics 5. Looking at your cat will give information concerning A. the cat's genotype. B. the cat's phenotype. C. the cat's recessive alleles. D. the cat's heterozygous alleles. 6. Which sentence is correct? A. Different alleles of the same gene are located at the same locus on different homologous chromosomes. B. Different alleles of the same gene are located at different loci on different homologous chromosomes. C. Different genes of the same alleles are located at the same locus on different homologous chromosomes.

6 D. Different alleles of the same gene are located at different loci on the same chromosome. 7. An Aa individual A. has a homozygous genotype. B. has a heterozygous phenotype. C. has a heterozygous genotype. D. has a homozygous phenotype. 8. In Mendel's initial experiments, an example of the F2 generation would be A. 75 round seed plants to 25 wrinkled seed plants BIO TWO SDS| SESI 2021/2022 3 |KMPk B. 75 green seed plants to 25 yellow seed plants C. 75 white-flowered plants to 25 purple-flowered plants D. all of the above 9. Some people experience PTC paper on tongue as bitter, others as tasteless. This character is hereditary in nature. Suppose T stands for dominant gene of ability to taste and t for recessive gene, the GENETIC make up of a person who cannot taste is A.

7 TT B. tt C. Tt D. None of these 10. Two plants are crossed, resulting in offspring with a 3:1 phenotypic ratio for a particular trait. This suggests A. that the parents were true-breeding for contrasting traits. B. incomplete dominance C. that a blending of traits has occurred. D. that the parents were both heterozygous 11. Which of the following is part of the law of segregation? i. there are two factors controlling a given characteristic, ii. one factor is dominant over the other factor, iii. the two factors separate into different gametes. A. i and ii B. i and iii C. ii and iii D. i, ii, and iii 12. Mendel crossed pure breeding plants having smooth seeds with pure breeding plants having wrinkled seeds.

8 The F1 plants had smooth seeds. Then the F1 plants were allowed to self-fertilize. Mendel collected 600 F2 plants. How many of these would be expected to have smooth seeds and how many wrinkled seeds? A. 400 smooth seeds and 200 wrinkled seeds B. 300 smooth seeds and 300 wrinkled seeds C. 450 smooth seeds and 150 wrinkled seeds D. 150 smooth seeds and 450 wrinkled seeds 13. A GENETIC cross between an individual showing a dominant phenotype (unknown genotype) and a homozygous recessive individual is known as a_____ A. back cross B. reciprocal cross C. self-cross D. test cross 14. Two characters that appear in a 9:3:3:1 ratio in the F2 generation should have which of the following properties?

9 A. Each of the characters is controlled by a single gene. B. The genes controlling the characters obey the law of independent assortment. C. Each of the genes controlling the characters has two alleles. D. A, B and C are correct 15. A GENETIC cross of two plants results in offspring with 9:3:3:1 ratio for a BIO TWO SDS| SESI 2021/2022 4 |KMPk particular trait. This condition shows _____ A. the genes controlling the traits were located on same chromosome B. multiple allele C. that both parents were heterozygous D. monohybrid cross 16. How many unique gametes could be produced through independent assortment by an individual with the genotype RrSsTTUu? A. 4 B. 8 C. 16 D. 32 17. A pointed contour off the hairline on the forehead or known as widow s peak is dominant to straight hairline in human.

10 A woman with widow s peak married a man with straight hairline. They had a daughter with widow s peak which later also married to a man with straight hairline. What is the percentage of their first child having widow s peak? A. 100% B. 70% C. 50% D. 25% 18. In fowl, the allele for black feather is incomplete dominant to white feather and heterozygous is bluish-grey in phenotype or known as Andalusian blue. The second locus controls the texture of the feathers, in which silky feathers is recessive to normal feathers. Self-crossed were done on Andalusian blue bird with silky feathers. Predict the phenotype ratio of the offspring. A. 1 black, silky: 2 blue, silky: 1 white, silky B.