SI Online Plant Genetics Biology SI Online Plant Genetics (Practice questions) Topic 10 Spring 2010 Dr. Hughey’s Bio 3 (Lab.) Designed by Pyeongsug Kim ©2010 sibio@att.net

Designed by Pyeongsug Kim, ©2009 A heterozygous white-fruit squash has been pollinated with the pollen of a green- fruited squash. White fruit is dorminant over colored (W, w). Is it monohybrid or dihybrid cross? Monohybrid cross 2) What alleles will be carried by the eggs? By the pollen grains(sperms)? Eggs: Ww Pollen: ww 3) What are the genotypes and phenotypes of the F1 generation? What is the ratio in each? Use punnett square. See next slide 4) If a heterozygous F1 squash is self-pollinated, what are the genotypes and phenotypes of the F2 generation? What is the ratio in each? Use punnett square. See next slide Designed by Pyeongsug Kim, ©2009

Designed by Pyeongsug Kim, ©2009 3) What are the genotypes and phenotypes of the F1 generation? What is the ratio in each? Use punnett square. w w Genotypes: Ww, ww Ratio: Ww : ww = 1 : 3 Phenotype: White-fruit squash, Green-fruit squash Ratio : white-fruit : green-fruit = 1 : 3 W Ww Ww w ww ww 4) If a heterozygous F1 squash is self-pollinated, what are the genotypes and phenotypes of the F2 generation? What is the ratio in each? Use punnett square. W w Genotypes: WW, Ww, ww Ratio: WW : Ww : ww = 1 : 2 : 1 Phenotype: White-fruit squash, Green-fruit squash Ratio : white-fruit : green-fruit = 3 : 1 W WW Ww w Ww ww Designed by Pyeongsug Kim, ©2009

Designed by Pyeongsug Kim, ©2009 A homozygous green tall maize has been pollinated with pollens of a albino dwarf maize. - Green color is dominant over albino (G,g). - Tall stature is dominant over dwarf stature (T,t). 1) Is it monohybrid or dihybrid cross? What is the parental genotypes? Dihybrid cross; GGTT, ggtt 2) What alleles will be carried by the eggs? By the pollen grains(sperms)? Eggs: GT ; sperms: gt 3) What are the genotypes and phenotypes of the F1 generation? Use punnett square. See next slide 4) If the F1 generation is self-pollinated, what will be the appearance of F2 generation? See next slide 5) What will be the ratio genotypes and the ratio phenotypes in F2 generation? See next slide Designed by Pyeongsug Kim, ©2009

Designed by Pyeongsug Kim, ©2009 2) What are the genotypes and phenotypes of the F1 generation? Use punnett square. Genotypes: GgTt Phenotype: Green tall maize GT gt GgTt 4) If the F1 generation is self-pollinated, what will be the appearance of F2 generation? Alleles in F2: GT, gT, Gt, gt Genotypes: GGTT, GGTt, GGtt, GgTT, GgTt, Ggtt, ggTT, ggTt, ggtt Phenotype: Green tall maize, Green dwarf, White Tall, white dwarf GT gT Gt gt GT GGTT GgTT GGTt GgTt gT GgTT ggTT GgTt ggTt Gt GGTt GgTt GGtt Ggtt gt GgTt ggTt Ggtt ggtt Designed by Pyeongsug Kim, ©2009

Designed by Pyeongsug Kim, ©2009 5) What will be the ratio genotypes and the ratio phenotypes in F2 generation? Genotypes ratio GGTT : GGTt : GGtt : GgTT : GgTt : Ggtt : ggTT : ggTt : ggtt =1 : 2 : 1 : 2 : 4 : 2 : 1 : 2: 1 GT gT Gt gt GT GGTT GgTT GGTt GgTt gT GgTT ggTT GgTt ggTt Gt GGTt GgTt GGtt Ggtt gt GgTt ggTt Ggtt ggtt Phenotypes ratio Green Tall : Green dwarft : white Tall : white dwarf = 9 : 3 : 3 : 1 Designed by Pyeongsug Kim, ©2009

Designed by Pyeongsug Kim, ©2009 Is the left corn result from monohybrid cross? Or dihybrid cross? How do you know? Monohybrid; two colors(yellow and purple) are present and ONLY one type of endosperm(starch) is present. Is the left corn result from monohybrid cross? Or dihybrid cross? How do you know? Dihybrid; two colors(yellow and purple) are present and two type of endosperm (starch and sweet) is present. Designed by Pyeongsug Kim, ©2009

Designed by Pyeongsug Kim, ©2009 I choose this two column! But, it’s up to you. Is the above corn result from monohybrid cross? Or dihybrid cross? How do you know? Monohybrid; two colors(yellow and purple) are present and ONLY one type of endosperm(starch) is present. What are the penotypes in this corn? Yellow startch, Purple startch What are the POSSIBLE genotypes in this corn? Let, yellow(Y) purple(y) starch(Su) sweet (su) YYSuSu, YYSusu, YySuSu, YySusu, yySuSu, yySusu What are the ratio of phenotypes in this corn? Yellow startch : Purple startch = 19 : 50 Designed by Pyeongsug Kim, ©2009