SI Online
Plant Genetics
(Practice questions)
Topic 10
Spring 2010
Dr. Hughey’s Bio 3 (Lab.)
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A heterozygous white-fruit squash has
been pollinated with the pollen of a
green- fruited squash.
White fruit is dorminant over colored (W, w).
1) 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
3) What are the genotypes and phenotypes of the F1 generation? What is the ratio in each? Use punnett square.
w
w
W Ww Ww
w ww
ww
Genotypes: Ww, ww
Ratio: Ww : ww = 1 : 3
Phenotype: White-fruit squash, Green-fruit squash
Ratio : white-fruit : green-fruit = 1 : 3
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
W WW Ww
w Ww ww
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
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
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
GT
gT
Gt
gt
GT GGTT GgTT GGTt GgTt
gT GgTT ggTT GgTt
ggTt
Gt GGTt GgTt
GGtt
Ggtt
Ggtt
ggtt
gt
GgTt
ggTt
Genotypes: GGTT, GGTt, GGtt, GgTT,
GgTt, Ggtt, ggTT, ggTt, ggtt
Phenotype: Green tall maize, Green
dwarf, White Tall, white dwarf
Designed by Pyeongsug Kim, ©2009
5) What will be the ratio genotypes and the ratio phenotypes in F2 generation?
GT
gT
Gt
gt
GT GGTT GgTT GGTt GgTt
gT GgTT ggTT GgTt
ggTt
Gt GGTt GgTt
GGtt
Ggtt
Ggtt
ggtt
gt
GgTt
ggTt
Genotypes ratio
GGTT : GGTt : GGtt : GgTT : GgTt : Ggtt
: ggTT : ggTt : ggtt
=1 : 2 : 1 : 2 : 4 : 2 : 1 : 2: 1
Phenotypes ratio
Green Tall : Green dwarft : white Tall : white dwarf
=9 : 3 : 3 : 1
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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
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 So, The answer is 1:3.
close to 1:3
©2009
Designed by Pyeongsug Kim,