Download Given that in corn (Zea maize) purple grain is dominant to yellow grain

Name: _____________________________________
1.
Given that in corn (Zea maize) purple grain is dominant to yellow grain.
Explain your answer without using a genetic diagram.
class: _________ class no:____
Work out the genotype of the ears.
(Work example)
Let P be the allele for purple grain and p be that for yellow grain
The genotype of the yellow ear parent is pp.
Since yellow is recessive to purple
The genotype of the purple ear parent is PP.
All the F1 is purple, the yellow parent
will only provide an p allele to the F1.
Thus they must have received one purple allele
from their purple parent. Since all F1 are purple, the
Purple parent should be
homozygous PP.
The F1 are heterozygous (Pp) since their parents are homozygous.
In the F2 the, the phenotypic ratio is 62 purple : 19 yellow (3 rows)
~
3
: 1
The monohybrid ratio is consistent with the expectation of a F1 heterozygous interbreed
result.
2. Given that in corn (Zea maize) smooth grain is dominant to wrinkled grain.
P
F1 X F1
F2
Work out the genotype of the ear.
Explain your answer.
3.
Given that in corn (Zea maize) smooth grain is dominant to wrinkled grain and purple is dominant to yellow.
genetic diagram.
Work out the genotypes of the ear.
Explain your answer with a
purple/smooth =
yellow/smooth =
purple/wrinkled =
yellow/wrinkled =
4. Further examples in corn genetics:
Ear
Observed number and ratio
Suggest possible parent
genotypes
Ear A
Ear A
purple = 378
yellow = 122
3 purple
1 yellow
Rr x Rr
Ear B
Ear B
1 purple
purple = 247
1 yellow
yellow = 253
Rr x rr
purple = 247
yellow = 253
Ear C
Ear D
Ear C
1 purple smooth
purple/smooth = 124
1 purple wrinkled
yellow/smooth = 123
1 yellow smooth
purple/wrinkled = 127
1 yellow wrinkled
yellow/wrinkled = 123
Rr Stst x rr stst
Ear D
Rr Stst x Rr Stst
purple/smooth = 280
yellow/smooth = 93
purple/wrinkled = 95
yellow/wrinkled = 32
5. Interpretation of dihybrid test cross result:
Phenotype of offspring
Genotype of unknown pea plant with round and
yeoolw seeds
All Round and yellow
Round yellow to Round green = 1:1
Round yellow to Wrinkled yellow = 1:1
Round Yellow / Round green / Winkled yellow /
wrinkled green = 1:1:1:1
6. More genetic problems
i)
ii)
6. ans