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annapnle annapnle
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12 years ago
Part I:
Questions:
1.  Which of the following gives you the most information about an individual?
a.  phenotype
b.  genotype

2.  Dominant alleles are represented by:
a.  an upper case letter
b.  a lower case letter
c.  it does not matter what type of letter is used

3.  In fruit flies, gray body color is dominant over black body color.  Using the letter G to represent body color, what is the genotype of a heterozygous gray bodied fly?
a.  GG
b.  gg
c.  Gg
d.  GGgg

4.  All of the offspring of two gray bodied flies are also gray.  What can you conclude about the genotypes of the parent flies?
a.  They are both heterozygous
b.  They are both homozygous dominant
c.  They are both homozygous recessive
d.  You cannot conclude anything definitively about the parental genotypes

5.  Some of the offspring of two gray bodied flies are black.  What can you conclude about the genotypes of the parent flies?
a.  They are both heterozygous
b.  They are both homozygous dominant
c.  They are both homozygous recessive
d.  You cannot conclude anything definitively about the parental genotypes

6.  Can the genotype for a gray-bodied fly be determined?  Why or why not? Describe all of the possible genotypes for a fly with that phenotype.


7.   Explain why an organism with a homozygous dominant genotype has the same phenotype as an organism with a heterozygous genotype.



8.  What genetic information can be obtained from a Punnett square?  What genetic information cannot be determined from a Punnett square?
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wrote...
12 years ago
7.   Explain why an organism with a homozygous dominant genotype has the same phenotype as an organism with a heterozygous genotype.

Because the dominant gene always appears in the phenotype, whether or not it is "pure" (homozygous) or "mixed" (heterozygous). The recessive gene does what it says: it is recessive to the dominant gene. So, if it comes between the two, the dominant always appears. Of course, this only happens in your average Dominant-Recessive traits.
could of, should of, would of...
wrote...
Valued Member
Educator
9 years ago
6.  Can the genotype for a gray-bodied fly be determined?  Why or why not? Describe all of the possible genotypes for a fly with that phenotype.

Assuming that we are talking about fruit flies, then you should be able to determine this. Gray bodied flies would be the dominant and ebony bodied flies would be recessive. So, the results can only be a homozygous dominant fly (GG) or heterozygous fly (Gg). If you cross that fly with a ebony bodied fly (gg) and there is a result of some ebony bodied flies, then you know the original fly was heterozygous. If you result in all gray flies, then it was dominant.
wrote...
Valued Member
Educator
9 years ago
8.  What genetic information can be obtained from a Punnett square?  What genetic information cannot be determined from a Punnett square?

[Solved] What genetic information can be obtained from a Punnett square?
wrote...
Staff Member
9 years ago
6.  Can the genotype for a gray-bodied fly be determined?  Why or why not? Describe all of the possible genotypes for a fly with that phenotype.


7.   Explain why an organism with a homozygous dominant genotype has the same phenotype as an organism with a heterozygous genotype.



8.  What genetic information can be obtained from a Punnett square?  What genetic information cannot be determined from a Punnett square?

Yes. In order to determine the genotype in a fly showing dominant body color it must be cross bred with a fly expressing the recessive trait of being lighter colored. If any offspring express the recessive trait of a lighter body the gray-bodied fly will have a genotype of dominant/recessive carrier alleles ex. Aa but if all offspring express the dominant trait of a darker body it can be inferred that the genotype is dominant/dominant alleles or AA. Both combinations would be acceptable for the gray-bodied fly.

A Punnett square can determine the likelihood of a combination of alleles to be expressed in an offspring between two parents as well as what their genotype will look like.

A Punnett square does not always determine what the phenotype will be.
junebugc14
Ask another question, I may be able to help!
wrote...
Valued Member
Educator
9 years ago
1.  Which of the following gives you the most information about an individual?
a.  phenotype
b.  genotype

A.
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