Question

3 question all linked together:

I need help with: The first one, I believe I got right, however, I am stuck on the second part of the question. Can someone review it, and help me. If my first part of the question is wrong, can someone explain it?

Second and third question, also a double check to see if I have done this right.

1)A farmer performs a test cross on his erect-eared sow (female pig). Explain the purpose of a test cross and describe the other individual involved in the cross.

In pigs, erect-ears is dominant (E) to drooping-ears (e)

The answer I have put so far:

The purpose of a test cross is to figure out the unknown genotype in the parental cross, we know that there is one genotype that is visible in a test cross which is recessive homozygous "ee" which will allow the offspring phenotype is to determine the other genotype in the cross. Will, it is "EE or Ee" by doing the test cross

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2)create a Punnett square for each test cross possibility: I did these two, am I missing any? Or did I do these wrong?

In pigs, erect-ears is dominant (E) to drooping-ears (e)
The first option

	E	E
e	Ee	Ee
e	Ee	Ee

The second option would be:

	E	e
e	Ee	ee
e	Ee	ee

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The last part for double-checking is:

Write a summary sentence explaining the result of each test cross:

The answer I put:

Option one with the parent type "EExee" you would get the offspring F2 that would all be erect ears dominant, which would allow their offspring to produce a variety of selection from EE, Ee, ee,

Option two also give you a variety of selection from Ee,ee and this would have a 50% that it would be erect ears, and 50% dropping ears

Answer 1

For first part, your answer is correct. A test cross is always conducted with a homozygous recessive individual to know the know the genotype of the target individual.

For the second part, the crosses that you have performed in the punnett square is absolutely right. There could be 2 genotypes of the female pig - EE or Ee.

When EE is test- crossed with ee, it will produce all heterozygous dominant offsprings which have erect ears.

When Ee is test crossed with ee, it will produce 50% heterozygous dominant offsprings (Ee) which have erect ears and 50% homozygous recessive offsprings (ee) which will have drooping ears.

There are few corrections in your summary. I have boldened them out.

Option one with the parent type "EE x ee" you would get the F1 offspring that would all be erect ears heterozygous dominant (Ee), which would allow their offspring to produce a variety of selection from EE, Ee, ee,

Option two also give you a variety of selection from Ee and ee and in this would have a 50% heterozygous dominant offsprings (Ee) which have erect ears and 50% homozygous recessive offsprings (ee) which will have drooping ears.