1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
KonstantinChe [14]
3 years ago
9

The following F2 results occur from a dihybrid cross (AaBb x AaBb): purple: A_B_ 9/16 white: aaB_ 3/16 white: A_bb 3/16 white: a

abb 1/16 If a double heterozygote (AaBb) is crossed with a fully recessive organism (aabb), what phenotypic ratio is expected in the offspring? _________ a. 3 (purple) : 1(white)b. 3 (whilte) : 1(purple)c. 1(purple): 1(white)d. 9 (purple): 1(white) I know the answer is B but I want to know why. Please provide a good explanation for a good rating.
Biology
1 answer:
e-lub [12.9K]3 years ago
8 0

Answer:

b. 3 (whilte) : 1(purple)

Explanation:

The first dihybrid crossing is between AaBb x AaBb

Now, if the double heterozygous traits self crossed, we have the following gametes shown below for the F₂ crossing.

AaBb = (AB, Ab, aB, ab)

                    AB                     Ab                     aB                     ab

AB                AABB                AABb                AaBB                AaBb

Ab                AABb                AAbb                AaBb                Aabb

aB                AaBB                 AaBb                aaBB                aaBb

ab                AaBb                 Aabb                 aaBb                aabb

We were being told that the results are;

purple: A_B_ 9/16

white: aaB_ 3/16

white: A_bb 3/16

white: aabb 1/16

From above, we can see that the same is true;

For Purple color; we Have (AABB and AaBb) since A is dominant to a and B is dominant to b.

∴ From the above punnet square; we have 9 purple colors which are:

(AABB, AABb, AaBB, AaBb, AABb, AaBb, AaBB, AaBb, AaBb) = 9/16

white: aaB_ ( since B is dominant to b, it can be either BB or Bb)

= (aaBB, aaBb, aaBb) = 3/16

white: A_bb ( since A is dominant to a, it can be either AA or Aa)

= (AAbb, Aabb, Aabb) = 3/16

white: aabb i.e homozygous recessive = (aabb) = 1/16

Furthermore, the question goes further by saying:

If a double heterozygote (AaBb) is crossed with a fully recessive organism (aabb), what phenotypic ratio is expected in the offspring?

If AaBb self crossed, we have:  (AB, Ab, aB, ab)

If aabb self crossed, we have: (ab, ab, ab, ab)

                    AB                     Ab                     aB                     ab

ab                AaBb                Aabb                aaBb                 aabb

ab                AaBb                Aabb                aaBb                 aabb

ab                AaBb                 Aabb               aaBb                 aabb

ab                AaBb                 Aabb                aaBb                aabb

AaBb ( purple)

= 4/16

= 1/4

= 0.25

= 25%

Aabb (white)

= 4/16

= 1/4

= 0.25

= 25%

aaBb (white)

= 4/16

= 1/4

= 0.25

= 25%

aabb (white)

= 4/16

= 1/4

= 0.25

= 25%

Now the proportion of white to purple =  (25%+25%+25%): 25%

=  75%:25%

= 3(white):1(purple)

We can therefore conclude that the expected phenotypic ratio in the cross between a double heterozygote (AaBb) with a fully recessive organism (aabb) yeids;

3 (whilte) : 1(purple)

You might be interested in
What does the mass of an object depend on? Force of gravity Temperature of the object Time taken for an event to occur Amount of
AlexFokin [52]
It's the amount of matter that makes up the object
if the same object is placed in different force of gravity rate, the mass will still be unchanged.
3 0
3 years ago
Read 2 more answers
What are some similarities between prokaryotic and eukaryotic cells?
hichkok12 [17]
They both follow a pattern of semi conservative replication
5 0
3 years ago
What life cycle adaptation does the desert gold poppy have that helps it reproduce and survive in its dry desert environment?
earnstyle [38]
It is the last one that says, it can produce seeds all year around that can grow in dry and wet conditions.
5 0
3 years ago
What is the purpose of transcription and translation?
tresset_1 [31]
Answer: The purpose of transcription is to move the information from the DNA to the ribosomes with the help of mRNA. Then we have translation it occurs on ribosomes and its purpose is to assemble amino acids into proteins.

Explanation:
the steps of transcription:
1. unzipping the DNA
2. build the RNA molecule
3. detach the mRNA molecule
4. rewinds the DNA molecule
If u want the steps of translation tell me :)
8 0
3 years ago
1. Why are these moths called "peppered moths?"
riadik2000 [5.3K]

Answer:

they got black dot on their white wings.

Explanation:

And black pepper moths dont but they are natural selected from the white pepper moths.

8 0
3 years ago
Other questions:
  • Oxycontin abusers are typically young white males. <br> a. True <br> b. False
    9·1 answer
  • 1) What are the two parts of the nervous system?
    7·1 answer
  • Which of the following philosophical approaches is modern evolutionary biology based upon?
    12·1 answer
  • Which of the following is produced by adding 1% to 5% agar to nutrient broth that is then boiled and cooled?
    7·2 answers
  • In muscle the source of a "phosphate molecule needed to recharge an adp molecule to an atp molecule" is
    10·1 answer
  • Occasionally, one space object travels through the shadow of another space object. When the moon moves between the sun and Earth
    8·1 answer
  • A female Drosophila with the mutant phenotype a is crossed to a male who has the mutant phenotype b. In the resulting F1 generat
    11·1 answer
  • 20 Points!!!! Answer ASAP!!! Describe the process of oil extraction in complete sentences. Be sure to include information about
    14·2 answers
  • Please help with 13
    10·1 answer
  • Which is responsible for the granular appearance of cells in the stratum granulosum?
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!