In pea plants, tall plants (T) are dominant over short plants (t). If a heterozygous tall pea plant is crossed with a homozygous recessive short pea plant, what percentage of the offspring is expected to be tall.

Question

(HINT: use a Punnett square to help you with this question)

(1 point)
Responses

25%
25%

0%
0%

50%
50%

75%
75%
Question 18
If a black chicken (BB) is crossed with a white chicken (WW) and incomplete dominance is observed, what are the expected phenotypes of the offspring?(1 point)
Responses

All black
All black

All gray
All gray

All red
All red

All white
All white
Question 19
In cattle, coat color is controlled by codominant alleles. A red-coated cow (RR) is crossed with a white-coated bull (WW). What are the expected phenotypes of the offspring?(1 point)
Responses

All pink coat
All pink coat

All red coat
All red coat

Red and white coat
Red and white coat

All white coat
All white coat
Question 20

Complete the mRNA sequence that will be formed from the DNA sequence below, then identify the amino acids using the codon chart provided above.

(6 points)
Put responses in the correct input to answer the question. Select a response, navigate to the desired input and insert the response. Responses can be selected and inserted using the space bar, enter key, left mouse button or touchpad. Responses can also be moved by dragging with a mouse.
TAC CGC CCC
mRNA Response area Response area Response area
Amino Acid Response area Response area Response area


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Answer 1

Question 17:
If a heterozygous tall pea plant (Tt) is crossed with a homozygous recessive short pea plant (tt), we can create a Punnett square:

      T        t
    -----------
t |   Tt   |  tt  |
    -----------
t |   Tt   |  tt  |
    -----------

From the Punnett square, we see the following results:

• 2 Tt (tall)
• 2 tt (short)

Since there are 2 tall plants and 2 short plants, this means 50% of the offspring are expected to be tall.

Answer: 50%

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Question 18:
In this question, a black chicken (BB) is crossed with a white chicken (WW) and incomplete dominance is observed. Incomplete dominance means that the offspring will be a blend of the two phenotypes.

Therefore, all offspring will display a gray phenotype (since black and white mix to give gray).

Answer: All gray

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Question 19:
In cattle, coat color is controlled by codominant alleles. A red-coated cow (RR) is crossed with a white-coated bull (WW). With codominance, both traits appear in the phenotype without blending.

Thus, the expected phenotypes of the offspring will be red and white coats, since both alleles express themselves.

Answer: Red and white coat

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Question 20:
For the mRNA transcription from the given DNA sequence (TAC CGC CCC), you first need to transcribe the DNA into mRNA. The base pairing occurs as follows:

• A pairs with U (in RNA, T in DNA is replaced with U)
• T pairs with A
• C pairs with G
• G pairs with C

Given the DNA sequence:

• TAC -> AUG (mRNA)
• CGC -> GCG (mRNA)
• CCC -> GGG (mRNA)

So the resulting mRNA sequence is:

• AUG GCG GGG

Now, using a codon chart to identify the corresponding amino acids:

• AUG = Methionine (Met)
• GCG = Alanine (Ala)
• GGG = Glycine (Gly)

Thus, the complete response is:

mRNA: AUG GCG GGG
Amino Acid: Met Ala Gly