Question

question 1
for sneaky snakes, being rude (r) is dominant to being respectful (r). complete the cross below, and determine the phenotype (dominant : recessive) ratio.

	r	r
r	#3	#4

2 (#5) : 2 (#6)

column a\tcolumn b

1. ____ #1\ta. sneaky
2. ____ #2\tb. rr
3. ____ #3\tc. rr
4. ____ #4\td. rr
5. ____ #5\te. respectful
6. ____ #6\tf. rude

\t\tg. sweet

Explanation:

Step1: Analyze #1 (r and R cross)

To find the genotype for #1, we cross the row allele \( r \) with the column allele \( R \). So the genotype is \( Rr \) (matches option d).

Step2: Analyze #2 (r and r cross)

Crossing \( r \) (row) with \( r \) (column) gives \( rr \) (matches option c).

Step3: Analyze #3 (r and R cross)

Crossing \( r \) (row) with \( R \) (column) gives \( Rr \) (matches option d). Wait, no, wait—wait, the first row is \( r \), first column (top) is? Wait, the Punnett square: the top row is \( R \) and \( r \), left column is \( r \) and \( r \). So #1: \( r \times R = Rr \) (d), #2: \( r \times r = rr \) (c), #3: \( r \times R = Rr \) (d)? No, wait the left column is two rows: both \( r \). So first row (left) \( r \), top column \( R \): #1 is \( Rr \) (d). First row (left) \( r \), top column \( r \): #2 is \( rr \) (c). Second row (left) \( r \), top column \( R \): #3 is \( Rr \) (d). Second row (left) \( r \), top column \( r \): #4 is \( rr \) (c). Now for phenotypes: \( Rr \) is dominant (rude, f), \( rr \) is recessive (respectful, e). So #5: the dominant phenotypes (from \( Rr \)): there are two \( Rr \) ( #1 and #3) and two \( rr \) ( #2 and #4). Wait, the ratio is 2 (dominant) : 2 (recessive). So #5: dominant phenotype is "rude" (f), #6: recessive is "respectful" (e). Wait, let's recheck:

• #1: \( Rr \) (d) → phenotype: rude (f)
• #2: \( rr \) (c) → phenotype: respectful (e)
• #3: \( Rr \) (d) → phenotype: rude (f)
• #4: \( rr \) (c) → phenotype: respectful (e)

So the dominant genotypes (\( Rr \)) are two ( #1 and #3), recessive (\( rr \)) are two ( #2 and #4). So #5 (dominant phenotype) is "rude" (f), #6 (recessive) is "respectful" (e). Wait, but the options for #1 - #4:

1. #1: \( Rr \) → d
2. #2: \( rr \) → c
3. #3: \( Rr \) → d? Wait no, wait the left column is two \( r \)s, top row is \( R \) and \( r \). So:

• Top row (columns): \( R \), \( r \)
• Left column (rows): \( r \), \( r \)

So:

• Cell #1: row \( r \), column \( R \) → \( Rr \) (d)
• Cell #2: row \( r \), column \( r \) → \( rr \) (c)
• Cell #3: row \( r \), column \( R \) → \( Rr \) (d)
• Cell #4: row \( r \), column \( r \) → \( rr \) (c)

Now phenotypes:

• \( Rr \): rude (f)
• \( rr \): respectful (e)

So the dominant phenotypes (rude) are from \( Rr \) cells (#1, #3) → 2 cells. Recessive (respectful) from \( rr \) cells (#2, #4) → 2 cells. So:

1. #1: d (Rr)
2. #2: c (rr)
3. #3: d (Rr)
4. #4: c (rr)
5. #5: f (rude)
6. #6: e (respectful)

Wait, but let's confirm each step again.

Step1: #1 Genotype

Row allele: \( r \), Column allele: \( R \). Genotype: \( Rr \) (option d).

Step2: #2 Genotype

Row allele: \( r \), Column allele: \( r \). Genotype: \( rr \) (option c).

Step3: #3 Genotype

Row allele: \( r \), Column allele: \( R \). Genotype: \( Rr \) (option d).

Step4: #4 Genotype

Row allele: \( r \), Column allele: \( r \). Genotype: \( rr \) (option c).

Step5: #5 Phenotype (Dominant)

Dominant allele is \( R \), so \( Rr \) shows dominant phenotype (rude, option f). There are two \( Rr \) cells (#1, #3), so dominant count is 2, phenotype: rude (f).

Step6: #6 Phenotype (Recessive)

Recessive allele is \( r \) (homozygous \( rr \)), phenotype: respectful (option e). Two \( rr \) cells (#2, #4), so recessive count is 2, phenotype: respectful (e).

Answer:

1. d
2. c
3. d
4. c
5. f
6. e