In mice, black coat color (B) is dominant over brown (b), and a solid pattern (S
ID: 23334 • Letter: I
Question
In mice, black coat color (B) is dominant over brown (b), and a solid pattern (S) is dominant over white spotted (s). Color and spotting are controlled by genes that assort independently. A homozygous black, spotted mouse is crossed with a homozygous brown, solid mouse. All the F1 generation are black and solid. A testcross is then carried out on the F1 mice.Give the genotypes of the parents and the F1 mice, then give the genotypes and phenotypes, along with their expected ratios, of the progeny expected from the testcross.
Explanation / Answer
In mice, black coat color (B) is dominant over brown (b), and a solid pattern (S) is dominant over white spotted (s). Color and spotting are controlled by genes that assort independently. A homozygous black, spotted mouse is crossed with a homozygous brown, solid mouse. All the F1 generation are black and solid. A testcross is then carried out on the F1 mice.
Give the genotypes of the parents and the F1 mice, then give the genotypes and phenotypes, along with their expected ratios, of the progeny expected from the testcross.
In mice, black coat color (B) is dominant over brown (b),
and a solid pattern (S) is dominant over white spotted (s).
homozygous black, spotted mouse--------BBSS
homozygous brown, solid mouse.-----genotype---------bbss
BBSS X bbss-----------parents
All the F1 generation are black and solid. genotype---------BbSs
TEST CROSS
F1 genotype—BbSs X bbss
gametes
BS
bS
Bs
bs
bs
BS bs
bS bs
Bs bs
bs bs
bs
BS bs
bS bs
Bs bs
bs bs
bs
BS bs
bS bs
Bs bs
bs bs
bs
BS bs
bS bs
Bs bs
bs bs
Test cross ratio =1:1:1:1
genotype
phenotype
BS bs
black, spotted mouse
4/16
bS bs
brown, spotted mouse
4/16
Bs bs
black, spotted mouse
4/16
bs bs
brown, solid mouse.-----
4/16
gametes
BS
bS
Bs
bs
bs
BS bs
bS bs
Bs bs
bs bs
bs
BS bs
bS bs
Bs bs
bs bs
bs
BS bs
bS bs
Bs bs
bs bs
bs
BS bs
bS bs
Bs bs
bs bs
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.