A black guinea pig crossed (Rufus) is crossed with an albino guinea pig (Rolo) produces 12 black offspring. When the albino (Rolo) is crossed a second black guinea pig (Reese), 7 blacks and 5 albinos ar obtained. What is the best explanation for this genetic situation? Write the genotypes for the parents and offspring?
2007-12-19 08:59:58 · 1 answers · asked by Tim Yoon 1 in Science & Mathematics ➔ Biology
Black must be dominant to albino.
In the first cross, Rufus must have been homozygous for black (BB) and Rolo was bb.
P BB x bb
F1 all Bb, all black
In the second cross, Rolo was bb and Reese must have been heterozygous black (Bb).
P bb x Bb
F1 1 bB: 1bb
1 black: 1 albino
The actual 7 black: 5 albino is very close to 1:1. The small difference between the expected and the actual is by chance.
2007-12-19 09:10:39 · answer #1 · answered by ecolink 7 · 1⤊ 0⤋