Ở ruồi giấm, giả sử cặp gen thứ nhất gồm 2 alen A,a nằm trên NST số 1, cặp gen thứ 2 gồm 2 alen B,b và cặp gen thứ b

\(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyqaiaadg % gacqGHxdaTcaWGHbGaamyyaiabgkziUkaaigdacaWGbbGaamyyaiaa % cQdacaaIXaGaamyyaiaadggaaaa!431B! Aa \times aa \to 1Aa:1aa\)

\(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSaaaeaaca % WGcbGaamizaaqaaiaadkgacaWGebaaaiabgEna0oaalaaabaGaamOy % aiaadsgaaeaacaWGIbGaamizaaaacqGHsgIRdaqadaqaaiaaicdaca % GGSaGaaG4maiaadkeacaWGKbGaaiOoaiaaicdacaGGSaGaaG4maiaa % dkgacaWGebGaaiOoaiaaicdacaGGSaGaaGOmaiaadkgacaWGKbGaai % OoaiaaicdacaGGSaGaaGOmaiaadkgacaWGKbaacaGLOaGaayzkaaGa % amOyaiaadsgaaaa!5644! \frac{{Bd}}{{bD}} \times \frac{{bd}}{{bd}} \to \left( {0,3Bd:0,3bD:0,2bd:0,2bd} \right)bd\)

\(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGceaqabeaacqGHsg % IRcaaIWaGaaiilaiaaiodadaWcaaqaaiaadkeacaWGKbaabaGaamOy % aiaadsgaaaGaaiOoaiaaicdacaGGSaGaaG4mamaalaaabaGaamOyai % aadseaaeaacaWGIbGaamizaaaacaGG6aGaaGimaiaacYcacaaIYaWa % aSaaaeaacaWGcbGaamiraaqaaiaadkgacaWGKbaaaiaacQdacaaIWa % GaaiilaiaaikdadaWcaaqaaiaadkgacaWGKbaabaGaamOyaiaadsga % aaaabaGaamiwamaaCaaaleqabaGaamyraaaakiaadMfacqGHxdaTca % WGybWaaWbaaSqabeaacaWGfbaaaOGaamiwamaaCaaaleqabaGaamyz % aaaakiabgkziUkaadIfadaahaaWcbeqaaiaadweaaaGccaWGybWaaW % baaSqabeaacaWGfbaaaOGaaiOoaiaadIfadaahaaWcbeqaaiaadwea % aaGccaWGybWaaWbaaSqabeaacaWGLbaaaOGaaiOoaiaadIfadaahaa % WcbeqaaiaadweaaaGccaWGzbGaaiOoaiaadIfadaahaaWcbeqaaiaa % dwgaaaGccaWGzbaaaaa!6B01! \begin{array}{l} \to 0,3\frac{{Bd}}{{bd}}:0,3\frac{{bD}}{{bd}}:0,2\frac{{BD}}{{bd}}:0,2\frac{{bd}}{{bd}}\\ {X^E}Y \times {X^E}{X^e} \to {X^E}{X^E}:{X^E}{X^e}:{X^E}Y:{X^e}Y \end{array}\)

Tỷ lệ kiểu hình đời con có 3 tính trạng trội và 1 tính trạng lặn là:

\(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSaaaeaaca % aIXaaabaGaaGOmaaaacaWGHbGaamyyaiabgEna0kaaicdacaGGSaGa % aGOmamaalaaabaGaamOqaiaadseaaeaacaWGIbGaamizaaaacqGHxd % aTcaaIWaGaaiilaiaaiEdacaaI1aGaamiwamaaCaaaleqabaGaamyr % aaaakiabgUcaRmaalaaabaGaaGymaaqaaiaaikdaaaGaamyqaiaadg % gadaqadaqaaiaaicdacaGGSaGaaG4mamaalaaabaGaamOqaiaadsga % aeaacaWGIbGaamizaaaacqGHRaWkcaaIWaGaaiilaiaaiodadaWcaa % qaaiaadkgacaWGebaabaGaamOyaiaadsgaaaaacaGLOaGaayzkaaGa % ey41aqRaaGimaiaacYcacaaI3aGaaGynaiaadIfadaahaaWcbeqaai % aadweaaaGccqGHRaWkdaWcaaqaaiaaigdaaeaacaaIYaaaaiaadgea % caWGHbGaey41aqRaaGimaiaacYcacaaIYaWaaSaaaeaacaWGcbGaam % iraaqaaiaadkgacaWGKbaaaiabgEna0kaaicdacaGGSaGaaGOmaiaa % iwdacaWGybWaaWbaaSqabeaacaWGLbaaaOGaamywaiabg2da9iaaic % dacaGGSaGaaG4maiaaikdacaaI1aaaaa!78E1! \frac{1}{2}aa \times 0,2\frac{{BD}}{{bd}} \times 0,75{X^E} + \frac{1}{2}Aa\left( {0,3\frac{{Bd}}{{bd}} + 0,3\frac{{bD}}{{bd}}} \right) \times 0,75{X^E} + \frac{1}{2}Aa \times 0,2\frac{{BD}}{{bd}} \times 0,25{X^e}Y = 0,325\)