a, X = G = 30% nên A = T = 20%
X = X1 + X2 = 30%N = 60%N1
X1 = G2 = 40% thì X2 = G1 = 60% - 40% = 20%
T = T1 + T2 = 20%N = 40%N1
A1 = T2 = 20% thì X2 = G1 = 40% - 20% = 20%
b, Số nucleotit của ADN: 450 x 20 = 9000
A = T = 20% x 9000 = 1800
G = X = 30% x 9000 = 2700
X1 = G2 = 40% x 4500 = 1800
X2 = G1 = 20% x 4500 = 900
A1 = T2 = 20% x 4500 = 900
X2 = G1 = 20% x 4500 = 900