(1) parents are homozygous. The experimental results show that the dominant gene must control yellow, and white flowers should also be dominant for safflower and yellow flowers. According to the results of the second generation of the experiment, red should be controlled by double recessive genes. Combined with the gene control chart of traits, we can know that gene 1 should be controlled by A and gene 2 should be controlled by B. Therefore, the genotype of yellow flower should be aaB-, the genotype of safflower should be aabb, and other genotypes are white flowers, including A-B- and A-BB.

(2) Because the parents are homozygous, the genotype of yellow flower is AaBb, and the genotype of safflower is aaBB. In the second experiment, due to the deformation of 9: 3: 3: 1 after selfing, the offspring should be AABB, and the parents of Baihua should be AABB. In the third experiment, after the test cross, the offspring appeared 2: 1: 1, and the offspring should be AaBb, indicating that the parent Baihua B is AABB.

(3) In the second experiment, the second generation of * * * has 9 genotypes, and the number of white flowers should be 9-3=6. Homozygous white flowers are AAbb and AABB, and the ratio of homozygous white flowers to all white flowers is 2 12 = 16. In the second generation, 13 yellow flowers are homozygous and 23 are heterozygous, so

(4) In the third experiment, F2 generation 12AaBb hybridized with safflower AaBb, and the middle white flower: yellow flower: safflower = 4: 1: 3.

(5) When two different genotypes of white flowers are crossed, the first generation has only two colors: white and yellow. Since the yellow genotype is aaB- and the safflower is aabb, which means that bb will not appear, then the white color should be AaBB×AaBb or AABB× AABB.

So the answer is:

( 1)a？ b

(2)aaBB AAbb AABB

(3)6? 16? 12?

(4)4: 1:3?

(5)AaBB×AaBb or AaBB×AaBb