(1), ① Gametes are the only medium to transfer genetic materials between parents and children, and play a bridge role in connecting parents and children.

② The four cross combinations given in the table all belong to the inheritance of a pair of relative characters. In the first cross in the table, the offspring of tall stem: short stem = 2 10: 70 = 3: 1, so it is judged that it belongs to heterozygosity and short stem belongs to recessive trait, so it can be judged that the other three groups of parents are composed of genetic factors: ②aa×aa, ③. ④ AA× AA。 Homozygote of tall stem in all progeny = 265,438+00× 65,438+0/3 = 70, accounting for 70/(265,438+00+65,438+090+300) = 65,438+00%.

③ It is inferred from (2) that the genetic factors of G, C and A are aa, AA and AA respectively.

④ The mating modes of ①, ②, ③ and ④ are heterozygous selfing, recessive homozygous selfing, test crossing and homozygous hybridization respectively.

⑤ The genetic factors of tall stem and short stem are in accordance with the separation phenomenon.

(2)① In Experiment 3, the ratio of red fruit to yellow fruit in offspring is close to 3: 1, so red fruit is dominant and yellow fruit is recessive.

② Experiment 1 is a test cross experiment, and the parental genotype is aa×aa；; ; In experiment 2, red fruits× yellow fruits were crossed, and all the offspring were red fruits, which indicated that red fruits were homozygous. The parental genotype was AA×aa, and the experimental three-way heterozygosity was self-crossing, and the parental genotype was AA× AA.

So the answer is:

(1)① Gamete

② 10

③aa、AA、AA

④ Heterozygote self-crossing, recessive homozygote self-crossing and test crossing.

⑤ separation

(2)① Red fruit? three

②Aa×aa AA×aa Aa×Aa