(1) As shown in the figure, both corn seeds and soybean seeds have a structure of 1 embryo and 2 seed coats. The embryo includes ①hypocotyl, ②germ, ③radicle, and ④cotyledon. The main differences between the two seed structures are: first, corn seeds have a structure of 3 endosperms; second, they have different numbers of ④ cotyledons. Corn seeds have one cotyledon, and bean seeds have two cotyledons. The nutrients of corn seeds are stored in 3 endosperms. , the nutrients of the bean seeds are stored in the ④ cotyledons.

(2) The embryo includes ①hypocotyl, ②germ, ③radicle, and ④cotyledon. When seeds germinate, ③ the radicle is the first to break through the seed coat and develop into a root, and ② the embryo develops into stems and leaves. It can be seen that the embryo is an important part of the seed and will develop into the larvae of the plant in the future.

(3) In the ①hypocotyl, ②germ, ③radicle, and ④cotyledons of soybeans, the nutrients of the seeds are stored in the ④cotyledons. During seed germination, ③ the radicle is the first to break through the seed coat and develop into a root, and ② the embryo develops into stems and leaves. ①The hypocotyl develops into the part that connects the root and stem.

So the answer is: (1), embryo; seed coat; 3 endosperm; ④ cotyledons

(2), 1 embryo

(3), ④ Cotyledons; ③ radicle; ② embryo