(1) In the figure, 1 is hypocotyl, 2 is embryo, 3 is radicle and 4 is cotyledon. These four parts constitute six embryos of the seed. Embryos will develop into stems and leaves of new plants in the future, radicles will develop into roots of new plants, hypocotyls will develop into parts connecting roots and stems, and cotyledons will provide nutrition for the development of embryos, hypocotyls and radicles. It can be seen that embryos are developed.

(2) D in Figure B is cotyledon, which is used to store nutrients needed for seed germination.

(3) The embryo [6] in Figure A is the main part of the seed; After sperm and eggs combine to form fertilized eggs, this reproductive mode from fertilized eggs to germ cells is called sexual reproduction.

So the answer is: (1)[2] germ; [3] radicle;

(2) cotyledons; Store nutrients for seed germination;

(3) fertilized eggs.