(1) The nutrients of maize seeds are stored in endosperm, and the main component of the stored nutrients is starch, which turns blue when exposed to iodine. So drop a drop of iodine solution on the corn seed profile shown in the figure, and the part that turns blue is the endosperm, indicating that the endosperm contains a lot of starch.

(2) In the structure of maize seed, embryo is a young life, which consists of [2] embryo, [3] hypocotyl, [4] radicle and [6] cotyledon.

(3) Comparing the structure of kidney bean seed and corn seed, the similarity between them is that they both have seed coat and embryo, but the difference is that one cotyledon of corn seed has endosperm, while two cotyledons of kidney bean seed have no endosperm.

(4) Take 10 corn seeds with the same growth state in group A and group B, cut off the embryos of the seeds in group A with a blade, put them into a Petri dish filled with soaked napkins without treatment, cultivate them under the same suitable conditions, and observe the germination of the seeds.

So the answer is:

(1)5 endosperm; Endosperm contains a lot of starch.

(2) two germ; ③ hypocotyl; 4 radicle; 6 leaves

(3) Both of them have seed coat and embryo; One cotyledon of corn seed has endosperm, and two cotyledons of kidney bean seed have no endosperm.

(4) Take 10 corn seeds with the same growth state in group A and group B, cut off the embryos of the seeds in group A with a blade, put them into a Petri dish filled with soaked napkins without treatment, cultivate them under the same suitable conditions, and observe the germination of the seeds.