Solution

Unlike bryophytes and pteridophytes, in gymnosperm, the male and female gametophytes don't have an independent free-living existence.
They remain attached to the sporophytes. After fertilization, these developed into an embryo and the ovule into seeds. Seeds are not covered.
So 3 generation live inside one seed of gymnosperm- the embryo and the female gametophytic tissue and the seed coat and the nucellus which is the female sporophytic tissue.

SOLUTION

Nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis (hemimetabolism) before reaching its adult stage.

Juvenile hormone is produced by corpora allata in insects, it favors the development of juvenile characteristics. During larval life, this hormone predominates and each moult yields another larger juvenile and keeps the larva in immature condition or maintains juvenility.

Ecdysone is a steroidal, moulting hormone of prothoracic gland, in insects that triggers metamorphosis.

Parotid glands secretes serous saliva through the parotid duct into the mouth, to facilitate mastication and swallowing and to begin the digestion of starches