A researcher has developed two stains for use with seed plants. One stains sporophyte tissue blue; the other stains gametophyte tissue red. If the researcher exposes pollen grains to both stains, and then rinses away the excess stain, what should occur?

A) The pollen grains will be pure red.

B) The pollen grains will be pure blue.

C) The pollen grains will have red interiors and blue exteriors.

D) The pollen grains will have blue interiors and red exteriors.

E) Insofar as the pollen grains are independent of the plant that produced them, they will not absorb either stain. 2

A) The pollen grains will be pure red.

Explanation:

Plants have alternation of generations, this means that there are two different stages in their life-cycle: a sexual haploid (n) phase and an asexual diploid phase (2n). These phases occur in different individuals, so there is an haploid plant called gametophyte that carries gametes and after fecundation, it will rise a diploid sporophyte (asexual).

In seed plants, the sporophyte is the plant that we normally see, and the gametophyte is reduced into an organ of the sporophyte. The male gametophyte is the pollen that is produced in the sporangium in anthers (parts of sporophyte). When a pollen grain fecundes a female gametophyte (egg), it will produce a diploid embryo or new sporophyte.

Therefore, if the researcher exposes pollen to both stains, these grain will stain red, because red stain identifies gametophyte tissue.