Question

Endosperm in gymnosperms is:
(a) Haploid
(b) Diploid
(c) Triploid
(d) All of the above

Answer 1

Hint: We know that in angiosperms, double fertilization occurs which results in the formation of a triploid endosperm. However, this is not the case with gymnosperms. Gymnosperms have two sperm cells as well but one of them degenerates. As a result, there is no real endosperm.

Complete answer:
In gymnosperms, the reproductive structures are called cones. The female cone consists of a diploid cell called megasporocyte which is covered in the integuments along with megasporangium. These 3 elements are together called ovules in gymnosperms. This megasporocyte undergoes meiosis producing 4 haploid megaspores. However, only one of these survives at the end and becomes a female gametophyte which contains 2 or 3 archegonia. Each of the archegonia will form an egg. On the other hand, in male cones, reproductive cells called microsporocytes are present inside the microsporangia which also undergo meiosis forming 4 haploid microspores. Each microspore develops into a pollen grain or male gametophyte. The pollen grain thus contains two prothallial cells, a generative cell, and a tube cell. The generative cell and the tube cell will participate in reproduction and the other two will degenerate soon. So, before the pollen tube reaches the female gametophyte the sperm cell divides to produce two sperm nuclei. One of them unites with the egg nucleus and the other degenerates. On maturation of archegonia, the 2 sperm nuclei are discharged in the pollen tube.
So, the correct answer is ‘(a) Haploid’.

Note: Following fertilization, the endosperm is the tissue formed in all the flowering plants and serves the function of providing nutrition to the growing embryo. It surrounds the embryo and provides nutrition in the form of starch.