Tag: asexual and sexual reproduction in plants

The ovule of flowering plants are located inside the gynoecium and are connected to the placenta which is a parenchymatous tissue via a stalk-like structure called the funiculus.

A. Female gametes are also called eggs or ovum. They are created during the cellular reproduction process known as meiosis. The resulting gamete cell is a haploid cell.

When in a flower, the internode between the corolla and the androecium is lengthened so as to raise the androecium high up in the air then that internode is called Androphore. It is an extension of the receptacle carrying the androecium and the gynoecium, typical of the caper family. In Passiflora, androphore is lightly differentiated.

When pollen tube enters through the micropyle, the phenomenon is known as porogamy. When pollen tube enters to the embryo sac through the tissue of the chalaza, the phenomenon is known as chalazogamy. When pollen tube enters through the base of a funiculus or the integument, the phenomenon is known as mesogamy. Isogamy is a form of sexual reproduction that involves fusion of gametes of similar size and structure. 

Ovule means 'small egg'. In seed plants, the ovule is the surface that gives rise to and contains the female reproductive cells. It consists of three parts: the integuments form its outer layers, the nucellus and female gametophyte in its center. The female gametophyte specifically termed as megagametophyte is also called the embryo sac in angiosperms.

The mature ovule contains in its central part a region called the nucellus that in turn contains an embryo sac with eight nuclei, each with one set of chromosomes. The two nuclei near the centre are referred to as polar nuclei. In the pines, the female gametophyte develops within the tissues of the nucellus and acquires abundant food reserves. The proembryo forms after a period of free-nuclear division in the zygote, and the tier of cells above the basal four then elongates to form a suspensor which pushes the embryonic group deep into the gametophyte.

Endothecium is defined as the lining of the inner cavity of the anther. It is present as a middle layer. 

If chromosomes of megaspore mother cell are 10; it ensures that the diploid number is 10. 2n = 10. Therefore, n = 5. Aleurone layer will be triploid in nature. Thus, the number of chromosomes in aleurone layer = 15.

The pollen tube ultimately enters an ovule through the micropyle and penetrates one of the sterile cells on either side of the egg ( synergids). These synergids begin to degenerate immediately after pollination. 
Synergids are haploid in nature. Thus, if root cell has 2n = 42, synergids will have n = 21.