Sexual Reproduction in Flowering Plants Test - 15

The process of fusion of two polar nuclei with one male gamete is called as triple fusion. The resulting cell becomes primary endosperm cells that forms endosperm.

The synergids have special cellular thickening at micropylar tips called filiform apparatus which help in guiding pollen tube into egg synergids for fertilisation to form embryo.

The coconut water from tender coconut is nothing but free nuclear endosperm made up of thousands of nuclei. The surrounding white kernel is the cellular endosperm.

Pollen tube is formed by germination of pollen grain on stigma of flower. Pollen grain is transferred from stigma to receptive female gametes by pollen tube formed in the style of the pistil.

A typical angiospermic embryo sac contains 8 nuclei which includes 3 egg apparatus at micropylar end, 3 antipodal cells at chalazal ends and 2 polar nuclei at the centre of embryo sac.

Crop improvement programme is carried out to obtain crops with desired traits that may be more yields, resistance to disease, higher nutrient value etc. Two plants having desired traits are hybridized to obtain combination of desired traits.

Primary endosperm cell is triploid because it is formed by fusion of two polar nuclei and one male gamete called triple fusion. Primary endosperm cells divides further to form endosperm that provide nourishment to embryo.

Embryogeny in dicotyledonous plants involves mitotic division of zygote to form proembryo, further division in proembryo results into globular embryo followed by heart-shaped embryo to mature embryo.

In embryo, the portion of embryonical axis above the level of cotyledon is epicotyl which terminates with Plumule or stem tips above the above the level of cotyledons,

monocotyledonous embryo contain only one cotyledon. In grass family, cotyledon is called as scutellum. In monocotyledonous embryo radicle and root cap is covered by coleorhiza.