Question

describe what double fertilization means in angiosperms

Answer 1

FERTILIZATION: It is a reproductive process where Egg(Female gamete) fuses with Sperm(Male gamete) to form zygote.
Double Fertilization: Its is a process where one female gamete fuses with two male gametes.

This kind of fertilization is an important characteristic of angiosperms(Flowering plants).
Flower is a reproductive part with separate male and female reproductive organs. Both reproductive organs produces gametes
male gametes are called sperms and female gametes are known as eggs.

Process of reproduction occurs by means of pollination where male gametes containing reaches to the stigma through style and finally reaches ovary.
One Haploid male gamete fuses with haploid female gamete that is egg to form a diploid zygote and, another male gamete fuses with two polar nuclei to form 3n primary endosperm nucleus.

After division Zygote forms Embryo and Primary Endosperm nucleus forms primary endosperm cell and then endosperm.
Now will have a look into embryo development

After fertilization zygote forms embryo and after embryo formation no other sperm cell can approach female ovary. Fertilized ovule forms a seed and ovary tissues forms fruit flesh enclosing seeds.
During embryo development zygote divides to form terminal cells on upper side and basal cells on lower side.
Terminal cells help in transportation of nutrients to developing embryo.
Basal cell forms proembryo.

Embryo Development stages in Flowering Plants:
1) In this stage Terminal cells divides to form a globular pro embryo and basal cell forms suspensor which helps in anchoring embryo.

2)The Embryo takes heart shape due to presence of cotyledons.
3) Embryo grows, gets crowded and begins to bend
4) Embryo completely fills the seed.