Question

Two marks question:
List the post-fertilization events in angiosperms.

Answer 1

Hint: Angiosperms are the most developed species in the plants which have stems, flowers, leaves, and roots. A series of events take place pre and post-fertilization which complete the process of reproduction to take place in plants. In the reproductive system of plants, after fertilization, several changes cause the development of the fruit.

Complete answer:
Four events take place post-fertilization:
(1) Endosperm development- The tissue present in the seed starts the development of the embryo. There are three stages to it- nuclear formation (a division of the nucleus to create a wall free nuclear endosperm), cellular wall formation (the development of the cell wall from the periphery), and helobial formation (formation of an intermediate endosperm in between the nuclear a cellular endosperm).

(2) Development of the Embryo- After the formation of the zygote, the development of the embryo is the most important step. This process of development of the embryo from the zygote is known as embryogeny. It takes place via various steps, where first is the development of the pre-embryo and the next is the development of the full embryo.

(3) Seed development- The seed has three parts:
• The seed coat- made up of double-walled integuments, the outer membrane is called the testa which is the hardest part of the seed coat. The inner membrane is called the tegmen. A micro-opening on the seed coat called micropyle helps water and oxygen entry.
• The cotyledons- depending upon whether monocot or dicot plant, there are one or two cotyledons present in the seed. They are generally thick and swollen for the preservation of food.
• The embryo axis- the embryonic root and shoot are together called the embryonic axis.

(4) The fruit development- Differentiation and cell division processes in the ovary leading to the development of the fruit. The ovary wall matures and forms a pericarp whose primary role is protecting the seed from damage.

Note: The central axis is situated between the plumule and radicle which is known as the embryonal axis. The axis above the radicle is the hypocotyl and the part lying below the radicle is known as the epicotyl. This process helps in the formation of fruit and seeds, which thereby leads to the existence of species and progeny to live.