Question

With the help of a well labelled diagram of fertilization in flowering plant, explain the process of fertilization in the flowering plant from the pollination to that of double fertilization​

Answer 1

What is Fertilization?

In plants, fertilization is a process of sexual reproduction, which occurs after pollination and germination.

Fertilization can be defined as the fusion of the male gametes (pollen) with the female gametes (ovum) to form a diploid zygote. It is a physicochemical process which occurs after the pollination of the carpel. The complete series of this process takes place in the zygote to develop into a seed.

In the course of fertilization, male gametes get transferred into the female reproductive organs through pollinators (honey bees, birds, bats, butterflies, flower beetles) and the final product will be the formation of the embryo in a seed.

Fertilization Process

In flowers, the pollen grain germinates after the pollination of the carpel and grows into the style by creating the pathway for the pollen grain to move down to the ovary.

The pollen tube opens into the ovule through the micropyle and bursts into the embryo sac. Here, the male nucleus unites with the nucleus of an egg inside the ovule forming a diploid zygote, which later swells up and develops into a fruit.

Types of Fertilization

Fertilization process can be grouped into three types and are classified mainly based on the entry of the pollen tube into the ovule.

• Porogamy

It is the common type of fertilization carried out in all angiosperms or flowering plants. In this type of fertilization, the pollen tube enters the ovule through the micropyle.

• Chalazogamy

This type of fertilization is carried out on all Casuarina species of plants. In this condition, the pollen tube enters the ovule through the pollen tube.

• Mesogamy

This type of fertilization is seen in all Cucurbit plants, such as pumpkin, ridge gourds, bitter gourd and other gourd plants. In this type of fertilization, the pollen tube enters the ovule through its middle part or through the integuments of the ovule.

Double Fertilization

Double fertilization is a process of fertilization characterized by the fusion of a female gametophyte with two male gametes. In this mechanism, one sperm cell fuses with the egg-producing zygote, and the other fuses with the two polar nuclei to make the endosperm. All angiosperm plants undergo double fertilization.

${ \huge\rm \pink {(✯ᴗ✯)H}\rm \blue {A} \rm \purple {N}\ \rm \green{J} \rm\red {U}\ \rm \orange {H} \rm{U} \rm \gray{I(✯ᴗ✯)}}$

Answer 2

Answer:

Fertilisation occurs after pollen grains fall on the stigma. Upon falling on the stigma, the pollen grains burst and grow a pollen tube taht passes downwards from the style to the ovary containing the ovule. The male gamete present in the pollen moves downward through the pollen tube and reaches the ovule.

Explanation: