Page 1 - 2._Lesson_Notes-Sexual_Reproduction_in_flowering_Plants

SAI International School
Subject- Biology, Class X
Chapter- How do Organisms Reproduce?
Subtopic- Sexual reproduction in Flowering Plants.
Module-20
Lesson notes

Sexual mode of Reproduction

 Sexual mode of reproduction involves two individuals – one acting as male
and the other acting as female. The two gametes, belonging to different sex,
fuse with each other to form a zygote leading to the development of a new
generation.
 Fertilisation brings about fusion of nuclei of gametes. The two nuclei
(belonging to two gametes), each having single set of chromosomes
(haploid), fuse to form zygote having a double set of zygote, i.e., diploid (one
set paternal and the other set maternal). The zygote developes into an adult
body of the organism.
 Higher animals possess gonads, the primary sex organs. The gonads
produce haploid gametes by meiotic division. The testis, which are male
gonads, produce sperms and the ovaries, which are female gonads, produce
eggs or ova after meiosis. This ensures production of diploid no. of
chromosomes in zygote, when the gametes fuse.

Advantages of Sexual Reproduction over Asexual Reproduction

1. Since fusion of male and female gametes come from two different organisms
and from sexually distinct individuals, the offspring exhibit diversity of
character.
2. Meiosis provides opportunity for new combination of genes. It plays a
prominent role in the origin of new species and leads to variation required
for evolution.

Sexual Reproduction in Plants

In flowering plants, sexual reproduction occur within specialised reproductive organs,
called the flowers. Thus, a flower may be defined as a specialised condensed
reproductive shoot on which are inserted the essential reproductive parts.
Parts of a flower-. A typical flower has four floral parts: sepals, petals, stamens,
and carpels. Examples: rose, hibiscus

 Unisexual flowers : A unisexual flower is defined as a flower that possesses
either stamens or carpels. Example; Papaya, Watermelon, Cucumber, Maize,
White mulberry,

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