Provides every relevant knowledge about the topic for the students of Grade- 7 and 8

3. • In sexual reproduction male and female cells (Androecium and
Gynoecium), called gametes, unite to form a single cell, called a
zygote. This zygote then undergoes cell division, ultimately giving
rise to a new plant body. Offspring produced sexually, however,
have two parents and so, though they certainly resemble the
parents, the offspring are not necessarily identical to them.
Consequently, sexual reproduction is a process that increases
variation among offspring.

7. • Carpels : These are the female reproductive organs and are found in the center of
the each flower. They consist of a hollow Ovary which contains Ovule. The
Ovule contain the female gamete. After fertilization, the ovary will become the
fruit, protecting the ovule which becomes the Seed. Above the Ovary there’s a
narrow Style which ends in the Stigma. The Pollen grains or Anthers
(Androecium) stick to the Stigma during Fertilization.
• Stamens : These are the male reproductive organs and are found in a ring
(Whorl) around the Carpels. A Stamen consist of a Stalk (Filaments) bearing an
Anther. Each Anther is made of 4 pollen sacs in which pollen grains grow and
develop. Pollen grains contain the male gametes.

9. Ovary And Ovule role in Reproduction

10. Pollination

11. • Pollination is a process by which pollens are transferred from ‘Anthers’ to the
Stigma of a plant or flower, thereby enabling reproduction and fertilization.
• Biotic Pollination
• Abiotic Pollination
Pollination
• Self Pollination
• Cross Pollination
Pollination
Process

12. • Biotic Pollination : The process of pollination which requires pollinators :
organisms that carry or over the pollen grains from anther to the Stigma.
This is done by insects mostly; but also by vertebrates like Bats, Humans and
Birds.
• Abiotic Pollination : It refers to situations where pollination is mediate
without involvement of other organisms. Abiotic pollination occurs by wind
and sometimes by water in case of aquatic plants.

13. • It occurs when pollen from one plant Anther to the same plant
Stigmas or to the other flower s on the same plant. Self
Pollination occurs in Monoecious Plants: the flowers on a plant
are androecium, other flowers on the same plant have gynoecium
also, then its mainly done. Self pollination may include autogamy:
where pollen moves to gynoecium part or stigmas of the same
flower or Geitonomy: where pollen is transferred to another
flower on the same plant.

14. It occurs when pollen is transferred to Stigma of another flower of the different plant. It
occurs on Dioecious plants, Protandry, Protogyny and on the plants which are self-
incompatible.
• Dioecious Plants: Either have Androecium or Gynoecium, which can’t reproduce unisexually.
• Protandry: Anthers of some flowers mature first. Pollination of immature stigma on the
same plant is not possible.
• Protogyny: The stigmas mature first and Anthers are immature.
• Self-incompatibility: Pollen tubes doesn’t grow well, so no fertilization takes place.
Cross Pollination is done by pollinators like honeybees, hummingbird, bats, wasps, other
insects etc. The Cross Pollination is sexual but it have individual Androecium(Anthers) and
Gynoecium(Stigmas or female part) on different plants.

18. • Asexual Reproduction requires only on e parent which means it
produce unisexually. It have either Androecium or Gynoecium.
Asexual reproduction is a mode of reproduction by which
offspring arise from a single organism, and inherit the genes of
that parent only. There is no sexual union of gametes. Asexual
reproduction generates individuals that are genetically identical
to the mother plant.

21. • Fragmentation or clonal fragmentation in multicellular or colonial organisms
is a form of asexual reproduction or cloning in which an organism is split
into fragments. Each of these fragments develop into mature, fully grown
individuals that are clones of the original organism.
• The simplest green plants, Algae, reproduce by an asexual method known as
fragmentation. In filamentous algae, such as Spirogyra, the filaments
accidentally break into many fragments. Each fragment may give rise to a
new filament of the algae.

23. • In some lower plants special reproductive units called spores, develop
asexually on the parent body. The spores are microscopic and covered by
protective wall. On reaching a suitable environment they develop into a new
plant body, for example, in bread moulds, moss, fern.

25. • The roots, stems and leaves are the vegetative parts of a plant. When new
plants are produced from these parts, the process is called vegetative
propagation or vegetative reproduction.
• Natural Methods:
• Many plants reproduce naturally using stems, roots and leaves.

26. • Some plants such as Asparagus and Sweet potato have tuberous roots. These
roots have adventitious buds which grow into a new plant. Thus they can be
used for propagation.
• Sometimes reproduction by roots can be done by cutting the down root hairs
and put it into another soil where should be only warm and with plenty of
water.

28. • Vegetative propagation through stem is very common in plants. The
underground modification of stem, such as rhizome, in ginger, tuber in
potato and bulb in onion have buds which develop into a new plant and are
therefore used to carry out vegetative propagation of the plant in the field.
• The bud make its place itself which grow into the same plant species.

30. • Even leaves are used for vegetative propagation of plants. For
example, Bryophyllum leaves have buds on their margin. These
buds grow into small plantlets which on detachment from the
mother plant grow into independent plants.

32. • Layering is bending a low growing, flexible stem to the ground. The method
is as follows. Cover part of th stem with soil, leaving the remaining above the
soil. Bend the tip into a vertical position and stake in place. The sharp bend
induces root, thereby giving rise to a new plant. Example: Jasmine, grapevine,
Bougainvillea etc.
• These plants have long bales or stem which cant climb properly, So the bales
are put inside the soil which grow into the same plants species.

34. • Many plants are grown through their stem cuttings, for example, Rose,
Croton, Money plants, Sugarcane, etc. Cuttings of these plants can be grown
even in water where they strike roots and develop adventitious buds.
• The cutting can be done only when there lot of strength in the stems or
leaves.

36. • A very common method of artificial propagation is grafting. It is
taking a part from one plant and making it grow on another plant. The
method is useful in propagating improved varieties of many flowers
and fruits such as rose, bougainvillea, mango, apple, etc.
• In this process a small branch is inserted into a rooted plant. The
rooted plant called stock is stronger. In this stock a stem cutting from
the desired plant is inserted which is known as scion or graft. The
grafted end of stock and scion fit well with each other and are bound
firmly with tape or rubber-band until their tissues unite and become
one