This document discusses reproduction in various forms of life. It describes asexual reproduction, which does not involve sex cells and occurs through mechanisms like budding, fragmentation, and regeneration. It produces offspring that are genetically identical to the parent. Sexual reproduction involves the union of egg and sperm to produce offspring with genetic variation. It summarizes the process of sexual reproduction in flowering plants, including pollination, fertilization, fruit and seed development, and seed germination.
2. Reproduction
Forms the next generation of species
The means to continue life (perpetuation
of species)
May be sexual or asexual
3. Asexual
reproduction
Sexual
reproduction
Does not involve
gametes or sex
cells
Occurs in many
forms and is
performed by many
lower forms of
organsims,
including plants
No genetic variation
in organisms
Involves sex cells
The sperm and the
egg unite to form a
zygote
Characteristic of
many organisms,
including plants,
animals and
humans
Increases genetic
variation among
4. Examples of Asexual
reproduction
Fission – one cell divides into two either
longitudinally, transversely or even
diagonally
E.g. Algae Volvox and Ulothrix, paramecia,
amoeba, bacteria and corals
Fragmentation – pieces of an organism may
break off and develop into whole organisms
Colonies of algae, sea anemone, comb
jelly, flatworms
6. Budding – cells in some areas of an
organism’s body organize themselves to
form new individuals or buds
Hydra (freshwater polyp)
Parthenogenesis (virgin birth) – an egg
possessing diploid chromosomes develops
into an adult without being fertilized
Daphnia, rotifers, snails, honeybees and
sea urchins
Examples of Asexual
reproduction
8. Paedogenesis – smaller larvae develop
from bigger larvae and grow up to
become adults
Flukes, taperworm, ascaris
Regeneration – demonstrated by sea
stars; when a sea star is cut into pieces,
such that each arm has aportion of the
central disk, each piece grows the rest of
the central disk and the for other arms
Examples of Asexual
reproduction
10. Conjugation
Sexual reproduction in lower forms of life
Genetic material (not necessarily gametes)
is transferred between two individuals
through a protoplasmic bridge before
allowing autotomy (voluntary separation of
a body part) to take place
Paramecium, bacteria and cyanobacteria,
fungi
11. Examples of Asexual
reproduction
Common bread mold (amag) – reproduces
through spores encased inside a capsule-
like container called sporangium
Mosses and ferns – spore-producing plants
Spores – primary structures responsible
for asexual reproduction in mosses and
ferns
12.
13. Asexual or Vegetative Reproduction
in Flowering Plants
Vegetative
Reproductio
n
Natural
Runners
Leaf
reproduction
Tip layering
Artificial
Layering
Grating and
Budding
Cutting
14. Natural Vegetative Reproduction
Runners – grow along the ground from the
parent plant; forms adventitious roots and
shoots at the tips
Strawberry
Tip layering – allows their aerial stems to arch
downwards so that their tips touch the ground
Blackberry, raspberry and spider plant
Leaf reproduction – new plants develop along
the margins of their leaves
katakataka
15. Artificial Vegetative Reproduction
Cutting – portions of stems and roots are
removed and transferred to loose, damp soil or
sand
Herbaceous and woody plants such as rose
Layering – stimulates the growth of roots on a
stem; a stem is buried in the ground then cut
when roots are formed
Grafting and budding – splicing together of two
stems or the union of their two cambium layers
16. Sexual Reproduction in Flowering
Plants: Floral Parts
Calyx – collection of sepals
Corolla – collection of petals
Stamen – male reproductive part
Filament – slender stalk
Anther – produces colored grains called
pollen, which contains sperm nuclei
17. Pistil/Carpel – female reproductive part
Stigma – sticky topmost part
Style – slender stalk that supports the
stigma
Ovary – swollen base
Ovules – found inside the ovary
18.
19. Stages of Sexual Reproduction in
Plants
a. Formation of Gametes
a. Megasporogenesis – formation of
female gametophyte
b. Microsporogenesis – formation of male
gametophyte
Sporogenesis – involves a reduction
division process that produces haploid
gametes: egg in embyo sac and sperm
in the pollen grain
20. b. Pollination – transfer of the pollen grain
from the anther to a stigma of a flower
a. Self-pollination – pollen is transferred
from the anther to the stigma of the
same flower
b. Cross-pollination – pollen is transferred
from the anther to the stigma of another
plant
21. c. Double-fertilization
Pollen grain with two nuclei (generative and tube
nucleus)
generative nucleus moves into the pollen tube
and forms two sperm nuclei
tube nucleus grows through the stigma, style
and into the ovule, clearing the way for the
entry of sperm nuclei
1 sperm nuclei (N) + 1 egg (N) = zygote (2N)
1 sperm nuclei (N) + 2 polar nuclei = endosperm
(3N)
22. d. Fruit and seed development
ovary fruit
ovule seed
Seed embryo, stored food and seed coat/testa
Embryo cotyledon, hypocotyl and epicotyl
23. e. Seed Germination
Viability – ability of the seed to germinate
Conditions:
a. Suitable temperature ( between 16C and 27
C)
b. Plenty of moisture
c. Sufficient oxygen
Seedling young plant that develops out of a plant
embryo from a seed
radicle – root
hypocotyl – shoot
cotyledons – seed leaves