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Asexual Reproduction &
Plant reproduction
Asexual & Sexual Reproduction
• Sexual reproduction produces offspring that are
genetically different from their parents.
• Asexual reproduction produces offspring
genetically identical to their parent.
• Examples:
1. Binary Fission
2. Budding
3. Spore Production
4. Fragmentation
5. Parthenogenesis
Modes of Reproduction
Asexual Reproduction
• One parent cell divides by mitosis to
produce 2 identical cells that are
clones of the parent
Types of Asexual Reproduction
1. Budding - an outgrowth on the parent organism
that develops into a new organism
that eventually separates from the
parent.
• Example-yeast and hydra
http://www.youtube.com/watch?v=489CSop00sY
2. Binary fission –DNA is copied through mitosis,
causing the original parent cell to split into
two smaller, genetically identical cells.
Example-bacteria
http://www.youtube.com/watch?v=D
Y9DNWcqxI4
3. Spore production - spores are produced by
mitosis and are released from the original
parent cell for dispersal.
• Example – Fungi (Rhizopus stolonifera)
http://bcs.whfreeman.com
/thelifewire8e/content/cat
_010/30040.html
4. Fragmentation – when a piece of the parent
organism breaks off and is dispersed. Each
section is able to form a new organism.
• Example - House plants formed from cuttings
Planaria flatworm
5. Parthenogenesis – when offspring are
produced from unfertilized eggs
• Example - some insects, such as the Oleander aphid
Sexual Reproduction
• In sexual reproduction new individuals are
produced by the fusion of haploid gametes
to form a diploid zygote.
• Sexual reproduction offers the benefit of
generating genetic variation among
offspring, which enhances the chances of
the population's survival.
Sexual Reproduction in Angiosperms
Parts of the flower
Pistil: The ovule producing part of a flower.
Stigma: the sticky surface at the top of the pistil; it
traps and holds the pollen.
Style: the tube-like structure that holds up the
stigma.
Ovary: where ovules are produced
Ovule: The female gamete (i.e. Egg)
Stamen: The pollen producing part of a flower
Anther: The part of the stamen where pollen is
produced.
Filament: thread-like part that holds up the anther
Pollen: the male gamete (i.e. sperm)
Fruit - the mature ovary
Seed - the mature ovule
Life Cycle of Flowering Plants
1. Pollination
– Pollen is transferred from the anther to the
stigma
– Two types:
i. Self-pollination: occurs within the same
flower, or between flowers on the same plant
ii. Cross-pollination: Occurs between flowers on
different plants
2. Fertilization
– Pollen tube grows down through the style to deliver
sperm nucleus to the egg
– Egg and sperm unite to form a zygote
3. Seed Development
– Zygote grows and develops into an embryo plant
– Ovule wall thickens to become a seed coat
– Seed also contains stored food for the developing
embryo
4. Fruit Development
– Ovary tissue develops to enclose the seeds
– This is called the fruit (ex: apple, tomato, green
pepper
– Aids in seed dispersal
http://www.youtube.com/watch?v=RuYrFwDuYn0
What is found in a pollen grain?
1. A generative nucleus which divides to produce
two sperm nuclei
2. A tube nucleus which causes the pollen tube to
grow
What is found in an ovule?
• The ovule contains:
1. One Egg
2. Two polar bodies
What is double fertilization?
• When the pollen tube enters an ovule:
– one sperm nucleus fuses with an egg to form
the zygote (2n)
– the other combines with two polar nuclei to
form the endosperm (3n) - a food reserve
• http://www.youtube.com/watch?v=Gq8NWh98wQs