Transcript Asexual Reproduction

Asexual Reproduction
IGCSE Biology
Asexual reproduction
Asexual reproduction involves NO
fertilisation between male and female
gametes.
Offspring are genetically identical to their
“parents”
Can you think of some examples of
organisms that asexually reproduce?
What is a clone?
A clone is genetically identical to its “parent”
How do plants reproduce asexually?
• Tubers eg potato – grows shoots
• Runners eg strawberries
• bulbs eg tulips
Definition
Sexual
Reproduction
Asexual
Reproduction
•Involves sex cells and
fertilisation
•Does not involve sex
cells and fertilisation
•Only one parent plant
Advantages/
Disadvantages
•Offspring are not
genetically identical to
one another
•There is variation in
the offspring
•This means that they
are able to adapt to
their surroundings and
evolve.
•Offspring have no variation
•Offspring are genetically
identical to one another.
This is an advantage when
the parent is well adapted
to its habitat.
•
Does not need a partner
– saves time and energy
to attract a mate.
•
Very quick – bacteria
can produce an
offspring in about 20
minutes
Asexual reproduction
• Also known as vegetative propagation
• 3 methods of (natural) vegetative propagation
-tubers
-bulbs
-runners
Tubers
Tubers are underground
food stores which stores
food over the winter and
provides a new plant with
food until it can make its
own.
Examples: potato,
artichoke, yam, cassava,
water chestnut, arrowroot
TaroJapanese
potato
Food made by the new plant
is sent to make new tubers.
Thereby reproducing itself.
Let´s plant a tuber!
• Take a small pot/cup and half fill with compost
• Take seed potato and place into your cup
• Cover the potato with more compost until the cup is 2/3
full
• Water your potato and cover with cling film
• Don´t forget to put your name, the date and the type of
plant on your cup!
Bulbs
• E.g. daffodils, lilies
Let´s plant a bulb!
• Take a small pot/cup and half fill with compost
• Take a baby onion and place into your cup
• Cover the onion with more compost until the cup is 2/3
full
• Water your onion and cover with cling film
• Don´t forget to put your name, the date and the type of
plant on your cup!
Runners
Runners are side shoots
which grow out from the
parent plant.
Buds form at points along
the runner and eventually
these buds form roots and
grow into new plants.
Examples: spider plant
(Anthericum), strawberry
(Fragaria x ananassa)
Let´s plant out a runner!
A spider plant is a good example of a plant that produces
runners
The end of the runner can be ‘pegged down’ into a small
pot of compost using wire
When the roots are established, the runner is cut close to
the new plant and the wire removed
Artificial Propagation
• 2 methods used to cultivate plants
asexually
-taking cuttings
-grafting
Cutting
Cuttings are small pieces of stem with some
leaves attached, the new plant grows from this.
They can be placed in moist
soil or water (and sometimes
dipped in rooting
powder).
Let´s take a cutting!
• Take a small pot/cup and fill 2/3 with compost
• Take your cutting and dip the end in rooting powder
• Gently plant into your cup
• Water your cutting and cover with cling film
• Don´t forget to put your name, the date and the type of
plant on your cup!
Grafting
A cut stem of one plant (with good flower or
fruit growth) (the graft) is taken and firmly
attached to the rootstock of another plant
(which has a strong, established root system)
(the stock).
Examples- roses, fruit trees
Commercial aspects
Artificial propagation has allowed us to
adapt and improve plants for our own
use.
Some of the benefits include:
•Quick production of large numbers of
genetically identical plants.
•Specific varieties, desired features or
consistent quality can be produced
especially in fruit, flowers.