cbse asexual reproduction by chitran mandal
TRANSCRIPT
Sexual Reproduction
Asexual Reproduction
Definition •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
•Offspring have no variation
•Offspring are genetically identical to one another
Tubers are underground food stores which stores food over the winter and provides a new plant with food until it can make its own.
Food made by the new plant is sent to make new tubers. Thereby reproducing itself.
Examples: potato, artichoke, yam, cassava, water chestnut, arrowroot
Taro- Japanese potato
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)
They can be placed in moistsoil or water (and sometimesdipped in rootingpowder).
Cuttings are small pieces of stem with some leaves attached, the new plant grows from this.
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
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.
Fission the separation of the parent into two or more
offspring of equal size Budding
new individuals split off from existing ones Fragmentation and regeneration
the breaking of the body into several pieces, some or all of which develop into new adults
Par thenogenesis Development of unfertilized eggs
Parent divides into halves after nucleus replicates
No parent remains daughter cells grow to normal size
Occurs in , , and
2 equal
2
bacteria protozoa algae
Parent organism divides into halves
Daughter cell forms from outgrowth or off parent
Buds may or remain attached and form a
2 unequal
bud
break offcolony
Ability to back missing parts The more the organism, the
it is to regenerate Occurs in simple organisms such as
and
grow
complexharder
starfish flat worm
In this form, the body of the parent breaks into distinct pieces, each of
which can produce an of fspring.
Pieces of coral broken off in storms
can grow into new colonies.
A new starfish can grow from
one detached arm.
of a body of a multicellular organism gives rise to a organism
Common in - using stems, leaves, or roots
Can occur or
Piece new
plants
naturally artificially
Bulb-
Corm-
Tuber-
Runner-
Rhizome-
Short underground stem with stored food & fleshy leaves Ex. Onion, tulip
Short underground stem with stored food Ex. Water chestnut
Enlarged underground stem Ex. potato
(stolon) horizontal stem with buds along ground’s surface Ex. strawberry
Underground horizontal stem
Ex. ginger
Cutting- use of plant to reproduce (Ex. )
Layering- stem is over and covered with will root and form plant (Ex. )
Graf ting- stem or bud of one plant is to another plant
(Ex. )
partSpider plant
bent soilnew raspberry
joined
Seedless fruit treepermanently