6.2.1 Chapter 22 Cloning and biotechnology.
, 22.1 Natural cloning in plants:
Natural cloning in plants:
A form of cloning is asexual reproduction where the clones are genetically identical to the parent
organism and other clones
Vegetative propagation:
• It’s a form of asexual reproduction that occurs when a plant body part is separated and then
develops into a new plant using meristematic cells.
o Vegetative organs of plants include: Root and shoot tips, Axillary buds (where leaves
and the stem meet), Vascular cambium (between xylem and phloem)
▪ Naturally over time a young, miniature plant forms at these locations and
remains attached to its parent plant.
▪ At maturity the plantlet becomes detached from its parent and can live
independently
• It involves perennating organs, which enables plants to survive in adverse conditions – they
contain food from photosynthesis and remain dormant in soil. E.G.:
1. Bulbs (daffodils) – the leaf bulbs swell with stored food from photosynthesis. Buds
form internally which develop new shoots and new plants in the next growing
season
2. Runners (strawberry or spider plant) – a lateral stem grows away from the parent
plant and roots develop where the runner touches the ground
3. Rhizomes (marram grass) – specialised horizontal stem running underground, often
swollen with food. Buds develop and form vertical shoots which become
independent plants
4. Stem tubers (potato) – the tip of an underground stem becomes swollen with stored
food which develops to produce a new shoot.
Advantages of natural cloning:
• If conditions are good for the growth of the parent, they will also be good for the growth of
the offspring
• Cloning is relatively rapid, so the population size can increase quickly to take advantage of
suitable environmental conditions.
• Reproduction can be carried out even if there is only one parent.
• Lower costs
Disadvantages of natural cloning:
• The offspring may become overcrowded.
• There will be no genetic diversity so the whole population will be susceptible to the same
diseases and environmental changes.
• Selection is not possible as there is so little variation, so evolution is much less possible
Using natural clones in horticulture:
• Splitting up bulbs, removing young plants from runners and cutting up rhizomes all increases
plant numbers cheaply, and the new plants have exactly the same genetic material.
, 22.1 Natural cloning in plants:
Natural cloning in plants:
A form of cloning is asexual reproduction where the clones are genetically identical to the parent
organism and other clones
Vegetative propagation:
• It’s a form of asexual reproduction that occurs when a plant body part is separated and then
develops into a new plant using meristematic cells.
o Vegetative organs of plants include: Root and shoot tips, Axillary buds (where leaves
and the stem meet), Vascular cambium (between xylem and phloem)
▪ Naturally over time a young, miniature plant forms at these locations and
remains attached to its parent plant.
▪ At maturity the plantlet becomes detached from its parent and can live
independently
• It involves perennating organs, which enables plants to survive in adverse conditions – they
contain food from photosynthesis and remain dormant in soil. E.G.:
1. Bulbs (daffodils) – the leaf bulbs swell with stored food from photosynthesis. Buds
form internally which develop new shoots and new plants in the next growing
season
2. Runners (strawberry or spider plant) – a lateral stem grows away from the parent
plant and roots develop where the runner touches the ground
3. Rhizomes (marram grass) – specialised horizontal stem running underground, often
swollen with food. Buds develop and form vertical shoots which become
independent plants
4. Stem tubers (potato) – the tip of an underground stem becomes swollen with stored
food which develops to produce a new shoot.
Advantages of natural cloning:
• If conditions are good for the growth of the parent, they will also be good for the growth of
the offspring
• Cloning is relatively rapid, so the population size can increase quickly to take advantage of
suitable environmental conditions.
• Reproduction can be carried out even if there is only one parent.
• Lower costs
Disadvantages of natural cloning:
• The offspring may become overcrowded.
• There will be no genetic diversity so the whole population will be susceptible to the same
diseases and environmental changes.
• Selection is not possible as there is so little variation, so evolution is much less possible
Using natural clones in horticulture:
• Splitting up bulbs, removing young plants from runners and cutting up rhizomes all increases
plant numbers cheaply, and the new plants have exactly the same genetic material.
