Revision Powerpoint on biotechnology OCR A level Biology 2015
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Course
A2 Unit F215 - Control, Genomes and Environment
Institution
OCR
Revision Powerpoint with in depth detail on the topic. Can be printed with 2-4 slides to a page and cut out to make a mini revision booklet. Very colourful.
27 slides long
, Natural clones
Vegetative propagation, or natural cloning, is the artificial production of
natural clones for use in horticulture & agriculture. A structure forms from
the stem, leaf, bud or root of the parent plant & develops into a fully
differentiated new plant that is genetically identical to the parent.
Vegetative propagation often involves perennation organs, which enables
plants to survive adverse conditions. These contain stored food from
photosynthesis & can remain dormant in the soil. They’re a means of asexual
reproduction & a way of surviving one growing season to the next.
Natural plant cloning occurs in:
Bulbs e.g. daffodils- the leaf bases swell with stored food & buds form
internally which develop into new shoots in the next growing season.
Rhizomes e.g. marram grass- a rhizome is a specialised horizontal stem
running underground, often swollen with stored foods. Buds develop &
form new vertical shoots.
Stem tubers e.g. potato- the tip of the underground stem becomes
swollen with stored food to form a tuber. Buds on the tuber develop to
produce new shoots.
Runners e.g. strawberries- a lateral stem grows away from the parent
plant & roots develop where the runner touches the ground.
, Using natural clones
Natural plant cloning is used to produce Factors which increase
new plants by: success rate of most
cuttings:
Splitting up bulbs
Use a non flowering
Removing young plants from runners stem
Cutting up rhizomes Make an oblique cut in
Taking cuttings- short sections of the stem
Use hormone rooting
stems are taken & planted. Rooting
powder
hormone is often needed to encourage Reduce leaves to 2 or 4
growth of new roots. Keep cutting well
Propagation from cuttings is faster than watered
using seeds. It also guarantees the Cover the cutting with
a plastic bag for a few
plants quality as they’re genetically
days.
identical to the parent plant.
However there will be lack of genetic variation in the offspring
& therefore the appearance of a new disease or pest could
have catastrophic effects.
Sugar cane is usually propagated by cloning.
, Artificial cloning in plants
Micropropagation Process of making large numbers of genetically identical offspring
from a single parent plant using tissue culture techniques. It is used when a desirable plant:
• Does not readily produce seeds • Has been genetically modified or selectively bred with
• Doesn’t respond well to natural difficulty
cloning • Is required to be ‘pathogen free’ by growers. E.g.
• Is very rare bananas
Basic principles:
1. Take a small sample of tissue from a plant you want to clone-
Meristem tissue is often dissected out in sterile conditions
to avoid contamination.
2.The sample is sterilised, usually by immersing it in sterilising
agents e.g. bleach, ethanol or sodium dichloroisocyanurate.
The latter does not need to be rinsed off which means the
tissue is more likely to remain sterile. The material removed
from the plant is called the explant.
3.The explant is placed in a sterile culture medium containing a
balance of plant hormones which stimulate mitosis. The cells,
proliferate forming a mass of identical cells (a callus)
4.The callus is divided up & individual cells or clumps from the
callus are transferred to a new culture medium containing a
different mixture of hormones & nutrients which stimulates
the development of genetically identical plantlets.
5.Plantlets are potted into compost to grow into small plants
6.The young plants are planted out to grow & produce a crop.
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