Transcript STRUCTURES AND FUNCTIONS IN LIVING ORGANISMS

Mr. Lajos Papp
The British International School, Budapest
2014/2015
Food production
Crop plants
Describe how glasshouses and polythene tunnels can
be used to increase the yield of certain crops.
If plants are grown in greenhouses or polyethene
tunnels they can be protected from the environment.
Temperature, levels of water, fertiliser and even carbon
dioxide can be controlled carefully to ensure maximum
yields. Increasing the availability of all these factors
will tend to increase growth.
Understand the effects on crop yield of increased
carbon dioxide and increased temperature in
glasshouses.
Increasing the level of carbon dioxide increases the rate
of photosynthesis and thus the rate of growth.
Increasing the temperature will tend to increase the rate
of metabolic reactions although temperatures that are
too high are damaging.
Understand the use of fertiliser to increase crop
yield.
Plants need some substances in order to grow well.
These are called mineral nutrients and come from the
soil. Fertilisers, like manure, contain a range of
chemicals that help to improve the soil. Because manure
comes from a living source it is called an organic
fertiliser.
https://www.youtube.com/watch?v=dpKuVh8xXXs
Understand the reasons for pest control and the
advantages and disadvantages of using pesticides
and biological control with crop plants.
Plants do not provide food just for humans. A wide
range of animals and insects will eat crop plants if they
are not protected. These animals are called pests and
farmers use pesticides to kill them.
Pesticides are poisons but chemists have tried to ensure
that they only poison the pests, not the crop plants or the
consumers of the food.
An alternative approach to pesticides is to use
biological control systems. Pests can be food for other
creatures and if these creatures are introduced into a
field they will destroy the pests and so protect the crops.
advantages
disadvantages
pests
can
develop
initially very effective, resistance to pesticides,
pesticides
easy to apply,
can
be
used
almost all crops.
bioaccumulation
with damage
other
can
living
organisms,
expensive.
biological
no poisons involved so not 100 percent effective,
no harm to wildlife or can be difficult to apply,
control systems humans.
not suitable for all crops.
Micro-organisms
Understand the role of yeast in the production of
beer.
The production of alcohol is a process that utilises
yeast. The anaerobic respiration of yeast produces
ethanol, the basis of alcoholic drinks, and carbon
dioxide which can give the drink a sparkling quality.
In beer-brewing the starch breaks down into a sugar
solution inside the germinating barley grains. This is
called the malting stage. The sugar solution is then
drained off and fermented with the yeast. The flavour
of the beer is developed by adding hops to the mixture.
Describe a simple experiment to investigate carbon
dioxide production by yeast, in different conditions.
Experiment
Variables
Procedure
Data collection
Data processing
Conclusion
Fish farming
Explain the methods which are used to farm large
numbers of fish to provide a source of protein,
including:
maintenance of water quality,
control of intraspecific and interspecific predation,
control of disease,
removal of waste products,
quality and frequency of feeding,
and the use of selective breeding.
Fish farmers maximise production by:
1. stocking
fish
at
high
densities
(note
that
overstocking may lead to problems of intraspecific
predation, when fish prey on each other),
2. supplying adequate, high quality food,
3. choosing the best fish to breed from,
4. protecting against pests with chemical pesticides,
5. taking steps to minimise risk of disease,
6. protection from predators,
7. removing waste products.
Selective breeding
Understand that plants with desired characteristics
can be developed by selective breeding.
Understand that animals with desired characteristics
can be developed by selective breeding.
A farmer has a herd of cattle which he uses to produce
milk. The cows in his herd will vary in quantity and
quality of milk they produce. To improve the herd, the
farmer will pick out the cows that produce the largest
quantities of the best milk and breed only from them.
He will use a bull that has a mother or sisters who are
good milk producers, or that is known to produce
daughters who are good milk producers.
The farmer can continue his selective breeding
programme for many generations, each time picking
only the best milk producers to be mothers of the next
generation. The milk production of his herd will
gradually increase.
Genetic modification (genetic engineering)
Describe the use of restriction enzymes to cut DNA
at specific sites and ligase enzymes to join pieces of
DNA together.
The structure of DNA.
A restriction enzyme cuts DNA. The enzyme cuts
through the phosphate backbones of the double helix
without damaging the bases.
Different enzymes known as ligases can be used to join
fragments of DNA together.
Describe how plasmids and viruses can act as
vectors, which take up pieces of DNA, then insert
this recombinant DNA into other cells.
Find the part of the DNA that contains the gene you
want.
Remove the gene using restriction enzymes to cut the
DNA either side of the gene.
Insert the gene into the genetic material of the organism
you want to change using ligase enzymes.
This can be done directly but it often involves using
vectors. Vectors can be viruses or plasmids. A plasmid is
a circular unit of DNA. The gene is first inserted into
the vectors, which then transfer the gene to the desired
host when they infect it.
Understand that large amounts of human insulin can
be manufactured from genetically modified bacteria
that are grown in a fermenter.
http://www.nlm.nih.gov/exhibition/fromdnatobeer/exhib
ition-interactive/recombinant-DNA/recombinant-dna-
technology-alternative.html
Evaluate the potential for using genetically modified
plants to improve food production (illustrated by
plants with improved resistance to pests).
The production of new varieties of disease-resistant
crops has obvious benefits. It should allow us to grow
larger amounts of food more cheaply.
If plants are able to resist the diseases caused by certain
pests then we will be able to use less pesticide.
This should cost less and also provide a health
advantage to farmers who will not be exposed to the
same levels of pesticides as before.
There are concerns that genetically modifying crops
may lead to problems. The genes that code for
resistance could spread from the modified crop species
to another closely related wild one. This plant would
then have an advantage over other plants and this could
unbalance ecosystems.
Cloning
Describe the process of micropropagation (tissue
culture) in which small pieces of plants (explants)
are grown in vitro using nutrient media.
Many small pieces are cut from the chosen plant. These
pieces are called explants. The pieces are sterilised by
washing them in mild bleach to kill any microbes.
In sterile conditions the explants are transferred onto a
growth medium that contains nutrients as well as plant
hormones to encourage growth. The explants should
develop roots, shoots and leaves.
When the plants are large enough they can be
transferred to other growth media and eventually to a
normal growth medium.
Understand how micropropagation can be used to
produce commercial quantities of identical plants
(clones) with desirable characteristics.
Describe the stages in the production of cloned
mammals involving the introduction of a diploid
nucleus from a mature cell into an enucleated egg
cell, illustrated by Dolly the sheep.