Food security and agriculture
population growth, food production and farming sustainability issues
applications of biotechnology, pest control, hydroponics
Doc Brown's Biology Revision Notes
Suitable for GCSE/IGCSE/O level Biology/Science courses or equivalent
This page will help you answer questions
such as ...
How is food security defined?
How can we increase food production?
How can be devise sustainable
Can GM crops help? Why are GM crops
controversial? Are there alternatives to GM crops?
engineering: uses - making insulin, medical applications, GM crops, food
security gcse biology
Thoughts on the world's
population and the production of food
Food and the world's population, which is
now around 7 billion people (~7 x 109 individuals!).
Lets start with some statistics - two graphs of population and energy
use - pretty similar, surprise!
The graphs shows the acceleration of the world's population and their
corresponding energy use.
Not surprisingly, I would imagine a graph of food
demand would be similar to provide the whole population of the world,
ideally, with food security.
This begs the question 'how do we maintain a
constant food supply in a sustainable way and protect the environment in
Although I have no data myself on the world's total food production,
there are some graphs on ...
which clearly show a similar pattern in rising agricultural production
attempting to meet our needs.
BUT how long can this be sustained?, and there
(billions?) of undernourished people suffering from starvation and
disease, primarily from lack of local food production for one reason
or another e.g. climate conditions, war, overuse of soil using
non-sustainable agricultural practice.
To minimise the effects of lack of food, everyone should have access
to safe nutritious food - sufficient as well as providing a balanced
diet - this concept is known as 'food security'.
Food security can be simply defined as ...
state of having reliable access to a sufficient quantity of
safe, affordable and nutritious food".
The World Food Summit definitions:
(i) Food security exists when all people, at
all times, have physical, social and economic access to sufficient,
safe and nutritious food which meets their dietary needs and food
preferences for an active and healthy life. Household food security
is the application of this concept to the family level, with
individuals within households as the focus of concern.
(ii) Food insecurity exists when people do not have adequate physical,
social or economic access to food as defined above.
threatens food security?
The problems facing us in tackling food
The UN estimates from ~2020
(i) there could be nearly 1 billion people
suffering from food insecurity i.e. undernourished with their
health at risk,
(ii) and food production needs to be
increased by 60% by 2050 to meet the increase in population
number estimated to be 10 billion by then.
In the sections below, in no particular order
of priority, I've discussed various issues concerning the
difficulties that will, and are, being encountered in trying to feed
everyone on the planet adequately.
(a) The world's population keeps on
increasing with high birth rates in developing countries, which
are also often the poorest and least able to provide food security
for all of their populations.
It will not easy for the current
agricultural systems to keep pace with the rate of increase in
the world population.
(b) Farming is affected by insect
pests, weeds, fungi and pathogens like bacteria and viruses.
Any new infestation of pests (including
locusts) and pathogens will reduce crop yields.
The plants gene pool may not cope with a
new disease and the lack of 'genetic resistance' means many
plants will become diseased and damaged sufficiently to
reduce crop yields of saleable edible food.
This requires the application of expensive
insecticides, herbicides and fungicides or using GM products to
maintain high crop yields, but its difficult to avoid
(c) Agriculture is greatly affected by
environmental conditions e.g. the local weather, particularly
drought conditions from lack of rain leading to reduced yields and
total crop failure - global warming won't help!
This often happens in hot dry countries
where the greatest state of food insecurity exists.
The food security targets may well become
more difficult to achieve with climate change.
Any change in the climate can affect
growth patterns of crops, with both positive (perhaps increased yields
in a warmer/wetter climate) and negative consequences (famine as
a result of drought and good soil blown away).
effect, global warming, climate change from fossil fuel burning
(d) Poor quality soil lacking in
nutrients or water means crops will fail, even if they are GM.
The quality of soil initially depends on
the local geology, but the weather and climate change will have
their effects e.g. heavy rain can wash fertile soil away.
Any form of soil pollution will
affect the growth of crops reducing fertility of the soil and
Soil contamination is caused by
the presence of various human-made chemicals. It is often
caused by industrial activity e.g. factories or mining, agricultural chemicals or
improper disposal of waste. The most common chemicals
involved in pollution are hydrocarbons, solvents, pesticides, lead, and
other heavy metals.
(e) The richer developed countries able to
buy and import selected food products from poorer countries.
But the purchase of exports from poorer countries
means there is less food available to feed the indigenous
population - 'cash crops' for export brings in much needed
revenue but leads to food scarcity for
the poorest people - who are often the ones growing the crops!
At the same time, as people become
wealthier in developing countries, demands for a wider variety of foods in their diet
will increase e.g. more expensive more fish and meat and this
increases food production pressure and doesn't help food
security for many other less wealthy people.
See section (i) on biomass because cattle
is an inefficient way of 'growing' food.
(f) The poorest countries with the greatest
food needs are also the least able to afford the initially high
costs of farming.
You need expensive fertilisers, machinery
and fuel, livestock, seeds (GM and non-GM) plus pest control systems to sustain
any significant agricultural production.
This makes it difficult for poorer less
developed countries to produce enough food to feed their own
It also means that if its costly to
produce food, the price at the market place increases - the
poorer you are less food you can buy and perhaps of less quality
Many richer countries give aid to
poorer countries, and long may it be so, but politics and
globalisation economics don't always help!
(g) Poorer underdeveloped countries,
particularly in Africa, but not exclusively, suffer from the
effects of political unrest including civil war and terrorist
Economic interests, including mining and
Any lack of political stability in a country
makes it difficult to retain the constant agricultural
production of much needed food for the people.
(a) to (g) are very much about growing crops
of edible grain or vegetables and raising cattle for milk or meat,
but fish is a very important source of food (protein,
essential oils and vitamins).
(h) Unfortunately in many parts of the world
fish stocks are declining due to over fishing.
We can be talking about lakes, seas or
oceans, and if you take out too many fish too quickly, there is
not sufficient time for enough fish to reproduce and grow into
Overfishing, especially of young
fish prior to reproducing, means food chains are disrupted and
we run the risk of species of fish disappearing from lakes,
seas, and areas of the oceans.
There are plenty stretches of water on
the planet were fish stocks have decreased to very low
(i) Biomass and food chain considerations
As you move up a food chain you lose
energy and biomass at every stage.
Food chains, food webs, trophic
levels and biomass
gcse biology revision notes.
Therefore, for a given area of land,
you can produce more crops for food than rearing animals on
the same land - which often need extra food from crops or other
Crops, primary producers using
photosynthesis, are more efficient producers of food than
Many farm animals and fish are
partly reared on grain (e.g. corn, oats) that could have
been used for food - and to make matters even less
efficient, part of reared livestock and fish diets are
supplemented with protein food derived from other animals.
(j) Crops are being grown to partly replace
fossil by converting plant material into biofuels.
The idea is to replace non-renewable
fossil fuels from oil and gas with renewable plant based
fuels - like bioethanol, made by fermenting processed sugar
cane and other carbohydrate rich crops.
Unfortunately this uses land that
could be otherwise used for growing food crops for 'human
consumption' - not for fuelling road vehicles!
(k) Climate Change
Know and understand that levels of carbon dioxide and methane in the
atmosphere are increasing and contribute to
These two gases are known as 'greenhouse gases' because they reabsorb
infrared radiation radiated from the Earth's surface, which of course is
heated directly by solar radiation, so the atmosphere acts as an insulation
layer like the glass panes of a greenhouse.
Know and understand that carbon dioxide can be sequestered in oceans, lakes
and ponds and this is an important factor in removing
carbon dioxide from the atmosphere.
tackling food security to avoid food insecurity
I realise the preceding section sounded all
very negative, but there are ways to help the situation with good
practice in land and sea management and protect the environment for the
We must be POSITIVE in our outlook and we are
an intelligent animal that can solve these problems!
efficiency in food production
BUT there are
still issues to be addressed!
We need sustainable methods of food production
to provide enough to feed the world's growing population.
Sustainable food production means
producing enough food to give everyone food security without
consumption outstripping supply AND without damaging the environment
This includes using, as far as possible, renewable resources of
food, materials and energy.
We need a variety of methods to increase food production
and avoid food insecurity because situations differ around the world.
Plants are the producers at the start of any
Producers (mainly plants) take in
the elements they need from their environment.
Molecular compounds like
water (roots), carbon dioxide (leaves) and mineral ions e.g.
nitrate for nitrogen, phosphate for phosphorus and small
quantities of metals like magnesium, iron, potassium and
zinc (absorbed by roots).
If plants don't get enough of
theses nutrients their growth is inhibited giving lower crop yields.
There can be lack of nutrients
in soil due the previous uptake of them by the previous crop or
the soil is poor in nutrients in the first place.
Farmers can replace the missing nutrients used
by the previous crop or enrich poor soils by applying artificial
fertilisers - but this can adversely affect the environment.
Overuse of fertilisers and pesticides can
lead to pollution problems - see
By boosting soil nutrition, growth is
increased and the subsequent yield increased.
Note: Yield can be defined as the
quantity of food produced by a specified area of land (the
growing time might be specified too).
Increased crop yields means increased food
production, whether the yield is measured as a grain crop
directly for food or the plant crop is fed to help raise herds
(a) GM crops can help, but it is only one approach
to increasing food production:
I've describe some ideas in more detail on my
crop developments page, applications so far include:
Genetically engineered crops designed to:
(i) be pest
resistant - insects/fungi/pathogens,
(ii) survive in drought conditions,
(iii) unaffected by herbicides used to protect the crop from
These are all potentially
beneficial applications of genetically engineered crops.
Crops can also be GM designed to combat certain nutrient
deficiencies e.g. increasing the content of a chemical in
'Golden Rice' that helps make Vitamin A in the body.
Again this is good science, the
concept of food security includes nutritional quality.
However, there are still issue of concern and
where GM might not help e.g.
Poor quality soil lacking in
nutrients or water means crops will fail, even if they are GM.
Hunger exists where people cannot afford to buy food, even if it is available,
therefore you need political and economic strategies to tackle
poverty and improve/make fairer the economy and maybe import
There is a danger that the agricultural
production of a country might be too dominated by multinational
companies that manufacture the GM seeds and are only
interested in maximising profits for the few (rich) at the
expense of the many (poor).
GM crops are not the complete answer and neither
should they always the 'first choice' in the future.
However, traditional methods of selective
breeding for crops (and animals too!) can still produce
varieties of crops and livestock which give improved yields.
Other genetic methods for increasing crop
Scientific research of plant genes gives
us detailed genomes of different plant species.
From this genome knowledge you can
selectively cross-breed plants which have advantageous genes
e.g. that give plants more resistant to
weather conditions (dry, wet, hot, cold) and other abiotic
factors - make crops more efficient in water use, cope with
and make them more resistant to biotic
factors such as pests e.g. insects and diseases which damage
(b) Poor soil can be improved by application of
fertilisers, but if overuse causes environmental problems.
Fertilisers contain important nutrients
for plants to grow e.g. nitrates for nitrogen, phosphates for
phosphorus, ions of magnesium and sulfate (for sulfur),
compounds of trace elements like
copper, zinc and boron.
The idea of using fertilisers is twofold:
(i) bring into use poor quality soil
deficient n nutrients,
(ii) replace nutrients
used up by the previous crops.
BUT overuse has created eutrophication
problems in lakes and rivers and they are not cheap,
particularly in the context of a poorer country.
The manufacture & use of fertilisers
NPK fertilisers-environmental problems
Infertile soils too acidic for growing
crops or raising cattle (pH <7), can be treated with alkaline
lime to increase the pH of the soil to a more neutral value (~pH
An assortment of agrichemical and
pharmaceutical products to increase yields
You can control disease and insect damage
without using GM crops by the use of herbicides and pesticides.
Pesticides are chemical compounds
designed to be toxic to any living thing that attacks crops and
reducing damage to crops and increase yields by utilising pest
microorganisms-pathogens including bacteria and fungi, a
variety of insects and mammals like rats.
The pest control is usually
sprayed onto crops to kill the 'pest', but they are
often toxic to humans and other animals that are not
considered as pests e.g. bees, ladybirds and birds of
prey are affected - anything higher in a food chain is
affected if their food supply is damaged.
The minimum 'safe level' of pesticide
is applied to minimise contamination of toxic chemicals
accumulating in the local ecosystem food chains.
Insecticides kill insects,
fungicides kill fungi, herbicides kill weeds.
Again, as with fertilisers, they are not to be
overused and unfortunately organisms like insects and bacteria can
undergo mutations and develop 'strains' resistant to e.g. a
or insecticide product.
This is happening all the time, so new costly
products have to be developed all the time.
As well as treating plant crops with anti-pest
agents, you can vaccinate livestock against certain diseases.
Antibiotics can be given to animals to protect against bacterial
pathogens - but this means antibiotics have entered the food chain,
so we may consume them - not good for our immune system?
Plant growth hormones are applied to
crops to encourage growth and increase crop yields.
You can also control when crops ripen and
harvesting - as far as I know, these methods are not controversial.
Hormone control of plant growth and uses of plant hormones
gcse biology notes
Cattle can also be given hormones to
increase milk and meat yields - but this also means these hormones
are entering the food chain to reach us!
(d) You can use biological methods to control
You can deploy other organisms to reduce pest
numbers which can act as predators or parasites.
e.g. cane toads were introduced into
Australia to eat beetles causing crop damage.
These biological methods can be
more sustainable than chemical pesticides, so less harmful to the
They do not involve toxic chemicals
that can poison harmless organisms and accumulate in food
chains and passed on from one trophic level to the next.
This means less pollution, less risk
to people and other wildlife!
BUT, there is often a 'but' e.g. the cane
toads are now a 'pest' because they poison native animals that
Quote from Wikipedia: "The long-term
effects of toads on the Australian environment are difficult to
determine, however some effects include the depletion of native
species that die eating cane toads; the poisoning of pets and
humans; depletion of native fauna preyed on by cane toads; and
reduced prey populations for native insectivores." - not good!!!
Introducing one organism to control
another can lead to unintended consequences.
You can control aphids (greenfly and black
fly) by employing a predatory insect - can be very effective in the
confines of a large greenhouse.
e.g. ladybirds will eat greenfly.
Parasites, via a vector' have been
introduced to control pests e.g. some flies lay their eggs on
slugs to kill them.
Bacteria can be used to infect
caterpillars with diseases.
(e) To avoid overfishing and keep fish
stocks at sustainable levels
We must only take out numbers of fish that
still allow breeding at a rate to keep a constant sustainable population.
A sort of 'rate of breeding = rate of
fishing' = sustainability situation!
You can do this in several ways:
(i) Placing limits on the numbers of fish extracted from the lake or fishing ground.
(ii) Fishing nets can have various mesh
sizes depending on the species being fished.
This controls the size of fish
caught and helps reduce the number of
accidently 'unwanted' and resulting 'discarded' fish.
A bigger mesh will allow smaller fish
to 'escape' and grow into breeding adults, hence helping to
maintain fish stocks.
(iii) Fish can be 'factory farmed' in
cages where they cannot escape (aquafarms).
In fish farms, the cages are placed in more sheltered
estuaries or bays to minimise the effect of rough water and
their natural food is often supplemented with other
fish-based protein products. There is a quite a lot of criticism of
ALL factory farming methods (see section (f) below) and the
following comments ....
Nearly half of all fish consumed
worldwide each year are raised in aquafarms. Farmed fish
spend their entire lives in cramped, sometimes dirty enclosures,
and many suffer from parasitic infections, diseases, and
debilitating injuries - which means chemicals and
antibiotics are used to help the fish survive.
The Food and Agriculture Organization of the United Nations
reports that the aquaculture industry is growing three times
faster than land-based animal agriculture, and aquafarms
will surely become even more prevalent as our natural
fisheries become exhausted.
(f) Livestock management
(i) You can limit the of farm animals and keep
them in a temperature controlled environment to reduce their
movement and reducing the transfer of energy from livestock to the
This increases efficiency because the
animals use less energy moving around and controlling their body
temperature and so more energy is released in growth for the
same feed input.
This seems to me to a form of factory
(ii) Calves and chickens can be factory farmed
by raising them in small confined indoor pens - but many people find
this style of farming unacceptable.
The animals like 'battery hens or chickens'
(for eggs or meat) are
cramped allowing the rapid spread of any disease - requiring animals
reared in this way to be treated with antibiotics - again these
become part of our food chain.
The animals must be fed with protein based
feed, reducing the efficiency of this form of protein production.
People have every right to question the
ethics of factory farming and point out the cruel unnatural and
uncomfortable conditions under which these animals are made to
(g) Mycoprotein - another application of
biotechnology using fungi
Modern biotechnology techniques can be used to
culture and make large quantities of useful microorganisms to
This done in huge vats (fermenters) under very
controlled conditions e.g temperature, type of microorganism and
Mycoprotein is the ingredient common to all
Quorn™ 'artificial meat-free' protein products.
It is a high protein meat substitute for
meals acceptable in the diet of vegetarians.
It is high in protein, high in fibre, low in
saturated fat and contains no cholesterol, and therefore quite a
nutritious component of any diet.
Mycoprotein is made in fermenters similar to
those found in a brewery.
It's made by adding oxygen, nitrogen (from
ammonia/nitrate), carbohydrate (e.g. glucose syrup) and essential minerals to
a fungus called Fusarium venenatum, which is grown in
The fungus grows the protein which is
'harvested', purified and converted into a safe edible mycoprotein food product.
It is estimated the carbon footprint of
mycoprotein is 4x less than that of producing chicken.
- growing plants without soil
Instead of using soil, plants
are grown with their roots 'dangling' into a nutrient
The plants must be supported
in some way - e.g. a frame with holes, through the plants grow.
The growth medium doesn't
have to be water, it can be course particles of mineral or
fibres e.g. gravel or brown fibres from coconuts.
Advantages of hydroponic
horticulture to maximise growth and maximise yields
Its easier to control pests
Nutrient levels can be
accurately controlled e.g. the concentrations in the hydroponic
Hydroponics can be used where
plants cannot be grown in soil - either there is no soil or it
is so infertile and devoid of nutrients for plants to grow.
It can be used if the climate
is unsuitable e.g. areas of very low rainfall - but you still
need a water supply.
Examples of the use of
hydroponic plant culture
Large scale glasshouses (big
greenhouses!) are used to cultivate tomatoes and lettuce and
other salad crops on big commercial scale.
Disadvantages of hydroponics
Large quantities of
artificial fertilisers must be used.
The capital cost to set up a
'hydroponic farm' is high.
If a disease enters the
system (e.g. big glasshouse) it can spread quickly from plant to
plant causing major damage to crops.
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Some learning objectives for this page
Know and understand that at each stage in a food
chain, less material and less energy are contained in the biomass of the
Realise that this means that the efficiency of food production can be improved
by reducing the number of stages in food chains.
As you move up a food chain, at
every stage you lose biomass and therefore energy, so the greater the number
of stages in food chain from producer to final consumer, the food production
becomes less and less efficient.
Because of the fewer stages in
the food chain, it is more efficient to produce food by growing crops than
raising herds of animals if you compare the efficiencies of equal areas of
However a healthy diet should be
varied diet, so meat or meat substitutes are important, but it is possible
to grow cereal crops with a higher protein content.
Also, not all land is suitable
for growing crops and poor quality land in upland areas of wild moorland may
be more suitable for sheep for mutton and deer for venison.
Know and understand that he efficiency of food
production can also be improved by restricting energy loss from food animals
by limiting their movement and by controlling the temperature of their
Intensive farming, where animals
are constrained in large 'sheds' with limited movement and kept in a warmer
environment, does improve efficiency of meat production making it cheaper
for the farmer to produce food by reducing production costs.
This makes cheaper food for us
via our local shops and supermarkets and supermarkets have a powerful
influence on the cost of food but are increasingly being pressured to source
from farmers who adhere to strict standards of animal husbandry - but this
is not the case in all countries.
Less energy is wasted as body
heat and animals grow fatter on less food, and animal feed is becoming
increasingly costly, but, at what cost to the quality of existence of these
factory farmed animals?
There are also disadvantages to
intensive farming eg the over-crowded conditions are ideal for the spread of
disease eg avian flu in chickens, foot-and-mouth-disease in cows. To combat
these diseases by treating the animals with antibiotics increases production
costs and introduces these same antibiotics into the food chain, so
potentially weakening our own immune system if we become infected.
But, these 'factory farming'
methods means the lives of the quality of life of these animals is much
reduced compared to living out in open fields with plenty of space to move
about freely, fresh air and sunlight, hence consumer demand for organic meat
from animals not intensively farmed.
Know and understand that fish stocks in the oceans are
Know that it is important to maintain fish stocks at a level where breeding
continues or certain species may disappear altogether in some areas.
Fish stocks of popular varieties
are becoming alarmingly low in many regions of our seas and oceans due to
over-fishing, which itself derives from the food demands of increasing
Know and understand that net
size and fishing quotas play an important role in conservation of fish
Fishing quotas are all about
controlling the number of fish caught and the size of the fishes allowed to
be caught e.g. fishing boat catches are carefully monitored and recorded and
fishing nets inspected to check that the mesh spacing in the nets is not too
small so that too many small immature fish (who can breed later) are not
caught and hopefully unwanted species of fish or other marine creatures (eg
crustaceans like crabs, lobsters, crayfish) can escape!
Understand that this is an
example of sustainable food production, so that the numerical catch rate can
match the numerical growth rate of the fish species we like to eat.
Such methods are needed because
food chains are being disrupted and species may die out from particular
oceanic regions from intensive fishing from huge trawlers and factory ships.
Know and understand that the fungus Fusarium is useful for producing
mycoprotein, a protein-rich food suitable for
vegetarians and is a meat substitute eg like the commercial product 'Quorn'
(though it does need tasting up a bit!).
Know that the fungus is grown on glucose
syrup (supplies energy for the process as well as the carbon, hydrogen and
oxygen for the protein molecules), in aerobic conditions (air containing
oxygen needed), with a source of nitrogen eg ammonia or ammonia compounds
(nitrogen is the other important element in amino acids and proteins).
Fungi grow rapidly in moist warm
conditions so production rates are quite efficient and it doesn't require as
much land - though do need sufficient land to the maize from which the
glucose syrup is made. When the raw materials have been consumed by the
Fusarium fungi the biomass is
harvested and purified to be used in various food products.
The glucose syrup is made from
breaking down maize starch with the appropriate enzyme containing
microorganism, though in the mycoprotein production it is important that
only the correct microorganism is present to ensure the right biochemistry
happens and other microorganisms start multiplying. Therefore all
ingredients must be heated and sterilised to kill all microorganisms and the
air filtered to remove airborne microorganisms, before the mycoprotein
forming fungi are introduced into the fermenter - which itself must be first
sterilised with very hot steam.
In poor third world countries
mycoprotein might be a good efficient substitute for inefficient meat
production from animals grazing on large areas of relatively barren
infertile land, but is the source of nitrogen from ammonia cheap? I don't
Know and understand that humans often upset the balance
of different populations in natural ecosystems, or change the environment so
that some species find it difficult to survive.
Know and understand that with so many people in the
world, there is a serious danger of causing permanent damage not just to the
local environments but also to the global environment unless our overall
effect is managed carefully.
Know and understand that humans rely on ecosystems for
food, water and shelter.
You should be able to use your skills, knowledge and understanding to:
analyse and interpret scientific data concerning
evaluate methods used to collect environmental data
and consider their validity and reliability as evidence for environmental
There is a considerable amount
of climate data being collected around the world every day and many weather
records go back tens and even hundreds of years.
Thermometers provide temperature
data of the air and oceans, water collectors for rainfall, snowfall records,
glacier size and their rates of melting, satellites can map rain clouds,
storm patterns, glacier areas etc.
So, we are not short on data,
and the consensus is that the Earth is warming, and by 1-2oC over
that past 100-150 years. It doesn't sound much, but a 1oC rise
does represent a huge amount of extra energy in our global weather system!
It is important that the data
record is as long and accurate as possible. Computer modelling of the
climate and trying to make predictions is not easy because there are so many
variables and many not very predictable.
evaluate the methods being used to feed and provide water to an
increasing human population, both in terms of short term and long term
evaluate the use of biogas generators,
You should have considered a number of biogas
generator designs ranging from third-world generators
supplying a single family to commercial generators,
you should understand how the
output from a biogas generator might be affected by climatic conditions,
evaluate the positive and
negative effects of managing food production and distribution, and be able
to recognise that practical solutions for human needs may require compromise
between competing priorities,
You should consider:
the differences in efficiency between producing food
from animals and plants,
the pros and cons of factory farming of animals,
the implications of ‘food miles’
- some food imports have come from thousands of miles away from the source
of food production.
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