Key Area 1(a) : Food supply Unit 3: Sustainability and Interdependence.
-
Upload
lillian-ross -
Category
Documents
-
view
221 -
download
0
Transcript of Key Area 1(a) : Food supply Unit 3: Sustainability and Interdependence.
Food security and sustainability
• Why is food security an increasing issue in the human population?
• The human population is increasing more rapidly than food production.
• Less land is available for food production.• What is meant by sustainable food
production?• Continuing production of food without
causing damage or degrading the natural resources that were used to produce it.
CfE Higher BiologySustainability
and Interdependenc
e
Food security and sustainability
• Human populations have to access food and use this food over a sustained period of time.
• This is important because?• Survival – avoid starvation• Health – avoid malnutrition (safe and
nutritious food have more benefits)
CfE Higher BiologySustainability
and Interdependenc
e
Food security
CfE Higher BiologySustainability
and Interdependenc
e
QUANTITYSufficient amounts of
food
QUALITY
Nutritious and provides a
balanced diet.
ACCESS
Economic means to obtain food.
Food securit
y
Factors affecting food security• Complete the table to give
explanations of these factors.
CfE Higher BiologySustainability
and Interdependenc
e
Factors that underpin food security
Explanation
Sustainability
Accessibility
Availability
Usage
Factors affecting food security
CfE Higher BiologySustainability
and Interdependenc
e
Factors that underpin food
security
Explanation
Sustainability A food source that is able to support populations, maintain its productivity and endure over time without causing any ill effects.
Accessibility A food source that is easily available, near to where it is required and ready to use.
Availability It is convenient, ready to use, easily obtained over long periods.
Usage It is easy to use, process and manage.
Food security and sustainability
• Using the case study in the text book on page 226, answer the following questions.
• What reasons are there that present the challenge of providing a secure supply of food?
• What contributions has ‘biological science’ made to meeting this challenge?
• What other agencies could be involved in a more ‘interdisciplinary approach’ to food security.
CfE Higher BiologySustainability
and Interdependenc
e
Food security and sustainability
• What are the natural factors that can affect food production?
• Drought• Pests• Flooding• Disease• Desertification• Insecticide resistance• Write a short explanation of how each of these
could effect food production. Use a named example where possible.
CfE Higher BiologySustainability
and Interdependenc
e
Food Production• Natural resources are vital for food
production.• We need to find an appropriate
balance between
CfE Higher BiologySustainability
and Interdependenc
e
Providing enough
sustainable quality food
Preventing damage/further damage to the environment
Food Production – factors to consider
CfE Higher BiologySustainability
and Interdependenc
e
SUSTAINABILITY
Global warming
PollutionSoil: erosion & fertility
Deforestation
Write the biological issue or impact each factor could have on the sustainability of current and future food production
Food Production• Ultimately food production depends on plant
growth.• The main producers of human food are displayed
below:
CfE Higher BiologySustainability
and Interdependenc
e
Food Production• Small numbers of green plant
species are relied on as main sources of food.
• These small numbers equate to approximately 95% of the worlds food supply.
• The earth itself, however, has at least 75000 species of edible plants.
CfE Higher BiologySustainability
and Interdependenc
e
Food Producti
on
Competition
Weeds or too dense planting will slow growth
Pests
Decrease yield, either by feeding on crops or by making the plant less healthy
Breeding higher yield cultivars
Will increase yield, but some require more intensive farming methods and are more dependent on particular soil profiles and nutrients
Disease
Decrease yield as the plant is less healthy. May also produce food that is unsuitable for eating
Soil profile
The depth of soil / drainage etc will determine what type of crop you can grow
Soil nutrients
Plants need specific nutrient profiles. Some may need to be added using fertlisers. Can also use crop rotations
Food chains and energy loss• The sun is the ultimate source of energy for most
communities of living things.• Green plants absorb some of the sun’s light
energy to make their own food by photosynthesis.• The other organisms in a food chain are
consumers because they all get their energy and biomass by consuming and eating other organisms.
• Not all energy available to organisms at one stage can be absorbed by organisms at the next one.
• The amount of energy decreases from one stage to the next and only about 10% is passed on.
CfE Higher BiologySustainability
and Interdependenc
e
Pyramids of Numbers• Pyramids of numbers can be produced based on a
food chain and each layer in the pyramid is called a trophic level.
• Grass grass hopper frog snake hawk
CfE Higher BiologySustainability
and Interdependenc
e
Food chains and energy loss• Draw a food chain where plants are consumed by
humans.• Draw another food chain where animals are
consumed by humans.• What can you deduce by comparing these two food
chains?• The shorter the food chain the greater the quantity
of energy held in the food.• The fewer the trophic levels the less energy lost.• Therefore more food is generated per unit area of
land when plant crops are grown.• Livestock generates less food per unit of land.
CfE Higher BiologySustainability
and Interdependenc
e
Photosynthesis• Write the summary equation for
photosynthesis.
Carbon + water oxygen + glucoseDioxide sugarCO2 + H2O O2 + C6H6O12
• Other additional factors that are necessary for photosynthesis to take place are: sunlight and chlorophyll
CfE Higher BiologySustainability
and Interdependenc
e
Photosynthesis – getting the light• When the light hits a leaf there are 3
things that can happen to it.
• It can be Absorbed (usedin photosynthesis)Reflected
Transmitted
CfE Higher BiologySustainability
and Interdependenc
e
Reflected12%
Absorbed83% but only 4%
used in photosynthesis
Transmitted5%
Photosynthesis• The light that is absorbed is absorbed by
the pigments in the chloroplasts.
CfE Higher BiologySustainability
and Interdependenc
e
Granum
Starch grain
Inner membrane
Outer membrane
Stroma
Lamella
Photosynthesis• This light is known as ‘visible light’
on the radiation spectrum.• It covers a narrow band of
wavelengths ranging from 380nm to 750nm.
CfE Higher BiologySustainability
and Interdependenc
e
Absorption Spectra• What does Absorption mean?• taking something in• An absorption spectrum shows the
specific wavelengths of light that are absorbed.
• In a leaf more than one pigment is involved in the absorption of light.
• These can be separated by using paper or thin layer chromatography.
CfE Higher BiologySustainability
and Interdependenc
e
Name the colours along the spectrum below and shade them in (ROYGBIV)
Wavelength of light (nm)
700600500400
Violet Indigo Blue Green Yellow Orange Red
Wavelength of light (nm)
700600500400
Shade in the spectrum below showing the areas where light is absorbed
Absorption spectra• The absorption spectra shows how
strongly the different pigments absorb at different wavelengths.
• From this information, why are chloroplasts green?
• They are green because they absorb every other colour apart from green.
CfE Higher BiologySustainability
and Interdependenc
e
Photosynthetic pigments
CfE Higher BiologySustainability
and Interdependenc
e
It can also be shown by graphing the wavelength in nm (on the x-axis) against the relative absorbance (on the y-axis).
Photosynthetic pigments• Chlorophyll a and b absorb mainly blue
and red light.• The other pigments, called carotenoids
absorb other colours of light (including the blue-green region of the spectrum) and pass this energy on to the chlorophyll.
• These carotenoids are also called accessory pigments.
CfE Higher BiologySustainability
and Interdependenc
e
Photosynthetic pigments• Why is it useful to the plant to have
several different pigments?• They can absorb more of the
wavelengths of light.
CfE Higher BiologySustainability
and Interdependenc
e
Action spectra• An action spectra shows the rate of
photosynthesis at different wavelengths.
CfE Higher BiologySustainability
and Interdependenc
e
Photosynthetic pigments• A close correlation can be seen between
the overall absorption spectrum for the leaf pigments and the action spectra for photosynthesis.
• The action spectra is made up of all the absorption spectra added together.
• It shows the amount of photosynthesis you get from each wavelength of light (all of the different pigments working together)
CfE Higher BiologySustainability
and Interdependenc
e
Separation of Photosynthetic pigments
• Pigments from leaves can be extracted using a suitable solvent.
• These can then be separated using either paper or thin layer chromatography.
• The different pigments can be identified by their position on the paper and their colour.
• Rf values can be calculated for each pigment.
CfE Higher BiologySustainability
and Interdependenc
e
Separation of Photosynthetic pigments
Propanone is usually used as the extraction solvent.A mixture of propanone and petroleum ether is used as the chromatographic solvent.
CfE Higher BiologySustainability
and Interdependenc
e