Posts Tagged ‘food’

  • Distinguish between biotic and abiotic (physical) components of an ecosystem.

*Biotic: refers to the living components of an ecosystem. (the community)

*Abiotic: refers to the non-living factors of an ecosystem. (the environment)

Ecosystems are made up of living and non-living components. The living part of the environment consists of the organic part of the ecosystem; animals, plants, algae, fungi and bacteria. These are called biotic components. The non-living part of the environment is made up of physical components such as; air, light, water, temperature, soil, minerals and climatic atmosphere. These are called abiotic components. These two components work together to sustain the environment.

  • Define the term trophic level.

Trophic level refers to the feeding level within a food chain. It is the position that an organism occupies in a food chain, or a group of organisms in a community that occupy the same position in food chains.

  • Trophic level 1 – producer
  • Trophic level 2 – herbivore (primary consumers)
  • Trophic level 3 – carnivore (secondary consumers)
  • Trophic level 4 – carnivore (tertiary consumer)
    • Identify and explain trophic levels in food chains and food webs selected from the local environment.

    *Producer: The organism in the ecosystem that converts abiotic components into living matter, they help the ecosystem by producing new biological matter.

    *Consumer: These organisms cannot produce their own food, so they eat other organisms to get the energy and matter they need.

    * Decomposer: Feed on dead biomass which is created by the ecosystem.

    *Herbivore: Only feed on producers.

    *Carnivore: Feed on all organisms including producers and consumers.

    *Top carnivore: This organism can not be eaten by any other organism.

    Sun: Provides the abiotic matter to the grass

    Grass: Producer and autotroph, provide food for the deer.

    Deer: The primary consumer and herbivore of the grass.

    Wolf: The secondary consumer/Top consumer and carnivore, feeds on the deer and cannot be eaten by any other organism.

    Ecosystems contain many interconnected food chains that form food webs. Food chains always begin with the producers (usually photosynthetic organisms), followed by primary consumers (herbivores), secondary consumers (omnivores or carnivores) and then higher consumers (tertiary, top). Decomposers feed at every level of the food chain.

    Diagrams of food webs can be used to estimate the knock-on effects of changes to the ecosystem.

    Biomass and energy decrease at each trophic level so there is a limit in how much trophic levels can be supported in a ecosystem. Energy is lost as heat at each stage of the food chain, on only energy stored in biomass is passed on to the next trophic level. After 4 or 5 trophic levels there is not enough energy to support another stage.

    Local example: (Lake in Sweden)

    Producer: Freshwater shrimp

    Primary consumer: Bleak

    Secondary consumer: Perch

    Secondary consumer: Northen Pike

    Top consumer: Osprey

    • Explain the principles of pyramids of numbers, pyramids of biomass, and pyramids of productivity, and construct such pyramids from given data.

    Pyramids are graphical models showing the quantitative differences between the trophic levels of an ecosystem. There are three types:

    • Pyramids of numbers: This records the number of individuals in each trophic level.

    • Pyramid of biomass: This represents the biological mass of the standing stock at each trophic level at a particular point in time. Biomass should also be measured in units of energy, such as J m-2. They can show greater quantities at higher trophic levels because they represent the biomass present at a given time. Both pyramids of numbers and biomass represent storages.

    • Pyramid of productivity: This shows the flow of energy through each trophic level. Measured in units of flow gm-2 yr-1 or Jm-2 yr.

    In accordance with the second law of thermodynamics, there is a tendency for numbers and quantities of biomass and energy to decrease along food chains; therefore pyramids become narrower as one ascends.

    • Discuss how the pyramid structure affects the functioning of an ecosystem.

    This Youtube clip explains the interactions in food chains and the vulnerability of the top carnivores.

    • Define the term species, population, habitat, niche, community and ecosystem with reference to local examples.

    *Species: A group of of organisms that interbreed and produce fertile offspring. If two species breed together they create a hybrid, this cannot produce viable gametes and is sterile.

    *Population: A group of the same species living in the same area at the same time, and can interbreed.

    *Habitat: The environment in which a species normally lives.

    *Niche: Where and how a species lives. A species share of a habitat and the resources in it.

    *Community: A group of populations living and interacting with each other in a common habitat.

    *Ecosystem: A community of inter-independent organisms and the physical environment they inhabit.

    • Describe and explain population interactions using examples of named species.

    Ecosystems contain many interactions between the populations, the interactions are varied and can be divided into; competition, predation, mutualism and parasitism.

    *Competition: A common demand by two or more organisms upon a limited supply of a resource; for example, food, water, light, space, mates, nesting sites. It may be intraspecific or interspecific.

    *Parasitism: A relationship between two species in which one species (the parasite) lives in or on another (the host), gaining all or much (in the case of the partial parasite) of its food from it.

    *Mutualism: A relationship between individuals of two or more species in which all benefit and non suffer.

    *Predation: This is when on animal or plant hunts and eats another animal.

    Here are 3 Youtube links about Interspecific interactions.

    • Outline the issues involved in the imbalance in global food supply.

    There is enough food on the world to feed us all, however there is an imbalance in the food supply globally. Many people from the LEDCs are suffering from not getting enough energy, proteins and minerals. Around 3/4 of the world’s population is not eating enough and an average of 1 million are going hungry, the majority of these people lives in the LEDCs. It is estimated that every 6 seconds a child dies of hunger.

    The price of food plays a major role here, if prices were to just increase by 10% it could lead to an increase of 40 million people in food poverty. However even though there is such a huge group of people in need of food there is a surplus of food in the MEDCs with markets producing to much food for the population.

    This has lead to people in the MEDCs to consumer more food then they need as the MEDCs increased wealth has allowed them to buy more. There are import tariffs imposed by the MEDCs to make the import of food more expensive, which can ruin the exporting countries.

    In the LEDCs they make money for the country through food production, from crops such as sugar cane and tobacco. So they need this production for making money but when the MEDCs increase import tariffs the LEDCs are in trouble.

    MEDCs want to make money from products in the country and not let the imported goods become the cheaper choice. Despite all this prices of food in the MEDCs is fairly expensive as seasonal foods have disappeared as imports fill gaps. The struggle in the LEDCs to make money has caused prices to rise, this makes it difficult for the population to afford local productions.

    Climate changes have also affected the LEDCs as droughts for example reduce the amount of growing land. Global warming could lead to countries suffering from high temperatures which could destroy crops.

    As more land is used for settlement and industry, there is an increase in intensifying production on existing farm land. MEDCs food production is complex as it involves high levels of technology, low labour and high fuel costs. MEDCs have become more technocentric.

    Agriculture in the LEDCs are in contrast and have low levels of technology, lack of capital and high levels of labour.

    • Compare and contrast the efficiency of terrestrial and aquatic food production systems.

    *Second law of thermodynamics: states that energy goes from a concentrated form (like the sun) to a dispersed form (like heat), the  availability of energy to do work therefore diminishes on the system becomes increasingly disorder. It explains how energy transformations in living systems can lead to loss of energy from the system. The order in living systems is only maintained by constant input of new energy from the sun.

    We get to see from the second law of thermodynamics that energy conversion through food chains is inefficient and that energy is lost by respiration and waste production at each level within the food web.

    Energy in sunlight -> producer (90% energy lost) -> primary consumer (9% energy lost) -> secondary consumer (0.9% energy lost)

    100% -> 10% -> 1% -> 0.1%

    Terrestrial systems:

    Most food is harvested from low trophic levels (producers and herbivores). Systems that produce crops are more energy efficient then those which produce livestock. This is because energy is greater in proportion in the low trophic levels. Even though it is efficient to use arable systems, many cultures still use livestock as part of their farming system. Taste and cultural demand play a major role in this and the animals also provide a source protein which is essential for the human diet. Animals are also used as working animals in some cultures.

    Terrestrial farming systems are divided into several types:

    • Commercial farming: is farming for profit, often of a single crop
    • Subsistence farmer: produces only enough yo geed their family with non to sell for profit

    Both commercial and subsistence can be intensive or extensive farms.

    • Intensive farms: take a small area of land but aim for a high input
    • Extensive farms: are large in comparison to the money and labour put into it

    The efficiency of the system can be calculated by comparing outputs to inputs per unit area of land.

    Aquatic systems:

    Due to human taste, most food harvested is from the higher trophic levels where the total storage is much smaller. There is less energy then crop production, although energy conversion is aquatic systems are more efficient then terrestrial chains, the system receives less sunlight then terrestrial chains.

    • Compare and contrast the inputs and outputs of materials and energy (energy efficient), the system characteristics, and evaluate the relative environmental impacts for two named food production systems.

    Terrestrial Systems:

    Intensive Charolais beef production in France:

    In Western Europe the Charolais beef is one of the beef brands chosen. Through selective breeding and genetic engineering bloodlines that puts weight on exist but has a low fat cover. Charolais lives under controlled conditions, they are fed with high proteins and treated with antibiotics to make sure they are healthy. Lots of energy is used in transporting and processing the finished meat.

    Cattle raised outdoors however grown on single monoculture ( cultivation of a single crop on a farm or in a region or country) grass land in large fields with a high stock rate. To keep the productivity of these fields going, large amounts of fertilizer are used.

    This intensified farming e the 1940’s with the aim of producing cheaper meat has led to habitat loss as they have been removed to make bigger fields and cases of Eutrophication have increased as excess use of fertilizers and large amounts of slurry produced in the system enter water courses. Fear of causing antibiotic resistance in human bacteria through bioaccumulation.


    • energy for food distribution
    • food supplements
    • selective breeding and genetic engineering (system characteristics)
    • indoor rearing
    • fertilizers to maximize grass production
    • antibiotics and hormones


    • cheap meat (socio-cultural)
    • habitat destruction to make bigger fields (environmental impact)
    • antibiotic resistance
    • Eutrophication

    Nomadic cattle grazing of the Himba:

    The Charolais beef production can be contrasted with the Nomadic cattle grazing of the Himba. The Himba people are from North West Namibia, they survive by being Nomadic hunters/grazers. They also have a tight bond with the cattle they graze. During the dry seasons the Himba move their cattle from area to area until the grass is used up until the raining season, they go to better pastures. Cattle to the Himba are very important as they provide; meat, milk, skins and even dung for fires. Prestige between the Himba is seen by how many cattle they have, not the size of the cattle. The cattle during the dry season may start competing with herbivores. This has increased especially with global warming drought periods. This can lead to soil erosion as extra grazing pressure removes the grasses that hold the top soil together.


    • nomadic grazing moving from place to place so land has a chance to recover
    • cattle survive on low grade natural forage with no supplements
    • during drought cattle die as grass disappears adding patches of nutrients to the soil (environmental impact)


    • Himba cattle provide meat, milk and fuel (dung)
    • owning cattle gives status in community (socio-cultural)
    • during drought times Himba cattle compete with wild grazers for food this can lead to soil erosion as well as food shortage (environmental impact)
    • Discuss the links that exist between social systems and food production systems.

    There are many links between social systems and food production system. Examples given are shifting cultivation, wet rice agriculture (South-East Asia) and agrilbusiness

    Shifting cultivation

    Shifting cultivation supports small communities and sometimes individual families. It is also known as ”slash and burn” agriculture, as new land is cleared by cutting down small areas of forest and setting fire to them. Ash fertilizers the soil for a while and the clearing produced enables crops to grow. When the land can’t be used any more, the farmer goes to a new land area. Once the land has recovered, farmers go back to the land.

    This is performed in many tropical forest areas, such as the Amazon regions. This is possible as there is low population density. If population densities increase too much, old land is returned too before fertility has been restored, this encourages shifting cultivation. There are people who have close connection with nature, like shifting cultivators in the Brazilian Amazon. They show a closer connection between social systems and ecological systems than the societies living away from natural systems, such as city dwellers. Urban capitalists in Brazil are more likely to view the interior of a country as a new frontier, and the rainforest as a resource for development and cash (technocentric approach). The lack of understanding of the nature makes them underestimate the true value of natural resources. They may also make decisions which produce wasteful and damaging actions.

    Wet rice ecosystem of South-East Asia

    Padi field agriculture has become the dominant form of growing rice in South- East Asia. It is intensive subsistence farming, using high labour but low technology. As there is a high population, a lot of food is needed. Especially rice as it is part of the Asian diet as well as their culture. Padi fields are placed by rivers and areas that flood naturally, so that the fields get new deposits of silt and increased fertility. They should be placed in heavy clay soils, as sand and light textured soils are not suitable as water drains away. Warm weather and high rainfall help productivity all year round.


    Supply most of the products found in supermarkets. Many have travelled long distances from around the world. Its a non-seasonal climate food supply throughout the year, so once-seasonal crops are available year-round in MEDCs.

    The aim of agribusiness is to maximize productivity and profit to compete with the global market. This is large scale monoculture, intensive use of fertilizers and pesticides, mechanized ploughing and harvesting, and food production geared to mass markets including export.

    This type of agriculture has a huge impact on the environment, with loss of biodiversity, and increased run-off pollution. National political economies encourage agribusiness as it supports the national income, this had lead to many people living off farming to move into the towns and cities to get new work.

    One of the most interesting activities I participated in was the IB Gala on December 2009. It was such a success that the IB students organized a second Gala this Christmas. I was also a charity gala, saving money for unfortunate children. This event made us all carers as we showed a lot of respect and empathy towards poor students in other countries. We came to know about their situation last year and continued to help them out again. Although this year the Gala had some changes of course it got better! It was based on the theme of Christmas, the Gala was filled with more interesting things; like a magic show, a Christmas play and dancing. This made us risk-takers as new things were introduced to the Gala; we were not sure whether the audience would enjoy the shows. This year it was not as hard as we knew what to do, as we experienced a Gala last year. Although it still took time to think of new ideas so it will be fun for the people watching.

    The way we collected money for the schools this year was through selling tickets to the Gala, selling lottery tickets and selling food which the students made themselves to the audience. A few shops were kind enough to sponsor gifts for the Lottery. We had to be principled here as there was money involved and also found that contained ingredients that might be dangerous to others. We were sure to inform all the people what each type of food contained so nothing serious would happen.

    This year I aided by helping in the food area, I was selling the food and making sure the refreshments looked presentable. I was responsible of having enough on the table and not making a mess. I really enjoyed this job as I was communicating with many of the parents and younger students, which on normal days I don’t have the chance to due to the little time and being busy with class. It was exciting to meet new people as they all came from a variety of countries; hence their children are in international programs. What made the Gala what it was the wonderful performances done about Christmas, people sang, had a play and danced. It would be a great idea to continue this Gala every year during December as an IB tradition at our school.



    CAS reflection – IB GALA

    Posted: January 10, 2011 in CAS
    Tags: , , , , , , ,

    One of the most interesting activities I participated in was the IB Gala on December 2009. It was a Charity Gala saving money up for schools in Morocco and Nepal, which many IB students helped organizing. This event made us all carers as we showed a lot of respect and empathy towards poor students in other countries. We came to know about their situation and decided we HAD to help them out. It was interesting and fun because we included so many activities which I have never experienced in Katedralskolan before. This also made us risk-takers as it was the first time Katedralskolan goes through this type of Gala, we did not know what would happen or if anyone would even show up. It took us a while to think of ideas and to plan out what will be happening throughout the event. We had meetings and practices to prepare for the Gala. Here we were communicators and thinkers as we expressed our ideas and opinions about what to do, as well as working effectively for a successful event. However the Gala was a big success in the end and we decided to repeat it for the next Christmas also.

    The way we collected money for the schools was through selling tickets to the Gala and selling food which the students made themselves to the audience. We had to be principled here as there was money involved and also found that contained ingredients that might be dangerous to others. We were sure to inform all the people what each type of food contained so nothing serious would happen.

    The most exciting part of the whole Gala for me was the International Catwalk. The Catwalk was made up of many IB students and some teachers dressed up in a specific country or continents national dress. Each country was represented by 2 or more people. I was representing the United Arab Emirates along with another guy from a younger IB class. We both dressed in their national dress and chose a certain type of music to walk through the auditorium. The auditorium was filled with students and parents who waited anxiously for each country representative to walk through the doors in their beautiful clothes. The feeling was great with all eyes on you. The crowd cheered more and more as each pair walked passed them. This Gala was really an eye opener for us and the audience as we began to understand and be open to traditions of other societies and places in the world. I personally loved this event and am glad to know that we will be having a similar one also raising money for the unfortunate next Christmas.