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Energy flow and nutrient cycles

Organisms such as plants and animals need energy for growth, movement and reproduction. They get this in the form of nutrients from the food they eat.The main source of energy for life on earth is the sun. The sun provides energy to producers that use photosynthesis to grow and become food for consumers.Consumers include herbivores, carnivores and omnivores. Decomposers break down discarded plant and animal (organic) materials into simpler substances, whichreturns nutrients to the soil and atmosphere for new plants to use to grow.

Food chain

A food chain is a series of nutrients and energy moving through a chain of organisms. Below is an example of a simple food chain in a grassland. Thearrows show the movement of energy from one organism to another.

IMAGES sourced from: http://www.flickr.com/photos/blueridgekitties/4625665988/sizes/o/in/photostream/



Activity 1:

Can you trace a food chain of the vegetables, fruit, cheese, eggs or meat that you had for breakfast or will have for dinner?

Activity 2:

  1. In the food chain shown above which of the three organisms is the
    1. Herbivore
    2. Carnivore
    3. Producer
  2. Draw a food chain showing at least 4 organisms.
  3. Producers use sunlight to manufacture their own food. Write a word equation as well as a balanced equation to depict this process.
  4. Draw in the decomposers in the above food chain. Ensure that the direction of the arrows is correct.
  5. What animal will feed on the leopard?

Food web

A food web is made up of a number of food chains. It represents the different feeding relationships in an ecosystem or a biome. It is usually morecomplicated than a food chain because organisms can get their energy or food from more than one source. The presence of a number of food sources makes thesystem more stable. If one organism is removed, the whole system will not collapse, unlike in a single food chain.

(image source: http://per8eocreview.wikispaces.com/ )

Activity 3: human food web

  1. Divide into teams of at least five students each and stand in a circle.
  2. One person in each group takes a ball of wool or string. This person is the sun and starts the food web.
  3. The first person (sun) holds onto the end of the wool and throws the ball of string to another person in the group.
  4. The person who catches the ball has to name themselves something that uses energy from the sun (primary producer).
  5. The person holding the ball (primary producer) has to hold the string with one hand and toss the ball to another student in the circle with his/her otherhand.
  6. The person who catches the ball has to name something that eats or is eaten by the previous organism named.
  7. Carry on until everyone in the circle is holding the ball. You can throw the ball to someone who has already named themselves, as long as they eat you orare eaten by you
  8. Look at the web you have created and the ones the other groups have created.
  9. Are some webs more complex than others? Why?

(source: http://www.oercommons.org/courses/got-energy-spinning-a-food-web/view)

Trophic levels and the food pyramid:

The trophic level of an organism is the position it holds in a food chain and depends on how much energy it consumes or produces. The trophic level of eachorganism can be drawn as a pyramid starting with the producers at the bottom and moving up through the food chain.

The organism at the bottom gives the most energy and needs the least and the organism at the top needs the most energy and releases the least. Energy islost from activities at every level - through heat, egestion, urination andreproduction (pregnancy and egg-laying). This is why there is less and less energy as you move up the pyramid.

Producers, eg. Plants are on the first level, or bottom of the pyramid, because they produce their own nutrients using energy from the sun and therefore have alot of energy to pass on.

Primary Consumers, eg. Herbivores are on the second level because they feed off plants

Secondary Consumers, eg. Carnivores feed on herbivores so they get their energy from plants indirectly and are on the third level.

Tertiary Consumers, eg. Carnivores feed on organisms below them in the pyramid

(image source: http://per8eocreview.wikispaces.com/)

Figure 3. Food pyramid

Trophic levels can be drawn as a pyramid of numbers, where each level shows the number of organisms (look at figure 3). They can also contain the biomass of apopulation. The biomass is the mass of living organisms in an ecosystem.

Activity 4:

Look at the food web and the diagram showing the different trophic levels.

  1. Identify a food chain that has three trophic levels.
  2. Identify a food chain that has four trophic levels.
  3. Name 2:
    1. Producers
    2. Primary consumers
    3. Secondary consumers
    4. Tertiary consumers
  4. There are very few tertiary consumers compared to the primary consumers. Why?
  5. What will happen if the impala is removed from the food web?

(source: http://www.learner.org/courses/envsci/interactives/ecology/ )

VIDEO: http://www.youtube.com/watch?v=TE6wqG4nb3M

This a catchy song about food chains to help you remember.

VIDEO: http://www.youtube.com/watch?v=-YwW-iWxLr4&NR=1

Bill Nye the Science Guy talks about the Food Web

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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why and for what was five kingdom of classification of organisms introduced
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Comment on the ozone depletion over the period of 1982 to 1996
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Source:  OpenStax, Siyavula: life sciences grade 10. OpenStax CNX. Apr 11, 2012 Download for free at http://cnx.org/content/col11410/1.3
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