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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

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
Do somebody tell me a best nano engineering book for beginners?
s. Reply
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Devang Reply
are you nano engineer ?
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?
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
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what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
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I'm interested in nanotube
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Ramkumar Reply
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Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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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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