Sunday, March 15, 2009

Assignment

Watch the youtube video "Song on Food Chain" and give your comments on what you have learnt about food chains and food webs from the video.

2 comments:

  1. I like this video very much and it allows me to recap on food chains, energy requirements and the connections among living things! I really like the diagrams inside the song!

    Previously, I had a hard time understanding food chains but now I can understand it better.

    I have learnt:
    -More about primary consumers
    -Each level in a food chain yields only ten percent of the former level's energy.
    -When energy passes through the food chain, it gets dissipated.
    -Nutrients get recycled and are consumed again.

    Oh, the only thing I don't quite understand was the lines "There are bones and leaves you can't digest that really make a dent. And don't ignore the weighty cost of metabolic rent." What does it mean?

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  2. It's great that you've enjoyed the video.

    You have asked a fabulous and perceptive question! Let me explain the lyrics for you.

    When an organism --think of a cow, for example -- eats something, it has to use a lot of the energy in that food just to keep itself alive. All of that energy gets radiated into the environment as heat. As a result, the food that an animal eats isn't available to organisms in the next trophic level. The food that keeps you alive is the "metabolic rent" and it's a big chunk of the 90% of energy lost from one level to the next.

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