what is biomass and how come it shortens in the food chain?

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help im really stuck!

Posted Wed 6th March, 2013 @ 06:04 by Anisa -Team GR

7 Answers

  • 2 votes

its basically biological material and the reason that the arrows shorten is due to the fact that at each stage energy is lost. The energy is lost because an animal who recieves a certain amount of energy will use some up by movement. Another way in which energy could be lost is by death of an animal as the next animal can't consume all of it.

Answered Wed 6th March, 2013 @ 08:21 by Darlene
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Thank you ! **

Answered Fri 8th March, 2013 @ 06:10 by Anisa -Team GR
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Answered Thu 15th August, 2013 @ 19:47 by Anisa -Team GR
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Answered Mon 21st October, 2013 @ 20:00 by Anisa -Team GR
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Answered Sun 1st December, 2013 @ 16:43 by Anisa -Team GR
  • 0 votes

Biomass is the total mass of living organisms at any stage in a food chain. So if you take a single food chain, starting with grass, the total mass of grass present in the area is the biomass for that stage. 

Fresh biomass includes the water of the organism, while dry biomass includes killing the organism and removing the water, which gives more accurate results. However due to the small sample size with dry biomass (becuase you don't want to kill too many) the results lack reliability.

It shortens in the food chain because less mass of organisms can be supported further along the food chain due to energy losses. 

Answered Fri 27th December, 2013 @ 09:47 by Tilly - Team GR
Edited by Tilly - Team GR on Fri 27th December, 2013 @ 09:47
  • 0 votes

I have learnt that Biomass is the total dry mass of organisms. When you dry out a sample and weigh it, it gives you the biomass. Each rabbit has to eat a large amount of grass and each fox will eat a few rabbits, so the biomass decreases along the food chain.

This is because the grass has lost lots of energy through respiration, and the rabbits need to consume a large amount of grass each, to gain enough energy. However, these rabbits lose even more energy from respiration and movement, therefore only one fox can eat the rabbits involved in this particular foodchain because if he shared the rabbits with the other foxes, he would not be gaining enough energy.

Approximately 10% of the energy obtained at each stage of the food chain is lost, so only 90% of the energy that the rabbit has obtained from the grass is passed onto the fox. He has to eat more rabbits, and the rabbits have to eat more grass to make up for the energy losses, so if you think about going backwards along the foodchain, it is easier to understand why the biomass increases.

If you burnt the dry mass (biomass) of a sample of an organism in a calorimeter, you can measure the amount of energy it contained. Energy is directly linked to biomass, so another way of thinking about it is how energy decreases along the foodchain.

Answered Sun 9th March, 2014 @ 17:22 by Sophie