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SCIPAD - BIG IDEAS - BOOK 1
LIFE AND THE TAIAO
Energy Loss
Energy transfer between organisms is never fully efficient. Typically, only about 10% of the energy
consumed by an organism is available for growth. The remaining 90% is used to power life processes
such as respiration, movement and waste production. This inefficiency limits the number of trophic
levels that can be sustained in an ecosystem.
1. To represent the flow of energy through a food chain, a teacher set up the following
demonstration.
She filled the beaker labelled ‘Producer’ with 100 mL of water. The water represents the
amount of energy in the producers.
(a) State how much water she should transfer to the beaker labelled ‘primary
consumer’. (i) in millilitres. 			 (ii) as a percentage.
(b) Explain why you chose this amount by describing why the consumer can’t get
access to all of the energy (as represented by the water). 



(c) State how much water she should then transfer from the beaker labelled ‘primary
consumer’ to the beaker labelled ‘secondary consumer’ 			 ml
(d) If the food chain had continued to the next level what percentage of energy would
the third-level (tertiary) consumer have received from the secondary consumer?
		
(e) How much water would be have transferred into the a tertiary consumer’s beaker?
		
60 units are used
during respiration and
lost as thermal energy.
30 units are lost in
waste products.
10 units are used
for growth.
100 units of energy
are consumed.
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