Expert: Walter Hintz - 6/6/2006

Question
Which food chain represents the most efficient use of energy for humans?  Or None?

Food Chain 1: Sunlight, then 1000 kg of green plants, then insects, then fish, then humans

Food Chain 2: Sunlight, then 1000 kg of green plans, then cattle, then humans

Food Chain 3: Sunlight, then 1000 kg of green plants, then humans

Or, NONE of them?


A follow up to the above food chain thought....

If the insects in the above food chain 1 were destroyed by an insecticide, which organismns would be affected?

Food Chain 1: Sunlight, then 1000 kg of green plants, then insects, then fish, then humans

1. Only humans
2. Only green plants
3. Only fish
4. Fish and humans  

Answer
1st question
Food chain 3.  This is because of the 2nd Law

2nd question
 In my opinion all are affected in some way whenever any component in a food chain is eliminated.  Therefore the right choice is not here.  At first thought 4 would seem correct but if the insects are not consuming the plants then the plant population is affected.