Adaptations Chemicals Forces Genetics Earth Electricity Timeline 
Home Jnr Science Biology
Year 8

Toxic build up

There is toxic material all around us. Some of it breaks down into non hazardous substances, while other can accumulate and build up in a food chain.

Mercury can be extremely dangerous. When it builds up in the ecosystem, it can  cause nervous and reproductive damage to mammals.

So how does it build up?

Lets say one plankton absorbs 1 gram of mercury. One fish eats 5 plankton, meaning the fish now has 5 grams of mercury in it.

In turn that fish is eaten by a bigger fish, along with 5 of his friends who also ate plankton. The big fish now has 52 grams of mercury in it.

Finally we eat a 5 big fish. Meaning we now have 260 grams of mercury in us.


2. Using the food web above write the name of a

(a) Using the food web, write the name of a:

(i) Carnivore   ______________________

(ii)  Herbivore   ________________________

(iii) Producer  __________________________

(iv) Primary Consumer  _____________________

(v) Secondary Consumer  _______________________

(vi) Tertiary Consumer  __________________________

(b) A disease has wiped out most of the flat winkle population. Giving an explanation, what will happen to the numbers of

(I) Grey Mullet _____________________________________________________________________

(II) Crab ___________________________________________________________________________

(III) Lobster _________________________________________________________________

3. Explain the term Bio accumulation, and explain how top predators are at risk.