Biological magnification of persistent toxins would be greatest in a

Question

A.  deer.
B.  fox.
C.  polar bear.
D.  mushroom.
E.  oak tree.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?

Gather Content
· What do you already know about biomagnification?

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

  Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

C.  polar bear.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses biomagnification.
· What type of thinking is required?
        o This question is asking you to take what you already know and apply it to this unfamiliar situation.
 
Gather Content
· What do you already know about biomagnification?
        o Environmental pollutants can reach high levels in some organisms due to biomagnification.
        o For instance, DDT is an insecticide that was sprayed widely in the decades following World War II, often on wetlands to control mosquitoes. During the years of heavy DDT use, populations of ospreys, bald eagles, and brown pelicans—all birds that catch large fish—plummeted. Ultimately, the use of DDT was connected with the demise of these birds.
        o Scientists established that DDT and its metabolic products became more and more concentrated in the tissues of animals as the compounds were passed along food chains. Animals at the bottom of food chains accumulated relatively low concentrations in their fatty tissues. But the primary carnivores that preyed on them accumulated higher concentrations from eating great numbers, and the secondary carnivores accumulated higher concentrations yet. Top-level carnivores, such as the birds that eat large fish, were dramatically affected by the DDT. In these birds, scientists found that metabolic products of DDT disrupted the formation of eggshells. The birds laid eggs with such thin shells that they often cracked before the young could hatch.
        o Decades after DDT was banned, populations of ospreys, eagles, and pelicans are rebounding dramatically.
  Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Toxic chemicals like DDT accumulate in the largest quantities in higher level carnivores like a polar bear.
        o A fox is also a predator, but a fox typically eats herbivores, whereas a polar bear eats other predators (seals), so it is higher up the food chain.

  Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that top predators are most vulnerable to the effects of biomagnification?