This summer, you are returning to the research station in Costa Rica to follow up on the population of butterflies you have been studying. You are disappointed to find that there are fewer this year than last. In fact, at dinner your friends studying frogs and birds are complaining about the same thing. What type of influence do you suspect?

Question

A.  a density-independent effect like an introduced predator
B.  a density-dependent effect like environmental disruption
C.  a density-independent effect like environmental disruption
D.  a density-dependent effect like an introduced predator

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 factors that affect many different populations of organisms? What other information is related to the question? 


Choose Answer:
Given what you now know, what information is most likely to produce the correct answer?


Reflection 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.  a density-independent effect like environmental disruption


Clarify question:
What is the key concept addressed by the question?
You are being asked to explain the cause of a large drop in populations of several unrelated species.

What type of thinking is required?
This is an analysis question, you will need to break the question down into its components in order to get to the answer. 


Gather Content:
What do you already know about factors that affect many different populations of organisms? What other information is related to the question? 
Density-dependent effects change as the population size changes. Diseases are a good example, a disease will have an easier time spreading in a large population especially if the individuals live close together. Density-independent effects are not affected by population size. Hurricanes and other natural disasters are good example of density-independent effects.


Choose Answer:
Given what you now know, what information is most likely to produce the correct answer?
A density-dependent environmental disruption is the most likely explanation for a drop in the population size of several unrelated species in one particular area.


Reflection 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?
Were you to select all the correct answers? You needed to break down the answer choices to figure out which one would best explain the drop in populations. Also you needed to figure out that an environmental disturbance was a density-independent effect.