Question

select the correct answer.
unwanted dumping of chemicals has caused pollution in a particular region, leading to a decrease in the number of insects. bluebirds feed on these insects, and bigger birds prey on the bluebirds. what effect would this situation likely have on the population of the bluebirds and their predators?
a. the population of bluebirds will decrease, but the number of predators will increase.
b. the population of bluebirds will increase, but the number of predators will decrease.
c. the population of bluebirds and the number of predators will increase.
d. the population of bluebirds will decrease, leading to an eventual decrease in the number of predators.
e. the population of bluebirds and the number of predators will not be affected.

Explanation:

1. First, analyze the food chain: Insects are prey for bluebirds, and bluebirds are prey for bigger birds (predators).
2. The pollution reduces insect numbers. Since bluebirds feed on insects, their food source decreases, so bluebird population will decrease.
3. With fewer bluebirds, the predators (bigger birds) that feed on bluebirds will have less food. Over time, the predator population will also decrease as they struggle to find enough food.
4. Now evaluate the options:

• Option A: Says bluebird population decreases (correct) but predator population increases (incorrect, as predators lose food). Eliminate A.
• Option B: Says bluebird population increases (incorrect, as their food is reduced). Eliminate B.
• Option C: Says bluebird population increases (incorrect) and predator population increases (incorrect). Eliminate C.
• Option D: Bluebird population decreases (correct) because of less insects. Then, as bluebirds decrease, predators (that eat bluebirds) have less food, so predator population will eventually decrease (correct). This matches the analysis.
• Option E: Says predator population is not affected (incorrect, as their food source is affected). Eliminate E.

Answer:

D. The population of bluebirds will decrease, leading to an eventual decrease in the number of predators.