Question

I WILL GIVE 20 EXTRA POINTS!!

How did the egg shell of either species return to their original thickness by 1980? Suggest a reason to explain your answer.

Answer 1

No; some DDT might have remained in the environment even after it was banned in 1973.

Hopefully this helped! :D

-LavenderVye

Answer 2

Due to DDT ban

Step-by-step explanation:

DDT is an pesticide or insecticide which got banned because of its harmful effect in environment.

According to the graph the eggshell of both the bird species A and B are thick in 1930 but begin to thin after 1940 as DDT (Dichlorodiphenyltrichloroethane) introduced in the ecosystem.

Eggshell return to their original thickness by 1980 because DDT got banned after 1970. DDT is a harmful pesticide which alter the bird's calcium metabolism which leads to thin eggshells.

Hence, due to banning of DDT after 1970,egg shell of either species return to their original thickness by 1980.