Beginning over 5,000 years ago, corn (maize) was first ...

[Capo]

Beginning over 5,000 years ago, corn (maize) was first domesticated in ________.
 
  A) Brazil B) Portugal C) Spain D) China E) Mexico

Question 2

Why is a springtime hole observed over the Antarctic but not usually over the Arctic?
 
  What will be an ideal response?

[kiamars2010]

Answer to Question 1

E

Answer to Question 2

The springtime hole results from a release of Cl from cloud surfaces as the clouds heat up. It does not occur in the Arctic because the polar vortex there is not as consistent, as it is broken up by atmospheric waves (gravity waves) generated by the passage of tropospheric winds over mountain chains. Hence, air in the Arctic winter stratosphere is periodically replaced by high-ozone, high-NOx air from lower latitudes. By contrast, air in the Antarctic winter stratosphere is isolated, and so odd nitrogen can be removed by PSC formation, allowing chlorine species to wreak their havoc on ozone.