And equator cross the northern or southern part of south america south america is located mostly in which two hemispheres

It is located in the southern and western hemispheres. If you look at the equator, it splits the earth into two hemispheres. Northern and southern. South America would be in the Southern Hemisphere since it is below the equator. That's why it has south in it's name. The prime meridian splits the earth is eastern and western hemispheres. America is in the Western Hemisphere. Europe is in the eastern hemisphere. So, South America is in the Western Hemisphere

Ba population changes in response to a change in environment

What are the options?