SCI 200--Unit Milestone--Practice 1 Questions and Answers 100% Solved

Correctly identify what event, agent or process of those given below is responsible for the current atmosphere on Earth of 20% oxygen. Volcanic activity Photosynthesis Ozone layer formation The water cycle Photosynthesis Which of the following statements about continental drift is true? Because of continental drift, the majority of most continents' landmass remains underwater, which has severely limited biodiversity. After the continents were separated, continental drift slowed, until today it is almost nonexistent. All of the continents were once one big super-continent, but their separation created more coastline, which was beneficial for biodiversity. About one hundred million years ago, all of the continents were one giant landmass called Pangaea. All of the continents were once one big super-continent, but th