Why do you think 02 levels rose dramatically and then fell after the Cambrian Explosion? a. Too many plants evolved and took away the oxygen from the atmosphere.

b. There was a large break up of supercontinent Rodinia. This released a lot of O2 into the atmosphere.

c. A meteor hit the Earth and cleared out all the oxygen.

d. So many new life forms were doing cellular respiration. This took in a lot of 2.

Me brainliest 1. what does a red shift mean? blue shift? 2. describe the big bang theory. according to this theory, how old is the universe? 3. scientists believe the universe is expanding. what is the evidence that supports this? 4. describe a nebula.5. describe the 3 types of galaxies. what is a barred spiral galaxy? 6. what is a light year? how far is alpha centauri from earth? 7. describe the universal law of gravitation. be sure to include gravitational force between two objects.8. describe the planets’ orbits around the sun.9. what is the asteroid belt? where is it located? 10. describe rotation and revolution of earth. what determines an earth day and year? 11. how do galaxies exist? 12. compare and contrast the inner and outer planets.13. what causes the seasons?