The ________ in our atmosphere is the result of photosynthesis by ...

[Collmarie]

The ________ in our atmosphere is the result of photosynthesis by plants.
 
  Fill in the blank(s) with correct word

Question 2

Briefly describe how an impact could lead to a mass extinction.
 
  What will be an ideal response?

[at]

Answer to Question 1

oxygen

Answer to Question 2

A large impact could send huge quantities of dust into the atmosphere, where it would block out sunlight for several years. The surface cools and plants die for lack of sunlight. Effects propagate through the food chain, leading to death and extinction on an enormous scale. Acid rain may have killed vegetation and acidified lakes. Chemical reactions may have produced nitrous oxides that dissolved in the oceans and killed marine organisms.