The tundra is broken up into 2 parts. What are these 2 parts?

What protects the lining of the stomach from acidic gastric juices?

Which events are likely to be catastrophic to an ecosystem? select the three correct answers.a-hurricane.b-steady population growth.c-seasonal flooding.d-introducing of an aggressive invasive species.e-tsunami.

Describe the response the kidneys have to dehydration and excessive water intake. what happens to the concentration of urine in each case ?