How do animals get rid of excessive nitrogen?

How does the molecular clock work? a. it analyzes the brain functionality of two different species. b. it examines and compares the physical characteristics of two different species. c. it illustrates relationships between two different species. d. it compares the number of mutations that exist in the dna of two different species.

Consider this plant cell which organelle is labeled g

When lactate builds up in a runners muscles it causes a burning sensation what causes this to occur