Here are the 10 mistakes identified and corrected in the passage:

1. **who** (Line 1) should be **which**.
2. **changed** (Line 3) should be **changing**.
3. **unit, The** (Line 4) should be **unit. The**.
4. **IPCN** (Line 5) should be **IUCN**.
5. **percent** (Line 5) should be **percentage**.
6. **based at** (Line 6) should be **based on**.
7. **evaluating** (Line 7) should be **evaluated**.
8. **this** (Line 8) should be **these**.
9. **create** (Line 9) should be **creating**.
10. **potential** (Line 12) should be **potentially**.

Here is the corrected passage:

An endangered species is a population of an organism **which** is at risk of becoming extinct because it is either few in numbers, or threatened by **changing** environmental or predation parameters. An endangered species is usually a taxonomic species, but may be other evolutionary significant **unit. The** World Conservation Union (**IUCN**) has calculated the **percentage** of endangered species as 40 percent of all organisms **based on** the samples of species that have been **evaluated** through 2006. Many nations have laws offering protection to **these** species: for example, forbidding hunting, restricting land development or **creating** reserves. Only a few of the many species at risk of extinct actually make it to the lists and obtain legal protection. Much more species become extinct, or **potentially** will become extinct, without gaining public notice.