영어 문장 해석 부탁드려요

아래 문장들의 해석이 궁금합니다.
1. Environmentalists are worried that northern spotted owls may not survive if the forests where the owls roost continue to disappear. 여기서 if는 어떻게 해석하나요?
2. have been hunted into extinction
3. woman can become withdrawn
4. If, for example, a teenager dresses like his or her favorite rock star, that rock star has referent power over the teenager.