1. What is the difference between a phrase and a clause?
Clauses:
A dependent clause is a group of related words that has both a subject and a verb.
Examples:
if a whole chain of plants and animals is affected
when one species dies out completely

2. Clauses continued…
An independent clause presents a complete thought and can stand alone as a sentence.
Examples:
This ancient oak tree may be cut down.
Why would anyone want that to happen?

3. Phrases
A phrase is a group of related words that lacks either a subject or a predicate (or both).
Examples:
guards the house (lacks a subject)
the ancient oak tree (lacks a predicate)
with crooked old limbs (lacks both)

4. More about phrases…
Phrases usually take their names from the main words that introduce them.
Examples:
The ancient oak tree (noun phrase)
with crooked old limbs (prepositional phrase)
has stood its guard (verb phrase)
very stubbornly (adverb phrase)
protecting the little house (verbal phrase)