Things the interviewer may be looking for:

Is she excited about learning? Is she motivated? Curious?
Does she see connections? What are her feelings about her experiences?
Is she articulate? Interesting? Does she have a sense of humor?
How independent is she? Mature? Does she feel responsible for herself?
Do you think she could contribute to Wellesley? Benefit from Wellesley?
Has she taken advantage of her opportunities? Has she had many?
Is she adventurous or cautious? A leader or a follower? A joiner or a loner?
Has she thought about what she wants from college?