The personality test and the personality questionnaire are used in order to determine a candidate's typical reactions and attitudes to various situations. These tests might try to identify how well you get on with others, your normal reaction to stressful situations or your feelings about the kind of people you like to work with.
Personality Test Conditions
It is unlikely that personality tests or questionnaires will be timed or indeed have right or wrong answers. Do not let this lack of exam conditions fool you. Some employers will know precisely what they are looking for in terms of an ideal "Personality Profile" and it is up to you to meet their expectations. It is unwise to try to fake the answers. These questionnaires usually have some type of internal checking where the same question is asked with different wording early and late in the test to try to detect dishonest answers.
Ultimately, there is little point in pretending to be the kind of employee a firm is looking for if you are not right for them. If they think your personality is unsuitable for their company, their company is probably also unsuitable for your personality.