By far, the most important responsibility you have is to be truthful in your responses.
Your contribution to the research is one of the most valuable components of the research. It requires that you answer all questions honestly. Market research findings depend on your sincerity.
To establish that you meet research criteria, your first step will be to answer questions to establish that you are qualified to participate in the specific study. Healthcare research studies typically need people who have a specific condition or disease, take a drug, or provide care to a certain type of patient.
By the way, not being a good fit for a study, even when it seems like you are, can happen because the research may need a mix of ages, or an even split of genders, or some other criteria that can make even the best participants unqualified for one study, yet qualified for a similar study weeks later.