2, 3 or 4 markers: It somewhat depends on the question, but generally you want to add one point/elaboration of info for one mark.
for example if the question 'What is the importance of verbal and non-verbal communication to humans and animals. Give an example [3 marks]'
here, you'll want to give 3 points. One marks will be for explaining about how animals don't have language so they communicate may non-verbally. Another mark for saying that humans have language, so we can speak openly to others to communicate. Final mark will we for the examle, like peacocks using their feathers to attract a mate.
5 (/6?) markers: these are usually evaluate questions. What are you evaluating? A study or a theory? If it is a study, you want to say what was good or bad about the study. If it a theory, you want to say if there is any supporting evidence, or if it actually testible or applicable to real life
Generalisability - who were the participants. Can it be generalised to the whole world? Were the participants only male or only american? The we can't say it is the same for females for asians
Reliability - does the researcher have consistant results? Are there other studies to support this? Does it make intuitive sense?
Application - can this study be applied to real life?
Validity - do the results satisfy the hyposthesis?
Ethics - was it ethical? (coughcoughzimbardo)
Design - lab or open field study