Whether they make tasks harder or easier is dependent on your school and the teacher's decisions-often the task is set so that it is feasible to be completed within the timeframe of the task, teachers don't usually set tasks that are easier for them to mark-rather they set tasks that can be safely conducted and usually the school has sufficient equipment for it as well an experimental result can be obtained in a relatively short time-i.e. within an hour, and they set tasks that allows them to assess practical skill outcomes and the relevant objectives of the task listed on the notification sheet.
Tips for preparing for practical examinations in bio, and can also be applicable to other science subjects are
1)You must understand and differentiate the terms accuracy, validity and reliability and for each prac you have done so far-you should know these three terms in relation to the experimental method and apparatus, as well as independent, dependent and controlled variables, areas for improvement and possible sources of error in experiments, you must understand ways in which accuracy/validity/reliability can be improved for each experiment, as well as being able to do risk assessments
2)Think about what experiments in the syllabus will give you a result in the set time frame of your task-if you did an experiment that involves observation over several days, then it is logical that experiment is unlikely to be in your practical, ask a former student what they did last year for bio-it will give you some ideas of the kind of prac they are going to ask-although there may be variations, you can study those possible experiments in more detail than others
3)If you are required to draw graphs or diagrams-make sure you use a pencil and bring a rubber, it is much easier to rub out mistakes-make sure you have a watch-and adhere strictly to the time frame, say for example, if you have two parts, don't spent too much time on part 1-because you will not have enough time to finish part 2-if any question or part is too hard, come back to it-just circle it and come back if you have time
4)Don't panic, make sure your handwriting is legible, you have adopted the most appropriate form of recording your results-i.e. whether it be labelled diagrams or tables, make sure to have headings and sub-headings where appropriate to make it easier to read-allocate your time according to the marks of the question-read each question carefully-don't miss out any parts-and answer nothing but what the question asks-highly recommend you to read it several times and highlight key words to make sure you don't miss out any marks
5) might be a good idea to make sure you know verbs like evaluate, explain, assess, critically analyse, justify, contrast, compare, means-I don't think you will get a glossary of words and definition in your exam-not impossible, but unlikely
Make sure you rest well, bring all the required equipment and follow my above advice-I wish you all the best in your upcoming prac assessment hope this helped