IB DP Biology Mock Exam SL Paper 1B Set 1 - 2025 Syllabus
IB DP Biology Mock Exam SL Paper 1B Set 1
Prepare for the IB DP Biology Exam with our comprehensive IB DP Biology Exam Mock Exam SL Paper 1B Set 1. Test your knowledge and understanding of key concepts with challenging questions covering all essential topics. Identify areas for improvement and boost your confidence for the real exam
Question
(a) Melatonin helps to control circadian rhythms in the body. The graph shows the mean levels of melatonin in the body in day and night workers over 24 hours.
(i) State where melatonin is produced in the body.
(ii) Describe one difference between melatonin levels of day and night workers.
(iii) Deduce, with a reason, what time of day would be a good time to take melatonin if you have travelled over several different time zones and are jet-lagged on your arrival.
(b) The Davson-Danielli model of membrane structure was proposed in the 1930s. When electron micrographs of membranes were first produced, they were used as evidence for this model. The micrograph shows two adjacent membranes (indicated with arrows).
Explain how the appearance of membranes in electron micrographs was used as evidence to support the Davson-Danielli model.
Answer/Explanation
Ans:
a) i. pineal gland ;
ii. lower in night workers
OR
later increase/phase difference/shift in night workers;
iii. Time of day:
around 18:00 (locally);
OR
time that is in the range of local standard bed time;
Reason:
need to re-establish the increase that occurs after 18:00 hours / reestablish circadian rhythm /
OWTTE;
b) a. the black lines represent proteins;
b. forms a ‘sandwich’/2 layers;
c. there is a clear layer in the centre;
d. (the clear layer) is composed of phospholipids;