Discuss two effects of the environment on physiological processes. (22)

Discuss (22) – A considered and balanced review, including a range of arguments, factors or hypothesis. Opinions and conclusions presented clearly supported by appropriate evidence.


*A little note on this, I would personally advise you to avoid this question at all costs if it comes up as a 22 mark. That is because the Waterhouse et al. study needed for explaining the effects of Jet Lag is ridiculously complicated and it comes to a stupidly simple and pointless conclusion.



Stress on Immune System

Work-related stress
Kiecolt-Galser et al – Stress in exam study (Work-related stress)
[A] Investigate the stress from examinations and its effect on the immune system.
[P]
  • Participants were 75 first year medical students (49 males, 26 females).
  • Blood samples were taken before and during their exams.
  • Immune functioning was assessed by measuring the T-cell activity in the blood sample.
  • Students were given survey for self assessment on psychiatric symptoms.
[F]
  • Samples taken before exam had more T-cells.
  • Students that claimed that they felt lonely in the survey had a more vulnerable immune system.
[C]
  • Stress decreases the functionality of our immune system.
[E]
  • Confounding variable: No control over other factors that might have affected the immune system e.g. Caffeine, drugs, diet, sleep etc.
  • Correlational study: cannot identify cause and effect relationship.
  • Did stress cause sickness? Or did sickness cause stress?
  • Only students were used in the sample.




Jet lag on Bodily Rhythm

Block and Davidson – Jet lag on mice
[A] To examine if there is a link between the daily cycle and the death of rats.
[P]
  • 39 male mice, 9 young, 30 old.
  • Mice were divided in three groups.
  • Normal cycle (Control)
  • West bound traveling (12 hours of light delayed for 6 hours once a week)
  • East bound traveling (12 hours of light advanced by 6 hours once a week)
  • Experiment lasted 8 weeks.
[F]
  • 17% of the control group died (natural cause).
  • 32% of west bound died.
  • 53% of east bound died.
  • Experiment was repeated
  • This time, experimenters delayed the light once every four days.
  • The mice died more easily, especially the “eastbound” mice.
  • Anxiety level remained the same throughout the entire experiment (measured a stress hormone).
[C]
  • The rats did not die of stress, died because of the constant changes in body rhythm.
[E]
  • Link to principle - Animal research can provide insight into human behaviour.
  • Method was scientific
  • Measured the level of stress hormone to determine the cause of death.
  • Despite that, it just disproved one cause of death, there can be other causes although unlikely.
  • Assumption made on concluding, that death is cause by changes in body rhythm.



Waterhouse et al. – Jet lag study
[A] Identify some determinants of jet lag and its symptoms.
[P]
  • 85 subjects were used, 54 male, 31 female.
  • Athletes, coaches, academics from UK attending a conference in Australia.
  • A widespread of
  • Age
  • Sleep habits
  • Fitness
  • Time arrival in Australia
  • Previous travels to Australia
  • 24 hours flight – UK -> Singapore (one hour stopover) -> Australia.
  • Participants were studied during the flight and for the first 6 days in Australia.


  • During Flight
  • Group 1 (1/3 of the subjects)
  • Left UK at local evening time, arrived Australia at 06:00.
  • 32 subjects recorded the amount of time they spent asleep on both flights.
  • Group 2 (2/3 of the subjects)
  • Left UK in the morning, arrived Australia in the late afternoon.
  • 25 subjects recorded the amount of time they spent asleep on both flights.
  • Fitness was determined from a questionnaire, and took into account the age of the subject.
  • Subjects were awarded a score between 1 to 5 (5 being fittest).
  • Chronotype was determined by questionnaire.
  • 7 were morning type, 1 was evening type, the rest were intermediate.


  • In Australia
  • Subjects were asked to fill in a questionnaire about jet lag, using a visual analogue scale.
  • The amount of jet lag
  • The amount of fatigue
  • Time they got to sleep
  • Ease of sleeping and staying asleep
  • Time they woke up
  • Alertness 30 minutes after waking
  • Subjects were shown the questionnaire before the journey, so they know what to be aware of.
[F]
  • Results made in Australia showed that symptoms of jet lag decreased over time.
  • Men showed a slight tendency to sleep later and record less fatigue.
  • May be due to a masculine stereotype (self fulfilling prophecy).
  • Old subjects showed less jet lag and fatigue.
  • Contradicts with Block & Davidson’s Study.
[C]
  • Conclude that different factors can affect jet lag.
[E]
  • Methodology was not scientific enough, only measured based on self evaluation surveys.
  • Possible confounding variable: Male participants showed less fatigue because of masculine stereotypes.
  • Analogue visual scale was used which meant the scale did not categorize the response.



LO conclusion


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