| Date | May 2015 | Marks available | 1 | Reference code | 15M.3.HL.TZ2.1 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 2 |
| Command term | State | Question number | 1 | Adapted from | N/A |
Question
The evolution of increased body size in mammals has been accompanied by an increase in life span. Another variable that could affect life span is brain size. Data was analysed from 47 mammalian species.
State the relationship between brain mass and maximum life span.
Identify the group with the widest range of brain mass.
Compare the brain mass and life span of primates and marsupials.
Discuss how a larger brain size and longer life span might have contributed to the evolution of these species.
Markscheme
as brain mass increases life span increases / positive/direct relationship/correlation
other placental mammals
Do not accept answers stating only numerical values without comparative wording.
a. larger brain size allows for higher intelligence/better cognition/more complex brain functions;
b. more efficient food finding / escape from predators;
c. longer life span favours parental care / survival for more reproduction;
d. (these advantages) favour natural selection which leads to evolution;
Examiners report
The majority of candidates could state the relationship between brain mass and maximum life span and could identify the group with the widest range of brain mass.
The majority of candidates could state the relationship between brain mass and maximum life span and could identify the group with the widest range of brain mass.
Whereas some candidates could quickly establish all the key elements for the comparison, others provided incomplete complex answers.
Many discussed brain mass and life span in terms of human evolution instead of using the data about all species on the graph.
