IB Biology SL 3.1.1 Variation as a Defining Feature of Life
Practise IB Biology SL 3.1.1 by identifying sources of variation and interpreting continuous traits and population data.
- Syllabus
- First assessment 2025
- Course
- Biology SL
- Level
- SL
Practise IB Biology SL 3.1.1 by identifying sources of variation and interpreting continuous traits and population data.
Psammonobiotus balticus belongs to a group of protists (unicellular eukaryotic organisms) that have a shell surrounding most of the cell, which provides shelter from predators. The graph shows the frequency of varying shell lengths in a population of P. balticus.

State, giving a reason, the type of variation shown by shell length.
a. (it shows) continuous variation;
b. as there are many intermediate lengths between the two extremes / normally distributed
OR
no distinct categories
OR
all shell lengths are possible (between the extremes);
b. bell shape curve is not sufficient.
2
Marking guidance:
max