IB Biology SL 4.1.2 Causes of Genetic Variation
Practise explaining how mutation, meiosis and sexual reproduction create variation that enables evolution and speciation.
- Syllabus
- First assessment 2025
- Course
- Biology SL
- Level
- SL
Exam points
- Explain how mutation and chromosome change generate heritable variation.
- Relate meiosis, random fertilisation and sexual reproduction to evolutionary potential.
D4.1.2—Roles of mutation and sexual reproduction question 1
[Maximum number: 8]
Explain how sexual reproduction can eventually lead to evolution in offspring.
offspring vary in traits;
variation results from sexual reproduction;
independent assortment of alleles (during meiosis of spermatogenesis/ oogenesis) contributes to variation;
meiosis is the cellular process that produces gametes;
crossing over (during meiosis) increases variation; fertilization (combination of different genomes) contributes to variation;
more offspring may be produced than the environment can hold; struggle for existence can occur; offspring whose traits best adapt them to environment will survive/survival of fittest;
change in environment will lead to survivors with new/different traits;
correct use of term natural selection/selective pressure;
variation is heritable / over time more offspring born with new trait;
change in gene pool; when entire population (of a species) exhibits new trait, evolution has occurred;
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