Genetics asks you to connect three ideas: what the inherited material is, how it passes from parents to offspring and why offspring differ. This page shows how the lessons connect and where to begin.
The cluster sits inside SPM Science. If your school teaches it in a different order, follow your school and use the lessons below as checkpoints.
What are the four skills in this cluster?
Each lesson builds on the one before it, so the order below is the order to study.
- Distinguishing genes, chromosomes and DNA: three words, three sizes.
- Completing basic inheritance diagrams: parents, gametes, offspring and ratios.
- Explaining variation with examples: why siblings differ.
- Interpreting genetic information without deterministic claims: what a pattern can and cannot tell you.
Then test the whole cluster with the genetics practice set.
How does one trait travel through the lessons?
Here is a worked example. A plant has a gene for flower colour, with one version for purple and one for white. The gene is a section of DNA, and the DNA is packed into a chromosome inside the nucleus.
The plant passes one version of the gene to each gamete. A cross diagram then shows which combinations can form in the next generation. Variation appears because different gametes meet, and a careful statement says what ratio is expected, not that one particular offspring must be purple.
That one trait touches every lesson, which is why the order helps.
Who should start where?
If the words feel slippery, begin at lesson one and do not move on until you can explain each term without notes. If you know the words but diagrams go wrong, start with lesson two and use the simple inheritance cross explorer on your own traits.
If your difficulty is wording answers, go to lesson four. The Science glossary lists the terms with short examples.
If you want a teacher to work through the cluster with you, see online one-to-one Science tuition.