Biology · GCSE · Reproduction & Genetics
Genetic crosses and Punnett squares
Genetic crosses and Punnett squaresFree2:45Heddy Score 3 of 7, below the standard
What you need to know
- A Punnett square shows the alleles each parent can pass on and the combinations their offspring can inherit.
- Each parent contributes one allele for the gene.
- Reading the grid gives the expected ratio of the offspring types.
- The second example is another single-gene cross, and the speaker leaves more complicated crosses for another video.
In this clip
Runs 2:45, from 0:00 to 2:45 of the full video.
Heddy ScoreSeven checks every clip must pass before students see it: trusted, on the map, accurate, focused, accessible, safe, and proven by students.3/7, Below the standard
See the seven stars
- Trusted source · passed. The creator's own upload, live and playable here.
- On the map · not judged yet. A teacher watched it: it mainly teaches this map topic.
- Spec-true · not judged yet. Accurate, and right for the current UK specification.
- Focused · passed. One idea, short enough to watch in one go.
- Accessible · passed. Good captions, clear sound and pictures.
- Safe for children · not judged yet. Right for 11 to 16 year olds, with no sales pitch.
- Proven · not judged yet. Earned from our students: they learn from it, find it helpful and watch it to the end.
Our students
Not enough students yet
Our own students' answers. These are what move ★7 Proven.On YouTube
How the Heddy Score works1.29M views · 12K likes · 2 Minute Classroom 178K subscribers
As reported by YouTube on 2026-11-01. Not part of the Heddy Score.Why we picked it
A short worked example of how to fill in a Punnett square and read the offspring ratio.
2 Minute Classroom on YouTubechecked 2026-10-18
Plays from youtube-nocookie.com. No YouTube cookies until you press play.