Everything for the Genes and Heredity test: study cards, the traps to dodge, and a practice quiz at three levels — Foundation, On-Level, and Challenge. Work here, or print it and use a pencil — both count.
Each parent carries one of each: a B and a b. Each one passes down only one.
That is a Punnett square. It gives a probability, not a promise: one in four, every single time — no matter how the last one turned out.
Four things people get wrong
⚠️People often think…
Dominant means stronger, or more common.
Dominant only means it shows whenever it is present. Plenty of dominant traits are rare, and plenty of recessive ones are everywhere.
Dominant is about showing, not about winning.
⚠️People often think…
If you don't show a trait, you don't carry it.
Bb shows the dominant trait and carries the recessive one, quietly, ready to pass on. That is how two brown-eyed parents can have a blue-eyed child.
A recessive trait needs two copies to show. One copy just rides along.
⚠️People often think…
Things you do to your body get passed to your kids.
Acquired traits are not in your DNA. Muscles built at the gym, a scar, a learned skill — none of it is written into what gets passed on.
If it happened to the body, it does not travel.
⚠️People often think…
A 1-in-4 square means exactly one of four puppies.
A Punnett square gives probabilities, not promises. Four puppies can come out with none, or with all four — 1 in 4 is the chance for each one separately, like a coin.
Each offspring rolls its own dice.
Fill the boxes, then read them
1Watch one
Bb crossed with Bb. What fraction of offspring show the recessive trait?
Fill the four boxes: BB, Bb, Bb, bb.
A recessive trait shows only with two copies.
Only bb has two copies.
1 out of 4. The two Bb boxes carry it without showing it.
2Do one with me
Now cross Bb with bb. Fill in the four boxes and read them.
How many boxes come out Bb?
How many come out bb?
So the chance of showing the recessive trait is
💬One sentence, then you move on
Why does a recessive trait need two copies to show up?
3Try one
A weightlifter spends ten years building huge muscles. Will their baby be born with them? Write yes or no.
I want a hint first
Ask whether the change happened in the DNA, or only in the body.
💬Last one — then you're done here
Why is a Punnett square a probability and not a promise?
Where this goes
Where this lives
Eye color, a family history at a doctor's office, and why two brown-eyed parents can have a blue-eyed child without anything being strange about it.
What this feeds
Heredity feeds everything in life science that follows — health, farming, and the traits you see in every family.
One card at a time — tap “Show me” to check yourself, then Next. Start at Foundation; when those feel easy, climb.
Helpful Hints
🪆 The size order — smallest to biggest
DNA → gene → chromosome → nucleus → cell. A gene is a section of DNA; chromosomes are packages of DNA; humans carry 23 pairs.
DNA is the alphabet, genes are the words, chromosomes are the chapters.
🅱️ Geno vs. pheno — the two-letter trick
Genotype = the Genes (the letters, like Bb). Phenotype = the Physical (what you see, like brown eyes). Capital = dominant; lowercase = recessive.
Genotype = Genes. Phenotype = Physical.
⚠️ Traps the test loves
Dominant does NOT mean stronger or more common — it only shows whenever present.
A recessive trait needs TWO copies (bb). Bb shows dominant but CARRIES the recessive.
Acquired traits don’t pass on — gym muscles and scars aren’t in your DNA.
Punnett squares give PROBABILITIES, not promises.
Mutations aren’t all bad — most are neutral, a few even help.
🏗️ The DNA → protein pipeline
DNA holds instructions → ribosomes build PROTEINS → proteins build the trait. Change the DNA (mutation) → maybe change the protein → maybe change the trait.
DNA writes it, protein builds it, the trait wears it.
🎯 How the test will ask
At least one Punnett square to fill in — practice Bb × Bb (3:1) and Bb × bb (1:1) until automatic.
“Explain why siblings differ” = each parent gives a random half; different halves, different combos.
Mutation questions want the pipeline: DNA change → protein change → trait change.
✅ Before the test, can you…
Order DNA, gene, chromosome, nucleus by size?
Fill in a Bb × Bb Punnett square and give the ratio?
Tell genotype from phenotype in one sentence?
Trace a mutation from DNA to protein to trait?
Give one example of selective breeding and one of genetic engineering?
Term
Meaning in 10 words or less
Heredity
Traits passing from parents to offspring.
Gene
A section of DNA coding one instruction.
Chromosome
A packaged bundle of DNA; humans have 23 pairs.
Allele
One version of a gene (B or b).
Dominant
Allele that shows whenever present (capital letter).
Recessive
Allele that shows only with two copies.
Genotype
The allele letters an organism carries (Bb).
Phenotype
The trait you actually see (brown eyes).
Punnett square
Grid predicting offspring probabilities.
Protein
Molecule built from DNA’s instructions; does the work.
Mutation
A change in DNA’s instructions.
Variation
Differences in traits within a species.
Selective breeding
Humans choosing which organisms reproduce.
Genetic engineering
Directly changing an organism’s DNA.
Pick your level
Look back at anything you missed — the hint that appeared is exactly what to reread tonight.
How sure did you feel?
Workshop
Work like a geneticist: label a Punnett square, tell genotype from phenotype, run the protein pipeline in order, then explain why two children of the same parents are not the same.
Your practice never leaves this device. There is no account and no sign-in. Your work is saved in this browser only, and you can erase it whenever you want.
Your practice record — saved on this device
This is your record of the module on screen — it stays here and goes nowhere. Independent means you got it right on the first tap; supported means you got it after the explain-and-retry, or marked ‘I had it’ on a revealed answer. Both count, and neither is a grade. If your teacher asks, copy the row or show them this screen.
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Traps met
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Explained in own words
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The answer key is for a teacher: it prints only from here, for the unit on screen. Print the study packet prints the study pages and a blank quiz — never the answers.