Mendelian genetics quiz: Punnett squares, dihybrid crosses, blood groups.
Test in ItalianThe questions of this simulator are in Italian, as in the real exam.
15 questions in 30 minutes, no penalty for wrong answers: monohybrid and dihybrid crosses, Punnett squares, incomplete dominance, blood groups, sex-linked inheritance and compound probabilities. The correct answer to every question and your weak topics arrive by email for free; with an account you see them straight away here, together with the score, which is already on the page for everyone. The guided step-by-step solution unlocks with your first lesson.
A free high-school biology quiz on Mendelian genetics, the kind of problems set in the first two years of high school and in Year 3.
| Topic | What it covers |
|---|---|
| Terminology | genotype, phenotype, alleles, homozygous and heterozygous, test cross |
| Monohybrid crosses | Mendel’s first law, 3:1 and 1:2:1 ratios, conditional probability |
| Dihybrid crosses | Mendel’s second law, gametes, 9:3:3:1 ratio |
| Incomplete dominance and codominance | 1:2:1 phenotype ratios, ABO blood groups |
| Sex-linked inheritance | colour blindness, haemophilia, males are hemizygous |
| Probability and pedigrees | product rule, sequences of children, family trees, meiosis |
15 questions drawn at random from a bank of 48 · 30 minutes · no penalty (blank = wrong = 0 points) · options shuffled on every attempt. Original questions, recalculated one by one.
Two worked examples from the test
Un individuo ha genotipo per un certo gene. Come si definisce rispetto a quel gene?
Solution
Il genotipo descrive i due alleli presenti in un individuo diploide per un gene.
- Due alleli uguali ( o ): l'individuo è omozigote (dominante o recessivo).
- Due alleli diversi (): l'individuo è eterozigote.
L'emizigote è invece l'individuo che ha un solo allele per quel gene, come i maschi umani per i geni sul cromosoma X.
Una pianta di pisello a fiori viola (carattere dominante) può essere oppure . La si incrocia con una pianta a fiori bianchi () e metà dei figli ha fiori bianchi. Qual è il genotipo della pianta viola?
Solution
Questo incrocio con un omozigote recessivo si chiama testcross (o reincrocio).
- Se la pianta fosse , produrrebbe solo gameti e tutti i figli sarebbero , cioè viola.
- Se fosse , produrrebbe gameti e in parti uguali: metà dei figli (viola) e metà (bianchi).
La comparsa di figli bianchi dimostra che la pianta viola portava un allele , quindi era eterozigote. Con un solo figlio bianco la conclusione è già certa.
In the online practice test you will find 13 more questions like these; the correct answer to every question arrives by email.
Where you lose marks in a genetics test.
Genetics problems in the first two years of high school and in Year 3 all look different and are almost all the same: write the parents’ gametes, cross them in a Punnett square and read off a probability. Marks are almost always lost at one of three moments: when writing the gametes (an AaBb individual forms four types, not two), when translating genotypes into phenotypes (with incomplete dominance the ratios change) and when going from the probability of one child to that of several children.
The most common trap is conditional probability: if the parents are Aa × Aa and you know the child has the dominant phenotype, the probability that it is heterozygous is two thirds, not one half, because the information has ruled out the genotype aa. With sex-linked inheritance there is also the difference between "a child" and "a male child": the probability of a colour-blind child from a carrier mother and a healthy father is one quarter, but among the boys alone it is one half.
The simulator recalculates every probability with exact fractions, and the explanations show the Punnett square or the product of the probabilities, so you see not only the result but the route to it. After the test the breakdown by topic tells you whether the problem is terminology, calculating probabilities or reading phenotypes.
Frequently asked questions.
Do I need to know Mendel’s laws by heart?
You need the concepts, not the wording: the quiz mostly checks that you can use them (write the gametes, build the Punnett square, multiply probabilities), because that is what class tests ask.
What is the difference between incomplete dominance and codominance?
In incomplete dominance the heterozygote has an intermediate phenotype (a pink flower from red and white), in codominance both traits show (blood group AB). The quiz has a question for each case.
Are there questions on gene linkage or crossing-over?
Only at a conceptual level: one question asks when independent assortment holds. Calculations with distances between genes and genetic maps are not included.
Can I retake the quiz?
Yes. On every attempt 15 different questions are drawn from a larger bank and the options change order.
What do I see at the end of the practice test?
The correct answer to every question and your weak topics arrive by email for free; with an account you see them straight away here, together with the score, which is already on the page for everyone. The guided step-by-step solution unlocks with your first lesson.
Is genetics not adding up for you?
The quiz tells you whether terminology or probability calculation is what blocks you. In lessons we work on your weak points with graded exercises and timed tests.