Back to the full dot-point answer
NSWBiologyQuick questions
Module 5: Heredity
Quick questions on Punnett squares and Mendelian inheritance: HSC Biology Module 5
10short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is setting up a Punnett square?Show answer
A Punnett square predicts the possible genotypes and phenotypes of offspring from a given parental cross.
What is standard monohybrid cross?Show answer
This is the canonical 3:1 ratio Mendel observed.
What is dihybrid cross?Show answer
When tracking two independent genes, set up a 4 × 4 Punnett square with the four possible gametes from each parent (AB, Ab, aB, ab).
What is probability rules?Show answer
When tracking multiple events:
What is step 1?Show answer
Identify the parental genotypes. Step 2. Write the possible gametes from each parent across the top and down the side. Step 3. Fill in each cell with the combined genotype.
What is wrong gametes?Show answer
Each parent contributes only ONE allele per gene to each gamete. A heterozygous parent (Aa) produces TWO types of gametes (A and a), not four (AA, Aa, Aa, aa).
What is failing to simplify ratios?Show answer
2:2 is the same as 1:1. 4:2 is the same as 2:1. Markers reward simplified ratios.
What is confusing genotype and phenotype?Show answer
Genotype = letters (AA, Aa, aa). Phenotype = trait (purple, white).
What is independent probability for separate children?Show answer
Each child is an independent event. The "probability the next child is affected" does not depend on the previous children. 1/4 each time.
What is capitalisation matters?Show answer
A means dominant, a means recessive. Be consistent. Markers often use unfamiliar letters (e.g.