Genetics
Dihybrid Cross: How to Get the 9:3:3:1 Ratio (4×4 Punnett Square)
A dihybrid cross gives a 9:3:3:1 phenotype ratio. Learn how to find the four gametes, fill the 16-box grid, and use the product rule, with worked pea examples.
16 min read
Genetics blog
Genetics guides, Punnett square tutorials, and calculator help
Practical articles for students, teachers, and biology learners who want clear explanations of inheritance, probability, genotypes, phenotypes, and genetic calculator results.
GeneticsFeatured article
Codominance Examples: Blood Type, Roan & Sickle Cell
The clearest codominance examples explained: ABO blood type, roan coat color, and sickle cell trait, with worked Punnett squares and genotype tables.
15 min read
Latest articles
Genetics
Dog Coat Color Calculator: Predict Puppy Colors
Learn how dog coat color genetics works and predict puppy colors with a Punnett square. Covers the B and E loci, black, chocolate, and yellow Labradors, and epistasis.
16 min read
Genetics
Dihybrid Cross: Forked-Line Method vs Punnett Square
Compare the forked-line method, the 16-box Punnett square, and the probability method for dihybrid crosses. Learn which is fastest and when to use each one.
16 min read
Genetics
Genotype vs Phenotype: What's the Difference?
Genotype is an organism's genetic code; phenotype is its observable traits. Learn how they differ, how genes shape traits, and why the same genotype can vary.
14 min read
Genetics
Homozygous vs Heterozygous: How to Tell Them Apart
Homozygous means two identical alleles; heterozygous means two different alleles. Learn how to tell them apart, why looks can deceive, and what carriers are.
17 min read
Genetics
How to Do a Punnett Square: A Step-by-Step Guide
Learn how to do a Punnett square step by step. Find parent genotypes, work out gametes, fill the grid, and read the ratios, with clear worked examples.
6 min read
Genetics
Incomplete Dominance vs Codominance Explained
Incomplete dominance blends two alleles into one trait; codominance shows both at once. Learn the difference, with snapdragon, blood type, and roan examples.
16 min read
Genetics
Monohybrid Cross: How to Get the 3:1 and 1:2:1 Ratios
A monohybrid cross gives a 3:1 phenotype and 1:2:1 genotype ratio. Learn where these ratios come from and how to work them out, with Mendel's pea examples.
13 min read
Genetics
Multiple Alleles Explained: Examples and Genetics
Multiple alleles means a gene has three or more versions in a population. Learn how dominance hierarchies work, with ABO blood type, rabbit coat, and fly eye examples.
16 min read
Genetics
Sex-Linked Traits: How to Do X-Linked Punnett Squares
Learn how sex-linked inheritance works and how to build X-linked Punnett squares for colorblindness and hemophilia, including carrier mothers and why males are affected more.
16 min read
Genetics
What Is a Punnett Square? Definition, Diagram, and How to Read One
A Punnett square is a grid that predicts offspring genotypes and phenotypes from a genetic cross. Learn its parts, history, and how to read one, with examples.
7 min read