- Species is an inherited characteristic
- Genes are able to determine the inherited characteristics of a living thing
- Therefore, genes are able to determine the species of a living thing

- A snake is a kind of animal
- A lizard is a kind of animal
- Different kinds of animal belong to different type of species
- Toad is a kind of animal
- Therefore, toad, snake, and lizard are different species

- Genes are able to determine the species of a living thing
- Toad, snake, and lizard are different species
- So, the genes of toad, snake, and lizard determine their species

So, the genes of toad, snake, and lizard determine their species
Which of these determines whether a fertilized egg develops into a toad, a snake, or a lizard?
- A snake is a kind of animal 
- A lizard is a kind of animal 
- Different kinds of animal belong to different type of species 
- Species is an inherited characteristic 
- Genes are able to determine the inherited characteristics of a living thing 
- Toad is a kind of animal