Ratios, ratios, ratios

In classical genetics, phenotype and even genotype ratios are a mainstay for determining inheritance.  You can memorize the ratios, but it's important you understand what they're based on.

In this exercise, assume we're dealing with simple dominant/recessive relationships for two traits in a bean plant.  The bean can have yellow or orange pods and can be inflated or constricted.  Constricted or orange pods are novel (new) traits.  You cross a true-breeding orange, constricted bean line with one that is true-breeding for yellow, inflated pods.  The F₁ seeds are planted and all grow up to bear fruit which are yellow and inflated.  The F₁ are allowed to self-fertilize.
You have several tasks:

1. Design appropriate gene symbols.
2. Use a branch diagram to show the expected phenotypic distribution of the F₂ progeny.
3. Of the F₂ progeny, those with orange pods are selected and allowed to self.  What is the expected phenotypic distribution among these select F₃ progeny?
4. Demonstrate the expected ratios of progeny from a test cross for the original F₁ plants using a Punnett square.

Here's a full solution, but if you want to just see the solution for part 3 (as my students wanted) you can see a shorter version in the second YouTube video.

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Here's just the answer to 3: