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Sana has a tall pea plant and does not know if it is TT or Tt.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Sana has a tall pea plant and does not know if it is TT or Tt. She crosses it with a short tt plant. Her program fills the square for Tt with tt. How many of the four boxes are tall, and how many are short?
Need a reminder? The key ideaShow
A gamete is one letter of a parent: list("Tt") gives ['T', 't']. A child is "".join(sorted(a + b)), so the dominant capital letter comes first. Two loops over the parents' letters fill the Punnett square, and Counter counts the genotypes or the phenotypes. Tt with Tt gives 1 TT : 2 Tt : 1 tt, which is 3 tall to 1 short.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The gametes. Tt gives T and t. The tt parent gives t and t.
Step 2. The boxes. T with t gives Tt twice. t with t gives tt twice.
Step 3. Count. tall boxes (Tt) and short boxes (tt).
Step 4. What it tells Sana. A TT plant would give only Tt, all tall. If any short plants appear, her plant must be Tt.
Answer: tall and short, a 1:1 ratio.
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