MediumBiologyHigh School (9–10)GeneralHeredity and Evolution › Heredity and InheritanceNumericalBoard Exam
A pure tall pea plant is crossed with a pure short one, and the F1 plants pollinate themselves…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A pure tall pea plant is crossed with a pure short one, and the F1 plants pollinate themselves. The F2 has plants. How many do you expect to be tall, and how many short? How many of the tall plants do you expect to be pure-breeding (TT)?
Need a reminder? The key ideaShow
Each trait is set by a pair of gene copies, one from each parent. The dominant copy (T, tall) hides the recessive one (t, short). Pure tall (TT) crossed with pure short (tt) gives an F1 all Tt and tall. Tt crossed with Tt gives 1 TT : 2 Tt : 1 tt, so 3 tall : 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. Short. plants.
Step 2. Tall. plants.
Step 3. Pure tall. TT is part in : plants. The other tall plants are Tt.
Answer: tall, short, and of the tall plants are TT.
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