Complete a Punnett square that shows a test cross for a tall pea plant (RR x rr). Place the plant to be tested at the top of the Punnett Square.

we'll use () to indicate the different boxes

      ( )   (r)    (r)

     (R)  (Rr)  (Rr)

     (R)  (Rr)  (Rr)

You will have a 2 by 2 cell for your answer.  One set of your test (rr) will go across the top as is shown and the other will be vertical (RR) as shown.  Go down the line and put the letter you see at the top in each box and then do the same going across.

      ( )   (r)   (r)

      ( )   (r)   ( )

      ( )   (r)   ( )

      ( )   (r)   (r)

     (R)  (Rr) (R)

     (R)   (r)   ( )

I tried to make this a comprehensible as possible but just draw your diagram and put the letters in the exact order as shown and then read this.  It may make more sense that way.

Explanation:

d.

explanation: