Question 2 113 marks 13 minutes Suppose that in carrot plants, the I gene contro

Question

Question 2 113 marks 13 minutes Suppose that in carrot plants, the I gene controls root length while the c gene controls root colour. Each gene has two alleles. The allele gives long roots while / homozygotes have short roots. is dominant to l. Homozygosity for the c allele gives dark-orange carrots while homozygosity for the c allele gives white carrots c and c are incompletely dominant. A pure-breeding strain of long, dark-orange carrots is crossed with pure-breeding short, white carrots. a) Predict the phenotype(s) present in the Fi generation. Explain. 4 marks] Two individuals from the Fi generation are crossed to produce the F2 generation. Draw a Punnett Square to show the genotypes and predict the phenotypic ratio seen in the F2 generation. Make sure your clearly indicate which the genotypes give which predicted phenotypes. (9 marks] b)

Explanation / Answer

Answer:

Dark-orange = c+_

White = cc

Long= I+ _

Short = II

Long, Dark-orange (I+I+; c+c+) x Short, white (II;cc) ---P1

                                     Long, Dark-orange (I+I; c+c)---F1

F1 X F1

I+;c+

I+;c

I;c+

I;c

I+;c+

I+I+; c+c+ - (Long, Dark-orange)

I+I+; c+c - (Long, Dark-orange)

I+I; c+c+ - (Long, Dark-orange)

I+I; c+c - (Long, Dark-orange)

I+;c

I+I+; c+c - (Long, Dark-orange)

I+I+; cc - (Long, white)

I+I; c+c - (Long, Dark-orange)

I+I; cc - (Long, white)

I;c+

I+I; c+c+ - (Long, Dark-orange)

I+I; c+c - (Long, Dark-orange)

II; c+c+ - (Short, Dark-orange)

II; c+c - (Short, Dark-orange)

I;c

I+I; c+c - (Long, Dark-orange)

I+I; cc - (Long, white)

II; c+c - (Short, Dark-orange)

II; cc - (Short, White)

Long, Dark-orange = 9/16

Long, white = 3/16

Short, dark-orange = 3/16

Short. White = 1/16

I+;c+

I+;c

I;c+

I;c

I+;c+

I+I+; c+c+ - (Long, Dark-orange)

I+I+; c+c - (Long, Dark-orange)

I+I; c+c+ - (Long, Dark-orange)

I+I; c+c - (Long, Dark-orange)

I+;c

I+I+; c+c - (Long, Dark-orange)

I+I+; cc - (Long, white)

I+I; c+c - (Long, Dark-orange)

I+I; cc - (Long, white)

I;c+

I+I; c+c+ - (Long, Dark-orange)

I+I; c+c - (Long, Dark-orange)

II; c+c+ - (Short, Dark-orange)

II; c+c - (Short, Dark-orange)

I;c

I+I; c+c - (Long, Dark-orange)

I+I; cc - (Long, white)

II; c+c - (Short, Dark-orange)

II; cc - (Short, White)

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