Biology 9700 · AS & A Level · Natural and artificial selection
Natural and artificial selection — practice question
The red poppy, Papaver rhoeas, together with several daisy species in the family Compositae, frequently occur side by side as weeds in wheat fields. Fig. 5.1 illustrates how the percentage frequencies of red poppies and daisies changed in one area of wheat fields during a six year interval from 1998 to 2003. From 1985, metsulfuron-methyl was applied as a herbicide to control weeds in this wheat-field area. This continued for the whole six year period. In 1998, the first red poppy biotype X appeared. This red poppy possessed a particular mutation that was absent from ordinary red poppies.
(a)[4]
Describe how the percentage frequencies of daisies and red poppies changed over the six year period.
(b(i))[3]
Suggest the effect of this mutation on the structure and activity of the acetolactate synthetase enzyme of biotype X red poppies.
(b(ii))[1]
Suggest the effect of this mutation on the biotype X red poppies in the presence of metsulfuron-methyl.
(b(iii))[3]
With reference to Fig. 5.1, predict and explain the effect of biotype X red poppies on the relative proportions of weeds and wheat in the area of wheat fields in 2003 compared to 1998.
(c)[3]
Suggest how stopping the use of the herbicide metsulfuron-methyl and replacing it with a herbicide that inhibits a different target enzyme in weeds would affect the abundance of red poppies of biotype X.
Worked solution & mark scheme
This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: “gradual decrease in daisies and normal poppies” …