Biology 9700 · AS & A Level · Natural and artificial selection
Natural and artificial selection — practice question
The red poppy, Papaver rhoeas, along with several daisy species in the family Compositae, often occur together as weeds in wheat fields. Fig. 5.1 illustrates how the percentage frequency of red poppies and daisies changed in one area of wheat fields during the six year period from 1998 to 2003. From 1985, the herbicide metsulfuron-methyl was used to control weeds in this wheat-field area, and this continued throughout the six year period. In 1998, the first red poppy of 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 altered over the six year period.
(b(i))[3]
Suggest the effect of this mutation on the structure and activity of the acetolactate synthetase enzyme in biotype X red poppies.
(b(ii))[1]
Suggest the effect of this mutation on the biotype X red poppies when metsulfuron-methyl is present.
(b(iii))[3]
With reference to Fig. 5.1, predict and explain how biotype X red poppies would affect the relative proportions of weeds and wheat in the wheat-field area in 2003 compared with 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 change 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: “decline in daisies and normal poppies as time passed” …