Biology 9700 · AS & A Level · Classification

Classification — practice question

Exserohilum turcicum is a fungal pathogen. As its mycelium expands, it harms the leaves of maize plants, Zea mays. Damage to the leaves lowers crop yield.
(a(i))[2]

Complete Table 2.1 so that it shows one structural difference and one functional difference between E. turcicum and Z. mays.

(a(ii))[4]

Describe the principles used to classify organisms such as E. turcicum and Z. mays within the taxonomic hierarchy.

(b(i))[2]

Two inbred maize varieties, SKV50 and CML153, were crossed. The F1 hybrids produced were then self-crossed to give F2 offspring. The F2 plants were grown, and the percentage area of leaf damage caused by E. turcicum was recorded. Fig. 2.1 shows the findings for the F2 generation. The arrows indicate the mean percentage area of leaf damage for the two parent varieties. Explain how Fig. 2.1 can be used to decide which parent maize variety shows the greatest resistance to infection by E. turcicum.

(b(ii))[1]

State the name of the variation type shown by the maize F2 generation in Fig. 2.1.

(b(iii))[4]

Explain the genetic basis of the variation type shown by the maize F2 generation.

Worked solution & mark scheme

This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: A structural difference between E. turcicum and Z. mays

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI