Using the symbols in the key, fill in Fig. 3.1 by adding the chromosome sets of $T.\ aestivum$.
At the points marked Y and Z in the hybridisation process, a fertile hybrid was formed from a sterile hybrid. Explain why the hybrid $(AB)$ is sterile and what happened at the point marked Y in Fig. 3.1.
Discuss how far these experiments support the view that E$\beta$F acts as an alarm signal for aphids.
Other experiments indicate that E$\beta$F attracts predators of aphids, such as ladybirds. Explain how growing genetically modified wheat that secretes E$\beta$F could increase wheat yield.
Suggest why growing this genetically modified wheat might be acceptable to people who object to the growing of genetically modified insect-resistant maize or cotton.