Suggest two explanations for why the tarplant has become endangered.
State three reasons why species conservation is important.
Tarplant seeds may remain in the soil for several years. Dormant seeds can be induced to germinate by scraping the soil, which exposes them to light. This triggers gibberellin production in these seeds, causing germination. Explain how gibberellin brings about germination in seeds.
Long-term survival of tarplant seeds in the soil gives a reserve of seeds that may help secure the future survival of the tarplant. Very little is known about how tarplant seeds survive in the soil, or what proportion of these seeds can germinate. Researchers therefore used computer models to predict how these factors might influence the chance that the tarplant could become extinct. Their models used: • high or low survival values of tarplant seeds in the soil • different germination percentages of tarplant seeds. The model predictions are shown in Fig. 4.1.
With reference to Fig. 4.1, describe the effect of each of the following on the risk of extinction of the tarplant: - high compared with low survival of the tarplant seeds - different germination percentages of the tarplant seeds.
With reference to Fig. 4.1, discuss whether scraping the soil ought to be advised as part of the management strategy to try to conserve the tarplant.