Plant & Animal revision Q3

Wheat is an important cereal crop. Ryegrass is a weed in wheat fields. Wheat and ryegrass both belong to the grass family. Australian scientists investigated one aspect of competition between wheat and ryegrass. -Wheat plants were crushed up and mixed with distilled water. -Water-soluble substances in the crushed plants dissolved in the water to make the full-strength extract. -A series of dilutions of the full-strength extract were made. -Ryegrass seeds were put into each dilution and the percentage that germinated (started growing) was recorded. - If the seeds germinated, the seedling root length was also measured after 7 days. - The results were presented as percentages of a control experiment.

The graph shows the effects of different concentrations of wheat extract on the germination of ryegrass seeds and on the length of the roots of the seedlings that grew from them. Discuss the outcome of this experiment and what it suggests about wheat and its response to its environment. In your answer you should refer to the graph and: describe the interaction between wheat and ryegrass and its importance to wheat farmers compare the ryegrass seedling root length and germination, with the concentration of wheat extract fully explain the response between wheat and ryegrass that the results of this experiment suggest analyse the results to suggest how this response could provide an adaptive advantage to growing wheat plants.

There are seven species of spider monkeys (genus Ateles). All are large monkeys and inhabit the tropical forests of Central and South America from Mexico to Brazil. Geoffroy’s spider monkey, Ateles geoffroyi, is one of the largest monkeys and individuals can reach 60cm in height and weigh up to 9kg. They all have long, thin, curved feet and hands (the hands have no obvious thumb); the tail is long and prehensile. The monkeys are diurnal and inhabit the forest canopy feeding mainly on fruit, but may eat flowers, seeds, and nuts, leaves, and insects. They are social animals living in groups of about animals which have a complex social structure. Each group occupies a territory which the males mark using scent glands. Home ranges typically cover a large area which can be up to 900ha.The large groups frequently split up into smaller sub groups (of between 2 to 8 animals) during the day when foraging but come together again at night; most foraging occurs from dawn to mid morning. Females leave their birth group at puberty and join another group.

Discuss how the behavioural responses of the Geoffrey’s spider monkey provide it with an adaptive advantage in its ecological niche. In your answer you should : - explain the role of the territory and the home range - explain why females leave the group at puberty - explain how the foraging behaviour increases the survival of the monkeys

Carnations (Dianthus caryophyllus) are very popular as cut flowers and have been cultivated for this purpose for many years. Wild carnations are long day plants with insect pollinated flowers, mainly by butterflies. Discuss the factors that promote successful flowering and reproduction in wild carnations. In your answer you should : - describe the relationship between carnations and butterflies - explain how abiotic environmental factors induce (‘trigger’) and influence flowering in carnations - discuss the adaptive advantages of being a long day plant