CHAPTER 6 REVIEW QUESTIONS 6.1 a. b. Abiotic: non-living components of the environment. Biotic: living components of the environment. Habitat: place where an organisms is found. Environment: all of the biotic and non-biotic components of a habitat. 6.2 Energy: radiant energy; temperature; water, wind and air currents; wave action. Physical: water retention; water, wind and air currents; wave action; topography; background; shelter. Chemical: water; humidity; pH; mineral salts and trace elements; salinity. 6.3 Biotic: nutrients (including mineral salts) which involves plant and animal matter; clothing (derived from organic origin). Abiotic: water; particular temperature range; sunlight; shelter; clothing (synthetic); oxygen. 6.4 a. b. c. d. e. f. 6.5 6.6 Open habitat of inland Australia with a rainfall of less than 375 mm. Rainfall, temperature, humidity. Open habitat, grass, mate, other kangaroos (loose social interaction). Dingos, wedge tailed kangaroos, snakes, humans. During drought, pouch young die and then the female stops reproducing until the rain falls again. Heat is lost by panting and evaporative water loss from the lungs and from licking the forelimbs; production of a very concentrated urine; nocturnal behaviour. i. In good seasons they reach sexual maturity early and a female can have three young (joey at heel, joey in the pouch and a dormant embryo) simultaneously; able to withstand high air temperatures for several hours (cooling by panting and licking forearms); production of concentrated urine; active at dawn and dusk; energy storage in hamstring tendons of hind limbs makes locomotion efficient. ii. Availability of food and water. Stick insects look like a part of the plant on which they live – biotic. Geckos can change their colour so that they blend in with the background (e.g. lichen covered rocks) – abiotic. east facing slope milder morning sun subject to cooling afternoon sea breezes cooler temperature higher rainfall protected from winter westerly winds west facing slope hotter afternoon sun in the lee of afternoon sea breezes hotter temperature lower rainfall subject to westerly winds in winter Thus the vegetation on the eastern slope will tend to be greener, straight trunks, and adapted to milder conditions with a reasonable rainfall, whereas those on the western slope will be adapted to drier, hotter conditions: smaller, duller leaves; trees likely to show some bending or damage due to the westerly winds; less ferns, mosses and moisture loving plants, etc. 6.7 Climatic changes from a temperate, humid climate to a drier, colder climate; fires and very stable soils (no recent volcanic activity), resulting in low nutrient content. 6.8 A xerophyte is a plant adapted (e.g. hard, narrow leaves) to low ground water levels whereas a mesophyte is a plant adapted (e.g. large, soft leaves) to plentiful ground water levels. 6.9 a. b. c. A sclerophyte is a plant with rigid, often small leaves. They are adapted to soils of low fertility and also allow the plant to survive water stress and fire. Australian soils are termed ‘ancient’ in that there has been no recent volcanic activity to replenish soil mineral nutrients. The climate is such that much of the continent is subject to hot dry summers and so ground water levels are low and the possibility of fire is high. 6.10 a. b. Amount of lichen on the bark of trees, predators. Amount of pollution in the air which affects the lichen growth. 6.11 As a control to ensure that the birds were selecting a specific colour of the moth in each environment. 6.12 ‘Wallum’ refers to both a type of plant – the wallum oak Banksia aemula, and associated vegetation – and to the area in which this type of vegetation is found – sandy areas close to the sea in Queensland. 6.13 a. b. c. Low nutrient soils: association with nitrogen fixing bacteria in root nodules (e.g. wattles); mycorrhizae; extensive shallow root systems; lignotubers; insectivores. Water stress: large root system; sclerophylly; angling leaves towards the trunk; sunken stomata; hairs on undersurfaces of leaves. Fires: production of oils and tannins to encourage rapid burning; paper bark containing large amounts of water; dormant buds or lignotubers; underground rhizomes, tubers or bulbs to allow regrowth; thick bark. 6.14 Changes in temperature and rainfall can affect the growth of vegetation. This either directly or indirectly affects the animals in that area. When conditions are adverse, many plants become deciduous, or above ground parts die off. The animals may then either migrate out of the area or go into a state of torpor. 6.15 Organisms bring about changes in their environment by providing food or habitats for others, eliminating wastes, removing water, adding organic matter, absorbing light, taking in food from others, using others for habitats, altering carbon dioxide levels, removing minerals, providing shade, or altering oxygen levels. 6.16 a. b. c. d. e. Pioneer species: the first plants to colonise bare ground. Climax community: a community which remains stable over a very long period of time. Disclimax community: the result of vegetation changes due to degradation activities by organisms. Primary succession: stages in community change from bare ground to a climax community. Secondary succession: stages in community change which occur when the dominant species of a climax community is removed.