IB Biology Review

1. IB Biology Review Chapter 53: Community Ecology

2. Definitions Community� consists of all the organisms of all the species that inhabit a particular area it is an assemblage of populations of many different species Community Ecology� deals with the whole array of interacting species in a  community This area of research focuses on how  interactions such as predation, competition, and  disease, as well as abiotic factors such as disturbance,  affect community structure and organization

3. Habitat Realized Niche Detritivore Autotroph Biodiversity  Symbiosis Ecological Niche Saprotroph Interspecific Competition Heterotroph Competitive Exclusion Biomass Fundamental Niche 1.________________ is a particular environment, the typical location of a particular species. It is the organism�s �address� 2.________________ is the totality of an organism�s relationships with all the biotic and abiotic factors which make up the organism�s habitat 3._______________ is when two species compete or interact for a resource 4.______________ is the strong competition that can lead to the local elimination of one of the two competing species; the result is detrimental to both species (-/-) such as when two different species compete for a resource that is in short supply 5.______________ is a special type of interaction, where one organism lives on or in another and does not harm the host 6.______________ is the total mass of all individuals in a population 7. ______________ is the number of different species in a given geographical area 8.________________ is the niche potentially occupied by that species 9.________________ is the niche a species actually occupies in a particular environment 10._____________ is an organism that synthesizes its organic molecules from simple inorganic molecules 11._____________ is an organism that obtains organic molecules from other organisms 12._____________ is an organism that ingests non-living organic matter 13._____________ is an organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion

4. MC-1.

5. Define the term �niche.� Within a specific habitat of an organism it is the species role/profession An organism�s unique ability to survive in its habitat For example, nutrition/what it eats feeding habits (like the Nuthatch �hammering� the seeds) interactions with other species (aggression/competition) the time of day or night that it feeds breeding site

6. Describe fundamental niches and realized niches. Fundamental Niche� All the habitat the organism could live in if there were no competing species Realized Niche� The habitat that the organism actually inhabits due to competition for similar space from other species

7. MC-2. Prairie dogs once covered the expanses of the Great Plains. Their grazing made the grass more nutritious for the huge herds of bison, and a variety of snakes, raptors, and mammals preyed on the rodents. In fact, the black-footed ferret (now endangered) specialized in prairie dog predation. Today, growing neighborhoods have covered many prairie dog towns. Which of thefollowing statements about prairie dogs is not true? A. Their realized niche has diminished. B. They are commensals with the bison. C. They are reasonably considered a keystone species. D. Their fundamental niche remains unaltered. E. Their fundamental niche has diminished. Correct answer: E

8. Competitive Exclusion Principle No two species can coexist in the same niche One is out-competed and displaced/eliminated through strong competition Reduces competing species� space from the fundamental niche to the realized niche Use in an answer barnacle competition from Figure 53.2 in text

10. CC 53.1 According to the competitive exclusion principle, what outcome is expected when two species compete for a resource? Why? One of the competing species will become locally extinct because of the greater reproductive success of the more efficient competitor.

11. Definitions Intra-specific competition� interactions between individuals of a population of just one species Inter-specific competition� interactions between populations of two species

12. Types of Inter-specific Interactions 0 = No effect + = Positive effect - = Negative effect

13. MC-3. Evidence shows that some grasses benefit from being grazed. Which of the following terms would best describe this plant-herbivore interaction? A. mutualism B. commensalism C. parasitism D. competition E. predation Correct answer: A

14. MC-4. Which of the following is least likely to kill the organism it feeds on? A. herbivore B. predator C. seed eater D. carnivore E. parasite Correct answer: E

15. Definitions Trophic structure� The feeding relationships between species of a community Trophic levels� The different groups of organisms in a community Arranged as: Producers 1st Order Consumers 2nd Order Consumers 3rd Order Consumers 4th Order Consumers

16. What are the trophic levels?

17. Why does the energy pyramid look like it does? Energy transfer between trophic levels is never 100% efficient. Only 10-20% of energy is transferred How is the other ~90% of energy lost? Heat loss through cellular respiration Not all organisms in lower trophic levels are consumed The whole mass of the prey is not assimilated into the predator�s body Energy lost through the metabolic processes of the prey before they are consumed

18. MC-5. Consider a field plot containing 300 kg of plant material. Approximately how many kg of second-order consumer can be supported? A. 300 B. 100 C. 30 D. 3 E. 0.3 Correct answer: D 300 x 0.10 = 30 x 0.10 = 3

19. Definitions Food chain� a single pathway of feeding relationships among organisms in an ecosystem that results in energy transfer Food web� complex feeding relationships among all the organisms in an ecosystem that results in energy transfer

20. Be able to construct/draw an Antarctic food web with the following species or groups:Fishes, Copepods, phytoplankton, leopard seals, elephant seals, baleen whales, sperm whales, birds, krill, carnivorous plankton, crab eater seals, smaller toothed whales, humans, squids.Make sure arrows are going in the right direction.Be able to identify one or more food chains within this food web of at least 4 species long.

21. What is the benefit of a more complex food web? = biodiversity More stability because predators have a variety of choices for prey So if one prey species dies out, the predator can feed on other species

22. MC-6. In a food web with deer, clover, rabbits, and wolves, wolves would be the A. producers B. primary consumers C. secondary consumers D. tertiary consumers Correct answer: C

23. MC-7. Which of the following conditions would result from a more complex food web? A. lower rates of mortality B. stability C. high reproductive rates D. lower natality rates Correct answer: B

24. Ecological Succession Primary succession the creation of soil in a virtually lifeless area where there was no soil before Examples: after a volcanic eruption, or after a retreating glacier Secondary succession occurs when an existing community has been cleared by some disturbance that leaves the soil intact Examples: after a fire, flood, hurricane, or tornado

25. How does primary succession occur?

26. CC 53.3 How do primary and secondary succession differ? The initial absence of soil in primary succession and its presence at the beginning of secondary succession.

27. 1. Explain the niche concept using a named organism. (5 marks) Within a specific habitat it is the species� role/profession It allows different species to co-exist with each other by reducing competition For example, the white-breasted nuthatch shares temperate forest habitat with many species Nuthatches go down a tree in search of insects hiding under bark unlike most species which go up the tree looking for insects. In this way, it is able to get insects that others miss. Another aspect of its unique niche is that takes seeds, wedges them into a crevice of tree bark and then �hammers� the bark � this opens the seeds for eating. Yet another aspect of this birds niche is that it flocks together with black-capped chickadees and titmice. In this way, it is protected frompredators by being able to hear the warning calls of these species when predators approach

28. 2. Explain the significance of the principle of competitive exclusion. (3 marks) no two species can coexist in same niche; one is displaced / one survives; one species has an advantage over competitor / species compete with each other;

29. 3. Explain how parasitism differs from mutualism with reference to named organisms. (5 marks) Parasitism is a type of interspecific interaction where one organism benefits and one suffers; whereas Mutualism is when both benefit (neither suffer); An example of parasitism is a tapeworm in its human host The parasite gains food and energy whereas the human host loses food; Because of this, the host suffers weight loss and impaired nutrition; In a mutualistic interaction such as green algae and fungi in lichens; The algae gains protection; Whereas the fungi gains carbon compounds through the algae�s photosynthesis

30. 4. Explain reasons for the shape of the energy pyramid. (5 marks) Energy transfer efficiency between each trophic levels is (approximately) 10% from one level to the next; (in other words, 90% is lost at each level); heat loss through cellular respiration not all organisms in lower trophic levels are consumed the whole mass of the prey is not assimilated into the predator�s body (waste is produced) energy lost through the metabolic processes of the prey before they are consumed

31. 5. Explain why there are limits on food chain length by describing how energy enters, moves through, and exits a food chain in an ecosystem. (8 marks) energy enters from (sun)light; autotrophs capture (sun)light; energy flows through the trophic levels / stages in food chain; (eg. Producer>>Primary Consumer>>Secondary consumer>> Tertiary Consumer>>Quarternary Consumer) energy transfer efficiency between each trophic levels is (approximately) 10% from one level to the next; (in other words, 90% is lost at each level) energy loss through cellular respiration Energy is lost through heat Energy is lost because not all material is consumed Energy is lost because food that is not all assimulated and is lost as waste *Include a labeled energy pyramid (using kJ per square meter per year as x axis (kJ/m2/yr))

32. 6. Outline the changes in species diversity and production during primary succession (5 marks)

33. 7. In communities, groups of populations live together and interact with each other. Outline the importance of plants to populations of other organisms in a community. (6 marks) light is the initial source of energy for almost all communities; plants absorb light and use it in photosynthesis; plants produce food / organic matter; plants are the main producers in most communities; energy flows along food chains / webs from plants; first consumers eat plants / producers; second consumers eat first consumers that have eaten plants / producers; plants produce oxygen; oxygen needed for cell respiration by many organisms; dead plants / parts of plants available to saprotrophs / fungi and bacteria / detritivores;

34. 8. Distinguish between primary and secondary succession using an example of each. (6 marks) Primary succession occurs after a disturbance that leaves no soil An example is a cooled lava flow Primary succession occurs slowly Secondary succession occurs after a disturbance that leaves the soil intact An example is a forest fire Secondary succession can occur very rapidly

35. 9. Explain the effects of living organisms on the abiotic environment, with reference to the changes occuring during primary succession. An area with no vegetation such as volcanic rock Lichens and mosses are the first to colonize these areas Lichens break down the rock chemically Over time, dead lichens and mosses decompose, mixing with the decaying rock to form soil These �pioneer� species are gradually replaced by others Over time, the decaying plants improve soil structure Eventually a stable community develops