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Bio chapter 36


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1. What is surprising about the food chain described in the first 2 paragraphs? INTRO
The food chain is surprising because instead of animals eating animals on the outside, smaller animals are eating larger animals from the inside.
2. What is a community?
A community is an assemblage of all the populations of organisms living close enough together for potential interaction.
3. What are the 4 basic characteristics used to describe a community?
Its diversity, its prevalent form of vegetation, its response to disturbances, and its trophic structure.
4. What two components are used to describe biodiversity?
The biodiversity of a community – the variety of different kinds of organisms that make it up – has two components. One is a species richness, or the total number of different species in the community. The other is the relative abundance of the different species.
5. How could a community be similar with one of these components, but very different with the other component?
Two different communities can have the same four species – species A, B, C, and D – but the ratio relationship between the species is different.
6. What is described by the trophic structure of a community?
A Community’s trophic structure determines the passage of energy and nutrients from plants and other photosynthetic organisms to herbivores and then to carnivores.
7. What are the 3 main types of interactions among members of a community?
Competition, predation, and symbiosis.
8. What determines if two species will be competitors?
As population increases in density, competition for limited resources may eventually slow that population’s growth.
9. What is the “competitive exclusion principle”?
Says that two species so similar that they compete for the same limiting resources cannot coexist in the same place.
How is it demonstrated in barnacles?
The Balanus barnacles cannot survive above the water level, because they dry out. However, the Chthamalus barnacles can survive above the water level, and usually only inhabit this area that the Balanus barnacles are not in. However, when the Balanus barnacles are removed, the Chthamalus barnacles spread to this underwater area. But it the Balanus barnacles are re-introduced, they quickly push the Chthamalus barnacles out of the way.
11. Name several factors that determine a species’ ecological niche.
species’ niche, the species’ role in its community, or the sum total of its use of the biotic and abiotic resources of its habitat, are determined by several factors; temperature range, time of day they feed, and type of food they consume.
12. What is “resource partitioning”? Do you think it occurs rapidly or slowly? Why?
The division of environmental resources by coexisting species such that the niche of each species differs by one or more significant factors from the niches of all coexisting species.
13. How can you differentiate between a predator and a prey? How do herbivores fit into these categories?
In predation, an interaction where one species eats another, the consumer is called a predator and the food species is known as the prey. With a herbivore, the plant is the prey.
14. What is co-evolution? Give an example of how predation can lead to co-evolution.
Co-evolution is a series of reciprocal adaptations in two species. This can be demonstrated in the relationship between the caterpillar of the butterfly Heliconius and a plant, the passionflower Passiflora. The Passiflora has developed a toxic chemical that protect its leaves from most herbivorous insects, but the Heliconius caterpillars have digestive enzymes that break down the toxins. However, some of these Passiflora plants produce yellow sugar deposits that look like Heliconius eggs; female butterflies avoid laying their eggs on this plant, thus no hatchlings will feed on the leaf. However, the sugar deposits attract other insects to prey on heliconius eggs and larvae.
15. What seems to be the primary reason that plants have developed a wide range of chemical toxins to avoid being eaten?
The primary reason is probably that plants cannot run away from herbivores.
16. Name a chemical defense used by an animal and one used by a plant to avoid herbivory or predation.
The vivid markings of a poison-arrow frog warn of deadly alkaloids in the frog’s skin. The Passiflora produces toxic chemicals that protect its leaves from most herbivorous insects.
17. What is camouflage?
Camouflage is a skin pattern or color that allows an animal (or plant?) to blend into its surroundings.
18. What is a “keystone species”?
A keystone species is a species that exerts strong control on a community structure because of its ecological role, or niche.
19. Why are sea otters considered to be a keystone species here in the Pacific Northwest?
Sea otters are considered to be a keystone species because they eat sea urchins, which feed on kelp. If the sea otters’ numbers decrease, then the sea urchins become more abundant, making the kelp forests almost nonexistent.
20. What is a symbiotic relationship? What are the three main categories of symbiosis?
A symbiotic relationship is an interaction between two or more species that live together in direct contact. The three main types of symbiotic relationships are parasitism, commensalisms, and mutualism.
21. How do parasites usually differ from predators?
Parasites are usually smaller than predators.
22. How did natural selection affect both the parasite and the host in the case of the Australian rabbits?
The parasite that was introduced into the Australian rabbits killed a huge percentage of them, but the parasite selected for some rabbits, who for whatever reason were less affected by the parasite. This trait was passed on to younger generations, until the parasite had little effect on the Australian rabbit population.
23. How does commensalisms differ from parasitism?
In commensalism, one partner benefits without significantly affecting the other.
24. How does mutualism differ from these two?
Mutualism benefits both partners in the relationship.
25. Describe several of Dr. Gilliam’s arguments for the advantages of relatively frequent, low intensity fires.
First, following a fire in a forest, the variety of nonwoody plants, herbs, usually increase – nutrients such as phosphorus, nitrogen, and potassium increase. Next, in grasslands, if there is no fire, shrubs and trees will replace the grasses.
26. In what form does energy enter the model terrarium ecosystem? In what form does energy leave it?
26. In what form does energy enter the model terrarium ecosystem? In what form does energy leave it?
27. How is this energy flow different from the movement of materials in the ecosystem?
Chemical elements such as carbon and nitrogen are cycled between abiotic components and biotic components of the ecosystem. The plants acquire these elements in inorganic form from the air and soil and fix them into organic molecules.
28. What is a trophic structure of a community?
A trophic structure of a community is a pattern of feeding relationships, consisting of several different levels.
29. Who are the producers? What process do they perform?
Photosynthetic producers are organisms that use light energy to power the synthesis of organic compounds. They perform photosynthesis.
30. How do the secondary consumers differ from the primary consumers?
Primary consumers are herbivores, which eat plants, algae, or autotrophic bacteria. Secondary consumers are carnivores which eat the consumers from the level below.
31. Who are detrivores?
Detrivores derive their energy from detritus, the dead material produced by all the trophic levels
32. How do the decomposers differ from the detrivores?
Decomposers break down organic materials into inorganic ones.
33. Why is a food web considered to be a more realistic view of a community, compared to a food chain?
Because the relationships between animals are not linear.
35. Why is the owl considered to be both a secondary and a tertiary consumer?
The owl is considered both a secondary and a tertiary consumer because many of the small mammals and birds it eats are primary as well as secondary consumers.
36. What percentage of visible light is converted to chemical energy by photosynthesizers? What is this called?
Of the visible light that reaches plants, algae, and cyanobacteria, only about 1% is converted to chemical energy by photosynthesis.
37. Why does the energy budget of a community usually look like a pyramid? (Fig. 36.11, for example)
Because only 10% of the energy available at each trophic level becomes incorporated into the next higher level.
38. What can be concluded by comparing the two energy pyramids in Fig. 36.12?
It takes more energy to feed meat-eating humans than Vegetarian humans.
39. Why is meat considered to be a “luxury” food?
Because it is expensive and energy-inefficient to produce meat for consumption⬦possibly uses 100 times more energy than if people directly ate plants
40. What is an “abiotic reservoir”?
an abiotic reservoir is the part of the ecosystem where a chemical accumulates or is stockpiled outside of living organisms.
41. What drives the global water cycle?
the global water cycle is driven by heat from the sun.
42. What are the three main processes involved with the water cycle? Which one is primarily the work of plants?
Three main processes: precipitation, evaporation, and transpiration. Transpiration is primarily the work of plants.
43. How does human activity influence the water cycle?
One of the main sources of atmospheric water is transpiration from the dense vegetation making up tropical rain forests. People are destroying these forests, changing the amount of water vapor in the air. Also, by pumping large amounts of groundwater to the surface for irrigation, humans are increasing the rate of evaporation over land, which is not substituted with more rainfall.
45. How does carbon get recycled back into the abiotic reservoir?
Returned by respiration.
46. What is eutrophication? Why does it cause a depletion of oxygen in lakes?
Eutrophication is an increase in productivity of an aquatic ecosystem {Eutrophication is a process where added nutrients in ponds and lakes cause photosynthetic organisms such as algae and cyanobacteria to multiply rapidly, resulting in an algal bloom.} Heavy bacterial and algal growth greatly reduces oxygen levels at night, when the photosynthesizers respire.
47. How was Dr. Schindler able to determine that phosphorus was a major influence on the eutrophication of a lake?
he divided a lake into two basins; carbon and nitrogen were added to one basin, and phosphorus, carbon, and nitrogen were added to the other. There was tremendous algal bloom within weeks after adding phosphorus, but no change with just the carbon and nitrogen.
48. What are the major threats that Dr. Schindler believes face freshwater ecosystems today?
Acid precipitation, warming of the climate and changes in land use can affect lakes.
49. What is a zoned reserve, and why are they being developed?
A zoned reserve is an extensive region of land that includes one or more areas undisturbed by humans. Zoned reserves are being developed for the development of a social and economic climate in the surrounding lands that is compatible with the long-term viability of the protected core area.
Interspecific competition
If two different species are competiting for the same LIMITED resource. ....the growth of both populations may be inhibited
intraspecific competition
Competition within a species
symbiotic relaitonships
2 species taht have very close contact - one lives within the other species
What is Parasitism?
benefits one species, harms the other. Parasite and host...ex. flea and dog, lice and chimps, bacteria and people, tapeworms and people, ...coevolution involved. Over time, becomes less harmful.
What is commensalism?
One species benefits...the other is neutral. ex. whale and barnacles
What is mutualism?
Both benefit. ex. cleaner fish and larger fish, clown fish and sea anemone, bacteria in our gut that makes vitamin K,
formula for Cellular respiration
C6H12O6 -> 6CO2 + 6H2O
photosynthesis formula
6CO2 + H2O + sunlight -> 6O2 + C6H12O6
key idea of Darwin
Organisms interact with each other and the non-living environment and are influenced by each other and the non-living environment
2 main points of ecology
1) organisms exist in a web of interactions 2) Big difference between matter and energy - especially how they move around in an ecosystem
What is predation?
Predator and prey interaction...very important interaction in evolution
What is a keystone predator?
one species that has a very strong influence on diversity (pisaster[sea star])
has mass and volume
matter has cycles; due to action of detrivores and decomposers. [chemical cycling, nutrient cycling, carbon cycle]
reservoir for carbon
ocean, atmosphere
efficiency of energy conversions
not 100% efficient...some is turned into heat
what is Resource partitioning?
Long term effect - when species use different resources, its better for the species
an increase in productivity of an aquatic ecosystem

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