Biology HL Ecology Option

  1. What is the law of tolerance?
    The levels of one or more chemical and physical factors determine the abundance and distribution of organisms. When the factors fall below or rise above the levels tolerated by the species, the species will gradually cease to exist. Key terms here are zones of stress (above and below) and limits of tolerance.
  2. What is a species?
    A group of organisms sharing common characteristics that can be interbred to produce offspring that can interbreed.
  3. What are the limitations of the species concept?
    • Doesn’t account for asexually reproducing organisms.
    • Doesn’t classify species in extinct populations.
    • Doesn’t identify whether isolated populations belong to the same species.
  4. What is environment?
    The external surroundings that affect species’ survival and development.
  5. What are abiotic factors?
    • Salinity (Non-living, physical factors)
    • Temperature
    • pH
    • Sunlight
  6. What is spatial habitat?
    The environment in which the species lives.
  7. What is a keystone species? How can we identify a keystone species?
    A species that is not necessarily abundant but exerts strong control on the structure of the community. The keystone species can be identified using the removal experiment. Keystone species are usually species that serve as predators for species that would otherwise overpopulate and overtake the entire ecosystem and rapidly decrease biodiversity as a consequence.
  8. What are biotic factors?
    Predation (canadian lynx and arctic hare), Symbiosis (rhizobium is nitrogen fixing bacteria that provides nitrogen for plants), Parasitism (tape worm in human beings), Herbivory, Disease, Competition (coyotes and red foxes)
  9. Predation
    • An animal hunts and eats another animal, causes a negative feedback cycle,
    • Also kinda good for prey because it creates a superior breeding pool
  10. What is Herbivory?
    An area with a more abundant plant resource has a larger carrying capacity for the herbivore.
  11. What is the theory of competitive exclusion?
    • If two species share the same niche, one will outcompete and eliminate the other.
    • This was identified by Gause, who grew two similar paramecium species (p. Aurelia and p. audatum) separately and together and observed that p. Caudatum would die out when the two were cultured together.
  12. Fundamental niche is the full range of conditions in which a species can survive and reproduce.
    Realized Niche is the actual range of conditions. (limited by interactions with other species and its adaptations)
  13. What is a transect?
    It’s a method of sampling a population along a longitudinal section of an ecosystem. This method can be used to illustrate a particular gradient of an environmental factor, such as sunlight or soil moisture. Every 10 or 20 m, a quadrant is taken and the environmental factor and the number of species in the quadrant are noted. This method can only help us determine correlations. Additionally, this method is much easier to use with plants than animals, as they don’t move.
  14. What is an example of symbiosis?
    Zooxanthellae are single-celled algae that live in the tissue of reef-building coral. The coral provides the compounds and the environment for photosynthesis for zooxanthellae. In turn, the algae provide food for the coral. It gives the coral a boost of nutrients so that it can secrete the skeleton of calcium carbonate that it needs to build the reef. This is a highly efficient exchange of nutrients in a nutrient-poor environment.
  15. What is a community?
    Many species living together.
  16. What is an ecosystem?
    A community and the physical environment it interacts with.
  17. What is a trophic level?
    The position that an organism occupies in a food chain.
  18. What is an autotroph?
    Typically plants or algae that produce their own food.
  19. What is the second law of thermodynamics?
    Energy and biomass decrease along the food chain due to loss to heat.
  20. What is bioaccumulation?
    The buildup of nonbiodegradable pollutants within an organism or trophic level.
  21. What is the unit of storage:
    g/m2 or j/m2
  22. Why is not all of sunlight energy is used?
    • Reflection from clouds
    • Absorption by clouds
    • Reflection from the surface of the earth
    • Absorption by atmospheric levels and dust
  23. Explain Pyramid of Numbers
    • Number of each individual at each trophic level
    • Good for comparing populations through time
  24. Explain Pyramid of Biomass:
    • Biological mass of the standing stock at each trophic level at a specific point in time
    • May be misleading due to seasonal change and is hard to measure with many assumptions but good for comparing seasons
    • g x m-2 x y-1
  25. Explain Pyramid of Productivity:
    • Flow of energy through each trophic level of a foodchain over a period of time
    • Always pyramid due to second law of thermodynamics and directly comparable (no seasonal change shit)
    • kJ m-2 yr-1
  26. What is gross primary productivity?
    • Gross production is the total amount of energy trapped in the organic matter produced by plants (biomass accumulated) per area per time in kilojoules, measured as kilo jules per metre squared per year (kJ m−2 yr−1)
    • Food eaten- fecal loss for secondary productivity
  27. What is net productivity?
    Gross productivity - respiration (kJ m−2 yr−1)
  28. What is biomass?
    Biomass is the dry weight of an organism, measured in grammes per metre squared per year (g m–2 yr–1).
  29. What is a food web? What are its limitations?
    • Organisms might be on varying trophic levels
    • Omnivores are at a difficult position
  30. How can we measure the sustainability of food production?
    • We use the feed conversion ratio (mass of food eaten/ mass gained)
    • The higher the ratio, the lower the productivity
  31. How can we reduce the feed conversion ratio through sustainable agriculture?
    • Example would be: Fish farming
    • Efficient resource use
    • Preferring animals with less FCR.
  32. What is zonation?
    • Changes in community along an environmental gradient due to factors such as changes in latitude, altitude, tidal level, distance from shore or coverage by water
    • Biome distribution
    • Patterns in an ecosystem (bands of vegetation)
    • Distance from the sea on a rocky shore
    • Changes in ecosystems up a mountain
  33. What is succession?
    • Is the process of change over time in an ecosystem involving
    • pioneer, intermediate, climax communities
  34. What is primary succession?
    Occurs on a previously uncolonized substrate
  35. What is secondary succession?
    • Occurs in places where a previous community has been destroyed
    • Due to soil bank
  36. List Succession pls
    • Colonization: lichen and moss weather rock and produce dead material
    • Establishment: growth of moss, further weathering, beginning of soil formation, growth of small plants such as grasses and plants,
    • Competition: growth of small plants, larger herbaceous plants grow, shrubs, small trees
    • Stabilization + Climax
  37. What are the difference between primary and secondary succession?
    • No soil in primary, soil in secondary
    • No roots or seeds in primary, roots and seeds in primary
    • Low production in primary, high production in secondary
    • No life present in primary, secondary begins with a disturbance to the ecosystem
  38. What are the properties of Grasslands?
    • Not enough precipitation for forests, not little enough for deserts
    • Temperate grasslands: great plains, russian steppes
    • Tropical grasslands: savannas of east africa
    • High diversity, low productivity (grass)
    • With low humidity comes fluctuating temperature
    • Decomposition rate is low
  39. What are the qualities of a tropical rainforest biome?
    • Constant high temperature
    • High rainfall
    • Near the equator, little seasonal variation between the tropic of capricorn and cancer
    • High levels of biodiversity and NPP
    • Soil is low in nutrients
    • Evergreen
  40. What are the qualities of temperate forests?
    • Between 40-60 N
    • Cold winters and warm summers
    • Evergreen (needles or waxy) trees or deciduous trees (sheds its leaves)
    • NPP is lower than tropical but the second highest
    • Less biodiversity due to the forests being made one species tops 6 species
    • But the rainforests have very high dense canopies, there’s grass and ferns
  41. What are the qualities of deserts?
    • 30 N
    • Water is limiting factor , NPP is very low
    • Xerophytic adaptations, low decomposition due to low water, high salinity, low leeching
    • Roots either deep or extended on surface
  42. What are the qualities of tundra?
    • High latitude, low insolation
    • Water is ice, sunlight is low, NPP low
    • Decomposition is slow, nutrition is low, biodiversity is low
    • Larger animals for energy efficiency
    • formed due to the retreat of glaciers
    • Permafrost
  43. What are the qualities of taiga (coniferous forest)?
    • Slightly warmer than tundra
    • pine , spruce or fir
    • Small amount of precipitation but wet due to lack of evaporation
  44. What are Gershmal diagrams?
    • Litter, biomass and soil are stores
    • Weathering is input to soil
    • Runoff is an output of litter
    • Precipitation is an input to litter
  45. What is an example of humans interfering with nutrient cycling?
    Fish assimilate nutrients and release nitrogen and phosphates into the environment, which are critical to primary productivity. Overfishing and consequent habitat depletion have caused rapid diminishment of primary productivity and the collapse of marine fisheries. Sea grass beds are also important habitats for young fish. Loss of sea grass beds would result in a positive feedback cycle and lead to further reduction of fish populations.
  46. What is a close ecosystem?
    An ecosystem where energy exchange with the outside is made but no matter exchange.
  47. What is a disturbance?
    • An environmental factor that changes the structure or rate of change in an ecosystem.
    • Low levels of disturbance lead to increased competition and decrease in diversity.
    • Intermediate levels of disturbance ensure that a single species does not dominate the area and allows for different species to colonize the area.
    • High levels of disturbance reduce diversity.
  48. What are the risks and benefits of biological control?
    • It is better than chemical control, no pollution
    • Many tests must be carried out, it’s much harder to control (cane toads from hawaii were introduced in australia to control sugar cane beetles biologically. However, as they don’t have a natural predator and alternative food sources were available, the cane toad population increased rapidly as the beetles were not affected. Competitive exclusion has also negatively affected endemic species sharing a similar niche (skinks)
  49. What is biomagnification?
    • The increase in the concentration of nonbiodegradable pollutants along the food chain.
    • An example is DDT, which, although it’s useful in the control of the spread of malaria, led to the depletion of predator birds (american bald eagle) populations by affecting its eggs and cracking them.
    • Another example are microplastics, which cause damage to the digestive systems of marine animals when consumed. They also absorb the chemicals in the environment, which accumulate as chemicals in the bodies of the marine animals,
  50. What are some ways to deal with alien invasive species?
    The oriental fruit fly, which depleted fruit yields, was eliminated in Okinawa Japan by the introduction of sterile male flies and the use of insecticides in an 18 year program.
  51. What is In Situ and Ex Situ conservation?
    • In situ: species based conservation in its natural habitat
    • Ex situ: species based conservation outside of its habitat (botanical gardens, zoos)
  52. What are examples of environment management methods?
    • Restoration of the habitat (replantation)
    • Recovery of threatened species (happens when the habitat is restored)
    • Removal of invasive species (oriental fruit fly)
    • Legal protection (against hunting, pollution)
    • Funding and prioritizing (raising public awareness, protecting keystone species)
  53. What are the aims of in situ conservation? When is it not possible?
    • Protect the target species by maintaining its habitat
    • Protect the target species from predators
    • Maintain a large population
    • Maintain genetic diversity
    • Remove invasive species
    • In situ conservation isn’t possible when there isn’t sufficient genetic diversity, the population is very small or external factors such as natural disasters or human disturbance is not possible.
  54. What are some methods of ex situ conservation? When is ex situ conservation preferred?
    • It’s the last resort when the population has become very small and the habitat has been significantly depleted. There are three methods:
    • Captive Breeding: artificial insemination, choosing mates to preserve maximum genetic diversity, cryogenics. The disadvantage is that reintroduction may lead to the spread of disease and is very hard. (the mexican gray wolf, which was hunted as it preyed on livestock, was saved thanks to captive breeding)
    • Botanical gardens: Allows for the preservation of plants.
    • Seed banks
  55. What is evenness and richness?
    Species richness is the total number of species. Evenness is the relative abundance of organisms belonging to these species. For diversity, the ecosystem must both be even and rich.
  56. Advantages of zoos?
    • Raises public awareness
    • Sustainable funding
    • Allows controlled breeding for animals needing quarantine
    • Allows research
  57. Disadvantages of zoos?
    • Habitat is destroyed during ex situ conservation
    • Reintroduction of species into the wild is hard
    • May not have optimal conditions with insufficient funding
  58. Species based x habitat based?
    • Strength of species based is that it costs less and attracts more attention. The weakness of species based is that the habitat is destroyed in the process.
    • The strength of habitat based is that the entire ecosystem is protected, the ecosystem may be closely researched. However they require funding and political support, and areas may become isolated islands where a loss of biodiversity would occur.
  59. A mixed approach to conservation?
    Sichuan giant panda reserve, chengdu panda base + chengdu zoo, bejing zoo and 51 other zoos. (raises awareness, protects the habitat, successful reintroduction)
  60. Simpson’s index?
    • Total number (total number-1)
    • Divided by sum of number in single species(number-1)
    • Measures are relative, same sampling method must be used
    • High D better for conservation, more stable
    • Low D worse for conservation, indicator of disturbance, pollution or agricultural practices (or simply the nature of the biome)
    • Sample size and sampling technique affect the index, similar areas with similar populations must be compared
  61. What biogeographical factors affect species diversity?
    • Latitude gradient: As we move away from the equator, the species diversity decreases.
    • Elevation gradient: species diversity increases until the mid-point bulge and decreases afterwards.
    • The area effect: the larger the area, the higher the species diversity (the island theory) due to habitat diversity
  62. What are edge effects?
    Due to different abiotic conditions than the center (more wind, less humidity, warmer) different species are attracted to the edges, leading to competition with the species in the center. This might either promote diversity or reduce it. Generally, however, it promotes it as a diversity of habitats emerges. The area that is formed by two ecosystems overlapping has the highest biodiversity.
  63. How do we calculate magnification?
    Image size over Actual size (according to scale bar)
  64. What is osmolarity?
    It’s the measure of solute concentration.
  65. What are solutions with high osmolarity categorized as?
    • Hypertonic solutions.
    • Water flows in this direction.
  66. What are solutions with low osmolarity categorized as?
    • Hypotonic solutions.
    • Water flows from this direction.
  67. How do we estimate the osmolarity of tissue?
    Tissue is exposed to solutions with known osmolarity. Tissue will lose weight in hypertonic environment and gain weight in hypotonic environment. If there is no change in weight, the environment will have the same osmolarity as the tissue.
  68. How can we measure enzyme activity?
    Either the amount of substrate broken down or the rate of product formation must be monitored.
  69. What is the Rf factor?
    Used in chromotography. Distance component travels / distance solute travels
  70. Components and colors of leaf?
    • Light green: chlorophyll b
    • Dark green / blue: chlorophyll a
    • Yellow: Xanthophyll
    • Orange: Carotenoid
  71. What are the advantages of mesocosms?
    Variables can easily be manipulated, allowing us to model actual ecosystems.
  72. What are the disadvantages of mesocosms?
    Not an adequate simulation of an environment, causing organisms to act in ways they normally wouldn’t in their natural habitats.
  73. What is tidal volume?
    The amount of air taken in one breath.
  74. How can we measure ventilation?
    • Simple observation (number of breaths taken in a minute)
    • Recording the rise and fall of the chest using a chest belt and pressure meter
    • Spirometer (measuring the amount of air expelled in each breath), a balloon can also be used (placed in water and displacement measured)
  75. What is spirometry?
    Measuring the amount and speed of air inhaled and exhaled to diagnose diseases.
  76. What is a potometer?
    • It is a device that is used to estimate transpiration rates by measuring water loss / uptake.
    • The movement of the water bubble on the meniscus indicates the amount of water uptake. It’s important to note that not all of the water is used for transpiration. Some is used for photosynthesis and turgidity maintenance.
  77. S population curve?
    • Due to limited resources and limiting factors, the rate of growth slows down and fluctuates when the carrying capacity is reached. Has 4 phases:
    • 1.Lag phase: a small number of indivudals colonize the area nad have a small number of offspring
    • 2.Exponential growth phase: limiting factors are not restricting the rate of growth, no disease no predation, good temperature, good rainfall
    • 3.Transitional phase: limiting factors begin to affect the population and increased competition, disease and predation limit the rate of growth
    • 4.Stationary phase: population growth stabilizes and fluctuates due to abiotic and biotic factors.
  78. What is carrying capacity?
    Maximum number of individuals of a species that can be sustained by an environment.
  79. What are limiting factors?
    Factors that limit the distribution or number of a particular population. Limiting factors can be bottom up (nutrients) or top down (predation)
  80. What are density dependent limiting factors?
    Factors that are affected by the population size of the species (food, water supply, predation, disease)
  81. What are density independent limiting factors?
    • Not related to population density
    • Natural disasters
  82. What are the limitations of the capture and release method?
    • Might make marked animals more prone to predation
    • Assumes no immigration or emigration takes place
  83. What are the methods used by researchers to determine fish population sizes?
    • Studying catches by recording the number, age, length and species of caught and released fish.
    • Studying the catch per unit effort
    • Using research vessels: Randomly sampling fish populations using nets or using sound (echo) to monitor and sample fish populations
    • Using coded wire detectors for the lincoln index
    • Mathematical models
  84. How is the age of fish determined? Why is it important?
    The rings in the ear bones of fish serve as an indicator of age. Lack of older fish could be an indicator of overfishing, thus this is important.
  85. Why is it important to monitor fish populations?
    To determine maximum sustainable yield.
  86. What are the conditions required for nitrification?
    • Oxygen
    • Warm environment
    • Neutral pH
    • This increases the quality of soil
  87. What are the conditions required for denitrification?
    • Anaerobic conditions
    • High nitrogen input
    • Destroys ozone layer, decreases quality of soil, releases NO which is a GHG
  88. Explain the steps of eutrophication
    • High phosphates and nitrates in water initially lead to increased productivity and then an algal bloom
    • Algae block sun from reaching plants and lead to plant death. Additionally, dead algae are also decomposed by aerobic bacteria. This leads to a positive feedback cycle, as more nitrates and phosphates are released as the BOD increases and the oxygen in the water decreases.
    • Fish and other organisms die
  89. What is the effect of waterlogging on the nitrogen cycle?
    Water in soil creates anaerobic conditions in water, leading to denitrifying bacteria to prosper. This leads to a decrease in the amount of nutrients in the soil and reduces its quality. If water logging becomes a problem due to climate change induced flooding, this could heavily affect food crops and agricultural efficiency.
  90. Where is phosphorus stored?
    It is generally found in sedimentary rock in oceans. Unlike nitrogen, it takes a long time for phosphorus storages to form.
  91. Compare and contrast nitrogen and phosphorus
    • Both are key molecules for organisms
    • Nitrogen turnover time is much shorter than phosphorus
    • Both are nutrients in soil
    • Both are found in fertilizers
  92. What are the methods of nitrogen fixation?
    • symbiotic bacteria on plant roots
    • Free living bacteria
    • Industrial nitrogen fixation: burning of fossil fuels to produce fertilizers
  93. What are indicator species? How are they used?
    Indicator species are species that need known and particular environmental conditions to survive. The diversity and relative numbers of indicator species can be used to calculate biotic indices which help to monitor environmental changes. For example, the tubifex lives in poorly oxygenated water. Indicator species can also be used to identify the level of pollution in an area.
  94. What do we say instead of decomposition?
Card Set
Biology HL Ecology Option
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