Environment, Ecology and Climate

Biomes and Global Ecosystems

61 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 61 questions

  1. Which terrestrial biome represents the largest contiguous forest ecosystem on Earth, circling the subarctic high latitudes of North America and Eurasia with dense stands of coniferous evergreen trees?
  2. What name is given to the permanently frozen subsoil layer found throughout the Arctic tundra that prevents deep plant root penetration and creates boggy surface pools in summer?
  3. What mutualistic microscopic algae live inside the gastrodermal tissues of reef-building stony corals, providing corals with photosynthetic energy in exchange for shelter and metabolic nutrients?
  4. What specialized aerial root adaptations enable mangrove trees (such as Avicennia) to absorb atmospheric oxygen while growing in waterlogged, anoxic coastal mudflats?
  5. In an ecological food chain, approximately what percentage of energy is transferred from one trophic level to the next higher trophic level according to Lindeman's Efficiency?
  6. What term coined by ecologist Robert Paine describes a species whose presence and ecological role exert an exceptionally large influence on the structure and biodiversity of its entire ecosystem relat…
  7. Which international treaty, signed in Iran in 1971, provides the global framework for the conservation and wise use of wetlands and their natural resources?
  8. What type of ecological succession occurs on a newly formed, completely sterile substrate that has never previously supported life and possesses no biological soil (such as cooled volcanic lava or ret…
  9. What term describes the regional grassland biome of South America, spanning Argentina, Uruguay, and southern Brazil, renowned for its fertile deep soils and extensive cattle ranching?
  10. Which ocean depth zone extends from the sea surface down to approximately 200 meters, representing the only oceanic layer that receives sufficient sunlight for photosynthetic phytoplankton to generate…
  11. What phenomenon occurs when excessive agricultural runoff containing synthetic nitrogen and phosphorus fertilizers enters lakes or coastal bays, triggering massive algal blooms and subsequent oxygen d…
  12. What unique metabolic process is performed by chemotrophic bacteria living around deep-sea hydrothermal vents to produce organic carbohydrates in complete darkness without sunlight?
  13. Which biome is characterized by hot, dry summers and mild, wet winters, featuring dense evergreen fire-adapted shrubs known as chaparral in California and maquis around the Mediterranean basin?
  14. What major global biome contains the world's largest expanse of mangrove forest, the Sundarbans, shared between which two South Asian countries?
  15. Which process in the terrestrial nitrogen cycle converts atmospheric inert nitrogen gas () into bioavailable ammonia (), performed biologically by symbiotic bacteria like Rhizobium in legum…
  16. What term describes the non-living chemical and physical components of an ecosystem that influence living organisms, including sunlight, temperature, soil pH, salinity, and rainfall?
  17. Which non-gaseous biogeochemical cycle is uniquely classified as a sedimentary cycle because its primary geological reservoir resides in rocks and ocean sediments rather than the atmosphere?
  18. What term describes an ecological transition zone where two distinct biological communities or biomes meet and integrate, such as the boundary between a forest and an open grassland?
  19. What is the primary ecological reason why tropical rainforest soils (oxisols and ultisols) are paradoxically nutrient-poor despite supporting the densest plant biomass on the planet?
  20. Which marine mammal species plays a celebrated keystone role along the Pacific coast of North America by preying on herbivorous sea urchins, preventing the urchins from destroying giant kelp forest ec…
  21. Which type of ecological pyramid is ALWAYS upright and cannot be inverted in any stable natural ecosystem?
  22. What term describes the specialized ecological role, physical habitat space, and behavioral resource utilization of a specific organism within an ecosystem, famously distinguished from its 'habitat' b…
  23. Which desert, situated along the Pacific coast of northern Chile and southern Peru, is considered the driest non-polar desert on Earth, with some weather stations having never recorded rainfall?
  24. What ecological principle, formulated by Russian biologist G.F. Gause in 1934, states that two species competing for the exact same limiting resource cannot stably coexist if other ecological factors…
  25. Which vast tropical wetland system, situated primarily in west-central Brazil and extending into Bolivia and Paraguay, is recognized as the world's largest freshwater wetland biome?
  26. What term describes the natural evolutionary divergence of ecological traits or feeding behaviors that allows competing species to divide limited resources and avoid direct competition (such as Darwin…
  27. Which African biome features open grassy plains dotted with drought-resistant flat-topped Acacia and Baobab trees, hosting the world's greatest annual migration of over 1.5 million blue wildebeest and…
  28. What term describes organic carbon captured and sequestered by coastal marine ecosystems, particularly mangrove forests, seagrass meadows, and salt marshes, burying carbon in sediment for centuries?
  29. What type of plant is adapted to live in environments with very little liquid water, featuring specialized traits like water-storing succulent stems, reduced spine-like leaves, and thick waxy cuticles…
  30. Which international treaty, adopted in Washington, D.C., in 1973, regulates international cross-border trade in endangered wild animals and plants across three appendiced regulatory tiers to prevent s…
  31. What term describes non-parasitic plants (such as tropical orchids, bromeliads, and mosses) that grow physically anchored upon host tree trunks and branches to access sunlight in dense forest canopies…
  32. What term describes the maximum population size of a biological species that a particular environment can sustainably support indefinitely without degrading the environmental resource base?
  33. Which marine biodiversity hotspot, encompassing the waters of Indonesia, Malaysia, the Philippines, Papua New Guinea, Solomon Islands, and Timor-Leste, contains over 75% of all known coral species?
  34. What ecological process describes the gradual, predictable replacement of one plant and animal community by another over time following a severe disturbance (such as a wildfire) where the underlying s…
  35. In ecosystem food web energetics, what trophic category encompasses organisms such as earthworms, woodlice, dung beetles, and sea cucumbers that feed directly on dead particulate organic matter and an…
  36. What term describes the natural warming of the Earth's surface and lower atmosphere caused by atmospheric gases (such as water vapor, carbon dioxide, and methane) absorbing and re-radiating outgoing i…
  37. Which biome is characterized by broadleaf trees that undergo seasonal leaf abscission (shedding) in autumn to survive freezing winter temperatures, common across Eastern North America, Western Europe…
  38. What term describes the increasing concentration of persistent, lipid-soluble chemical toxins (such as DDT or methylmercury) in the fatty tissues of organisms at successively higher trophic levels in…
  39. Which cold ocean current flowing northward along the west coast of South America generates intense coastal upwelling of cold, nutrient-rich deep water, sustaining one of the most productive marine fis…
  40. What international environmental agreement, signed in Washington, D.C., in 1959, dedicated an entire continent exclusively to peaceful scientific research and prohibited military activity, nuclear tes…
  41. What term describes the symbiotic association between soil fungi and the roots of vascular plants, where the fungal hyphae dramatically increase water and phosphorus absorption in exchange for photosy…
  42. Which photosynthetic carbon-fixation pathway is employed by desert succulents (such as pineapple, agaves, and cacti) that open their stomata exclusively at night to capture carbon dioxide, storing it…
  43. What term describes the fraction of incident solar radiation that is reflected directly back into space by a surface without being absorbed, ranging from near 0.9 for fresh snow to under 0.1 for open…
  44. Which international treaty, opened for signature at the 1992 Rio Earth Summit, aims for the conservation of biological diversity, the sustainable use of its components, and the fair sharing of genetic…
  45. Which terrestrial biome is located primarily in the interior of North America and Eurasia, characterized by deep, organic-rich black soils (mollisols and chernozems) that have made it the premier grai…
  46. What term describes the natural continuous movement of water from the Earth's surface into the atmosphere via evaporation and plant transpiration, condensation into clouds, and return via precipitatio…
  47. What phenomenon occurs when the ocean absorbs excess anthropogenic carbon dioxide () from the atmosphere, forming carbonic acid and reducing seawater pH and carbonate ion concentrations?
  48. Which distinct biological community type is formed on volcanic islands and isolated archipelagos (like the Galápagos and Hawaii) where high rates of geographical isolation yield species found nowhere…
  49. What term describes the living components of an ecosystem—including producers, herbivores, carnivores, parasites, and decomposing microbes—that interact through food webs and symbiotic relationships?
  50. Which deep-sea zone lies below 6,000 meters in depth, restricted strictly to V-shaped oceanic trenches and submarine fractures (such as the Mariana Trench)?
  51. What term describes the process by which sulfur-oxidizing bacteria in deep-sea hydrothermal vents or caves synthesize organic sugars from carbon dioxide without any solar light, utilizing the oxidatio…
  52. What type of wetland is characterized by acidic, waterlogged peat soils, low mineral nutrient levels, and dense cushions of Sphagnum moss, receiving water almost exclusively from atmospheric precipita…
  53. Which major global biome is dominated by perennial grasses and forbs with very few trees due to low annual rainfall, seasonal droughts, and frequent wildfires, known as the Steppes in Eurasia?
  54. What term describes the complex network of interconnected and overlapping food chains within an ecological community, reflecting that most organisms consume and are consumed by multiple species?
  55. Which type of plant adapted to saline coastal or inland marsh environments possesses specialized root membrane barriers that filter out dissolved sodium chloride or excretes excess salt through leaf g…
  56. What term describes an introduced organism that establishes self-sustaining populations in a new non-native geographical ecosystem, outcompeting native wildlife and disrupting ecological balances?
  57. Which vertical canopy layer in a tropical rainforest comprises the tallest giant trees that tower 60 meters (200 feet) or more above the continuous forest canopy, exposed to intense sunlight and stron…
  58. What is the primary role of saprotrophic decomposers (bacteria and fungi) in a terrestrial ecosystem?
  59. Which cold, treeless high-altitude biome is found on mountain summits above the timberline across all latitudes, sharing harsh conditions with polar regions due to thin air, strong ultraviolet radiati…
  60. What term describes the natural benefits that purify air and water, decompose organic wastes, regulate local microclimates and pollinate crops at no direct cost to society?
  61. What term describes the natural ecosystem services that purify air and water, decompose organic wastes, regulate local microclimates, and pollinate agricultural crops without direct financial cost to…

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