Decomposition and Nitrogen Cycle Quiz

Decomposition

• Living things are composed of elements.
• Decomposition returns these elements to the air and soil after death or waste release.
• Bacteria and fungi are the primary decomposers.
• Decomposition rate depends on three factors:
  • Temperature: Warmer temperatures accelerate enzyme-driven microbial reactions, increasing decay speed.
  • Water content: Moist environments promote decay, as microbes need water to function.
  • Oxygen availability: Abundant oxygen accelerates decay, as many microbes require it for aerobic respiration.
• Food preservation slows decomposition by reducing suitable conditions for microbial survival and reproduction.
  • Refrigerating/freezing lowers temperatures to slow/stop microbial reproduction.
  • Airtight containers prevent microbial entry and sterilization kills them.
  • Drying food removes water, making survival impossible.

Nitrogen Cycle

• The atmosphere is ~78% nitrogen gas (N2).
• N2 is inert and unusable by plants and animals.
• Nitrogen must be converted to nitrates for plant use.
• Decomposers break down proteins in dead organisms and waste to return nitrogen to the soil.
• Nitrogen fixation converts atmospheric N2 into usable nitrogen compounds in the soil.
• Lightning provides the energy to convert N2 to nitrates.
• Decomposers break down organic matter releasing ammonia (NH3).
• Microorganisms (ammonia to nitrites, then to nitrates) convert ammonia to plant-usable forms.
• Nitrogen-fixing bacteria convert atmospheric N2 to ammonia.
• Denitrifying bacteria convert nitrates back to atmospheric N2.
• Some nitrogen-fixing bacteria reside in soil/roots of legume plants, forming a symbiotic relationship.

Water Cycle

• Solar energy evaporates water.
• Warm water vapor rises and cools.
• Condensation creates clouds.
• Precipitation (rain, snow, hail) provides fresh water.
• Water flows into bodies of water, repeating the cycle.
• Lack of precipitation causes drought.
• Desalination produces potable water by removing salts from seawater.
• Thermal desalination boils water, separating water vapor from salt.
• Reverse osmosis forces water through a membrane, separating it from salts under pressure.

Conservation and Biodiversity

• Biodiversity can be maintained and conserved through various methods.
• Human activity often reduces biodiversity, but some activities increase it.
• Reforestation in deforested areas increases biodiversity by providing habitats.
• Careful planning of reforestation efforts maximizes biodiversity by introducing diverse tree species.
• Species conservation schemes protect endangered species by:
  • Protecting natural habitats.
  • Establishing protected areas outside natural habitats (e.g., zoos).
  • Captive breeding programs to increase populations.
  • Seed banks for preservation of rare species.
• Maintaining biodiversity benefits humans by:
  • Ensuring food security.
  • Preventing damage to food chains.
  • Providing future medicines.
  • Supporting cultural aspects.
  • Fostering ecotourism.

Carbon Cycle

• Carbon is a finite element within the Earth.
• Photosynthesis is the entry point for atmospheric carbon dioxide into the cycle.
• Plants convert carbon to carbohydrates, proteins, and fats.
• Animals consume plants and acquire carbon compounds.
• Respiration releases carbon dioxide (CO2) from both plants and animals.
• Decomposition releases CO2 from dead plants/animals by microorganisms.
• Burning of fossil fuels (wood, etc.) also releases CO2 back into the atmosphere.

Investigating Ecosystems

• Quadrat sampling measures the proportion of different components in a 1m² area.

Food Security

• Increasing population and dietary shifts toward meat and fish negatively impact food security.
• There's less energy and biomass at higher trophic levels.
• Overfishing and environmental changes (climate change, soil pollution) pose risks to food security.
• Sustainability aims to meet current needs without impacting future generations.

Indicator Species

• Indicator species (sensitive to environmental changes) show human activity's impact.
• Water pollution can be indicated by oxygen-sensitive species (e.g., stonefly larvae, freshwater shrimp).
• Air pollution affects lichen types (e.g., clean air: green, fluffy lichens; polluted air: crusty lichens).

Ecosystems

• Ecosystems have different organizational levels:
  • Individual: a single organism
  • Population: all organisms of one species in a habitat

Human Impacts on Biodiversity and Eutrophication

• Human activities sometimes negatively impact biodiversity.
• Fertilizers leach into water bodies, causing eutrophication.
• Eutrophication: excess nitrates from fertilizers cause rapid algae growth, light blockage, plant death, and decomposition.

Food Chain, Tropic Layers, and Energy Transfers

• Energy transfer efficiency: = (energy transferred to next level / energy available at previous level) x 100
• Biomass transfer efficiency is calculated similarly.
• Trophic levels represent feeding positions in the food chain.