B7 - Ecology

• Habitat - the place where an organism lives
• Population - all of the organisms of one species living in a habitat
• Abiotic factors - non-living factors of the environment e.g temperature
• Biotic factors - living factors of the environment e.g food
• Ecosystem - the interaction between a community of living organisms and the abiotic environment
• Plants compete for:

  • Light
  • Space
  • Water
  • Mineral ions
• Animals compete for:

  • Space / territory
  • Food
  • Water
  • Mates
• A major change to the ecosystem (e.g a species going extinct) can have knock on impacts due to interdependence
• Stable community - species and environmental factors are in balance so population sizes stay roughly constant
• Abiotic factors:

  • Moisture level
  • Light intensity
  • Temperature
  • CO2 level
  • Wind intensity / direction
  • Oxygen level
  • Soil pH / mineral content
• Decrease in light intensity / temperature / CO2 could decrease rate of photosynthesis affecting growth and population size
• Decrease in mineral content could cause deficiencies and decrease growth and population size
• Biotic factors:

  • New predators
  • Competition
  • New pathogens
  • Food availability
• New predators could reduce the prey population, causing food shortages
• Adaptations:

  • Structural - features of an organisms body e.g shape / colour
  • Behavioural - organisms actions e.g migration
  • Functional - happen internally related to processes like metabolism e.g hibernation
• Microorganisms have many adaptations to live in a variety of environments e.g extremophiles live with high temperatures / pressures
• Food chain:

  • Arrows show direction of energy transfer
  • Producers e.g plants
  • Primary consumers e.g rabbits
  • Secondary consumers e.g foxes
• Predator / prey population cycle:

  • Prey population increase
  • Predators eat more and population increases
  • Prey are eaten and population decreases
• Quadrat practical:

  1. Place quadrat square in a sunny area
  2. Count number of each plant / organism
  3. Move quadratic to shady are
  4. Count again
  5. Compare numbers (you can repeat for mean)
• Transect practical:

  1. Mark a line with measuring tape e.g from a hedge to field centre
  2. Collect data by counting organisms along the line or quatrats
• Water cycle:

  1. Energy from the sun evaporates water from land and sea (evaporating from plants is transpiration)
  2. Water vapour rises, then cools and condenses to form clouds
  3. Precipitation falls from the clouds onto land
  4. It drains into the sea
• Carbon cycle:

  1. CO2 removed from atmosphere by plants and turned into carbon, then carbohydrates, fats, proteins
  2. Plants respire, returning some CO2 to the atmosphere
  3. Plants are eaten, and the carbon transfers to the animal
  4. Animals respite, returning CO2 to atmosphere
  5. Plants and animals die, they are eaten by animals and microorganisms who respite, returning CO2
  6. Animal waste is broken down by microorganisms
  7. Combustion releases CO2 also
• 1. Plants turn minerals from the soil into compounds that make up living organisms
  2. The minerals are returned to the soil in waste products, or when animals die and decay
  3. Material decay when they are digested by microorganisms. This happens faster in warm, moist, aerobic conditions
  4. Decay returns minerals to the soil
  5. In a stable community, minerals taken out and returned are balanced in a cycle
• Biodiversity - the variety of different species of organism on earth, or within an ecosystem
• Biodiversity is important to keep ecosystems stable, however, it is affected by human actions e.g waste production, deforestation, global warming
• Earth's population is increasing exponentially due to modern medicine and farming
• Humans are using up more raw materials due to:

  • More people
  • Higher demand for luxuries / more posessions
• Humans are polluting more:

  • Water - sewage and chemicals (e.g pesticides) pollute water sources
  • Land - chemicals for farming, buried nuclear waste, landfill
  • Air - smoke and acidic gases released by production
• Global warming:

  • Earth's temperature is a balance between energy recieved and reflected from the sun
  • Gases in the atmosphere insulate the earth and keep it acceptably warm
  • However, more gases produced causes more heat to be trapped, overheating the earth
• Global warming consequences:

  • Sea level rising
  • Changes in species distribution
  • Changes in migration pattern
  • Reduction in biodiversity
• Land use:

  • Himans use land for building, farming, waste disposal
  • This means less land for other organisms
  • Deforestation, habitat destruction
• Peat bog destruction:

  • Bogs are full of semi-decayed plants which form peat
  • Carbon is stored in the peat instead of released to the atmosphere
  • When peat bogs are drained, the plants get fully digested by microorganisms and release CO2
  • Peat is also burnt as fuel
  • Also destroys habitats
• Deforestation problems:

  • They absorb less CO2
  • CO2 released when plants are burnt / decay
  • Habitat destruction / loss of biodiversity
• Protecting biodiversity:

  • Breeding programmes - breeding in captivity to release
  • Habitat protection - protection and regeneration of endangered habitats
  • Preventing global warming - reducing deforestation / emissions
  • Reducing waste - reusing / recycling
• Biodiversity maintenance negatives:

  • Cost of programmes
  • Affect on local economy e.g loss of employment
  • Food security - pests normaly killed to protect livestock
  • Demand for land for housing / farming