B15 B16 B17 - ecology

• What is habitat

  The environment an organism lives in
• what is a population

  total number of organisms of the same species living in the same geographical area
• what is a community

  populations of all the different species living in the same habitat
• what is biotic

  living
• what is abiotic

  non-living - amount of water and minerals in soil
• what is an ecosystem

  the biotic and abiotic parts of an environment and how they react
• recourses organisms compete for

  • plants - light, space, water, mineral ions in soil
  • Animals - food, water, mating partners, territory
• what is interdependence

  species in A community depend on each other
• biotic factors - availability of food

  • all animals eat living organisms
  • if availability if food falls the number of organisms will fall
• biotic factor - new predator

  • population of prey species to fall
  • can effect existing predators if competing for same prey
• biotic factor - competition

  • if a species is outcompeted a population can fall so much numbers are no longer sufficient to breed
  • extinction
• biotic factor - new pathogens

  • if an infectious disease emerges and spreads it can wipe out a population
• abiotic factor - light intensity

  • plants need light for photosynthesis
  • if light intensity is too low rate of photosynthesis falls
  • plants grow more slowly
  • animals which feed on plants may not have enough food
• abiotic factor - temperature

  • if temp changes distribution of species change
  • animals migrate
  • plant species disappear
• abiotic factor - water

  • many species are adapted to deal with low levels of water
  • Plants and animals need water to survive
• abiotic factor - soil

  • pH and mineral content of soil
  • Plants
  • Cannot grow when soil is too acidic or alkaline
  • Need nitrate from soil to age amino acids for proteins
• abiotic factor - wind

  • intensity and direction
  • Plants
  • Strong winds blowing inland from sea can cause plants to lose water
  • plants growing in sand dunes adapted to reduce water loss
• Abiotic factor - gases

  • carbon dioxide and oxygen
  • Carbon dioxide is needed for photosynthesis
  • If co2 levels fall rate of photosynthesis decreases
  • Oxygen is needed for aerobic respiration
  • Level of oxygen stays fairly constant in air
  • Dissolved oxygen in water can fall on hot days
  • Harmful to aquatic organisms
• how do camels adapt

  • hot and dry conditions
  • hump on back to store fat - thermal insulator - reduces water loss from sweating
  • Thick coat on upper surface - insulator
  • leathery mouth - chew desert plants with thorns - good source of water
  • Long eyelashes - keep dust out of eyes
  • Wide feet - prevents sinking into sand
  • Concentrated urine and dried poo - reduce water loss
  • Can tolerate changes in body temp
• what are functional adaptations

  Adaptations to the body function of an organism
• what what are structural adaptationd

  change of body shape or body structure
• what are behavioural adaptations

  adaptations to lifestyle or behaviour
• Kangaroo rats adaptations

  • nocturnal - avoid heat of daytime
  • Live in burrows - keeps cool and protected from predators
• Artic fox adaptations

  • very thick fur - insulation and reduces heat Loss
  • Thick fur on feet - reduces heat loss to ice and snow
  • Very small airs - reduces surface area
  • white fur - camo for hunting
• Cactus adaptations

  • dry conditions
  • very small leaves to reduce water loss
  • Some cacti have no leaves only Spines
  • Spines protect cactus from animals
  • Extensive and shallow roots - catch as much water
  • Store water in stem - months without rain
• What are extremophiles

  Organisms adapted to live in extreme conditions
• adaptations of deep sea vent - extremophile

  • deep sea bed - high temp and pressure
  • bacteria are extremophiles
  • live in very high concentrations of salt
• What is the producer

  • Start of food chain
  • most food chains is a green plant
  • Could be algae or seaweed
  • Synthesise complex molecules/biomass
  • Biomass passes down food chain
• what are primary consumers

  • eat producers
• what is the secondary consumer

  • eats primary consumers
• what is tertiary consumer

  • eats a secondary consumer
• what are predators

  • consumers that kill and eat other animals
• what is prey

  animal being eaten
• Predator and prey graph

  • number of predators and prey rise and fall in cycles
  • Population of prey increases - predator population increases - population of prey falls - population of predator falls
  • Only true in stable community
• what is a stable community

  al abiotic and biotic factors are in balance
• 2 types of sampling

  • random sampling
  • Sampling across a transect
• what is random sampling

  • compare number of organisms in different areas
  • use quadrat - wooden or plastic square
  • count number of organisms in quadrat
  • plants or slow moving organisms
• total population size equation

  (total area / area sampled) x number of organisms in sample
• transect sampling

  • investigate wether number of species change across a habitat
  • tape measure or rope
  • quadrat to count organisms at intervals on transect
• Sampling required practical

  • to estimate an organisms population, or to observe population density change over a distance
  • Place 1m$^2$ quadrant in random grid positions and count organisms (ideally sample 10% of total area)
  • Calculate mean number per m$^2$ then multiply by total area to give an estimate of total population
  • To observe variation in population density over distance, move quadrant along a transect and record number per m$^2$
  • Plot density against distance