Ecology

• Habitat?

  The environment in which an organism lives
• Population?

  Total number of organisms of the same species living in the same geographical area.
• Community?

  Contains all living and non-living organisms in an environment
• Biotic


  Living factors
• Abiotic

  Non-living factors
• Ecosystem

  Both biotic and abiotic factors in an environment and how they interact
• Living organisms require a supply of materials from their surroundings eg water to survive or from other living organism - prey
• Problem of organisms eating other organism:

  they are often in short supply - have to compete with each other
• What/Who plants compete for?

  Light - space - water - minerals ions in the soil
• What do animals compete for?

  Food - water - mating partners - territory
• Interdependence

  All different species in a community depend on each other
• Some organisms provide shelter
• Plants can depend on animals like they depend on bees to spread their pollen
• If a species disappears from a community then it affects the whole community
• Stable community

  When the populations of the different species remain fairly constant - balanced
• 4 biotic factors

  Food

  New predator

  New pathogens

  Competition
• food

  Lions est animals - zebras eat plants - if the avaliability of food falls, number of organisms in that community will fall
• New predator 


  Cause population of a prey species to fall - also affects existing predators if competing for the same prey
• Competition

  If a species is outcompeted then population can fall so much that it can numbers are no longer sufficient to breed and species may be extinct.
• New pathogens

  If a disease emerges and spreads - can wipe out a species' population
• 7 different abiotic factors

  Light intensity

  Temperature

  Water

  pH and mineral soil content

  Wind intensity

  carbon dioxide

  oxygen
• Light intensity


  Abiotic: major effect on plants as they need it for photosynthesis - if the level of light is low - low rates of photosynthesis - plants grow slowly - animals that eat plants may not have enough
• Temperature


  abiotic: if temperature of an environment changes - causes the distribution of species to change - animals could migrate
• Water

  abiotic: needed to survive - but many species are adapted to having low levels of water
• pH and mineral soil content


  abiotic: many plants can't grow on soil which is too acidic or too alkaline - plants need certain minerals like nitrate which is used to make amino acids in proteins
• wind intensity

  abiotic: strong winds from the sea can cause plants to lose water - plants in sand dunes are adapted to reduce water loss
• carbon dioxide

  abiotic: used for photosynthesis - if CO2 levels fall then rate of photosynthesis can decrease
• oxygen


  needed for aerobic respiration - level of dissolved O2 in water can fall for eg on hot days - harmful to aquatic organisms
• Camels (structural adaptations)

  adapted to dry weather in deserts - hump of fat on back which is a thermal insulator - heat loss - reduces water loss from sweating; metabolic reactions can be used to produce water from the fat; thick coat of fur on upper part of body - insulator; leathery mouth - can chew plants which have thorns - good source of water; long eyelashes and hair in nostrils to prevent sand coming into their eyes; wide feet to prevent sinking into the sand
• Camels (functional adaptations)

  produce concentrated urine and dry faeces and it reduces water loss - can cope with intense heat of desert as they can tolerate very large changes in their body temp
• Kangaroo rat (behavioural adaptations)

  live in burrows during the day to protect them from predators and keep them cool - nocturnal - mainly active at night
• Arctic fox (structural adaptation)

  thick fur to provide insulation and reduce heat loss - has fur on soles of feet to reduce heat loss to the ice and snow - has small ears - reduces S.A of fox which reduces heat loss - it's coat is a source of camouflage to protect from predators
• Cactus

  adapted to live in dry conditions - have very small leaves which reduce water loss or have spines to reduce water loss and protect from animals - due to deserts dry conditions/doesn't rain they have extensive shallow roots which helps them catch a lot of water before it evaporates into ground and stores it
• Extremophiles

  Organisms adapted to live in extreme conditions
• Every Food chain starts with a producer which is important as they synthesise complex molecules
• Biomass

  the total mass of the living material that is found in an organism in a given area
• Consumers


  organisms that eat other organisms
• Predators


  Consumers who eat and kill other animals
• Prey


  Animal being eaten by another animal
• The numbers of predators and prey rise and fall in cycles and this is only true in a stable community