7. AQA GCSE Biology: Ecology

Ecosystem - The interaction of a community of living organisms with the non-living parts of their environment What is a community made up of? - The populations of different species or organisms that are all interdependent in a habitat Habitat - The environment in which an organism lives Population - The total number of organisms of the same species living in the same geographical area Interdependence - The way in which each species within a community depends on other species for food, shelter, pollination, seed dispersal etc Competition - The process by which living organisms compete with each other for limited resources (such as food, light or reproductive partners) What do organisms require to survive and reproduce? - A supply of materials from their surroundings and from the other living organisms there What do plants often compete with each other for? (4) - Light, space, water, and mineral ions from the soil What do animals compete with each other for? (3) - Food, mates and territory Stable community - Where all the species and environmental factors are in balance so that population sizes remain fairly constant What happens if one species is removed from a community? - It can affect the whole community Abiotic factors - Non-living factors Biotic factors - Living factors Name 7 abiotic factors and how they might affect a community - Litmuswoc 1. Light intensity - photosynthesis, breeding cycles linked to day length 2. Temperature - photosynthesis/plant growth, therefore animals which can survive 3. Moisture levels - both plants and animals need water to survuve 4. Soil pH and mineral content - distribution of plants, most struggle to grow where there is few mineral ions; low pH inhibits decay and therefore release of mineral ions 5. Wind intensity and direction - shape of trees and landscape, increases plant transpiration 6. Availability of oxygen - aquatic animals e.g. fish require high levels of dissolved oxygen 7. Availability of carbon dioxide - photosynthesis Name 4 biotic factors and how they might affect a community - FPOP 1. Availability of food - food allows animals to survive and breed successfully 2. New predators arriving - organisms with no defences against these predators may die out 3. One species outcompeting another so the numbers are no longer sufficient to breed - e.g. grey squirrels in Britain 4. New pathogens - organisms have no resistance so populations can be wiped out