Ecology By: Samuel Koh (2i4) (17)

Ecology Study of interactions – between organisms – between organisms and their surroundings

Environment Environment  Surroundings Biotic environment  living environment – Living things that an organism interact with Abiotic environment  physical environment – Physical factors such as light intensity, water and pH Biome – A large community in a distinct region defined by their dominant vegetation and climate – Grassland, tropical rainforest, desert, etc.

Biotic environment Organisms are interdependent – Food web Biological balance – Whole ecosystem affected by any change

Abiotic environment Animals and plants are directly affected by physical factors All animals depend on plants for food whether indirectly or directly – Plant  Herbivore  Carnivore Physical factors determine the types of plants in an environment, indirectly affecting animals

Water – Animals need water to survive – Plants need water for photosynthesis – Dependent on rainfall Adaptive features – Some animals have gills, fins, webbed toes or a streamlined body for wet environments – Plants such as cacti have needles instead of leaves to conserve water and fleshy stems to hold water

Light Intensity Light intensity – Sunlight needed for animals to see – Sunlight needed for plants to photosynthesise Adaptive features – echolocation for dark places – dense covering of hairs on leaves to reduce rate of transpiration in environments with high light intensity

Temperature – Extreme temperatures that are too high or low kills animals which are not adapted to it – Affects metabolism of organisms Adaptive features – Plants adapt to temperatures by shedding leaves to limit water loss – Some plants have needles instead of leaves, with adaptations such as a waxy coating to prevent water loss through transpiration

pH – Organisms are adapted to the pH of water in their environment to the point where extreme or sudden changes in pH can kill them – Soil pH also affects the type of plants that live there Adaptive features – Some fish can adapt to gradual changes in pH, and if they are born in water with a certain pH level, they would be more acclimated to that pH level, even if it is not their normal pH level

Oxygen level Oxygen content – Most organisms require oxygen for respiration – Plants produce oxygen through photosynthesis Adaptive features – Some organisms do not require oxygen for growth – Mangrove plants have breathing roots because of the low oxygen content in water – Some organisms have slower metabolisms to survive using little oxygen

Salinity – Salt concentration in water – Organisms in sea water lose water by osmosis – Organisms in fresh water gain water by osmosis Adaptive features – Fresh water fish have scales which reduce water diffusion and adaptations to retain salt such as gills which diffuse dissolved gasses but not salts – Saltwater fish have rigid cell walls to prevent cells from bursting – Some specialised fish such as salmon and eels can survive in freshwater and saltwater

Adaptation Organisms adapt to their environment, either behaviourally or structurally “Survival of the fittest” – Organisms with features that enable to them to survive in environment – Higher chance of surviving and passing on these traits

Individuals Ecosystem Community Populations are groups of is a group of Environment AbioticBiotic

Flow of energy The source of energy is the Sun, whether indirectly or directly The flow of energy is linear Energy is lost to the environment through heat due to respiration and decomposition Scavengers feed on dead organisms Decomposers break down faeces and dead organisms

Nutrient Cycle Nutrients in soil Producers such as plants Consumers such as herbivores Dead bodies and faeces are broken down by decomposers

Carbon Cycle Carbon Dioxide Plants Animals Photosynthesis Respiration Feeding Respiration and Decomposition

Online Quiz Both are very simple, but a hint for the first link would be that density dependent factors are factors that depend on population density, such as food and water. Density independent factors are the exact opposite, factors which do not depend on population density such as light intensity or temperature m m m m

Bibliography m m maintaining-ecosystem-functioning/ maintaining-ecosystem-functioning/