Ecosystems Test PDF

What is ecology? The study of how organisms interact with each other and with their environment. Environment = all the factors, both living and non-living, in an organism’s surroundings that affect it, e.g temperature, rainfall, the presence of other organisms. Habitat = the place where an organi...

What is ecology? The study of how organisms interact with each other and with their environment. Environment = all the factors, both living and non-living, in an organism’s surroundings that affect it, e.g temperature, rainfall, the presence of other organisms. Habitat = the place where an organism lives. Ecosystems An ecosystem is a system formed by a group of living things, interacting with each other and their non-living surroundings. The three main components of an ecosystem are: 1. Physical surroundings such as rocks, soil and water 2. Living organisms (the community) 3. Living and non-living factors that make up the environment, Eg. competition for food and amount of rainfall Factors influencing organisms Organisms in an ecosystem are affected by: Abiotic factors: non living things and Biotic factors: living things and interactions involving living things Factors influencing organisms Abiotic Biotic Temperature Population numbers Light Intensity Competitors Texture and pH of soil Collaborators Availability of water Predators Concentration of gases in water Disease causing organisms and or air parasites Availability of mates Interactions between living things Competition: occurs when organisms both try to obtain the same resource. Resources include, food, shelter and available mates Competition can be: Intraspecific: between members of the same species Interspecific: between members of different species Task: Give one example for both intraspecific and interspecific competition. Collaboration When living things interact in a way that provides benefit Examples: Dolphins hunting in packs Meerkats living in groups for protection against predators Mutualism When two organisms live closely together and both benefit. Example: The oxpecker bird eats the parasites (fleas and ticks) on the antelope Commensalism Where one organism benefits and the other is unaffected. Example: A possum living in a tree hollow The possum gains shelter, the tree is unaffected  Parasitism Where one organism lives on or in another organism (the host) and feeds off it. The host is usually harmed but not always killed. Example: A parasitic wasp lays its eggs on a caterpillar which will hatch and eat the caterpillar.. Summary 9.2 Sustainability Sustainability Most natural ecosystems are sustainable. This means they are capable of maintaining living conditions for the community. - A supply of matter - Energy - A large range of species Food chains: Producers Organisms such as green plants which are able to produce their own food (nutrition) through photosynthesis. Photosynthesis is the process whereby plants take in carbon dioxide through their leaves and water through their roots and using energy from sunlight, convert the CO2 and H2O into sugars (glucose) Photosynthesis equation Consumers Organisms such as animals that are unable to produce their own food. They must consume (eat) other organisms such as plants or animals to obtain their nutrition. Types of consumers Herbivores: only eat plants Omnivores: eat both plants and animals Carnivores: only eat other animals Food chains Food chains ○ Start with a producer ○ End with a consumer ○ Show the levels of consumers Decomposers Decomposers are organisms such as fungi and bacteria which break down dead materials and waste and recycle matter and nutrients back into the soil for producers to reuse. Energy flow in ecosystems The arrows on a food chain show the flow of energy in an ecosystem Uses of energy Living things use energy: To build new cells needed for growth and repair To provide energy for movement and internal processes Living things also lose energy as heat. Because living things use the energy they gain from food, only approx. 10% of all the energy found at each level in a food chain is passed onto the next level. Energy flow The progressive loss of energy along food chains explains why the chains are short. Rarely will they have more than four steps. There is little energy available to organisms by the time it reaches the end of the chain. This limits the number of organisms found at each level. Pyramid of Biomass Show the total mass of organisms at each stage of a food chain. These pyramids can be used to show the productivity of an area – how well the area supports life. Natural and Human Impacts Natural and Human Impacts How could this ecosystem be affected by drought? Abiotic factors: Biotic factors: Natural and Human Impacts How could this ecosystem be affected by introduced species? Abiotic factors: Biotic factors: Natural and Human Impacts How could this ecosystem be affected by chemical pesticides? Abiotic factors: Biotic factors: Natural and Human Impacts How could this ecosystem be affected by over fishing? Abiotic factors: Biotic factors: Earth’s Spheres