IB Biology - Unit 4 - Ecology SL/HL IB biology 11 SL Ecology topic. 2023 (A+)

IB Biology - Unit 4 - Ecology SL/HL IB biology 11 SL Ecology topic. 2023 (A+) Species - Answer-A group of organisms that can interbreed and produce fertile offspring. Habitat - Answer-The environment in which a species normally lives or the location of a living organism. Population - Answer-A group of organisms of the same species who live in the same area at the same time. Two populations in the same species that are separated from each other may develop differences in character, but they are considered the same species until they can no longer interbreed. Community - Answer-A group of populations living and interacting with each other in an area. There are various different types of relationships between species. all species are dependant on relationships with other species for long-term survival. Ecosystem - Answer-A community and its abiotic environment. Organisms depend on their non-living surroundings or the abiotic environment. Inorganic Nutrients - Answer-Both autotrophs and heterotrophs obtain inorganic nutrients form the abiotic environment. Carbon, hydrogen, and oxygen are needed to make carbohydrates, lipids, and other carbon compounds. Nitrogen and phosphorus are also needed to make these compounds. About 15 other elements are needed by living organisms. Ecology - Answer-the study of relationships between living organisms and between organisms and their environment. Nutrient Cycles - Answer-The recycling of chemical elements which is crucial for the long term survival of an ecosystem. There are various cycles included, such as the carbon cycle and the nitrogen cycle. Sunlight and Ecosystems - Answer-Energy cannot be recycled, so sustainability depends on continued energy supply. Sunlight is needed as the initial source of energy is from the sun. It is used by both autotrophs and heterotrophs. Energy conversion - Answer-Light energy is converted into chemical energy by photosynthesis. Respiration and Energy Release - Answer-The oxidisation of carbon compounds (e.g. glucose) in cell respiration turns these compounds into ATPs. The second law of thermodynamics states that energy transformation is never 100% efficient: some of the energy is turned into heat instead of ATP. Heat Energy - Answer-Heat energy cannot be converted into any other form of energy by a living organism. Heat is eventually lost to the abiotic environment. Energy Losses in Ecosystems - Answer-Energy is lost when moving from one trophic level to another, limiting the biomass of higher trophic levels. Not all of the organism is digested (we eat cow meat, but we don't eat the teeth or the fur). Uneaten materials are passed on to saprotrophs and detritivores. Not all parts of food ingested by organisms are absorbed. Energy in faeces is instead passed to saprotrophs and detritivores. Autotroph - Answer-An organism that synthesises its carbon compounds from simple substances such as CO2. In other words, they are self-feeding. Examples of autotrophs include photosynthesising plants and algae (which absorb light). Photosynthesis - Answer-Organisms use sunlight to synthesise nutrients from carbon dioxide and water. It is carried out in the chloroplasts. Mixotroph - Answer-An organism that is not exclusively autotrophic or heterotrophic. Heterotroph - Answer-An organism that obtains carbon compounds from other organisms e.g. humans. They are divided into groups: consumers, detritivores, and saprotrophs. Consumer - Answer-A consumer is a heterotroph which feeds on organisms by ingestion, meaning they digest it and absorb the products of the digestion. The organisms consumed are either alive or dead for a short time. e.g. Mosquitos, lions. Multicellular consumers versus unicellular heterotrophs: - Answer-Multicellular consumers, such as lions, take food into their digestive systems, while unicellular, such as Paramecium, consumers take food in by endocytosis digest food in vacuoles. Trophic Groups - Answer-Consumers are divided into trophic groups depending on what organisms they consume. Primary consumers feed on autotrophs, and secondary consumers feed on primary consumers... Detritivore - Answer-A heterotroph that ingests non-living organic matter. They eat dead plants, feathers/hairs, faeces, etc. They are important as they prevent dead organic matter from building up. They include earthworms and the larvae of dung beetles. Saprotroph - Answer-A heterotroph that digests externally. Saprotrophs secrete digestive enzymes into dead organic matter, then absorbs the products of digestion. They are also known as decomposers. Saprotrophs are important as they break down carbon compounds in dead organic matter so they can be used again by other organisms. Continues...