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
... [Show More] 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 -
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