Unit 7 Definitions Flashcards
Ecosystem
Self-contained unit made up of biotic and abiotic factors in the area
Population
Group of individuals of the same species in a habitat
Community
Organisms of all species that live in the same area
Habitat
Place where an organisms normally lives
Niche
All the conditions and resources required for an organisms to survive and reproduce
Random sampling
Sampling a population to eliminate bias
Systematic sampling
Regular sampling across an area
Mark release recapture
Method of estimating population size of animals
(Marked in 1st sample X no. In 2nd sample)/marked in 2nd sample
Abiotic factors
Concerned with non-living part of the environment
Biotic factors
Concerned with living part of the environment
Interspecific competition
Competition between organisms of different species
Intraspecific competition
Competition between organisms of the same species
Energy
Ability to do work
Phosphorylation
Process of adding a phosphate group (e.g. ADP ->ATP)
Light dependent reaction
Stage of photo synthesis in which light energy is required to produce ATP and reduced NADP
Light independent reaction
Stage of photosynthesis which does not require light energy directly, but does need the products of the light dependent reaction to reduce CO2 and form carbohydrate.
Oxidation
Loss of electrons, combining oxygen with a substance
Reduction
Gain of electrons, loss of oxygen from a substance
Electron carrier molecules
A chain of carrier molecules along which electrons pass, releasing energy in the form of ATP as they do so.
Photolysis of water
Light energy splits water molecules, yielding electrons, hydrogen ions and oxygen (from LDR)
Calvin cycle
A biochemical pathway (part of LIR) where CO2 is reduced to form carbohydrate.
CO2 + RuBP –> GP –> TP –> Glucose or RuBP
Limiting factor
A variable that limits the rate of a chemical reaction
Glycolysis
First part of cellular respiration to which glucose is broken down (in the cytoplasm to 2 molecules of pyruvate
Link reaction
Process linking glycolysis to the Krebs cycle (in the matrix of the mitochondria), where the 2 molecules of pyruvate are converted to CO2 and acetylcoenzyme A
Krebs cycle
Introducing acetylcoenzyme A into a cycle of oxidation-reduction reactions (in the matrix of the mitochondria) that yield some ATP and a large number of electrons
Electron transport chain
Use of electrons from the Krebs cycle to synthesise ATP via a series of oxidation-reduction reactions
Anaerobic respiration
Releasing energy from glucose without oxygen (produces lactate in animals and ethanol in plants and some micro-organisms)
Trophic level
Each stage in a food chain
Consumers
Organism that obtains its energy by feeding on other organisms
Gross production
Total quantity of energy that the plants in a community convert to organic matter
Net production
Gross production-respiratory losses
Energy transfer
(Energy available after the transfer/energy available before the transfer) X 100
Pyramid of number
A pyramid drawn with bar lengths proportional to the number of organisms present
Pyramid of biomass
Pyramid drawn with bar lengths proportional to the mass of plants/animals
Pyramid of energy
A pyramid drawn with bar lengths proportional to the energy stored in organisms
Biological control
Controlling pests by introducing predators
Selective breeding
Breeding of organisms by human selection of parents for certain characteristics
Saprobiontic micro organism
An organism that gets it food from the dead or decaying remains of other organisms
Green house gases
Gases such as methane and CO2 which trap more heat energy, raising the earths temperature
Ammonification
Production of ammonia from e.g. Urea and proteins
Nitrification
Converting ammonia into nitrites and the nitrates
Nitrogen fixation
Conversion of nitrogen gas intro nitrogen-containing compounds
Denitrification
Conversion of soil nitrates into nitrogen gas
Leaching
Process by which nutrients are washed from the soil into watercourses
Eutrophication
Consequence of an increase in nutrients in watercourses that leads to a decrease in biodiversity
Succession
The changes in an ecosystem, over time, of the species that occupy it
Pioneer species
A species that can colonise bare rock or ground
Climax community
The stable, final, community that exists in a balanced equilibrium
Conservation
Management of the Earth’s natural resources in such a way that maximum use can be made of them in the future.
Genotype
The genetic composition of an organism
Phenotype
The characteristics of an organism, resulting from its genotype and the environment
Gene
A length of DNA that codes for a polypeptide
Allele
One form of a gene
Homologous chromosomes
A pair of chromosomes that have the same gene lock and determine the same features
Dominant
An allele that is always expressed in the phenotype
Recessive
An allele that is only expressed in the phenotype when there is another identical allele
Heterozygous
When the alleles are different for a particular gene
Homozygous
When the alleles are the same for a particular gene
Sex linkage
Any gene that is carried in the X or Y chromosome
Co-dominance
Both alleles are equally dominant and are both expressed in the phenotype
Multiple alleles
More than two possible alleles for a particular gene
Gene pool
All the alleles of all the genes of all in the individuals in a population at any one time
Allelic frequency
The number of times the allele occurs within a gene pool
Stabilising selection
Selection that favours average individuals
Directional selection
Selection that favours individuals at one extreme
Speciation
The evolution of new species from an existing species
Geographical isolation
When a physical barrier prevents two populations from breeding with one another
