populations

• Population is the total number of individuals of one species living within an area at any given time.
• Ecology: The study of living organisms within a habitat and their interactions with both biotic and abiotic factors
• Ecosystem: A characteristic community of interdependent species interacting with the abiotic components of their habitat
• Habitat: The place in which an organism lives
• Population: A group of interbreeding organisms of the same species occupying a particular habitat
• Community: Interacting populations of two or more species within a particular habitat
• Environmental Resistance: Environmental factors that slow down population growth
• Biotic factors: Living factors within the environment, e.g. pathogens and predators
• Abiotic factors: Non-living environmental factors, e.g. air temperature, oxygen availability
• Niche: The specific role and position a species plays within a particular ecosystem
• Carrying capacity: The maximum number of individuals a population can sustain within a particular environment
• Intraspecific: Competition between members of the same species
• Interspecific: Competition between members of different species
• Random sampling: Method of sampling when abiotic factors are uniform
• Systematic sampling: Method of sampling when there is a change in abiotic factors
• Photosynthetic efficiency: A measure of the ability of a plant to absorb light energy
• GPP: The rate of production of chemical energy in organic chemicals by photosynthesis (kJ m-2 year-1)
• NPP: Gross primary productivity minus the energy used up by the producers in respiration in a year
• Biological productivity: The rate at which biomass accumulates in an ecosystem
• Secondary productivity: The rate at which consumers accumulate energy from assimilated food in biomass in their cells of tissues
• Biomass: The dry mass of organic matter of a group of organisms in a particular habitat
• Population Growth: Population numbers fluctuate depending on factors like birth rate, death rate, immigration, and emigration
• Population growth curve for an equilibrium species: Controlled within a stable habitat through competition, with phases like lag, exponential, stationary, and death
• Factors Affecting Population Size: Density dependent and density independent factors influence population growth
• Competition: Intra-specific competition (within the same species) and inter-specific competition (between different species) impact breeding success and survival
• The Concept of Niche: Only one species can occupy a particular niche within an ecosystem
• Sampling Techniques: Methods like random sampling, transects, and kite diagrams are used to study species abundance and distribution
• Energy Flow Through an Ecosystem: Producers, consumers, detritus, and decomposers play roles in energy flow within ecosystems
• Dead particulate organic matter is called detritus
• Decomposers feed from every trophic level
• Ecosystems rarely support more than 5 trophic levels because a lot of energy is lost through processes like respiration and excretion
• Light energy from the sun trapped by photosynthesis provides energy for almost all ecosystems
• Photosynthetic efficiency is a measure of a plant's ability to absorb light energy
• Gross primary productivity (GPP) is the rate of production of chemical energy in organic chemicals by photosynthesis
• Net primary productivity (NPP) is GPP minus the energy used up by producers in respiration, representing the energy in the plants' biomass
• NPP represents the potential food energy available to heterotrophs in ecosystems
• Consumers don't take all the potential energy because some parts of plants are inedible, indigestible, and wrong wavelengths for absorption
• Biological productivity is the rate at which biomass accumulates in an ecosystem
• Secondary productivity is the rate at which consumers accumulate energy from assimilated food in biomass
• Energy is lost in food chains through egested molecules, heat generated in respiration, and inedible parts of animals