Unit 5 - Populations In Ecosystems Flashcards
Definition of a population?
A population is individuals of the same species occupying one area, at one time, that can potentially interbreed.
Definition of a community?
A community is all the populations of all the species in one area at one time.
Definition of an ecosystem?
An ecosystem consists of the community and the non-living components of its environment.
Definition of a niche?
A niche is the role an organism plays in the ecosystem and how it interacts with the biotic and abiotic factors.
Definition of carrying capacity?
The maximum population size an ecosystem can support.
Population size can vary as a result of?
1) The effect of abiotic factors
2) Interactions between organisms (biotic) : interspecific and intraspecific competition.
Definition of an abiotic factor?
It is a non-living factor which affects the distribution of an organism.
Definition of a biotic factor?
A biotic factor is a living factor which affects the distribution of an organism.
How does temperature act as a abiotic factor?
If the temperature is too cold, enzymes have less kinetic energy, slowing metabolic reactions, such as respiration, which happen too slowly.
If the temperature is too high, enzymes may start to denature, preventing metabolic reactions and reducing survival.
Temperature can be measured using a thermometer or data logger with temperature probe.
How does light intensity act as an abiotic factor?
Light is needed for photosynthesis therefore the higher the light intensity, the greater the rate of photosynthesis. As plants photosynthesis more, more glucose is produced for a higher rate of respiration. More ATP is made to provide energy for seed/spore production and more growth.
Light intensity can be measured using a light meter.
How does water availability and humidity act as an abiotic factor?
All organisms need water. It acts as a solvent in cells to increase rate of reactions and is used in hydrolysis reactions. In plant cells it provide turgidity and is required for photosynthesis.
Organisms tend to lose water to the environment by evaporation. However, evaporation can be useful e.g. in lowering body temp.
The lower the humidity of the environment, the more water loss occurs.
Humidity can be measured using a whirling hygrometer or data logger with humidity probe.
How does pH act as an abiotic factor?
The pH of the environment, such as the soil or water, can affect enzyme rate of reaction and proteins such as carrier proteins in membrane. The further from the optimum pH the more the proteins/enzymes denature. The more the extreme the pH, the smaller the species richness present as there are less species adapted to survive extreme pH’s.
pH can be measured using an indicator or pH probe with a data logger.
Definition of intraspecific competition?
It is competition between members of the same species.
Definition of interspecific competition?
It is competition between members of different species.
Explain the trend in predator and prey graphs?
-Initially there is an increase in the prey population.
-More prey provides more food for predators.
-So after a delay, there is an increase in predator population.
-Predators eat more prey so the prey population decreases.
-With less food to eat the predator population then decreases as they die due to starvation.
-So then the prey population increases as less are being eaten and the cycle starts again.
