The organism in the environment - Paper 1 Flashcards
What is the definition for an ecosystem?
The interaction of all the organisms in a specific area and the environment around them. It includes all the biotic and abiotic factors that are present
What is the definition for a community?
All the organisms of different species that live in an ecosystem
What is the definition for a population?
All the individual of a particular species living in a particular habitat
What is the definition for a habitat
A place within an ecosystem with specific physical characteristics where a particular species is commonly found.
What is the definition for biodiversity
The variety of different species found in the community of an ecosystem
What are the different abiotic factors?
- temperature
- light
- pH
- Water and humidity
How does temperature (abiotic factor) affect and ecosystem?
- each species has an optimum temperature at which it can survive
- the further away from the optimum, the smaller the population that can be supported
- as temperature falls below optimum, enzyme activity slows down so metabolic waste is reduced
- above optimum, enzymes are denatured so chemical reactions decrease and the population grows more slowly
How does light (abiotic factor) affect an ecosystem?
- light is a necessity of life, it is the ultimate source of energy
- as light intensity increases, so does the rate of photosynthesis
- the greater the rate of photosynthesis, the faster plants grow and the more spores/ seeds they produce
- animals feed on these plants, so their population increases
- where light is limited, e.g in a cave or forest floor, population sizes are small or the species may be absent altogether
How does pH (abiotic factor) affect an ecosystem?
- affects the action of enzymes which have an optimum pH at which they work best
- appropriate pH= larger population of organisms
- very different pH = smaller/non existent population
- affects water, so affects populations in (e.g) ponds
- acid rain lands on soil so affects plants
How does water and humidity (abiotic factor) affect an ecosystem?
- where water is scarce, populations consist of those species which are well adapted to living in dry conditions
- humidity affects transpiration rates in plants and the evaporation of water from the bodies of animals
- in dry conditions, the populations of species adapted to tolerate such conditions is larger that those with no such adaptations
What are the different biotic factors?
- competition
- predation
- disease
How does competition (biotic factor) affect an ecosystem?
- individuals compete for scarce resources
- they may be competing with other individuals of the same species, e.g for mates
- or they may be competing with individuals of another species e.g for food, territory, water, light or shelter.
- the species that are best adapted to their environment will be better at competing and so will be more likely to win and their population size will increase.
How does predation (biotic factor) affect an ecosystem?
- population size is affected by predation
- the introduction of a new predator to an ecosystem, for example a new fox in the area, will have a direct effect on the size of the population of the prey species, for example the rabbit population size would decrease.
- similarly, if the prey species decreased, e.g because of disease, the predator species population size would decrease as predators struggle to find food and die of saturation.
How does disease (biotic factor) affect an ecosystem?
- pathogens living in an ecosystem may cause disease in some species
- this will directly affect the particular species and the size of its population will decrease, but it may also indirectly affect any species that rely on the affected species of food.
