Chapter 19 - Populations in ecosystems Flashcards
What is ecology?
Studying the inter-relationships between organisms and their environment
What are abiotic factors?
Non-living
What are biotic factors?
Living
What are the two major processes to consider in an ecosystem?
The flow of energy
The recycling of elements
What is a population?
A group of individuals of one species that occupy the same habitat and have the potential to interbreed successfully
What is carrying capacity?
The size of a population an ecosystem can support
What is a community?
Different populations living and interacting in the same area at the same time
What is a habitat?
The place where an organism usually lives
What are microhabitats?
Smaller units within a larger habitat, each with its own microclimate
What is a niche?
How an organism fits into its environment
What are adaptations?
Features that increase the chances of a species surviving and reproducing
Examples of adaptations to abiotic conditions (3)
Webbed paws - live and hunt on land and in water
Blubber - live in colder places with more food
Hibernation - conserves energy during cold months
Examples of adaptations to biotic conditions (2)
Bacteria produce antibiotics to kill off competition
Mating call - attracts members of the same species
What is population size?
The number of individuals in a population
Give two reasons why a population may fluctuate
The effect of abiotic factors
Interactions between organisms
In what instance is it useful to use a logarithmic scale?
Where the population grows rapidly over a short period of time
How does a logarithmic scale differ from a normal one/
Log(population) is plotted rather than the population itself
Give three reasons why a population may start to level out
Consuming and using up mineral ions
Winter brings lower temperatures and levels of light intensity
Bacteria collect at the surface and prevent light reaching those at the bottom
What are the four abiotic factors that influence the size of a population?
Temperature, pH, light intensity and water/humidity
How does temperature influence population size?
Enzymes - too low means there’s less kinetic energy for successful collisions and too high denatures the enzyme
Warm blooded organisms have to expend energy in maintaining their temperature levels
How does light influence population size?
Photosynthesis - more light means more photosynthesis. This increases their carrying capacity so more animals can survive
How does pH impact population size?
A pH other than the optimum releases H+ or OH- ions which interfere with and disrupt the hydrogen bonds
How does water/humidity impact population size?
Too dry means that more evaporation occurs, so there is no growth or food produced
Too wet means that special adaptions are required to survive and so diversity is reduced
What are the two types of competition?
Interspecific and intraspecific
What is intraspecific competition?
Individuals of the same species competing for resources
How does intraspecific competition impact a population?
The availability of resources determines the carrying capacity, and so population size
What is interspecific competition?
Individuals of different species competing for resources
How does interspecific competition impact a population?
Because the two species are occupying the same niche, one will have a competitive advantage over the other. This population will grow whilst the other will shrink and finally disappear
What is the competitive exclusion principle?
Where there are two species occupying the same niche, one will normally have a competitive advantage
The population of this species will grow and the population of the other will diminish
Conditions remain the same, leading to the removal of one species
When you are explaining how a factor influences population size, what is it important to link your explanation to?
The birth/death rate
What is predation?
One organism consuming another
Why is data gathered on predation in a lab generally not representative?
In the lab, the prey is usually exterminated by predators. This is because the size and type of habitat available is much smaller and less varied than in nature. There are also many more refuges in nature so although the prey population may fall to a low level, it rarely becomes extinct