Populations in ecosystems Flashcards
(30 cards)
What is an ecosystem?
All the organisms living in a community and their interaction with the abiotic conditions.
What are the biotic conditions?
The living features of an ecosystem.
What are the abiotic conditions?
The non-living features of an ecosystem.
What is a community?
All the populations of all the species living in a particular area at a particular time.
What is a population?
All the organisms of one species in a habitat.
What is a habitat?
The place where an organism lives.
What is a niche?
The role of a species within a habitat.
What happens if two species occupy the same niche?
They will compete with each other. One species will be more successful than the other until only that species is left.
What is an adaptation?
A characteristic an organism has that makes them more likely to survive breed and reproduce.
What is natural selection?
If an organism has an allele that codes for an advantageous characteristic they are more likely to survive, reproduce and pass on that allele to their offspring. This means the offspring is more likely to survive reproduce and pass on those genes as well. Over time the frequency of that allele increases and this leads to evolution.
What is the population size?
The total number of organisms of a species in a habitat.
What is the carrying capacity?
The maximum population size of a species that an ecosystem can support.
What happens to the population size if the abiotic conditions are ideal?
The organisms grow quickly and reproduce successfully. This means the population size increases.
What biotic conditions affect population size?
- Interspecific competition.
- intraspecific competition.
- Predation-prey relationships.
How does intraspecific competition affect population size?
Organisms of the same species will compete for the same resources. This will lead to there being a shortage of those resources. This means the organisms of that species won’t be able to grow and reproduce successfully. This decreases the population size. This decrease can then lead to an increase in population size as more resources will be available for the other members of the population.
How does interspecific competition affect population size?
If organisms of different species compete for the same resources the resources available to both populations will reduce. This means both populations will have less food and energy for growth and
reproduction so the population sizes will be lower for both species. One species will be better adapted to the environment meaning it will outcompete the other species.
How does predation affect population size?
Why should samples be random?
To avoid bias
Why must you do repeats when investigating a population of a species?
- To make sure that any patterns are not due to chance.
- So you get sufficient data.
- So you can calculate a mean and use it to make comparisons with other data.
How do you use a quadrat?
- Place it in an area.
- Measure the species frequency, which is how many times a species is present in the quadrant.
- You can also measure the percentage cover.
What is a transect used for?
To find out how organisms are distributed across an area.
Describe the mark release-recapture method.
P= (number caught in first sample x number caught in the second sample)/ number marked in the second sample
What is succession?
The process by which an ecosystem changes over time.
Where does primary succession take place?
On land that is newly formed or exposed.