Populations Flashcards
Habitat
The place where an organism lives.
Population
All the organisms of one species in a habitat.
Community
Populations of different species in a habitat make up a community.
Ecosystems
All the organisms living in a particular area and all the non living conditions.
Abiotic conditions
The non living features of the ecosystem. Eg. Temp and availability of water
Biotic conditions
The living features of the ecosystem. Eg. Presence of predators or food.
Niche
The role of a species within its habitat
Adaptation
A feature that members of a species have that increases their chance of survival and reproduction.
What is involved when investigating populations?
The abundance and distribution of a species in a particular area.
Abundance
The number of individuals of one species in a particular area.
Frequency
The number of samples a species is recorded in
Percentage cover
For plants only. How much of the area your investigating is covered by a species.
Distribution
Where a particular species is within the area you’re investigating.
Why are samples of populations taken?
It would be too time consuming to measure the number of individuals and the distribution of every species in the entire area you’re investigating so instead you take samples.
Describe how a student could investigate the percentage cover of daffodils in a field. 4 marks
She could use quadrats to measure the percentage cover of daffodils.
Several would be placed on the ground at random locations within the field.
The percentage of each quadrat thats covered by daffodils wpuld be recorded.
The percentage cover for the whole field could then be estimated by averaging the data collected in all of the quadrats.
Describe the mark-release-recapture method. 5marks
A group of snails would have been caught.
Marked in a way that wouldn’t harm them.
Then released back into the environment.
After a week a second sample would be taken.
The number marked in the second sample would have been counted.
Population size
The total number of organisms of one species in a habitat.
Interspecific competition
Competition between different species.
Intraspecific competition
Competition within a species for the same resources.
Predation
Where an organism kills and eats another organism.
How to calculate human population growth?
Calculated using birth and death rates.
Birth rate
The number of live births each year for every 1000 people in a population.
Death rate
The number of people that die each year for every 1000 people in the population.
Population growth rate
How much the population size increases or decreases in a year. Using birth and death rates.
Survival curves show
The percentage of all the individuals that were born in a population that are still alive at any given age.
