B4a: Ecology in the local environment Flashcards Preview

Biology > B4a: Ecology in the local environment > Flashcards

Flashcards in B4a: Ecology in the local environment Deck (19):

How is an estimate of the population size calculated? (2)

scaling up from a small sample area

the use of capture-recapture data and using the formula: population size = (# in 1st sample * # in 2nd sample) / number in 2nd sample previously marked


How are quadrats used?

square frames of a standard area are put on the ground to define an area; the numbers of organisms of particular species in the frame can then be counted


How are nets used?

nets used to catch animals such as butterflies or fish, allowing you to count and record numbers of animals


How are pitfall traps used?

small containers buried in ground which collect small animals, allowing you to sample the animals in the area


How are pooters used?

containers with a straw device, used to suck in small animals to identify and count them


Describe the Capture-recapture' technique (3)

1. capture a sample of organisms in an area (1st sample), count, mark, release them

2. recapture and count a second sample of organisms in the same area at a later date

3. count the total number of recaptured (prev marked) organisms in the 2nd sample


Explain the effect of sample size on the accuracy of an estimate of population size

the larger the sample size, the more plants and animals recorded, the more representative the sample, the higher the accuracy


Explain the need to make certain assumptions when using capture-recapture data (3)

no changes in pop size due to death, immigration, emigration

identical sampling methods used for both samples

marking not affecting survival rate of the organisms


What is a habitat

the place where one type of organism lives


What is an ecosystem

a ecosystem includes all the organisms in an area and how they interact with their surrounds, along with non-living conditions(rainfall, temperature, and the soil)


What is a community

all the populations of organisms that live together and interact in the same area(number of organisms living in a single area)


What is a population

the number of organisms of a species in a given area


How are transect lines used? (3)

they are tapes laid across an environment

quadrats are laid at regular intervals down the tape to record the distribution of the organisms inside

data are displayed as kite diagrams


Explain what it means for an ecosystem to be described as self supporting (2)

it is self sufficient - contains almost everything they need to maintain themselves: water, nutrients and essential elements like carbon all get recycled within the ecosystem

only things needed from outside is an energy source (Sun)


Describe zonation

a gradual change in the distribution of species across a habitat


What can result in the zonation of organisms in a habitat? (2)

organisms are adapted to live in certain physical conditions - more likely to survive and reproduce in areas with these conditions; many can only survive in conditions they're adapted to(specialists)

gradual change of an abiotic factor (e.g. light, temp, water, oxygen, salinity and soil quality) means some organisms are not adapted and are out-competed by others, so cannot survive/ reproduce, causing zonation


Compare the biodiversity of natural ecosystems and artificial ecosystems(2)

natural ecosystems have more biodiversity - they have more types of organisms
-humans control what organisms live in an artificial
ecosystem and remove all unwanted species


Examples of natural ecosystems(2)

Native woodlands



Examples of artificial ecosystems(2)

Forestry plantations

fish farms