B4a: Ecology in the local environment

Question 1

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

Answer 1

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

Question 2

How are quadrats used?

Answer 2

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

Question 3

How are nets used?

Answer 3

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

Question 4

How are pitfall traps used?

Answer 4

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

Question 5

How are pooters used?

Answer 5

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

Question 6

Describe the Capture-recapture’ technique (3)

Answer 6

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

Question 7

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

Answer 7

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

Question 8

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

Answer 8

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

Question 9

What is a habitat

Answer 9

the place where one type of organism lives

Question 10

What is an ecosystem

Answer 10

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)

Question 11

What is a community

Answer 11

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

Question 12

What is a population

Answer 12

the number of organisms of a species in a given area

Question 13

How are transect lines used? (3)

Answer 13

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

Question 14

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

Answer 14

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)

Question 15

Describe zonation

Answer 15

a gradual change in the distribution of species across a habitat

Question 16

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

Answer 16

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

Question 17

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

Answer 17

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

Question 18

Examples of natural ecosystems(2)

Answer 18

Native woodlands

lakes

Question 19

Examples of artificial ecosystems(2)

Answer 19

Forestry plantations

fish farms