populations

Question 1

whats a community

Answer 1

all populations of different organisms living and interacting in a particular place at the same time

Question 2

whats a habitat

Answer 2

place where an organism normally lives

Question 3

whats a population

Answer 3

group of individuals of the same species occupying same habitat at the same time

Question 4

whats a niche

Answer 4

all conditions and resources needed for an organism to survive and reproduce. how an organism fits into the environment. governed by the abiotic and biotic conditions

Question 5

whats an ecosystem

Answer 5

all the interacting abiotic and biotic features of a specific environment

Question 6

describe abiotic and biotic factors

Answer 6

biotic- living features of the environment

abiotic non living features e,g light temp. pH

Question 7

how do you set up a quadrat

Answer 7

set up a grid
choose random coordinates using a random number generator
place a large number of quadrats on coordinates
measure % cover of species (say how you do this)
large number, do a running mean until the mean stays stable and theres enough for a stats test

Question 8

what does % cover measure

Answer 8

abundance. an estimate of the area within the quadrat a specific plant or species occupies

Question 9

pos and neg of % cover measurements

Answer 9

+useful when counting individual organisms is impractical e.g too many or hard to distinguish 1 organism from another grow in clumps

• underestimates small organisms and overestimates large ones

Question 10

what is species frequency

Answer 10

number of individuals of each species in a quadrat

Question 11

what is the positive of random sampling

Answer 11

avoids bias

Question 12

what does deforestation/removal of hedges lead to

Answer 12

fewer species, less habitats, fewer food resources, increase of co2 in the air since less photosynthesis. farmers often benefit from hedges as have more predators for pests

Question 13

when should a transect and when should random be used

Answer 13

transect used for systematic when the area is not homogenous and there is a transition in the environment
random when area is homogenous

Question 14

how to use transects

Answer 14

place quadrats at regular intervals along the line
count plants/percentage cover in quadrats
use several quadrats
may not be representative

Question 15

describe mark release recapture

Answer 15

capture sample, mark them in some way and release
appropriate method of marking suggested doesn’t harm rub off
take second sample and count marked organisms
population= number in sample 1 x no. in sample / number marked in sample 2

Question 16

what are the assumptions of mark release recapture

Answer 16

population must remain stable so:
no emigration/immigration
no losses to predation
marking does not affect survival
birth rate death rate equal
all belong to one population

Question 17

what is carrying capacity

Answer 17

ecosystem can only support populations of a certain size. affected by abiotic factors, inter and intraspecific competition and predation.

Question 18

what are the two types of competition

Answer 18

intraspecific- between members of same species.
interspecific comp - between members of different species happens until one outcompetes the other. compete for things like food space light breeding territory etc

Question 19

what are predator prey relationships

Answer 19

hard to show in a lab. data from natural experiments should be taken with caution