7.1 Populations and ecosystems

Question 1

how does pH affect an ecosystem

Answer 1

can affect enzymes and surface proteins
breaks hydrogen bonds and changed tertiary structure

Question 2

how does light intensity affect an ecosystem

Answer 2

more light available = faster rate of photosynthesis therefore more energy for seed production increasing population

the more plants grow the more food is available for animals therefore less competition

Question 3

habitat

Answer 3

place where an organism lives

Question 4

population

Answer 4

all the individuals of a given species in the same area at the same time

Question 5

species

Answer 5

a group of closely related individuals which are capable of interbreeding and producing fertile offspring

Question 6

community

Answer 6

all the individuals of a given species living together in the same area at the same time

Question 7

niche

Answer 7

where an organism lives and what its role is there

Question 8

abiotic factors

Answer 8

non living factors which affect the distribution of an organism
e.g. temperature, light intensity, water availability, pH

Question 9

biotic factors

Answer 9

living factors which affects the distribution of an organism
e.g. competition, predation

Question 10

ecosystem

Answer 10

all the living and non living components of an area

Question 11

how does temperature affect an organism

Answer 11

temp effects enzymes in an organism and therefore its overall metabolism
TOO COLD: enzymes wont have enough kinetic energy to catalyse a reaction and organism overall activity goes down
TOO HOT: enzymes may denature overall activity decreases

Question 12

how does water availability and humidity affect an ecosystem

Answer 12

water acts as a solvent in cells and is involved in many reactions directly

Question 13

interspecific competition

Answer 13

between members of different species

Question 14

intraspecific competition`

Answer 14

between members of the same species

Question 15

describe how you would investigate the distribution of marram grass from one side of the dune to the other (3)

Answer 15

place transect from 1 side of the dune to the other
place quadrats at regular intervals along the transect
count percentage cover in quadrats

Question 16

outline a method the ecologists could have used to determine the plant species richness at one site (3)

Answer 16

using a quadrat measure out a 5m by 5m area
use a random number generator to determine coordinates to place quadrat at
count number of organisms of certain species in quadrat
repeat many time and calculate a running mean
continue until running mean within 0.5 of previous `

Question 17

how is mark-release-recapture used for estimating population size

Answer 17

a sample of a species is captured marked and then released back into the habitat
allow for enough time for organism to redistribute
recapture another sample of the species
count number of marked and unmarked
use n1 x n2 /nm to calculate population