6.3.1 ecosystems

Question 1

what is an ecosystem
6.3.1(a)

Answer 1

all the living organisms and non-living conditions in an area

Question 2

key word describing how ecosystems change over time
6.3.1(a)

Answer 2

dynamic

Question 3

how are ecosystems dynamic
6.3.1(a)

Answer 3

-pathogens can arrive
-species may arrive or leave -imm or -emi gration

Question 4

what are the 3 components of an ecosystem
6.3.1(a)

Answer 4

-habitat-physical location where organism lives
-population-all the organisms of one species
-community-all the populations of all the species living in an ecosystem

Question 5

what is the role of each species in an ecosystem called
6.3.1(a)

Answer 5

niche

Question 6

what is a biotic factor and name some examples
6.3.1(a)

Answer 6

living
eg-predation, competition and hunting

Question 7

what is a abiotic factor and name some examples
6.3.1(a)

Answer 7

non-living
eg-light, temperature and pH

Question 8

what are the 3 different types of dynamic changes an ecosystem can face
6.3.1(a)

Answer 8

-cyclic changes-changes repeat themselves in a predictable rhythm
-directional changes-they go in one direction and are irreversible
-unpredictable/erratic-dont have a particular direction and cant be predicted

Question 9

How can biomass be calculated experimentally
6.3.1(b)

Answer 9

1. collect sample of your species
   2.dry it in an oven at 80 degrees to remove water then measure the dry mass
2. multiply dry mass to reflect dry mass of total population size.

Question 10

what is a producer also known as
6.3.1(b)

Answer 10

photoautotroph

Question 11

how do producers create their own energy
6.3.1(b)

Answer 11

using light energy from the sun however only a small amount is converted into biomass

Question 12

what are the units for biomass
6.3.1(b)

Answer 12

energy per area of habitat per time
kj m-2 year-1

Question 13

give 3 reasons all the light energy isnt converted to biomass in producers
6.3.1(b)

Answer 13

1. light may not hit a chloroplast
   2.it may be the wrong wavelength of light so be reflected
   3.other factors eg-low CO2 may limit rate of photosynthesis

Question 14

how can you calculate biomass efficiency
6.3.1(b)

Answer 14

biomass efficiency=biomass present in higher trophic level/biomass present in previous trophic level x 100

Question 15

what is gross production
6.3.1(b)

Answer 15

total amount of energy used to form biomass

Question 16

what is net production
6.3.1(b)

Answer 16

total amount of biomass after respiration

Question 17

what is net production
6.3.1(b)

Answer 17

net production=gross production - respiratory losses

Question 18

name 3 reasons why all the biomass isnt transferred from producers to consumers
6.3.1(b)

Answer 18

1. some of the organism won’t be digested
   Eg-may not be able to digest the cellulose cell wall of the plant
   2.energy is lost through faeces and urine
2. energy is lost in respiration

Question 19

how can you improve ecosystem efficiency
6.3.1(b)

Answer 19

simply food chains by removing competeing organisms
reduce respiratory losses
eg-reducing reliance on repsiration to keep them warm by having a heater

Question 20

what is carbon fixation
6.3.1(c)

Answer 20

when producers take in CO2 for photosynthesis and use it to make organic carbon containing compounds

Question 21

how do producers and consumers release CO2 back into the environment
6.3.1(c)

Answer 21

respiration

Question 22

how are organic C containing compounds passed along the food chain
6.3.1(c)

Answer 22

when consumers eat producers

Question 23

what is decomposition
6.3.1(c)

Answer 23

when producers and consumers die organic C containing compounds remain in waste matter when broken down by decomposers this releases CO2 back into the environment

Question 24

what is combustion
6.3.1(c)

Answer 24

waste matter that isn’t decomposed is converted into fossil fuels which can be burnt to produce CO2

Question 25

which nitrogen-fixing bacteria converts NO2 into NH3 which can be used immediately by the plant and where is it found
6.3.1(c)

Answer 25

rhizobium and is found in root nodules

Question 26

which nitrogen-fixing bacteria converts NO2 into NH3 which dissolved in water in the soil to form ammonium ions and where is it found
6.3.1(c)

Answer 26

azotobacter and is found in soil

Question 27

what conditions does nitrogen fixing bacteria take place under
6.3.1(c)

Answer 27

anaerobic-nitrogen fixation doesn’t require O2

Question 28

what nitrifying bacteria do you need to convert ammonium ions into nitrite
6.3.1(c)

Answer 28

nitrosomonas

Question 29

what nitrifying bacteria do you need to convert nitrite into nitrate
6.3.1(c)

Answer 29

nitrobacter

Question 30

what conditions does nitrification occur under
6.3.1(c)

Answer 30

aerobic conditions as
-nitrifying bacteria need to carry out aerobic respiration
-O2 is used in nitrification

Question 31

describe the process of ammonification
6.3.1(c)

Answer 31

nitrate is absorbed by plants then animals eats the plants to make N containg compounds
death and excretion returns nitrogen back to the soil
this waste is fed on by decomposers and is converted into ammonia which is released in water in the soil forming ammonium ions

Question 32

what conditons does ammonification take place under

Question 33

what is denitrification
6.3.1(c)

Answer 33

when denitrifying bacteria converts nitrate into nitrogen gas

Question 34

what conditions does denitrification take place under
6.3.1(c)

Answer 34

anaerobic conditions
denitrifying bacteria carries out aerobic respiration

Question 35

what is succession
6.3.1(d)

Answer 35

when an ecosystem changes from simple to complex through a series of seral stages

Question 36

what is a pioneer species
6.3.1(d)

Answer 36

causes a change in the environment
makes it less hostile
enables other species to survive
reproduce asexually

Question 37

what is an immediate community
6.3.1(d)

Answer 37

when shrubs and trees decompose they release nutriants into the soil making it less hostile

Question 38

what is a climax community
6.3.1(d)

Answer 38

stable community which doesn’t experience succession

Question 39

what is deflected succession
6.3.1(d)

Answer 39

when human activities eg-agriculture prevents a stable climax community from forming

Question 40

what is plagioclimax
6.3.1(d)

Answer 40

community that is maintained by deflected succession

Question 41

how do you calculate distribution
6.3.1(e)

Answer 41

-use systematic sampling eg-by placing quadrat and pre-determine intervals

Question 42

how do you calculate abundance of a species
6.3.1(e)

Answer 42

-using percentage cover
-ACFOR scale

Question 43

how can percentage cover be made more accurate
6.3.1(e)

Answer 43

using a point frame

Question 44

how can you avoid bias
6.3.1(e)

Answer 44

use random sampling