Ecosystem

Question 1

Ecosystems are reffered to as ‘dynamic’ what does this term mean?

Answer 1

Ecosystem changes over time

Question 2

Name the three different types of changes that occur to ecosystems

Answer 2

• cyclic changes
• directional changes
• unpredictable/eratic changes

Question 3

define cyclic changes

Answer 3

changes that repeat themsleves in a rhytm

Question 4

define directional changes

Answer 4

not cyclic & goes in one direction

Question 5

define unpredictable/erratic changes

Answer 5

no rhytm and no constant direction

Question 6

Define ecosystem

Answer 6

all the interacting living organisms and non living factors in an area

Question 7

what are abiotic factors that affect an ecosystem?

Answer 7

• water availability
• temperature
• 02 availibility
• light intensity
• edophic (soil) factors i.e pH/type of soil

Question 8

what are biotic factors that affect an ecosystem?

Answer 8

disease,predation and competition

Question 9

what is meant by the term ‘niche’?

Answer 9

role of each species in an ecosystem

Question 10

Define trophic level

Answer 10

the stage/position in a food chain

Question 11

Define community

Answer 11

all the populations of different species who live in the same place at the same time who can interact with each other

Question 12

Define population

Answer 12

all organisms of one species who live in the same place and at the same time and can breed together

Question 13

Define biomass

Answer 13

the mass of living material in an area

Question 14

Define producer

Answer 14

converts inorganic molecules into organic molecules

Question 15

Define consumer

Answer 15

derives energy from other organisms

Question 16

How can we measure biomass?

Answer 16

• use a calorimeter
• measure the dry mass
• measure the temperature rise of water

Question 17

what are the biomass unit for normal habitats?

Answer 17

gm-2 yr-1

Question 18

what are the biomass units for marine/water habitats?

Answer 18

gm-3 yr-1

Question 19

Define elogial effieceny

Answer 19

efficeny in whihc biomass is transferred from one trophic level to another

Question 20

why is the efficency never 100%?

Answer 20

• sunglight reflected
• other factors i.e H20 availability affecting photosynthesis rates
• some energy use for ps to occur
• energy lost through respiration i.e metabolic heat
• lost through excretion
• some parts of the food not edible

Question 21

How can the percentage efficeny of energy transfer between producers and consumers be measured?

Answer 21

• primary energy/consumer energy x 100
• sample of producers collected
• sample of consumers collected
• measure biomass using calorimetre i.e burn sample in 02

Question 22

How can farmers increase ecological efficency?

Answer 22

• keep animals indoors
• reduce animal movement i.e zero grazing
• feed animals high protein content
• vaccinate animals
• use selective breeding/genetic engineering
• slaughter animal before mature

Question 23

what is the formula for ecological efficency?

Answer 23

• biomass transferred/ biomass intake

Question 24

decomposers are described as ‘saprophytic’ what does this mean?

Answer 24

they do external digestion

Question 25

describe the role of decomposers in decompisition

Answer 25

* bacteria is saprophytic/does external digestion by secreting enzyme * absorption of breakdown products * releases CO2 and H20 * break down of proteins makes ammonium ions (NH4+)

Question 26

what is the role of detritivores?

Answer 26

* they do internal digestion increasing the surface area and speeding up the process of decomposition

Question 27

Draw the carbon cycle

Answer 27

Question 28

write the formula for the process of nitrification, the type of reaction it is and name the bacteria involved

Answer 28

NH4+ -->No2- (nitrites)--> N03- (nitrates) * nitrosomonas and nitrobacter * oxidation reaction

Question 29

write the formula for ammonification

Answer 29

N02/N03- ---> NH4+

Question 30

write the formula for the process of denitrification, the type of reaction it is and name the bacteria involved

Answer 30

*N03- ---->N2 * anarobic ( only happens when theres no O2) *dentirifying bacteria - Pseudomonas

Question 31

Write the formula for nitrogen fixation and the bacteria involved

Answer 31

*N2 + 2H3 -> 2NH3 *azobacter and rhizobium

Question 32

where can Rhizobium be found?

Answer 32

in root nodules

Question 33

where is azobacter found?

Answer 33

in the soil

Question 34

Draw the nitrogen cycle

Answer 34

Question 35

What are the similarities between the carbon and nitrogen cycle?

Answer 35

* Co2 and NO2 are inorganic gases in the atmosphere * elements are fixed to organic compounds * both incoperated into plants then animals * animals obtains elements by feeding on plant * microorganisms return elements to atmosphere ( CO2 released during decomposition and N2 released by dentrifiying bacteria) * both break down organic macromolecules into living things * both release inorganic molecules CO2 ammonium ions (NH4+)

Question 36

What is the difference between decomposition and dentrification

Answer 36

* decompisition - breaks down dead organic matter and increases nitrate supply * wheres denitrification is the conversion of nitrates to N2 reducing nitrate supply

Question 37

Define sucession

Answer 37

progressive change in a community of organisms over time

Question 38

what is primary sucession?

Answer 38

occurs on land that is newly formed/there is no soil present

Question 39

what is secondary sucession?

Answer 39

occurs where soil is present but there is no animal/plant species

Question 40

what are pioneer species?

Answer 40

* species that begin the process of sucession often colonising an area as the first living things there * i.e mosses and lichen * they arrive before climax * are subject to greater change * have low biodiversity /less stable

Question 41

what is the role of pioneer species like mosses and lichen?

Answer 41

* fix N2 * tolerate extreme conditions * weather the rocks to create a layer of humus ( soil)

Question 42

Describe the process of sucession

Answer 42

* pioneer species - bgeins with bare rock, mosses and lichen and they have adaptations i.e nitrogen fixation * intermediate - out compete pioneer species i.e herb species followed by shrubs * climax community - final stable state * dominance by a few tree species * as the process continues there is increased nitrate /H20/organic content in the soil

Question 43

what is deflected sucession?

Answer 43

* when the natrual flow of sucession is halted i.e mowing the lawn

Question 44

Define th eterm plagioclimax

Answer 44

when sucession is artifically stopped

Question 45

what do we use to measure plants?

Answer 45

quadrat that are placed randomly

Question 46

what is used to measure distribution

Answer 46

belt transect

Question 47

How canwe use a belt transect to measure the distribution?

Answer 47

* use a quadrat every i.e 5m * count n of each species * use identification key * use a method to avoid recounting * calculate mean and repeat at different times of the year