5B- energy transfer and nutrient cycles

Question 1

what are producers

Answer 1

organism that produce there own food

Question 2

what is biomass

Answer 2

chemical energy stored in plant

or mass of living material

Question 3

how is energy transfered between organism

Answer 3

producers eaten by primary consumers then primary consumers eaten by secondary etc etc

Question 4

how can bio mass be measured

Answer 4

in terms of carbon mass

measure dry mass- mass of carbon is 50% of this

Question 5

how to collect dry mass

Answer 5

• dry sample of organiism in low heated oven
• weigh sample at regular intervals
• once weight becomes constant stop heating

Question 6

how to find chemical energy from dry mass

Answer 6

• heat sample of dry biomass and enrgy released is used to heat a known volume of water
• change in temp can be used to calc chem energy

Question 7

what is GPP

Answer 7

gross primary production

total amount of chemical energy converted from light energy by plants in a given area

Question 8

what is NPP

Answer 8

NPP= GPP- R

Question 9

Net production of consumers formula

Answer 9

N=I-(F+R)

Question 10

what is net primary production

Answer 10

energy available for plants to grow and reproduce

Question 11

how do insecticides wokr

Answer 11

kill insect pests whihc harm crops

so less biomass lost from crops so they grow larger increasing NPP

Question 12

how do herbicides work

Answer 12

kill weeds so reduce competition for energy of sun for other plant and also kills habitat for pest

Question 13

how do biological agents work

Answer 13

parasite liv/lay eggs on pests

pathogenic bacteria and virusses kill pests

Question 14

how do farmers reduce energy lost via repsiration

Answer 14

keep animals in pens so movement restricted

keep animals in warm pens so less energy lost by generating body heat

Question 15

what are saprobionts

Answer 15

decomposers which feed on remains of dead plants and there waste products allowing chemical elemnts to be recycled

Question 16

what are saprobionts

Answer 16

decomposers which feed on remains of dead plants and there waste products allowing chemical elemnts to be recycled

Question 17

explain saprobionts and extracellular digestion

Answer 17

saprobionts secrete enzymes and digest their food externally and then absorb the nutrients they need
during this organic compunds are broken down into inorganic ions

Question 18

what is saprobiotic nutrition

Answer 18

obtaining nutrients from dead organic matter using extracellular digestion

Question 19

what is mycorrihizae

Answer 19

fungi which forms symbiotic relatonship with plants

Question 20

explain how mycorrhizae works

Answer 20

fungi are made up of thin strands called hayphae which connect to plants roots
these increase plants surface area helping plants absorb ions an duptake water
hyphae absorb organicn compunds like glucose from plants

Question 21

What are the four stages of the nitrogen cycle

Answer 21

nitrogen fixation
ammonification
nitrification
denitrification

Question 22

explain nitrogen fixation

Answer 22

nitrogen gas tuened into nitrogen containing compunds by bacteria

bacteria is found in root nodules of leguminous plants

forms mutualistic relationship with plant gives plant nitrogen compounds and plant gives them carbs

Question 23

explain ammonification

Answer 23

nitrogen compounds from waste urine dead organisms turned into ammonia via saprobionts which goes on to form ammonium ions

Question 24

explain nitrification

Answer 24

ammonium ions in the soil are changed into nitrogen compounds

nitrifying bacteria change ammonium ions into nitrites
then other nitrifying bacteria changes nitrites into nitrates

Question 25

explain denitrification

Answer 25

nitrates in the soil are converted into nitrogen gas by denitrifying bacteria
happens under anaerobic conditions

Question 26

explain the phosphorus cycle

Answer 26

1-phosphate ions released into soil by rocks via weathering
2-phos ions taken in to plants via roots
3-phos ions transfered through food chain as plants eaten
4-phos ions lost from animals by waste
5-plants animal die saprobionts break them down releasing phos ions for assimulation by plants

Question 27

phosphate ion transfer in sea

Answer 27

weathering of rocks releases phosphate ions into sea then aquatic producers like algae takes it up then its passed onto birds like guano which produce phos ions as waste good fertilisers

Question 28

how does removing animals reduce nutrients in area

Answer 28

animals eat grass etc and are taken away so they cannot decompose and replace the nutrients

Question 29

what is artificial fertiliser

Answer 29

inorganic and contain pure chemicals like ammonium nitrate as powder or pellets

Question 30

what is natural fertiliser

Answer 30

organic matter- could be manure , composted veg, crop residue or/ and sewage sludge

Question 31

what is leaching in terms of fertiliser

Answer 31

when water soluble compounds in soil are washed away into nearby pomds and river

Question 32

when is leaching most likely to occur

Answer 32

if fertiliser is applied just before heavy rainfall

Question 33

which type of fertiliser leads to more leaching and why

Answer 33

artificial fertilisers as the inorganic ions are more soluble so excess minerals are not used straight away and more likely to leach off

natural fertilisers less liekly as they need to be decompsed before absorbtion by plants so release into soil more controlled

Question 34

what is more likely to be leached and why phosphates or nitrates

Answer 34

nitrates as they are more soluble in water

Question 35

what is eutrophication

Answer 35

1-mineral ions leached from fertilised feilds stimulate rapid growth of algae in rivers

2- large amounts of algae block light from reaching plants below

3-plants die as not able to photosynthesise

4-bacteria feed on dead plant increasing their population. this causes decreased oxygen as more aerobic respiration

5-fish and other animals die as their isnt enough oxygen dissolved in water