energy and ecosystems and stats test

Question 1

points to write in a null hypothesis

Answer 1

no significant difference

Question 2

answering a null hypothesis

Answer 2

statistical value is less than the critical value so
accept the null hypothesis
no significant difference
greater than 0.05 probability it is due to chance

the statistical value is greater than critical value so
reject null hypothesis
there is significant difference
less than 0.05 probability it is due to chance

Question 3

when to do a student t test

Answer 3

looking for differences between two means measured in data

Question 4

when to do chi squared

Answer 4

finding frequancies
collecting data about individuals in categories

Question 5

when to do spearmans rank (coralation coefficiant)

Answer 5

looking for a coralation in measurements from the same sample of different varriables

Question 6

why is only 1-3% of the suns energy converted into organic matter

Answer 6

90% of the suns energy is refelected
not all wavelengths can be absorbed
light may not hit the chorophyll
low co2 may limit rate of photosynthesis

Question 7

how is energy transfered in the ecosystem

Answer 7

through trophic levels

Question 8

how is energy lost from the system

Answer 8

heat
excretion - metabloic waste
egestion
not all of the organisum is eaten

Question 9

how is a calorimetre used to measure chemical energy store

Answer 9

sample is dried by heating in an oven to evapourate water
weigh the sample
put it in a container and set on fire
heat is transfered to the water
thermometre measured temperature

Question 10

how do you know when all the water is evapourated from a dry sample

Answer 10

when the mass doesnt change after each measurement

Question 11

how does the stirer in the calorimetre increase acuracy

Answer 11

distributes heat energy around the water

Question 12

what is gross production

Answer 12

total quantity of energy that the plants in a community convert to organic material

Question 13

what is respiratory loses

Answer 13

plants use 20-50% of the gorss production energy for respiration leaving little to be stored

Question 14

what is net production

Answer 14

rate at which plants store energy

Question 15

net production equation

Answer 15

net production = gross production - respiratory loses

Question 16

net production of consumer equation

Answer 16

net production of consumer = chemical energy igested - ( chemical energy lost in faeces + respiratory loses to environment)

Question 17

why do trophic levels rarely have more than 4 levels

Answer 17

biomass is less at higher trophic levels
total energy stored is less at higher trophic levels
insufficiant enrgy makes it up the levels to support a breedign population

Question 18

where does the main resevoir for phosphorus come from

Answer 18

mineral form in sedimentary rock which originate in the sea but are bought to the surface by geological uplifting, weathering and errosion

Question 19

phosphorus cycle

Answer 19

phosphate ions in the primary consumer transfer by assimilation to the secondary cnsumer
phosphate is released by saprobionts which decompose dead consumers
the dead material forms sediment rock
phosphate is released by weathering and errosion from the rock
phosphate in the soil is absorbed
repeat

Question 20

what is a mycorrhizae and what does it do

Answer 20

a fungi that grows around the roots of some plants
they assist in taking up water and mineral ions
they have symbiotic relationships with plants
the fungus produces hypae which increases the surface area if the root tissue so that it can take up more water and minerals

Question 21

nitrogen cycle

Answer 21

N2 in the air moves by nitrogen fixing to ammonia which dissolves in the soil to form ammonium ions
nitrifying bacteria turns it into nitrite and nitrates
these active transport to the plants which use nitrates and alpha glucose to form amino acids and protiens to feed animals
or
plants die and the nitrogen compounds are digested in ammonificiation by saprobionts to return the nitrogen to ammonia

some nitrates return to the air as nitrogen by dentrification by dentrifyign bacteria in water logged conditions

Question 22

what is nitrogen fixation

Answer 22

atmospheric nitrogen is fixed when it is combined with oxygen or hydrogen

Question 23

what is ammonification

Answer 23

saprobionts break down amino acids fro dead material into ammonia and then into ammonium ions

Question 24

what is nitrification

Answer 24

areobic nitrifying bacteria
oxidise ammonium ions to form nitrites

Question 25

what are two good soil properties

Answer 25

high oxygen concentration for aerobic respirtaion in nitrifying bacteria
source of nitrogen for ammonification

Question 26

why are fertilisers needed

Answer 26

intensive farming means biomass is removed so the minerals arent returned to the soil which decreases crop yeild

Question 27

what are inorganic fertilisers

Answer 27

they are enriched in nitrogen , phosphorus and potasium

easier to predict effect on crops
more concentrated so smaller amounts can be applied
convenient and easier to transport

Question 28

what are organic fertilisers

Answer 28

made of manure , fishmeal or compost

They prevent soil erosion
Improve water holding properties
Releases nutrients they hold over a long period of time

Question 29

What is leaching and how does it work

Answer 29

Soluble nutrients are dissolved by rain and carried into the soil out of the reach of plants. The leached nutrients are carried into bodies of water which can lead to eutrophication

Question 30

How does organic fertilisers reduce leaching

Answer 30

They must be broken down and decomposed by saprobionts
This means there is more time for plants to absorb them

Question 31

How does leaching effect water bodies

Answer 31

Nutrients enter the water and increase algae production which blocks the sunlight reaching lower plants so less photosynthesis and oxygen concentration decreases. Fish looses food source from dying plants
Pants decompose and co2 increases
Fish die