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A-level Biology > 5- Photosythesis, Respiration And energy Transfer, Nutrient Cycles > Flashcards

5- Photosythesis, Respiration And energy Transfer, Nutrient Cycles Flashcards

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1
Q

What does the lower epidermis do

A

Protects plants form water loss infection and injury

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2
Q

What is the photosynthesis equation (symbol)

A

6H2O + 6CO2 —> C6H12O6. + 6O2

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3
Q

In photosynthesis, light energy is first changed into ….
Energy and then into …… energy

A

Bond
Chemical

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4
Q

What are the 3 main stages of photosynthesis

A

Capturing light energy by photosynthetic pigments
Light dependent reaction
Light independent reaction

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5
Q

What are the products of the light dependent reaction

A

Reduced NAPD
ATP
o2

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6
Q

What are the 2 district regions in a chloroplast

A

Grana
Stroma

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7
Q

Describe the grana

A

Stacks up to 100 disc like structures called thylakoids
Some thylakoids have tubular extensions wich join up thylakoids to adjacent grana (called lamella)

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8
Q

Where is chlorophyll

A

In the thylakoids

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9
Q

Describe the stroma

A

Fluid filled matrix
Contains starch grains

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10
Q

What are the 2 raw materials of photosynthesis

A

H2O
Co2

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11
Q

Where does the light dependent reaction occur

A

Thylakoids membrane

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12
Q

Where does the light independent reaction occcur

A

Stroma

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13
Q

What are the products of the light independent reaction

A

Glucose

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14
Q

The light dependent reaction s involves the capture of Light, the energy is used for what 2 purposes

A

Add an inorganic phosphate to ADP making atp
Photolysis - H+ ions and OH - ions made when water is split by light

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15
Q

Oxidation results in energy …..

A

Given out

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16
Q

Reduction results in energy …

A

Being taken in

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17
Q

Describe the making of ATP in the light dependent rweaction

A

When a chlorophyll molecule absorbs light energy, it excites a pair of electrons within thus chlorophyll molecule.
They leave the chlorophyll molecule
The electrons that leave are taken up by an electron carrier, having lost a pair of e- they have been oxidised
The elctron carrier has been reduced

The electrons are now passed along a number of electron carriers in a series of oxidation and reduction reactions
These electron carriers form a transfer chain that is located in the thylakoids memebran e
Each new carrier is at a slightly lower energy level than the previous one so the electrons lose energy at each stage
Thus energy is used to combine and inorganic phosphate molecule with an ADP to make atp

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18
Q

What is photosytemt 2 called

A

Photosytem p680

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19
Q

Describe photolysis

A

The loss of electron that happen when light strikes the chlorophyll molecule leave it short of electrons

In order for the chlorophyll to continue to absorb light energy electrons must be replaced

They are replaced by water splitting a water molecule using light energy

This photolysis of water also yields protons

The protons are taken up by an electron carrier called NADP

When it takes up protons it becomes reduced

Reduced NADP is then passed onto the next stage with the electrons form they chlorophyl molecule

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20
Q

What is the bi products of photolysis

A

Oxygen

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21
Q

What is the photolysis equation

A

2H2O —>. O2 + 4H+. + 4e-

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22
Q

Give a summary of the chemiosmotic theory

A

Each thylakoids is in an enclosed chamber into which protons are pumped form stroma through proton carried

Energy to drive thsubcomes form e- released by photolysis’s

Photolysis also releases protons which inc in conc. in thylakoids space

Overall creates / maintain a conc gradient of portions across the thylakoids memebrane. High in thylakoids space low in stroma

The protons can only pass the thylakoid membrane through ATP synthase channels, the rest of the membrane is impermeable to protons, these channels form small granulesnon membrane surfaces AKA staked granules

As protons pass through these atp synthases channels cause changes to the structures of the enzymes which catalyses ADP + pi to atp

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23
Q

Chloroplasts adaptations

A

Thylakoids - large Sa - for attachment of chlorophyll electron carrier and enzymes that carry out light dependent reaction

Network of proteins in grana that hold chlorophyll molecules in a very precise manor that allows maximum absorbtionnofnlight

Granal mambranes have atpnsythase channel which catalysed atp production- their apps selectively permeable allowing a proton gradient

Chloroplasts have dna and ribosomes so they can quickly and easily manufacture proteins

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24
Q

Who discover the light independent stage of photosynthesis, how?

A

Melvin Calvin
Used c14 and traced

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25
Q

Describe the light independent stage of photosynthesis

A

CO2 diffuses through stomata and dissolves in water mesophyll, diffuses through cell surface membrane of plant cell, moves through cytoplasm and diffuses into chloroplast stroma

In stroma CO2 reacts with RUBP (5c ) which is catalysed by RuBiSCo

Reaction between CO2 and RuBP. Produces 2x GP (3c)

Reduced NADP and ATP are used to reduce GP into two times GAIP (3c)

NADP reform to go back to light dependent reaction to be reduced again and except more protons

Some TP molecules converted into organic substances such as starch cellulose lipids, nucleotides amino acids

Most TP molecules are used to make/regenerate RuBP using ATP

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26
Q

How many photosytstema are in a chloroplasts

A

2

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27
Q

What are the 2 photosytems

A

1 700 (absorbed light bast at 700nm)
2 680 (absorbed light best at 680nm)

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28
Q

Carbohydrates produced by photosynthesis and not used straight away, how are they stroedb

A

As starch grains in the stroma

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29
Q

What 3 things is the energy form photoionisation of cholorphyll used for

A

Making ATP from ADP and pi, this is called phosophorylation

Making reduced NADP from NADP

Splitting water into protonsm electrons and water ( pholysis)

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30
Q

What 2 types of phosphorylation does the light dependent stage inculde

A

Non cyclic
Cyclic
(Each of these process Hve differnt products )

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31
Q

What does non cyclic phosophorylation produce

A

ATP
Reduced NADP
O2

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32
Q

What does photosytem 1 do in the light dependent stage

A

Light is a doves by PS1 high excite electrons again to an even higher energy level
Final the electrons are transferred to NADP aloft with protons from the stroma to form reduced NADP

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33
Q

What does cyclic photolhosphorylation produce and why

A

ATP
Cyclic photophosphorylation only used PS1
It’s called cyclic becasue the electrons form the chlophyll molecule arnt passed onto NADP
But are passed back to PS1 via electron carriers
This means the electrons are recycles and can repeatedly flow through PS1
This process doesn’t produce any reduced NADP or O2 - it only proves a small amount of ATP

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34
Q

What is the Calvin cycle also known as and why

A

Carbon dioxide fixation
Because carbon from co2 is fixed into an organic molcule

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35
Q

How are carbohydrates ( hexose sugars ) made using TP. And GP

A

Joining 2 TP togetehr and larger carbohydrates are made by joining hexose sugars in differn ways

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36
Q

How are lipids made using TP. And GP

A

Made using glycerol which is synthesised from TP and fatty acids which are synthesised from GP

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37
Q

How are amino acids made using TP. And GP

A

Some amino acids are made form GP

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38
Q

How many molecules of TP are made earth cycle

A

2

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39
Q

For every 3 turns of the cycle …. Molecules of Tp are made
…/… of these TP molecules are used to regenerate…………

A

6
5/6
RuBP

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40
Q

For every 3 turns of the cycle only …. TP is procured that is used to make bexose sugar

A

1

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41
Q

6 turns of the Calvin’s cycle need …. ATP and …. Reduced NADP

A

18
12

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42
Q

Anaerobic respiration in plants and yeast produce what .

A

Ethanol and co2
And releases energy

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43
Q

Anaerobic respiration in humans procured what’s?

A

Lactate and reLEases energy

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44
Q

What makes ATP. A food energy source

A

ATP has Specific Properties that Make it a Good Energy Source
1) AT stores or releases only a small, manageable amount of energy at a time, so no energy is wasted as heat.
2) ‘s a small, soluble molecule so it can be easily transported around the cell.
3) Its easily broken down, so energy can be easily released instantaneously.
4) It can be quickly re-made.
3 It can make other molecules more reactive by transferring one of its phosphate groups to them (phosphorylation).
6 ATP can’t pass out of the cell, so the cell always has an immediate supply of energy.

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45
Q

What is a coenzyme

A

A molecule that aids the function of an enzyme

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46
Q

How do coenzymes work

A

Transferring a chemical group form one molecule to another

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47
Q

What is the coenzyme used in photosynthesis

A

NADP
NADP transfers hydrogen form one molecule to another

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48
Q

Examples of coenzymes used in respiration are

A

nad
Coenzyme A
FAD
………………,.,.,,.,.,.,.,.,,..,.,.,..,,..,.,,..,.,,..,,..,.,
NAD and FAD transfer hydrogen form one molecule to another -
A transfers acetate between molecules

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49
Q

Metabolic pathway definition

A

A series of small reaction controlled by enzymes

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50
Q

Phosphorylation Definition

A

Adding phosphate to a molcule

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51
Q

Photoionisation Definition

A

When light energy excited electrons in an atom or molecule, giving them more energy and causing them to be released, the release of electrons cause the atom or molecule to become a positively changed ion

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52
Q

Decarboxylation Definition

A

The removal of co2 form a molcule

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53
Q

Dehydrogenation Definition

A

The removal of hydrogen form a molcule

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54
Q

What do animals need energy for

A

Muscle contraction
Body temp regulation
Activate transport
DNA replication
Cell divison
Protein synthesis

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55
Q

Can a cell get energy directly form glucose , so

A

No
So energy released form glucose is used to make ATP
ATP diffused into part of cell where it is needed

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56
Q

When atp is hydrolysis
The chemical energy is released form where

A

The phosphate bond

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57
Q

What is the rate of photosynthesis effected by

A

Light intensity
Co2
Temperature

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58
Q

What is the law of limiting factors

A

At any given moment the rate of physiological process is limited by the factor that is at the least favourable value

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59
Q

Why is it hard to quantify photosynthesis

A

Level of co2 0.04%
Products of photosynthesis - hard to measure o2 in terrestrial plants
Temp changes - east to implement by rates of changes are difficult to quantity

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60
Q

When light is the limiting factor in photosynthesis the rate is a
Ways …….

A

Directly proportional to the light intensity

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61
Q

What is the light compensation point

A

It exists at the maximum amount of co2 absorbed responds to the o2 produced
Any further increase in rate would need inc co2

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62
Q

What are only certain wavelengths used in photosynthesis

A

Photosynthetic pig,ends chlorophyll a/b and carotene only absorbed red and blue light in the Sunlight

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63
Q

What is the optimum temp around for plants

A

25

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64
Q

At what temperatures are plants negatively effected and why

A

Photosynthesis involves enzymes (eg. ATP synthase and rubisco) if temp falls below 10°c the enzymes become inactive, move than 45° than may start to denature

Also at high temps stomata close to avoid too much water, this causes photosynthesis to slow down because less co2 enter leave when stomata are close

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65
Q

What is the optimum co2 % for photosynthesis

A

0.4% ( any high the stomata start to close)

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66
Q

What happens if a plant has too much water

A

The soil becomes water logged which reduced uptake of minerals which is needed to make chlorophyll

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67
Q

What is a saturation point

A

Where’s factor is no longer limiting the reaction
Something else has become the limiting factor

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68
Q

How do agriculture growers create optimum conditions for photosynthesis

A

Greenhouses ( glass houses)

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69
Q

How is co2 con managed in a glasshouse

A

Co2 is added or the air, by burning a small amount of propane in a co2 generator

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70
Q

How is light managed in greenhouses

A

Light can get thought glass and lamps are used at night

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71
Q

How is temperature managed in glass houses

A

Glasshouses trap heat energy from sunlight which warms the air, heaters and cooling systems can also be used to keep a constant optimum temperature and air air circulation system make sure the temperature is even throughout the glass house

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72
Q

Where can simsialr techniques that glasshouses used be used

A

Polytunnels (made of polythene, under which plants can be grown)

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73
Q

How did Calvin work out the light independent reaction

A

Lollipop
Algae are grown under light in thin transparent lollipop
Radioactive C14 in the form hydrogencarbonate is injected
At intervals samples on the photosynthesising algae are dropped into the hot methanol to stop chemical reactions instantly
The compound in the algae are separated by two water chromatography
The radioactive compounds are identified

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74
Q

What is an ecosystem

A

All the organisms living in a particular area and all the non-living (abiotic) conditions

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75
Q

What is a producer

A

Organisms that make their own food

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76
Q

Some of the sugars produced during photosynthesis are used in …… for what

A

Respiration to release energy for growth

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77
Q

Except respiration what is the rest of the glucose made from photosynthesis used for

A

Other biological molecules such as cellulose (in plant cells walls) these biological molecules make up the plants biomass

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78
Q

What is biomass

A

The chemical energy stored in a plant

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79
Q

How is energy transferred through living organisms of an ecosystem

A

When organisms eat other organisms ,

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80
Q

What can biomass be measures in terms of

A

Mass of carbon that an organism contains or the dry mass of its tissue per unit area per unit time

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81
Q

Why is dry mass uses as a measure of biomass rather than wet mass

A

Water content of living tissue varies

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82
Q

How is biomass measures (method)

A

1) dry mass is the mass of the organism with the water removed
2) to measure dry mass, a sample of the organism is dries, oftern in an oven at low temps, the sample is then weighed at regular intervals, once mass is constant you know all water has been removed
3) if needed the result can be sacked up to give the biomass of the total population or the area being investigated.

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83
Q

What is a typical unit for dry mass

A

Kg m-2

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84
Q

The mass of the carbon present generally is …..% of the dry mass

A

50%

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85
Q

Why is it usefull to give biomass over a particular time period

A

Biomass changes over time

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86
Q

What is atypical unit for biomass over a time period

A

Kg m-2 yr-1

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87
Q

How can you estimate the amount of chemical energy stored in biomass

A

By burning the biomass in a calorimeter
The amount of heat given off tells you how much energy is in it

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88
Q

What is chemical energy stores in biomass measured in

A

J or KJ

89
Q

Describe the method to find chemical energy in biomass, by calorimeter

A

1) a sample of dry biomass is burnt and the energy released is used to heat a known volume of water
2) the change in temperature of the water is used to calculate the chemical energy of the dry biomass

90
Q

What is gross primary production

A

The total amount of chemical energy converted form light energy by plants in a given area in a given time

91
Q

Approx. ….% of gross primary production is lost to the environment as …… when the plants respire.
What is this called?

A

50%
Heat
Respiratory loss(R)

92
Q

What is the remaining chemical energy that wasn’t lost to environment as heat called

A

Net primary production
(So NPP = GPP - R)

93
Q

What is rhe net primary production

A

The energy available to the plant for growth and reproduction - the energy is stored in the plants biomass. It is also the energy available to organisms at the next stage in the food chain. These include herbivores and decomposers

94
Q

T or f
Consumers also store chemical energy in their biomass

A

T

95
Q

How do consumers get energy

A

Ingesting plant material or animals that have eaten plant materials

96
Q

Is all the chemicals energy stored in the consumers food transferred to the next tropic level

A

No

97
Q

What % of the total available energy is lost in various ways as it’s transferred to thr next tropic level

A

90%

98
Q

Why is 90% of energy lost form one trophies level to the n3xt

A

1- not all the food is eaten (bones, roots) so the energy it contains is not taken in
2- some are indigestible so are egested as faeces
3- Some energy is also lost to the environment though respiration or excretion of urine

99
Q

Where is the energy thatgets transferred form one tropic level to the next stores
And what is this energy called

A

Consumers biomass
Consumers net production

100
Q

The net production of consumers can be calculated using what formula

A

N = I ( F + R)
N= net production
I= chemical energy in ingested food
F= chemical energy lost in faeces and urine
R= energy lost though respiration

101
Q

Respiration turns
…….. energy to ……. Energy

A

Chemical
Kinetic

102
Q

Photosynthesis turns

…….. energy to ……. Energy

A

Light enegy
Chemival enegy

103
Q

What is an ecosystem

A

Group of living and non living things and the relegationshop between them

104
Q

What Is a habitat

A

The place where an organism lives

105
Q

What is a population

A

All the organisms of one species who love in the same place at the same time and can breed together

106
Q

What is a community

A

All the populations of differnt species who live in the same place at the same time and can interact together

107
Q

What is a niche

A

The role it plays within an ecosystem

108
Q

What does a niche include

A

What it feeds on
What is excretes
How it reproduces

109
Q

Can 2 species have the exact same niche in the same ecosystem

A

No
Differnt species have to occupy differnt niches as they would compete with each other to much

110
Q

Biotic examples

A

Preditors
Disease agents
Competition
Symbiosis

111
Q

Abiotic examples

A

Wind
Sun
Ph
Co2 conc

112
Q

What are the 2 types of symbiosis

A

Mutualism
Parasitism

113
Q

What is an example of mutualism

A

When both benefit
Fly On an elephant help take insects out, and the fly has elephants protection

114
Q

Axample of parasitism

A

Tick sucking on human blood

115
Q

Are factors in an ecosyem changing

A

Yes

116
Q

T or f
Stable ecosystems are relatively consistent

A

T

117
Q

Are each organisms only members of one food chain,

A

No they are usually members of more than one and oftern feed on differnt tropic levels in differnt chains

118
Q

What is the average enegy transferred at each trophic level

A

10%

119
Q

How is energy lost between trophic levels

A

Can’t digest everything ( bones)
Used in respiration
Excretion of waste material

120
Q

What is chemical energy stored as

A

Up in biomass ( glucose)

121
Q

In respiration biomass is broken down to ….

A

Release energy

122
Q

What are the 3 pyramids in enegy transfer

A

Pyramid of biomass
Pyramid of numbers
Pyramids of enegy

123
Q

What is the shape always for a pyramid of biomass

A

Will always have a pyramid shape as producer is the only one who can make biomass

124
Q

What is calorimetry

A

Closed system used to calculate chemical energy stores in dry mass

125
Q

Brief calorimetry method

A

1) sample of dry material weighed, burned in a sealed chamber
2) heat from combustion heats water
3) 1g of water is heated by 1°c
4) if we know vol of H20 and temp rise we can calculate envy released form the mass of burnt biomass

126
Q

What do food chains and webs show

A

How energy is transferred through an ecosystem

127
Q

What is a food chain showing

A

Simple lines of energy transfer.

128
Q

What is each stage in a food chain called

A

Trophic level

129
Q

What does a food web show

A

Lots of food chains in an ecosystem and how they overlap

130
Q

What are decomposers

A

They break down dead or undigested material allowing nutrients to be recycled

131
Q

What do most farming practices aim to increase

A

The amount of enegy that is available for human consumption

132
Q

What 2 ways can farming practices increase energy available for human consumption

A

1j the energy lost to other organisms, eg, pests can be reduced
2j the enegy lost though respiration can be reduced

133
Q

1j the energy lost to other organisms, eg, pests can be reduced
How does this increase enegy available for human consumption

A

By simplifying food webs ( getting rid of food chains that don’t involve humanism enegy losses will be reduced and the NPP of the crop will increase

134
Q

Give 2 examples of how farmers can reduce pest numbers with chemical pesticides, and how it reduces pests

A
  • insecticides kill insect pests that eat and damage crops. Killing insect pests means less biomass is lost form crops, so they grow larger, which means NPP is greater
  • herbicides kill weeds, killing weeds can remove direct competition with the crop for enegy form the sun, it can also remove the preffered habitat or food source of the insect pests, helping to further reduce their numbers and simplify food webs
135
Q

Aside from chemical pesticides, what else can reduce number of pests

A

Biological agents

136
Q

2 examples of how biological agents reduce the number of pests

A

1)parasites live in or lay their eggs on pest insect. Parasites either kill the insect or reduce its ability to function.
(Eg, some wasp species lay their eggs inside caterpillars - the eggs hatch and kill the catapillers)

2) pathogenic bacteria and viruses are used to kill pests

137
Q

Do farmers use chemical or biological methods to reduce pesticides

A

They use an integrated system that combine both
They combined effect reduce pest numbers even more than either methord alone, so NPP increased even more

138
Q

How does controlling conditions livestock live in increase net production

A

More of their energy is used for growth and less lost through respiration

139
Q

What is 2 example of controlling conditions of livestock in increase production

A

1) movement increases the rate of respiration, so animals may b be kept in pens where movement in restricted
2) the pens are often indoors and kept warm so less energy is water by generating body heat

140
Q

What is the effect of controlling conditions of livestock

A

More biomass is produced and more chemical energy can be stored, increasing net production and the efficiency of enegy transfer to humans

141
Q

What are the benefits of controlling livestock conditions

A

More food can be produced in a shorter space of time , oftern at a lower cost

142
Q

What are the disadvantages of controlling livestock conditions

A

Ethical issues
Eg. Some people think that the conditions intensively reared animals are kept in cause the animal, pain, distress or restricts their natural behaviour so shouldn’t be done

143
Q

What is a natural ecosystem

A

One that hasn’t been changed by human activity

144
Q

What disrupts natural ecosystems recycling nutrients though food webs

A

Human activity

145
Q

What is a saprobiont

A

A type of decomposer

146
Q

What do microorganisms do

A

Feed on the remains of dead plants and animals and on their waste products, breaking them Down.this allows important chemical elements in their remaining to be recycled

147
Q

What do saprobionts do

A

Secrete enzymes and digest their good externally, then absorb the nutrients they need.

148
Q

Sacrobionts Secrete enzymes and digest their good externally, then absorb the nutrients they need.
What is thus known as

A

Extracellular digestion

149
Q

Saprobions Secrete enzymes and digest their good externally, then absorb the nutrients they need.
What happens in this process

A

Organic molecules are broken down into inorganic ions. O staining nutrients form dead organic matter using extreaxellular digestion is known as Saprobiotic nutrition.

150
Q

Some fungi form …… relationships with the roots or plants. What is this releationship knwo as

A

Symbiotic
Mycorrhizae

151
Q

What are fungi made up of

A

Lord thing strands called hyphae

152
Q

Describe fungis symbiotic relationship with plants and roots

A

Fungi’s hyphae connect to the plants roots
The hypha’s greatly increases the surface area of the plants root system. Helping the plant to absorb ions form the soil that are usually scarce ( eg. Phosphorus) hyphae also increase the uptake of water by the plant
In turn the fungi obtains organic compounds such as glucose form the plant

153
Q

What do plants and animals need nitrogen for.

A

Making proteins and nucleic acids (DNA / RNA)

154
Q

Can plants and animals use the nitrogen in the atmosphere

A

No they can use it in that from

155
Q

What does GPP stand for

A

Gross primary product

156
Q

What does gross primary product mean

A

The rate at which plants convert light energy to chemical energy

157
Q

What does NPP stand for

A

Net primary production

158
Q

What does net Primary production mean

A

Energy remaining that’s available to primary consumers as energy is lost when plants respire

159
Q

What does R stand for

A

Respiratory loses

160
Q

What is the equation for producers for primary production

A

NPP = GPP - R

161
Q

What is the equation for consumers for net production

A

N= I - ( F + R)

162
Q

N= I - ( F + R)
What does each the letter stand for

A

N= net production
I = chemical energy story of ingested food
F= energy lost in faeces and urine
R= energy lost in respiration

163
Q

Nitrite ion

A

NO2. -

164
Q

Nitrate ion

A

NO3. -

165
Q

What 4 compounds contain PO4 3-

A

DNA
RNA
ATP
phospholipid

166
Q

Phosphorus element

A

P

167
Q

Phosphate formula

A

PO4 3-

168
Q

Describe the phosphorous cycle

A
  1. Feeding and digestion - a plant is consumed by an animal the phosphate is fixed in the plants and is broke down in the digestive system. Consumers get there phosphate form the tropic level below them.
  2. Decomposition and excretion - saprobionts ( fungi / bacteria) they recycle nutrients so plants can reuse. The saprobionts break down waste form animuals and decaying organism is into organic ions that are accessible to plants again.
  3. Weathering / errosion of rock - phosphorous rock broken down by wind and rain are washed into rivers - microorganism changed phosphorous to phosphate so plants can absorb or mechanical mining of rock to make fertilisers
  4. Absorption - plants absorb phosphate ions through their roots through active transport
  5. Sedimentation - phosphate containing organisms deposited at the bottom of lakes / rivers - > becomes new rock form deposited silt and tectonic movements pouches the new rock to the surface
  6. Leaching - group water washed phosphate ions out to sea / lakes / rivers
169
Q

What is mycorrhizal interactions

A

Symbiotic relation between fungi and plants.
The mycorrhizal extend plant roots with fungal hyphae, inc SA for absorption (eg. Nitrogen / p)
Inc. plants water uptake ability ( especially in low moisture conditions)
mycorrhizae contribute to plant growth, health + resistance to environmental stress
Fungi receives carbohydrates / other organic compounds form the plants

170
Q

What is nitrogen fixation

A

When nitrogen gas in the atmosphere is turned into nitrogen containing compounds

171
Q

What is ammonificiation

A

When nitrogen compounds form dead organisms are turned into ammonia by saprobionts, which does on to form ammonium ions

172
Q

What is nitrification

A

Ammonium ions in the soul are changed into nitrogen compounds that can them be us3x by plants ( nitrates)

173
Q

What is denitrification

A

When nitrates in the soil are converted into nitrogen gas by denitrifying bacteria

174
Q

What is the nitrogen cycle

A
  1. Nitrogen fixation
    1) Nitrogen fixation
    • Nitrogen fixation is when nitrogen gas in the atmosphere is turned into nitrogen-containing
    compounds. Biological nitrogen fixation is carried out
    by bacteria They turn nitrogen into ammonia, which goes on to form ammonium ions in solution that can then be used by plants.
    • Rhizobium are found inside root nodules (growths on the roots) of leguminous plants (e.g. peas, beans and clover).
    • They form a mutualistic relationship with the plants
    — they provide the plant with nitrogen compounds and the plant provides them with carbohydrates.

2) 2) Ammonification
• Ammonification is when nitrogen compounds from dead organisms are turned into ammonia by saprobionts, which goes on to form ammonium ions.
• Animal waste (urine and faeces) also contains nitrogen compounds. These are also turned into ammonia by saprobionts and go on to form ammonium ions.

3) Nitrification
• Nitrification is when ammonium ions in the soil arechanged into nitrogen compounds that can then be used by plants (nitrates).
First nitrifying bacteria change ammonium ions into nitrites.
• Then other nitrifying bacteria change nitrites into nitrates.

  1. Denitrification
    When nitrated in the soil are converted into nitrogen gas by denitrifying bacteria - they use nitrated in the soil to carry out respiration and produce nitrogen gas
    Thus happens under anaerobic conditions eg, waterlogged soil
175
Q

Why cant plants and animals use atmospheric nitrogen

A

They need bacteria to convert it into nitrogen containing compounds first.

176
Q

What are the 4 processes that involve bacteria in the nitrogen cycle

A

Nitrogen fixation
Ammonification
Nitrification
Denitrification

177
Q

What is another way of nitrogen getting into an ecosystem

A

Lighting ( which fixes atmospheric nitrogen )
Artificial fertilisers ( they’re produced form atmospheric nitrogen on an industrial scale in the harber process )

178
Q

What do plants and animals need nitrogen to make

A

Proteins and nucelic acids

179
Q

Where is phosphorous found

A

In rocks and dissolved in oceans in the for, of phosphate ions

180
Q

Phosphorus cycle

A

Phosphate ions in rocks are released into the soil by weathering
Phosphate ions are taken into the plants through the roots.
Mycorrhizae (see previous page) greatly increase the rate at which phosphorus can be assimilated.
Phosphate ions are transferred through the food chain as animals eat the plants and are in turn eaten by other animals
When plants and animals die, saprobionts are involved in breaking down the organic compounds, releasing phasphate ions into the soil for assimilation by plants.
These microorganisms also release the phosphate ions from urine and faeces.
Weathering of rocks also releases phosphate ions into seas, lakes and rivers. This is taken up by aquatic producers, such as algae, and passed along the food chain to birds.
The waste produced by sea birds is known as guano and contains a high proportion of phosphate ions. Guano returns a significant amount of phosphate ions to soils (particularly in coastal areas. It is often used as a natural fertiliser.

181
Q

Crops take In minerals form the soil as they grow and then use them to …

A

Build up their own tissues

182
Q

When crops are harvested, they’re removed from the field where they’re grown rather than begining allowed to die and decompose.
What does this mean for mineral ions…

A

The mineral They contain eg. Phosphate amd nitrates are not retired to the soil by decomposers in the nitrogen or phosphorus cycle.

183
Q

How are phosphates amd nitrates lost form the system

A

When animals or animal products are removed from the land. Animals eat grass and other plants, taking in their nutrients. When they are taken elsewhere for slaughter or transfer to a differnt field, the nutrients aren’t replaced through they remains or water products

184
Q

What do fertilisers do

A

Replace the lost minerals, so more energy from the ecosystem can be used for growth, increasing the efficiency of energy transfer.

185
Q

Are fertilisers artificial or natural

A

Both

186
Q

What are artifical chemicals made from,

A

Inorganic
They contain pure chemicals (eg. Ammonium nitrate) as powder or pellets

187
Q

What do natural fertilisers contain

A

Organic matter, they include manure, composted vegetables, crop residue (the parts left over form the harvest) and sewage sludge

188
Q

What leads to fertilisers landing into waterways

A

Sometimes more fertiliser is applied then the plants need or are able to use in a particular time

189
Q

What is leaching

A

When water soluble compounds in the soil are washed away.
Eg. By rain or irrigation system
They are often washed into nearby ponds or rivers

190
Q

What can leaching lead to

A

Eutrophication

191
Q

When is leaching more likely to occur

A

If The fertilisers is applied just before heavy rainfall

192
Q

Is leaching more or less likely in organic or inorganic ions

A

Inorganic ions, in chemical feriltizers are relatively soluble. This means that excess minerals that are not used imediatly are more likely to leach into water ways.
In natural fertilisers,the nitrogen and phosphorus are still contained in organic moelcuels that need to be decomposed by microorganism before they can be absorbed by plants.this means that there release into the soil for uptake by plants is more controlled and leaching is less likely

193
Q

Is the leaching of phosphate more or less Likely than the leachinf of nitrates and why

A

Less
As phosphate is less soluble

194
Q

Using fertilisers changes what about the soil?

A

The balence of nutrients in the soil - too much of a particular nutrient can cause crops and other plants to die

195
Q

Describe eutrophication

A
  1. Mineral ions leached from fertilised fields stimulate the rapid growth of algae In ponds and rivers
  2. Large amount of algae block lights from reaching the plants below
  3. Eventually the plants die because they are unable to photosynthesis enough
  4. Bacteria feed on the dead plant matter. The increased number of bacteria reduced the oxygen concentration in the water by carrying out aerobic digestion
  5. Fish and other aquatic organism die because there isn’t enough dissolved oxygen
196
Q

Any change in a community of organism can cause a change in what (succession)

A

Their habitat

197
Q

Any change in a habitat can also cause a change in what ( succession)

A

Change in make up of community

198
Q

Give 2 examples of pioneer species

A

Lichen
Moss
Maram grass

199
Q

What is primary succession

A

Refers to the introduction of plants into areas that have not previously supported a community

200
Q

What is a pioneer species

A

The first organism to colonise an area

201
Q

Features of a pioneer species

A
  • early arrivals, rapid germination
  • axesual reproduction
  • can tolerate extreme conditions eg. Low nutrient levels
  • have good means of dispersal, usually by wind
  • ability to photosynthesis
  • notinfluences by or dependent on animal species
  • they are not able to compete for resources eg, light
  • may be able to fix nitrogen (eg, leguemes) and build up soil nutrients
202
Q

What does secondary succession refer to

A

The reintroduction of organisms into a bare habitat previously occupied by plants and animals
If the origional vegetation is removed the area rapidly becomes recolonised by a succession of differnt plants and animals

203
Q

How does succession happen
Eg, algae on bare rock

A

Errosion of the rockand build up of dead and rotting organisms produce enough soil for larger plants to grow. There replaced, or succeeded the algae
Then larger plants succeed smaller plants until a stable community is reached
This is called a climax community

204
Q

What are some features of a climax community species

A
  • species found in the end point community
  • have larger seeds ( with a large energy store) so that seedlings can survive low light intensity
  • have specialised niche
  • are unable to tolerate great functions in the water contents of soil
  • are strongly influenced by other orgnaums, eg competitors, herbivore, pollinators, seed dispersal agents and soil microorganisms
205
Q

Suggest abiotic factors that make colonisation plants difficult in sand dunes ( just above high tide lime)

A

Wind
Dry
Salt

206
Q

Explain the role of pioneer plants in succession of bare or rock or sand dunces

A

Stabilises environment
Inc organic material in soil
Holds more waters
Release more minerals / nutrients

207
Q

What elements do modern fertilisers contain

A

Nitrogen
Phosphorus
Pottasium

208
Q

Benefits of fertilisers

A

Allow more food to be grown on the same amount of land, support food security, to meet demands of growing population

209
Q

Negatives of excessive fertilisers (biodiversity)

A

Promotes fast growing species - so reduces biodiversity
Outcompeting slower-growing species so disrupts ecosystems and food chains

210
Q

Negatives of fertilisers ( leaching)

A

Soluble nitrates form fertilisers can leach into the ground water and surface water
Nitrates contamination affects drinking water and aquatic ecosystems

211
Q

What are the 3 negatives of fertilisers

A

Loss of biodiversity
Leaching
Eutrophication

212
Q

What is eutrophication

A

Fertilisers runoff leads to nutrient pollution in water bodies causing algal blooms
Algal blooms reduce oxygen levels, harming aquatic life and creating dead zones

213
Q

How does fertilisers link to sustainability

A

Optimising fertiliser use minimises ecological damage while maintains productivity

214
Q

Uses of plant other than food

A

Building material
Clothes
Medicines
Fuel
Livestock food

215
Q

What is a good system for plants to refix nutrients in the soil

A

Crop rotation

216
Q

What does the harber process do

A

Produces NH3,
By fixing N2 form the atmosphere

217
Q

What can NH3 from the harber process be turned into …. To be used on ….

A

NH4+ salts
To be used on fields as fertilisers

218
Q

Can all nutrients / fertiliser be leached

A

No only water soluble nutrients

A-level Biology (8 decks)

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