Topic 5 - Energy transfers Flashcards
1
Q
state the two stages of photosynthesis
A
LDR (light dependent reaction)
LIDR (light independent reaction) - also known as the dark reaction
2
Q
where does LDR occur
A
thylakoid membrane of chloroplast
3
Q
where does LIDR occur
A
stroma of chloroplast
4
Q
describe the structure of chloroplasts
A
did you mention:
double membrane (envelope), stoma containing thylakoid membrane, 70s ribosomes, circular DNA, starch granules, lamella, grana
5
Q
describe photoionisation in the LDR
A
- chlorophyll absorbs light energy which exites its electrons (higher energy levels)
- so electrons are released from chlorophyll (chlorophyll becomes positively charged)
6
Q
describes what happens after photoionisation in the LDR
A
some energy from electrons released in photoionisation is conserved in the production of ATP./reduced NADP:
- electrons move along electron transfer chain (electron carriers), releasing energy
- energy is used to actively pump pprotons from stroma into thylakoid
- protons move by facilitated diffusion down electrochemical gradient into stroma via ATP synthase
- energy used to join ADP and Pi to form ATP (photophosphorylation
- NADP accepts a proton and an electron to become reduced NADP
7
Q
state 3 products of LDR
A
ATP, reduced NADP, half an O2 molecule
8
Q
describe photolysis of water in the LDR
A
water splits to produce protons, electrons and oxygen (H2O –. 0.5 O2 + 2e- + 2H+)
electrons replace those lost from chlorophyll
9
Q
what is the light independent reaction known as (2 names)
A
the dark reaction or the calvin cycle
10
Q
where does the LIDR occur
A
stroma of the chloroplast
11
Q
what 2 products of the LDR is used in the LIDR
A
reduced NADP and ATP
12
Q
why are reduced NADP and ATP used in the LIDR
A
to reduce CO2
13
Q
describe the LIDR
A
- CO2 reacts with ribulose bisphosphate (RuBP) and is catalysed by the enzyme rubisco
- this forms 2 glycerate 3-phosphate (GP) molecules [3C]
- GP is then reduced to triose phosphate (TP) [3C]. this uses reduced NADP oxidised into NADP and ATP reduced into ADP + Pi
- some TP is converted into useful organic substances e.g. glucose (6C)
- some TP is used to regenerate RuBP (5C) in the calvin cycle using energy from ATP (ATP is reduced into ADP + Pi)
14
Q
does LIDR require light?
A
not directly
15
Q
describe how temperature affects rate of photosynthesis
A
temperature increases = rate increases
above optimun temperature, rate decreases = fewer sucessful collisions and fewer ES complexes form
16
Q
explain how temperature affects rate of photosynthesis
A
temp increases because enzymes like rubisco gain kinetic energy
enzymes will denature above optimun temperature. H bonds in tertiary structure break = fewer ES complexes form
17
Q
describe how light intensity affects rate of photosynthesis
A
light intensity increases as rate increases but above a certain light intensity, rate stops increasing
18
Q
explain how light intensity affects rate of photosynthesis
A
light increases as rate increases
LDR increases so more ATP and reduced NADP -produced so LIDR increases as more GP reduced to TP and more TP regenerates RuBP
above certain light intensity, rate stops increasing
another factor is limiting when light intensity rate stops increasing e.g. tmeperature or Co2 concentration
19
Q
describe how CO2 conc affects rate of photosynthesis
A
as CO2 conc increases, rate increases
above certain CO2 conc, rate stops increasing
20
Q
explain why CO2 conc affects rate of photosynthesis
A
rate increases as CO2 increases
LIDR increases as more CO2 combines w RuBP to form GP so more GP reduced to TP so more TP converted to organic substances and more RuBP regenerated
rate stopping after certain CO2 conc
another factor is limiting e.g. temp or light intensity
21
Q
what is the law of limiting factors
A
when a process depends on two or more factors, the rate of that process if limited by the factor which is in shortest supply
22
Q
what three factorrs can the rate of photosynthesis in a plant can be limited by
A
light intensity, conc of CO2, temperature
23
Q
what happens to rate of photosynthesis when temeprature is too low
A
lower kinetic energy so fewer sucessful collision and fewer ES complexes form and a slower rate of reaction = lower rate of electron transport chain/lower rate of carboxylation by rubisco
24
Q
what happen to rate of photosynthesis when temperature is high
A
high kinetic energy breaks the hydrogen bonds in the tertiary structure of enzymes and proteins involved in the LDR and calvin cycle. enzymes + proteins lose their tertiary structure and change shape [denature] so cannot perform role in LDR or calvin cycle
lower rate of electron transport chain/lower rate of carboxylation by rubisco
25
what happens to rate of photosynthesis when CO2 is low
less CO2 so less RuBP to combine with and less GP produced. So less GP for the NADPH2 and ATP to convert into and less TP = less glucose
26
what happens to rate of photosynthesis when light intensity is lower
less light
less photoionisation which means less electrons are excited
so reduced electron transport chain = less NADPH2 and ATP produced
CO2 will combine with RuBP to produce GP but cannot change into TP as no NADPH2 or ATP so less TP converted into glucose
27
when there is a line with a gradient what does this mean regarding limiting factors
independent variable is limiting the rate of photosynthesis - xaxis
28
when there is a flat line what does this mean in limiting factor graphs
a factor other than the independent variable is limiting rate of photosynthesis = yaxis
29
what happens to rate of photosynthesis when there is a lack of chlorophyll
this is mainly due to being deficient iin Mg2+ so less light absorbed, less photoionisation, reduced electron transport chain = less NADPH2 and ATP so reduced production of TP and so less glucose
30
how does a lack of water affect rate of photosynthesis
less water split into two to replace the electrons lost in the Photosystem II and so reduced photolysis of water so cannot replace electrons so stays ionised and reduced electron transport chain. less NADPH2 and ATP produced so less GP turned into TP which means less glucose
31
why are fertilisers are used
- to replace nitrates/phosphates lost when plants are harvested and livestock are removed
- those removed from soil and incorporated into biomass can't be released back into the soil through decomposition by saprobionts
- so improve efficiency of energy transfer = increase productivity/yield
faster growth, increased biomass, higher productivity (rate at which biomass is produced), higher yield and cheaper food
32
what are natural fertilisers made of
organic substances and ions are released during decompositioni by saprobionts e.g. manure, compost and sewage
33
what are artificial fertilisers made of
inorganic compounds of nitrogen, phosphorus and potassium
34
how do fertilisers increase productivity
nitrogen is an essential compound of amino acids, ATP and nucleotides in DNA all needed for plant growth. increased conc = plants develop quicker - greater leaf area, grow taller = more photosynthesis can occur and improved crop productivity
35
state 3 effects of using fertilisers
redeuced species diversity, leaching, eutrophication
36
state what happens in eutrophication
- rapid growth of algae in pond/river so light blocked
- submerged plants die as they cannot photosynthesise
- saprobionts decompose dead plant matter using oxygen in aerobic respiration
- so less oxygen for fish to aerobically respire, leading to their death
37
state how leaching affects it
phosphates/nitrates disssolve in water, leading to leaching of nutrients into lakes/river/oceans + eutrophication
pollutes watercourses
38
explain key advantages of using natural fertiliser over artificial fertiliser
- less water soluble so less leaching = eutrophication is less likely
- organic molecules require breaking down by saprobionts = slow release of nitrate/phosphate etc.
39
what is leaching
soluble mineral ions (nitrate ions) dissolve in rainwater and carry the ions deep into the ground beyond the reach of plant roots = mineral ions travel into watercourses (rivers and streams) via groundwater flow
40
state how fertilisers reduce species diversity
nitrogen rich soil favours the growth of grasses, nettles and other rapidly growing species which outcompete other species, leading to a reduced biodiveristy of plants = fewer plant speicies = reduced food sources and habitat options
41
what is eutrophication caused by
leaching of fertiliser into watercourses
42
what is eutrophication
soluble nitrates are washed into watercourse, algae absorb the nitrates and the opulation grows rapidly = alglal bloom which blocks aquatic plants so as they cannot photosynthesise, they die
lots of dead, organic material for bacteria to feed on = population grows rapidly = water is anoxic (lacking oxygen) due to anaerobic respiration.
lack of oxygen = reduced biodiversity as all organisms die
43
what can farmers do to increase growth
use greenhouses, propane burners, night lights, irrigation systems and pesticides
44
how does use of greenhouses increase growth in farming
increases radiation = increased LDR and increases temperature = increased KE
45
how does use of propane burners increase growth in farming
increase temperature = increased KE and increase CO2 = increased CAlvin cycle
46
how does the use of night lights increase growth in farming
more constant radiation = increased LDR
47
how does use of irrigation systems increase growth in farming
increased volume of water = increased LDR
48
how do pesticides increase growth in farming
kill pests which .....
leaves eaten = less photoionisation = reduced LDR
broken phloem tissue = reduced carbohydrates for respiration, storage and synthesis of molecules = reduced growth because reduced DNA reeplication, protein synthesis, cell division
damage root cells = reduced water and mineral ion absorption = reduced LDR and turgidity = reduced SA exposed so reduced LDR
mineral ion deficiency = reduced chlorophyll (less LDR), enzyme action, protein synthesis and ATP production
49
explain how crop farming practices increases efficiency of energy transfer
simplifying food webs to reduce energy/biomass losses to non-human food chains e.g.
- herbicides kill weeds = less competition for light so more energy to create biomass
- pesticides kill insects = reduce loss of biomass from crops
- fungicides reduce fungal infections = more energy to create biomass
fertilisers e.g. nitrates to prevent poor growth due to lack of nutrients
50
why are magnesium ions needed in fertilisers
required to synthesise chlorophyll molecules
51
why are nitrate ions needed in fertilisers
synthesises amino acids and mononucleotides = proteins, ATP, polynucleotides
52
why are potasssium ions needed in fertilisers
required for co-transport (NaK pump) = absorption of mineral ions by roots = generates osmotic pressure = movement of sucrose into the phloem
52
why are phosphate ions needed in fertilisers
to phosphorylate ADP into ATP, for phospholipids and nucleotides (mono and poly)
53
explain how livestock farming practices increase efficiency of energy transfer
reduce respiratory losses within a human food chain = more energy to create biomass:
- reduce movement and keep warm = less energy lost as heat from respiration
- slaughter animal while still growing/young when most energy is used for growth
- treated with antibiotics = prevent loss of energy due to pathogens
- selective breeding to produce breeds with higher growth rates
54
state 3 advantages of inorganic fertiliser
- can tailor the fertiliser to the specific needs of the soil/crop
- concentrated = large amount in small area
- soluble = easily spread in fields
55
state 2 disadvantages of inorganic fertilisers
favours the growth of fast growing plants (weeds) which results in reduced species diversity and doesn't replace soil structure, leaving it vulnerable to wind and soil erosion. solubleeading to leeching and eutrophication
56
how is the mitrochondrion structure adapted to its function
- long and thin = large SA:V for movement of particles in and out of mitochondrion = short diffusion distance
- envelope = controls what enters and exits = H+ conc gradient to be set up
- cristae = high SA for attachment of respiratory proteins
- has its own DNA and ribosomes = make its own respiratory proteins
57
state the structures found in mitochondria
- inner and outer membrane (envelope)
- cristae
- matrix
- 70S ribosomes
- mitochondrial DNA
- intermembranal space
58
overall reaction for respiration
glucose + oxygen -> carbon dioxide + water + (38 ATP)
heat energy is also released = exothermic
chemical energy released initiates condensation reaction of ADP to ATP
59
define respiration
a chemical reaction that releases the chemical potential energy from molecules
60
what is the difference btwn respiration and breathing
respiration occurs 'everywhere' but breathing occurs in the lungs
61
what does ATP stand for
adenosine triphosphate
62
why ATP
- muscle contraction
- metabolic processes such as protein synthesis
- phosphorylation of molecules to make them more reaction
- active transport
- good energy carrier = invovles one step reaction = immediate source of energy which is released in small manageable amounts
- easily reformed in a condensation reaction
63
why is ATP a bad source of energy
- easily hydrolysed
- cannot travel through the phospholipid bilayer as it is soluble = difficult to keep in one place. if kept in one place, affects water potential
64
what are the 4 main processes in aerobic respiration
substrate-level phosphorylation:
- glycolysis
- link reaction
- krebs cycle
- oxidative phosphorylation
65
what is the purpose of substrate-level phosphorylation
break down substrates to produce reduced co-enzymes to be used in oxidative phosphorylation
66
what does oxidative phosphorylation allow
create a H+ conc. gradient which allows phosphorylation of ADP to ATP
67
what is a co-enzyme
a non-protein compound necessary for the function on an enzyme
68
what co-enzymes are used in respiration
NAD, CoA, FAD
69
where does glycolysis occur
in the cytoplasm
70
where in the stage of respiration are co-enzymes used
reduced are used in the final stage of respiration (oxidative phosphorylation which produces a lot of ATP)
71
does glycolysis require oxygen
no
72
what happens in glycolysis
glucose is split into 2 molecules of pyruvate (a 3 carbon sugar) via phosphorylation
73
what two phases are there in glycolysis
energy pay off phase and energy investment (glucose -> triose phosphate -> pyruvate)
74
what are the resulting products of glycolysis
2 pyruvate molecules, net gain of 2 ATP molecules (4 overall gross gain of ATP molecules but 2 used in the reaction for phosphorylation to triose phosphate), 2 reduced NADP
75
where does the link reaction occur
matrix in the mitochondria
76
what happens in the link reaction
- pyruvate is produced in glycolysis is passed through the inner and outer membrane of the mitochondrion by active transport
- decarboxylatioin (CO2 removed from pyruvate) which requires enzyme decarboxylas
- CO2 diffuses out of the mitochondrion and cell
- dehydrogenation = hydrogen atom produced which is used by NAD to become reduced NADH
- coenzyme A picks up acetyl which results in acetyl coenxyme A (2C) which is then used in the Krebs cycle)
77
what occurs in the krebs cycle
- acetylee coenzyme A from the link reaction combines its acetyl group with oxalacetates (4C) to produce citrate (6C)
- citrate is decarboxylated and dehydrogenated to an intermediate 5C molecule
- futher decarboxylation and dehydrogenation produces an oxalacetate , 2 NADP molecules are reduced, FAD is reduced, ATP is produced and CO2 is produced.
- oxalacetate is now recycled with another acetyl coenzyme A to begin the cycle again
78
how many krebs cycles occur per glucose molecule
2
glucose > 2 triose phosphates > 2 pyruvates > 2 acetyl coenzyme As
79
what is produced in two link reactions which come from one glucose molecule
acetyl coenzyme A, 2 CO2, 2 NADH
80
what is produced in two krebs cycle from the one glucose molecule
4 CO2, 6 NADH, 2 FADH, 2 ATP
81
what is oxidative phosphorylation
it is the final stage of respiration where the majority of ATP is produced
82
where does oxidative phosphorylation occur
on the inner membrane of the mitochondria (cristae)
83
what does oxidative phosphorylation use and require to occur
it uses NADH, FADH and requires oxygen (known as the terminal electron acceptor)
84
what is oxidative phosphorylation also known as
the electron transport chain
85
give a brief description of what happens in oxidative phosphorylation
- hydrogen atoms are picked up and transported by NADH and FADH are split into H+ and e-
- electrons are passed down a series of electron transport carrier molecules (involves redox reactions) which releases energy that is then used to pump H+ into intermembranal space
- H+ diffuses down an electrochemical gradient (chemiosmosis) through ATP synthase which catalyses the condensation reaction of ADP and Pi
- once electrons have transferred their energy they combine with H+ in the mitochondrial matrix and oxygen to form water = oxygen is the terminal electron acceptor
4e- + O2 + 4H+ -> 2H2O
86
how many ATP molecules does NADH create
3
87
how many ATP molecules does FAD create
2
88
where is some energy lost in oxidative phosphorylation
heat
89
where in oxidative phosphorylation is energy released
electrons being passed from a higher energy carrier to a lower energy carrier = phosphorylate ADP to ATP
90
aerobic respiration requires oxygen, why is oxygen needed in oxidative phosphorylation
it is the terminal electron acceptor
91
what happens in oxidative phosphorylation if oxygen isn't available
oxidative phosphorylation cannot occur and the reduced NAD and FAD cannot be oxidised so the link reaction and krebs cycle stops, leaving only glycolysis
92
word equation for anaerobic respiration in animals
glucose -> lactate + (2 ATP)
93
word equation for anaerobic respiration in yeast (and plants)
glucose -> ethanol + carbon dioxide
94
how is pyruvate reduced in glycolysis in anaerobic respiration
reduced by the 2 NADs that come from glycolysis, recycling NAD, allowing further glycolysis to take place, converting it to lactate
95
what is pyruvate converted into in anaerobic respiration
lactate
96
what can happen to lactate when pyruvate is converted into it
- oxidised back to pyruvate, can be oxidised to release energy
- convert to glycogen as a store of carbohydrate
97
what occurs in anaerobic respiration as well as aerobic respiration
glycolysis
98
how is glycolysis able to occur when there is a lack of oxygen
oxygen isn't needed and the NAD is recycled to form reduced NAD to convert pyruvate into lactate
99
where does the Krebs cycle occur
in the mitochondrial matrix
100
where does oxidative phosphorylation occur
inner mitochondiral membrane
101
where does NAD regernation of anaerobic respiration occur
cytoplasm
102
suggest why anaerobic respiration produces less ATP per molecule of glucose than aerobic respiration
only glycolysis is involved, produces little ATP. no oxidative phosphorylation which forms a majority of ATP
103
how does pyruvate travel from glycolysis to the next reaction step if respiration is aerobic
active transporte
104
how does the oxygen debt occur
extra oxygen is needed to oxidise lactate to turn back into pyruvate (on top of oxygen already needed in respiation)
105
what happens to pyruvate in anaerobic respiration of yeast n plants
it is decarobyxlated and reduced by reduced NAD to form ethanol
106
how can you measure the rate of a reaction
measure the rate at which reactants/products are used up/made
107
which would be the easiest reactant/product to measure aerobic respiration
oxygen uptake or carbon dioxide production
108
why are respirometers left for a time period to stabilise
to let temperature, pressure and the respiration to stabalise and reach equilibrium
109
why would the fluid move in a manometer
there is a pressure gradient
110
how would you calculate the respiratory quotient
volume of CO2 produced/ volume of O2 absorbed
111
what can lipids be metabolised into
glycerol -> triose phosphate -> energy pay off phase in glycolysis
fatty acids -> acetyl coenzyme A -> combines with oxalacetate in the krebs cycle
112
what happens to flucose after photosynthesis (4 things)
used in:
- respiration
- stored
- growth
- transport
113
how is glucose transported
transported as sucrose
114
how is glucose stored
as starch or as lipids
115
how is glucose used for growth
- cellulose (cell walls)
- amino acids (proteins)
- deoxyribose (DNA)
- riibose (RNA)
116
define biomass
the total mass of living material in a specific area at a given time
117
define food chain/web
a diagram that shows the flow of energy/biomass through thee ecosystem
118
define trophic level
the position an organism occupies in a food chain/web (usually no more than 5)
119
define producers
an organism that can synthesis its own biological molecules and therefore produce its own biomass e.g an autotroph
120
define consumers
an organism that cannot synthesis its own biological molecule and so needs to obtain its biomass from other organisms
121
define what it means by primary/secondary/tertiary/quaternary
terms given to the consumers in a good chain. food chains rarely possess more than 4 consumers due to less of energy btwn trophic levels
122
define saprobionts
organisms that feed through saprotrophic nutrition (extracellular enzymes are released and digestion occurs outside of the organisms body) and are responsible for decay and decomposition
123
4 reasons why biomass is not 100% transferred
- lost in chemical bonds of excretory products (urine and CO2)
- entire organisms are not ingested bone, nails, fur
- entire organisms are not digested, absorbed, assimilated - passed out in faeces
- energy lost as heat to surroundings
- used in respiration so chemical energy is lost
124
how do we measure biomass
mean mass of individual in species * number of individuals in an area
125
how would we sample animals in a species in a large area
mark, release, recapture
126
what is an advantage of using fresh biomass
it is easier to measure
127
what is a disadvantage of biomass
less reprodducible/repeatable because the amount of water in a living organism varires throughout the day and between species greatly
128
what is the advantage of using dry biomass
it is more accurate
129
what are the disadvantages of using dry biomass/carbon
it kills the organism because we dry them out in a kiln so only small sample sizes which may not be as representative
130
how would we change fresh biomass into dry biomass
kill the sample humanly and dry in a kiln. monitor the dry sample until the mass on longer decreases for a set time period
131
for 2D habitats what unit do we measure biomass in
g m^-2
132
for 3D habitats what unit do we measure biomass in (aqautic habitats)
g m^-3
133
how do we measure chemical potential energy in biomass
burn the sample in a bomb calorimeter:
- dry biomass is burnt in pure oxygen in a sealed chamber which is then surrounded by a water bath
- use equation E= mcdeltaT
134
state 4 inorganic nitrogen containing compounds
NO3- , NO2-, NH3/NH4+, N2
135
state 4 organic nitrogen containing compounds
DNA, RNA, amino acids, proteins
136
state the equation used to calculate net production of consumers
N = I - (F +R)
where
- N = net production
- I = chemical energy store
- F = biomass lost in faeces and excretory products
- R = biomass/energy lost from respiration (heat energy)
137
state the equation used to calculate the net primary production
NPP = GPP - R
where
NPP = net primary production : resultant quantity of chemical potential energy found in biomass of the plant
R = stored chemical potential energy lost from respiration
GPP = gross primary production, total quantity of light converted into chemical potential energy
138
in natural ecosystems, most of the light falling on producers is not used in photosynthesis. state 5 reasons why
- Reflected back into space by earths atmosphere, absorbed by atmosphere
- Not all of suns light falls on photosynthetic organisms
- Some light does not hit a chlorophyll molecules
- Some wavelengths of light not absorbed
- Another factor could be limiting rate of photosynthesis
139
state 4 features of the bomb calorimeter which can ensure a valid measurement of the total heat energy released
- thermometer
- stirrer distributes the heat
- insulation reduces amount of heat lost
- water has a high specific heat capacity
140
state the 4 types of bacteria that are in the nitrogen cycle
they act as saprobionts, nitrifying bacteria, denitrifying bacteria, nitrogen-fixing bacteria
141
what is the role of saprobionts in the nitrogen cycle
- they decompose organic compoiunds (urea, DNA, proteins) in dead matter/organic waste
- secrete enxymes for extracellular digestion (saprobiotic nutrition)
- absorb soluble nutrietns and release mineral ions e.g. ammonium
142
what is the role of nitryfying bacteria
nitrification: the oxidation of ammonium ions intro nitrites and nitrates in aerobic conditions
NH4+ -> NO2- -> NO3-
143
what is the role of denitrifying bacteria
denitrification
- the reduction of nitrates to nitrogen gase in anaerobic conditions
NO3- -> N2
144
what is the role of nitrogen-fixing bacteria
nitrogen fixation
- converts nitrogen gas into ammonium ions
N2 - > NH4+
145
describe the role of bacteria in nitrogen fixation
nitrogen gas is converted into ammonia which forms ammonium ions in soil by nitroggen-fixing bacteria which may be found in root nodules
146
suggest why ploughing (aerating) soil increases fertility
- more ammonium is converted into nitrite and nitrate/more nitrification/more nitrifying bacteria
- less nitrate is converted to nitrogen gase/less denitrification/fewer nitrifying bacteria
147
state 9 biological molecules that contain phosphorus
phospholipids, DNA, RNA, ATP, ADP, TP, GP, RuBP
148
describe the phosphorus cycle
- phosphate ions in rocks are relased by erosion/weathering
- phosphate ions taken up by producers and incorporated into their biomass (absorption helped by mycorrhizae)
- phosphate ions are transferred through food chain e.g. as herbivores eat producers
- some phosphate ions lost from animals in waste products (excretion)
- saprobionts decompose organic compounds e.g. DNA in dead matter/organic waste, releasing phosphate ions
149
define mycorrhizae
the mutualistic symbiotic associations btwn fungi and plant roots
150
how do mycorrhizae benefit plants
- increase SA available for the absorption of water and minerals
- can hold water and dissolved minerals in the surrounding area of a root system
151
what does mycorrhizaee enable
- faster rate of growth due to an increased absorption rate of mineral ions
- plant able to resist drought conditions due to its sponge-like structure
