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MISS ESTRUCH FLASHCARDS > TOPIC 5: ENERGY TRANSFERS IN AND BETWEEN ORGANISMS > Flashcards

TOPIC 5: ENERGY TRANSFERS IN AND BETWEEN ORGANISMS Flashcards

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1
Q

Location of light
dependent
reaction

A

Thylakoid membranes of
chloroplast

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2
Q

Location of light
independent
reaction

A

Stroma of chloroplast

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3
Q

Thylakoid
membranes

A

Folded membranes containing
photosynthetic proteins
(chlorophyll)
embedded with transmembrane
electron carrier proteins
involved in the LDRs

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4
Q

Chlorophyll

A

Located in proteins on thylakoid
membranes
mix of coloured proteins that
absorb light
different proportions of each
pigment lead to different
colours on leaves

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5
Q

Advantage of
many pigments

A

Each pigment absorbs a
different wavelength of visible
light
many pigments maximises
spectrum of visible light
absorbed
maximum light energy taken in
so more photoionisation and
higher rate of photosynthesis

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6
Q

Light-dependent
reaction (LDR)

A

First stage of photosynthesis
occurs in thylakoid membranes
uses light energy and water to
create ATP and reduced NADP
for LIR
involves photoionisation of
chlorophyll, photolysis and
chemiosmosis

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7
Q

Photolysis

A

Light energy absorbed by
chlorophyll splits water into
oxygen, H+ and e
H2O -> 1/2O2 + 2e- +2H+

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8
Q

Products of
photolysis

A

H+
Picked up by NADP to form
reduced NADP for LIR
e
passed
along chain of
electron carrier proteins
oxygen
used in respiration or
diffuses out leaf via stomata

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9
Q

Photoionisation
of chlorophyll

A

Light energy absorbed by
chlorophyll excites electrons so
they move to a higher energy
level and leave chlorophyll
some of the energy released is
used to make ATP and reduced
NADP

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10
Q

Chemiosmosis

A

Electrons that gained energy
move along a series of electron
carriers in thylakoid membrane
release energy as they go along
which pumps proteins across
thylakoid membrane
electrochemical gradient made
protons pass back across via
ATP synthase enzyme producing
ATP down their conc. gradient

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11
Q

What happens to
protons after
chemiosmosis

A

Combine with co-enzyme NADP
to become reduced NADP
reduced NADP used in LIR

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12
Q

Products of
LDR

A

ATP (used in LIR)
reduced NADP (used in LIR)
oxygen (used in respiration /
diffuses out stomata)

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13
Q

Light
independent
reaction (LIR)

A

Calvin cycle
uses CO2, reduced NADP and
ATP to form hexose sugar
occurs in stroma which
contains the enzyme Rubisco
temperature-sensitive

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14
Q

RuBP

A

Ribulose Bisphosphate
5-carbon molecule

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15
Q

GP

A

Glycerate-3-phosphate
3-carbon molecule

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16
Q

TP

A

Triose phosphate
3-carbon molecule

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17
Q

Producing
hexose sugar
in LIR

A

Takes 6 cycles
glucose can join to form
disaccharides (sucrose) or
polysaccharides (cellulose)
can be converted to glycerol to
combine with fatty acids to
make lipids

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18
Q

Limiting factor

A

A factor which, if increased, the
rate of the overall reaction also
increases

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19
Q

Limiting
factors of
photosynthesis

A

Light intensity
CO2 concentration
temperature

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20
Q

How light
intensity limits
photosynthesis

A

If reduced, levels of ATP and
reduced NADP would fall
LDR limited - less photolysis
and photoionisation
GP cannot be reduced to TP in LIR

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21
Q

How temperature
limits
photosynthesis

A

LIR inhibited - enzyme
controlled (Rubisco)
up to optimum, more collisions
and E-S complexes
above optimum, H-bonds in
tertiary structure break, active
site changes shape - denatured

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22
Q

How CO2
concentration limits
photosynthesis

A

If reduced, LIR inhibited
less CO2 to combine with RuBP
to form GP
less GP reduced to TP
less TP converted to hexose and
RuBP regenerated

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23
Q

Agricultural
practices to
maximise plant
growth

A

Growing plants under artificial
lighting to maximise light
intensity
heating in greenhouse to
increase temperature
burning fuel to release CO2

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24
Q

Benefit of
agricultural
practices for plant
growth

A

Faster production of glucose ->
faster respiration
more ATP to provide energy for
growth e.g. cell division +
protein synthesis
higher yields so more profit

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25
Products of LIR
Hexose sugar NADP - used in LDR
26
Stages of aerobic respiration
1) Glycolysis 2) Link reaction 3) Krebs cycle 4) Oxidative phosphorylation
27
Location of glycolysis
Cytoplasm
28
Glycolysis
Substrate level phosphorylation - 2 ATP molecules add 2 phosphate groups to glucose glucose phosphate splits into two triose phosphate (3C) molecules both TP molecules are oxidised (reducing NAD) to form 2 pyruvate molecules (3C) releases 4 ATP molecules
29
Coenzymes
A molecule which aids / assists an enzyme NAD and FAD in respiration both gain hydrogen to form reduced NAD (NADH) and reduced FAD (FADH) NADP in photosynthesis gains hydrogen to form reduced NADP (NADPH)
30
Products of glycolysis
Net gain of 2 ATP 2 reduced NAD 2 pyruvate molecules
31
How many ATP molecules does glycolysis produce
2 ATP molecules used to phosphorylate glycose to glucose phosphate 4 molecules generated in oxidation of TP to pyruvate net gain 2 ATP molecules
32
Location of the link reaction
Mitochondrial matrix
33
Link reaction
Reduced NAD and pyruvate are actively transported to matrix pyruvate is oxidised to acetate (forming reduced NAD) carbon removed and CO2 forms acetate combines with coenzyme A to form acetylcoenzyme A (2C)
34
Products of the link reaction per glucose molecule
2 acetylcoenzyme A molecules 2 carbon dioxide molecules released 2 reduced NAD molecules
35
Location of the Krebs cycle
Mitochondrial matrix
36
Krebs cycle
Acetylcoenzyme A combines with 4C molecule to produce a 6C molecule - enters cycle oxidation-reduction reactions
37
Products of the Krebs cycle per glucose
8 reduced coenzymes 6 reduced NAD 2 reduced FAD 2 ATP 4 carbon dioxide
38
Location of oxidative phosphorylation
Cristae of mitochondria
39
Mitochondria structure
Double membrane with inner membrane folded into cristae enzymes in matrix
40
Role of reduced coenzymes in oxidative phosphorylation
Accumulate in mitochondrial matrix, where they release their protons (H+) and electrons (e-) regenerate NAD and FAD to be used in glycolysis/ link reaction / Krebs cycle
41
Role of electrons in oxidative phosphorylation
Electrons pass down series of electron carrier proteins, losing energy as they move energy released actively transports H+ from mitochondrial matrix to intermembranal space electrochemical gradient generated
42
How is ATP made in oxidative phosphorylation
Protons move down electrochemical gradient back into matrix via ATP synthase ATP created movement of H+ is chemiosmosis
43
Role of oxygen in oxidative phosphorylation
Oxygen is the final electron acceptor in electron transport chain oxygen combines with protons and electrons to form water enables the electron transport chain to continue
44
How would lack of oxygen affect respiration
Electrons can’t be passed along the electron transport chain the Krebs cycle and link reaction stop because NAD and FAD (converted from reduced NAD/FAD as they release their H atoms for the ETC), cannot be produced
45
Oxidation
Loss of electrons when a molecule gains hydrogen
46
Reduction
Gain of electrons a reaction where a molecule gains hydrogen
47
Location of anaerobic respiration
Cytoplasm glycolysis only source of ATP
48
Anaerobic respiration in plants & microbes
Pyruvate produced in glycolysis is reduced to form ethanol and CO2 pyruvate gains hydrogen from reduced NAD reduced NAD oxidised to NAD so can be reused in glycolysis 2 ATP produced
49
Anaerobic respiration animals
Pyruvate produced in glycolysis is reduced to form lactate pyruvate gains hydrogen from reduced NAD reduced NAD oxidised to NAD so can be reused in glycolysis 2 ATP produced
50
Other respiratory substances
Fatty acids and amino acids can enter the Krebs cycle for continued ATP synthesis
51
Lipids as respiratory substances
Glycerol from lipid hydrolysis converted to acetylcoenzyme A can enter the Krebs cycle
52
Proteins as respiratory substances
Amino acids from protein hydrolysis can be converted to intermediates within Krebs cycle
53
Producers
Plants produce their own carbohydrates from carbon dioxide (autotrophs) start of a food web
54
Energy transfer between trophic levels
Biomass and its stored energy is transferred through trophic levels very inefficiently most energy is lost due to respiration and excretion
55
Consumers
Heterotrophs that cannot synthesise their own energy obtain chemical energy through eating
56
Biomass
Measured in terms of: mass of carbon dry mass of tissue per given area
57
How is dry mass of tissue estimated
Sample of organism dried in oven below 100C (avoiding combustion + loss of biomass) sample reweighed at regular intervals all water removed when mass constant
58
Why is dry mass a representative measure of biomass
Water content in tissues varies heating until constant mass allows standardisation of measurements for comparison
59
Calorimetry
Laboratory method used to estimate chemical energy stored in dry biomass
60
Calorimetry method
Sample of dry biomass is burnt energy released used to heat known volume of water change in temperature of water used to calculate chemical energy
61
Gross primary production
Chemical energy stored in plant biomass, in a given area / volume total energy resulting from photosynthesis
62
Net primary production
Chemical energy stored in plant biomass after respiratory losses available for plant growth and reproduction - create biomass available to other trophic levels
63
Calculating net primary production
NPP = GPP - R R = respiratory losses to the environment
64
Calculating net production of consumers (N)
N = I - (F + R) I = chemical energy store in ingested food F = chemical energy store in faeces / urine R = respiratory losses
65
Units of productivity rates
kJ Ha-1 year-1 kJ is the unit for energy
66
Why is productivity measured per area
Per hectare (for example) is used because environments vary in size standardises results so environments can be compared
67
Why is productivity measured per year
More representative of productivity takes into account effects of seasonal variation (temperature) on biomass environments can be compared with a standardised amount of time
68
Why is energy transfer inefficient from sun -> producer
Wrong wavelength of light - not absorbed by chlorophyll light strikes nonphotosynthetic region (bark) light reflected by clouds / dust lost as heat
69
Why is energy transfer inefficient after producers
Respiratory loss - energy used for metabolism (active transport) lost as heat not all plant / animal eaten (bones) some food undigested (faeces)
70
Farming practices to increase energy transfer for crops
Simplifying food webs to reduce energy / biomass herbicides kill weeks -> less competition fungicides reduce fungal infections results in more energy used to create biomass fertilisers such as nitrates to promote growth
71
Farming practices to increase energy transfer for animals
Reducing respiratory losses (more energy to make biomass) restrict movement keep warm slaughter animal when young (most energy used for growth) selective breeding to produce breeds with higher growth rates
72
Saprobionts
Feed on remains of dead organisms and their waste products (faeces / urea) and break down organic molecules secrete enzymes for extracellular digestion
73
Mycorrhizae
Symbiotic relationship between fungi and roots of plants fungi act as extensions of roots increase surface area of system - increasing rate of absorption mutualistic relationship as plants supply fungi with carbohydrates
74
Importance of nitrogen to organisms
Used to create amino acids / proteins DNA RNA ATP
75
Nitrogen cycle stages
Nitrogen fixation nitrification denitrification ammonification
76
Nitrogen fixation
Nitrogen fixing bacteria break triple bond between two nitrogen atoms in nitrogen gas fix this nitrogen into ammonium ions
77
Nitrogen fixing bacteria
Fix nitrogen gas into ammonium ions free living in soil or form mutualistic relationship on root nodules of leguminous plants give plants N in exchange for carbohydrates
78
Nitrification
Ammonium ions in soil are oxidised to nitrite ions nitrite ions are oxidised to nitrate ions by nitrifying bacteria
79
Denitrification
Returns nitrogen in compounds back into nitrogen gas in atmosphere by anaerobic denitrifying bacteria
80
Ammonification
Proteins / urea / DNA can be decomposed in dead matter and waste by saprobionts return ammonium ions to soil - saprobiotic nutrition
81
Importance of phosphorius
Used to create: DNA RNA ATP phospholipid bilayers RuBP / GP/ TP
82
Fertilisers
Replace nutrients (nitrates and phosphates) lost from an ecosystem's nutrient cycle when crops are harvested livestock removed can be natural (manure) or artificial (inorganic chemicals
83
Natural fertilisers advantages
Cheaper than artificial fertilisers often free if farmer has own animals - recycle manure organic molecules have to be broken down first by saprobionts so leaching less likely
84
Artificial fertilisers advantages
Contain pure chemicals in exact proportions more water-soluble, so more ions dissolve in water surrounding soil. higher absorption
85
Natural fertilisers disadvantages
Exact minerals and proportions cannot be controlled
86
Artificial fertilisers disadvantages
High solubility means larger quantities can leach away with rain risking eutrophication reduce species diversity as favour plants with higher growth rates e.g., nettles
87
Leaching
When water-soluble compounds are washed away into rivers / ponds for nitrogen fertilisers, this can lead to eutrophication
88
Eutrophication
When nitrates leached from fields stimulate growth of algae algal bloom can lead to death of aquatic organisms
89
How does eutrophication lead to death of aquatic organisms?
Algal bloom creates blanket surface of water blocking light plants cannot photosynthesize and die aerobic bacteria feed and respire on dead plant matter eventually, aquatic organisms die due to lack of dissolved oxygen in water
90
Mutualistic relationships
A type of symbiotic relationship where all species involved benefit from their interactions
91
Role of saprobionts in nitrogen cycle
They use enzymes to decompose proteins/DNA/RNA/urea releasing ammonium ions

MISS ESTRUCH FLASHCARDS (8 decks)

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