Energy Transfers In And Between Organisms - 5 Flashcards
(137 cards)
1
Q
Where does the light-dependent reaction occur?
A
Thylakoid membranes of chloroplast
2
Q
Where does the light-independent reaction occur?
A
Stroma of chloroplast
3
Q
What are the main structures of a chloroplast?
A
Intermembrane, Inner membrane, Outer membrane
4
Q
What is a granum?
A
A stack of thylakoids
5
Q
What is contained within thylakoid membranes?
A
Folded membranes containing photosynthetic proteins (chlorophyll)
Also embedded with transmembrane electron carrier proteins
6
Q
What is the role of thylakoid membranes?
A
Involved in the light-dependent reactions (LDRs)
7
Q
What is chlorophyll?
A
Chlorophyll is located in proteins on thylakoid membranes and is a mix of coloured proteins that absorb light.
8
Q
How do different pigments affect leaf color?
A
Different proportions of each pigment lead to different colors on leaves.
9
Q
What is the advantage of having many pigments?
A
Each pigment absorbs a different wavelength of visible light, maximizing the spectrum of visible light absorbed.
10
Q
What is the result of having many pigments in photosynthesis?
A
Maximum light energy is taken in, leading to more photoionisation and a higher rate of photosynthesis.
11
Q
What is the light-dependent reaction (LDR)?
A
The LDR is the first stage of photosynthesis that occurs in thylakoid membranes.
12
Q
What does the light-dependent reaction use to create ATP and reduced NADP?
A
It uses light energy and water.
13
Q
What processes are involved in the light-dependent reaction?
A
The processes involved are photoionisation of chlorophyll, photolysis, and chemiosmosis.
14
Q
What is photolysis?
A
Photolysis is the process where light energy absorbed by chlorophyll splits water into oxygen, H+, and e-.
15
Q
What is the chemical equation for photolysis?
A
H2O -> ½O2 + 2e- + 2H+
16
Q
What are the products of photolysis?
A
H+, e-, oxygen
H+ is picked up by NADP to form reduced NADP for LIR; e- are passed along a chain of electron carrier proteins; oxygen is used in respiration or diffuses out leaf via stomata.
17
Q
What is photoionisation of chlorophyll?
A
Light energy absorbed by chlorophyll excites electrons to a higher energy level, causing them to leave chlorophyll.
Some of the energy released is used to make ATP and reduced NADP.
18
Q
What occurs during chemiosmosis?
A
Electrons move along a series of electron carriers in the thylakoid membrane, releasing energy that pumps protons across the membrane, creating an electrochemical gradient.
Protons pass back across via ATP synthase enzyme, producing ATP down their concentration gradient.
19
Q
What happens to protons after chemiosmosis?
A
Protons combine with co-enzyme NADP to become reduced NADP, which is used in LIR.
20
Q
What are the products of the Light Dependent Reactions (LDR)?
A
ATP, reduced NADP, and oxygen.
21
Q
What is the Light Independent Reaction (LIR) also known as?
A
The Calvin cycle.
22
Q
What does the Calvin cycle use to form hexose sugar?
A
CO2, reduced NADP, and ATP.
23
Q
Where does the Calvin cycle occur?
A
In the stroma.
24
Q
What enzyme is contained in the stroma for the Calvin cycle?
A
Rubisco.
25
What is temperature-sensitive in the Calvin cycle?
The reaction process.
26
What is RuBP?
Ribulose Bisphosphate, a 5-carbon molecule.
27
What is the role of Rubisco in the Calvin cycle?
It catalyzes the reaction involving RuBP.
28
What is Glycerate-3-phosphate (GP)?
A 3-carbon molecule involved in the Calvin cycle.
29
What happens to GP in the Calvin cycle?
GP is reduced to form triose phosphate.
30
What is Triose phosphate?
A 3-carbon molecule that is oxidised to form pyruvate in glycolysis.
31
How many cycles does it take to produce hexose sugar in the Light Independent Reactions (LIR)?
It takes 6 cycles.
32
What can glucose be converted into?
Glucose can join to form disaccharides (sucrose) or polysaccharides (cellulose) and can be converted to glycerol to combine with fatty acids to make lipids.
33
What is a limiting factor?
A factor which, if increased, the rate of the overall reaction also increases.
34
What are some agricultural practices to maximise plant growth?
Growing plants under artificial lighting to maximise light intensity, heating in greenhouse to increase temperature, burning fuel to release CO2.
## Footnote
These practices lead to faster production of glucose and more ATP for energy.
35
What is the benefit of agricultural practices for plant growth?
Higher yields lead to more profit.
## Footnote
Faster respiration provides more energy for growth, such as cell division and protein synthesis.
36
What are the products of LIR?
Hexose sugar and NADP, which is used in the light-dependent reactions (LDR).
37
What are the stages of aerobic respiration?
1) Glycolysis 2) Link reaction 3) Krebs cycle 4) Oxidative phosphorylation
38
Where does glycolysis occur?
Glycolysis occurs in the cytoplasm.
39
What is the net gain of ATP from glycolysis?
The net gain of ATP from glycolysis is 2 ATP.
40
What are the products of glycolysis?
The products of glycolysis are 2 pyruvate molecules, 2 reduced NAD, and a net gain of 2 ATP.
41
What is substrate level phosphorylation?
Substrate level phosphorylation is the process where 2 ATP molecules add 2 phosphate groups to glucose.
42
What happens to glucose phosphate during glycolysis?
Glucose phosphate splits into two triose phosphate (3C) molecules.
43
What happens to triose phosphate molecules in glycolysis?
Both triose phosphate molecules are oxidised, reducing NAD to form 2 pyruvate molecules.
44
How many ATP molecules are released during glycolysis?
4 ATP molecules are released during glycolysis.
45
What are coenzymes in the context of respiration?
Coenzymes are molecules that assist enzymes, such as NAD and FAD, which gain hydrogen to form reduced NAD (NADH) and reduced FAD (FADH).
46
What is the role of NADP in photosynthesis?
NADP gains hydrogen to form reduced NADP (NADPH).
47
How many ATP molecules does glycolysis produce?
Glycolysis produces a net gain of 2 ATP molecules.
## Footnote
2 ATP molecules are used to phosphorylate glucose to glucose phosphate, and 4 molecules are generated in the oxidation of triose phosphate to pyruvate.
48
Where does the link reaction occur?
The link reaction occurs in the mitochondrial matrix.
49
What are the steps of the link reaction?
1. Reduced NAD and pyruvate are actively transported to the matrix.
2. Pyruvate is oxidised to acetate, forming reduced NAD.
3. Carbon is removed and CO2 forms.
4. Acetate combines with coenzyme A to form acetylcoenzyme A (2C).
50
What are the products of the link reaction per glucose molecule?
The products are 2 acetylcoenzyme A molecules, 2 carbon dioxide molecules released, and 2 reduced NAD molecules.
51
Where is the Krebs cycle located?
Mitochondrial matrix
52
What combines with a 4C molecule in the Krebs cycle?
Acetylcoenzyme A combines with 4C molecule to produce a 6C molecule - enters cycle
53
What types of reactions occur in the Krebs cycle?
Oxidation-reduction reactions
54
What are the products of the Krebs cycle per glucose?
8 reduced coenzymes, 6 reduced NAD, 2 reduced FAD, 2 ATP, 4 carbon dioxide
55
Where does oxidative phosphorylation occur?
Cristae of mitochondria
56
What is the structure of mitochondria?
Double membrane with inner membrane folded into cristae; enzymes in matrix.
57
What is the role of reduced coenzymes in oxidative phosphorylation?
They accumulate in mitochondrial matrix, where they release their protons (H+) and electrons (e-); regenerate NAD and FAD to be used in glycolysis, link reaction, and Krebs cycle.
58
What is the role of electrons in oxidative phosphorylation?
Electrons pass down a series of electron carrier proteins, losing energy as they move; energy released actively transports H+ from mitochondrial matrix to intermembranal space, generating an electrochemical gradient.
59
How is ATP made in oxidative phosphorylation?
Protons move down the electrochemical gradient back into the matrix via ATP synthase; ATP is created; movement of H+ is chemiosmosis.
60
What is the role of oxygen in oxidative phosphorylation?
Oxygen is the final electron acceptor in the electron transport chain.
## Footnote
Oxygen combines with protons and electrons to form water.
61
What happens when there is a lack of oxygen during respiration?
Electrons can't be passed along the electron transport chain.
## Footnote
This causes the Krebs cycle and link reaction to stop because NAD and FAD cannot be produced.
62
What is oxidation?
Oxidation is the loss of electrons from a molecule.
## Footnote
This often involves a molecule losing hydrogen.
63
What is reduction?
Reduction is a reaction where a molecule gains electrons.
## Footnote
This often involves a molecule gaining hydrogen.
64
Where does anaerobic respiration occur?
In the cytoplasm.
## Footnote
Glycolysis is the only source of ATP.
65
What happens to pyruvate in anaerobic respiration in plants and microbes?
Pyruvate is reduced to form ethanol and CO2.
## Footnote
Pyruvate gains hydrogen from reduced NAD.
66
What is the role of reduced NAD in anaerobic respiration in plants and microbes?
Reduced NAD is oxidised to NAD so it can be reused in glycolysis.
67
How much ATP is produced in anaerobic respiration in plants and microbes?
2 ATP are produced.
68
What happens to pyruvate in anaerobic respiration in animals?
Pyruvate is reduced to form lactate.
## Footnote
Pyruvate gains hydrogen from reduced NAD.
69
What is the role of reduced NAD in anaerobic respiration in animals?
Reduced NAD is oxidised to NAD so it can be reused in glycolysis.
70
How much ATP is produced in anaerobic respiration in animals?
2 ATP are produced.
71
What other respiratory substances can enter the Krebs cycle?
Fatty acids and amino acids can enter the Krebs cycle for continued ATP synthesis.
72
What is glycerol from lipid hydrolysis converted to?
Glycerol from lipid hydrolysis is converted to acetylcoenzyme A.
## Footnote
It can enter the Krebs cycle.
73
What can amino acids from protein hydrolysis be converted to?
Amino acids from protein hydrolysis can be converted to intermediates within the Krebs cycle.
74
Who are the producers in an ecosystem?
Producers are plants that produce their own carbohydrates from carbon dioxide (autotrophs).
## Footnote
They are the start of a food web.
75
How is energy transferred between trophic levels?
Energy transfer between trophic levels is very inefficient.
## Footnote
Most energy is lost due to respiration and excretion.
76
What is glycerol from lipid hydrolysis converted to?
Glycerol from lipid hydrolysis is converted to acetylcoenzyme A.
## Footnote
It can enter the Krebs cycle.
77
What can amino acids from protein hydrolysis be converted to?
Amino acids from protein hydrolysis can be converted to intermediates within the Krebs cycle.
78
Who are the producers in an ecosystem?
Producers are plants that produce their own carbohydrates from carbon dioxide (autotrophs).
## Footnote
They are the start of a food web.
79
How is energy transferred between trophic levels?
Energy transfer between trophic levels is very inefficient.
## Footnote
Most energy is lost due to respiration and excretion.
80
What are consumers?
Heterotrophs that cannot synthesise their own energy and obtain chemical energy through eating.
81
How is biomass measured?
Measured in terms of mass of carbon or dry mass of tissue per given area.
82
How is the dry mass of tissue estimated?
Sample of organism dried in oven below 100C, avoiding combustion and loss of biomass. Sample reweighed at regular intervals until all water is removed.
83
Why is dry mass a representative measure of biomass?
Water content in tissues varies. Heating until constant mass allows standardisation of measurements for comparison.
84
What are consumers?
Heterotrophs that cannot synthesise their own energy and obtain chemical energy through eating.
85
How is biomass measured?
Measured in terms of mass of carbon or dry mass of tissue per given area.
86
How is the dry mass of tissue estimated?
Sample of organism dried in oven below 100C, avoiding combustion and loss of biomass. Sample reweighed at regular intervals until all water is removed.
87
Why is dry mass a representative measure of biomass?
Water content in tissues varies. Heating until constant mass allows standardisation of measurements for comparison.
88
What is calorimetry?
A laboratory method used to estimate chemical energy stored in dry biomass.
89
How is calorimetry conducted?
A sample of dry biomass is burnt, and the energy released is used to heat a known volume of water.
90
What is measured to calculate chemical energy in calorimetry?
The change in temperature of water is used to calculate chemical energy.
91
What does gross primary production refer to?
The total energy resulting from photosynthesis.
92
What does net primary production refer to?
The chemical energy stored in plant biomass after respiratory losses.
93
What is the significance of net primary production?
It is available for plant growth and reproduction, creating biomass available to other trophic levels.
94
What is the formula for Net Primary Production (NPP)?
NPP = GPP - R
95
What does 'R' represent in the NPP formula?
R = respiratory losses to the environment
96
What is the formula for calculating net production of consumers (N)?
N = 1 - (F + R)
97
What does 'I' represent in the context of energy?
I = chemical energy store in ingested food
98
What does 'F' represent in the context of energy?
F = chemical energy store in faeces / urine
99
What is the unit for energy in productivity rates?
kJ
100
What is the unit for productivity rates?
kJ Ha-1 year-1
101
Why is productivity measured per area?
Per hectare is used because environments vary in size
## Footnote
It standardises results so environments can be compared.
102
Why is productivity measured per year?
It is more representative of productivity and takes into account effects of seasonal variation on biomass. It allows environments to be compared with a standardized amount of time.
103
Why is energy transfer inefficient from sun to producer?
Energy transfer is inefficient due to the wrong wavelength of light not being absorbed by chlorophyll, light striking non-photosynthetic regions, light being reflected by clouds/dust, and energy being lost as heat.
104
Why is energy transfer inefficient after producers?
Energy transfer is inefficient due to respiratory loss (energy used for metabolism), energy lost as heat, not all plant/animal being eaten (bones), and some food being undigested (faeces).
105
What are farming practices to increase energy transfer for crops?
Practices include simplifying food webs to reduce energy/biomass, using herbicides to kill weeds (reducing competition), applying fungicides to reduce fungal infections, and using fertilizers such as nitrates to promote growth.
106
What are farming practices to increase energy transfer for animals?
Reducing respiratory losses by restricting movement, keeping warm, slaughtering animals when young, and selective breeding for higher growth rates.
107
What do saprobionts do?
They feed on remains of dead organisms and their waste products, breaking down organic molecules.
108
How do saprobionts digest food?
They secrete enzymes for extracellular digestion.
109
What is mycorrhizae?
A symbiotic relationship between fungi and the roots of plants.
110
What role do fungi play in mycorrhizae?
Fungi act as extensions of roots, increasing the surface area of the system and the rate of absorption.
111
What do plants provide to fungi in a mycorrhizal relationship?
Plants supply fungi with carbohydrates.
112
What are some uses of nitrogen in organisms?
Nitrogen is used to create amino acids, proteins, DNA, RNA, and ATP.
113
What are the stages of the nitrogen cycle?
The stages of the nitrogen cycle are nitrogen fixation, nitrification, denitrification, and ammonification.
114
What occurs during nitrogen fixation?
Nitrogen fixing bacteria break the triple bond between two nitrogen atoms in nitrogen gas and fix this nitrogen into ammonium ions.
115
What is the role of nitrogen fixing bacteria?
Nitrogen fixing bacteria fix nitrogen gas into ammonium ions and can be free living in soil or form mutualistic relationships on root nodules of leguminous plants.
116
What do nitrogen fixing bacteria receive from plants?
They give plants nitrogen in exchange for carbohydrates.
117
What happens during nitrification?
Ammonium ions in soil are oxidised to nitrite ions, and nitrite ions are oxidised to nitrate ions by nitrifying bacteria.
118
What is denitrification?
Denitrification returns nitrogen in compounds back into nitrogen gas in the atmosphere by anaerobic denitrifying bacteria.
119
What is ammonification?
Ammonification involves the decomposition of proteins, urea, and DNA in dead matter and waste by saprobionts, returning ammonium ions to soil.
120
What is the importance of phosphorus?
Phosphorus is used to create DNA, RNA, ATP, phospholipid bilayers, and RuBP/GP/Triose phosphate.
121
What does the phosphorus cycle include?
The phosphorus cycle includes deposition, including bones.
122
What do fertilisers replace in an ecosystem?
Fertilisers replace nutrients (nitrates and phosphates) lost from an ecosystem's nutrient cycle when crops are harvested or livestock removed.
123
What are the two types of fertilisers?
Fertilisers can be natural (manure) or artificial (inorganic chemicals).
124
What is an advantage of natural fertilisers?
Natural fertilisers are cheaper than artificial fertilisers and can often be free if the farmer has their own animals to recycle manure.
125
Why is leaching less likely with natural fertilisers?
Organic molecules in natural fertilisers have to be broken down first by saprobionts, making leaching less likely.
126
What is an advantage of artificial fertilisers?
Artificial fertilisers contain pure chemicals in exact proportions, are more water-soluble, and allow for higher absorption.
127
What is a disadvantage of natural fertilisers?
The exact minerals and proportions in natural fertilisers cannot be controlled.
128
What is leaching in the context of artificial fertilizers?
High solubility means larger quantities can leach away with rain, risking eutrophication.
129
What is eutrophication?
Eutrophication occurs when water-soluble compounds, like nitrates from fertilizers, are washed into rivers or ponds.
130
How do nitrates lead to eutrophication?
Nitrates leached from fields stimulate the growth of algae, leading to algal blooms.
131
What is an algal bloom?
An algal bloom creates a blanket surface of water that blocks light, preventing plants from photosynthesizing.
132
What happens to aquatic plants during an algal bloom?
Plants cannot photosynthesize and die due to lack of light.
133
What occurs after aquatic plants die from an algal bloom?
Aerobic bacteria feed and respire on dead plant matter, leading to a decrease in dissolved oxygen in the water.
134
What is the consequence of low dissolved oxygen in water?
Eventually, aquatic organisms die due to lack of dissolved oxygen.
135
How does eutrophication affect species diversity?
Eutrophication reduces species diversity as it favors plants with higher growth rates, such as nettles.
136
What is a mutualistic relationship?
A type of symbiotic relationship where all species involved benefit from their interactions.
137
What role do saprobionts play in the nitrogen cycle?
They use enzymes to decompose proteins, DNA, RNA, and urea, releasing ammonium ions.
