energy transfer between organisms Flashcards
1
Q
What is photosynthesis?
A
The process where glucose is formed from carbon dioxide and water using light energy, which is converted into chemical energy.
6CO2 + 6H2O → C6H12O6 + 6O2
2
Q
Where does photosynthesis take place?
A
In the chloroplasts.
3
Q
What are the adaptations of a leaf for photosynthesis?
A
- Large surface area
- Arrangement of leaves to minimize overlapping
- Thin structure
- Transparent cuticle and epidermis
- Long, narrow upper mesophyll cells
- Numerous stomata
- Many air spaces in spongy lower mesophyll
- Network of xylem and phloem
4
Q
What are the three main stages of photosynthesis?
A
- Capturing of light energy
- The light-dependent reaction
- The light-independent reaction
5
Q
What is the structure of chloroplasts?
A
Typically disc-shaped, 2-10 µm long, surrounded by a double membrane, containing grana (thylakoids) and stroma.
6
Q
What is oxidation?
A
Loss of electrons, loss of hydrogen, gain of oxygen, energy given out.
7
Q
What is reduction?
A
Gain of electrons, gain of hydrogen, loss of oxygen, energy taken in.
8
Q
What are the main photosynthetic pigments found in chloroplasts?
A
- Chlorophyll a
- Chlorophyll b
- Carotene
9
Q
What is a photosystem?
A
complex structures within the chloroplasts of plants that capture light energy and use it to generate ATP and NADPH, which are used as energy sources for cellular processes
10
Q
What occurs during the light-dependent reaction?
A
Light energy and water are used to create ATP and reduced NADP.
Occurs in thylakoid membranes and grana.
11
Q
What is non-cyclic phosphorylation?
A
A process involving photoionisation of chlorophyll, photolysis of water, production of ATP and reduced NADP, and chemiosmosis.
12
Q
What are the results of non-cyclic phosphorylation?
A
- NADPH
- ATP
- Oxygen (waste product)
13
Q
What is photoionisation of chlorophyll?
A
The process where chlorophyll loses an electron due to light energy absorption, resulting in ionisation.
14
Q
What is photolysis of water?
A
The splitting of water into oxygen, hydrogen, and electrons by light energy absorbed by chlorophyll.
15
Q
What is chemiosmosis?
A
The movement of protons across the thylakoid membrane through ATP synthase channels to produce ATP.
16
Q
What is NADPH production?
A
The reduction of NADP to NADPH using electrons and hydrogen ions from the stroma.
17
Q
What are coenzymes?
A
Molecules that aid the function of enzymes by transferring chemical groups between molecules.
18
Q
What is cyclic phosphorylation?
A
A process that only uses photosystem I (PSI) where electrons are recycled and no reduced NADP or oxygen is produced.
19
Q
Where do light-independent reactions occur?
A
In the stroma of the chloroplasts.
20
Q
What is the Calvin cycle?
A
The light-independent reaction where CO2 combines with RuBP to form TP, which can be used to produce glucose.
21
Q
What enzyme catalyses the reaction of CO2 with RuBP?
A
Rubisco (ribulose bisphosphate carboxylase).
22
Q
What is the limiting factor in photosynthesis?
A
The factor that is at its least favorable value at any given moment.
23
Q
What factors can limit the rate of photosynthesis?
A
- Light intensity
- Temperature
- Carbon dioxide concentration
- Water availability
24
Q
How many turns of the Calvin cycle are needed to produce one hexose sugar?
A
6 turns.
25
What is the role of ATP in the Calvin cycle?
Provides energy to reduce 3C GP into 3C triose phosphate (TP).
26
What does the law of limiting factors state?
At any given moment, the rate of a physiological process is limited by the factor that is at its least favourable value.
27
Name three factors that can reduce the rate of photosynthesis.
* Light intensity
* Temperature
* Carbon dioxide concentration
28
What is the effect of too much water on plants?
It causes waterlogged soils, reducing the uptake of minerals like magnesium.
29
How does light intensity affect photosynthesis?
The rate of photosynthesis is directly proportional to light intensity when light is a limiting factor.
30
What is the light compensation point?
The volume of oxygen produced and carbon dioxide absorbed due to photosynthesis is balanced by the oxygen absorbed and carbon dioxide produced by cellular respiration.
31
What happens to enzymes if the temperature falls below 10°C?
The enzymes become inactive.
32
What occurs to enzymes at temperatures above 45°C?
The enzymes denature.
33
What is the optimum concentration of carbon dioxide for photosynthesis?
0.4% carbon dioxide.
34
What happens to stomata when carbon dioxide concentration increases?
Stomata close due to increased acidity in guard cells.
35
What is the saturation point in relation to limiting factors?
A saturation point will be reached at which further increases in light intensity, temperature, or carbon dioxide concentration will have no effect on photosynthesis.
36
What is respiration?
Respiration is the breakdown of food/glucose to release energy in the form of ATP.
37
What are the two types of respiration?
* Aerobic respiration
* Anaerobic respiration
38
Where does aerobic respiration occur?
In the mitochondria.
39
What is glycolysis?
The splitting of the 6-carbon glucose molecule into two 3-carbon pyruvate molecules.
40
What is the product of the link reaction?
* 2 x acetylcoenzyme A
* 2 x reduced NAD
* 2 x CO2
41
What does the Krebs cycle produce?
* 6 reduced NAD
* 4 CO2
* 2 ATP
* 2 reduced FAD
42
What is the significance of the Krebs cycle?
* Breaks down macromolecules
* Produces hydrogen atoms for ATP synthesis
* Regenerates 4-carbon molecule
* Source of intermediate compounds for other substances
43
What are coenzymes?
Molecules that some enzymes require in order to function.
44
What is oxidative phosphorylation?
The mechanism by which energy from electrons is conserved in the formation of ATP.
45
What role does oxygen play in respiration?
Oxygen is the final electron acceptor.
46
What is the total ATP produced from one glucose molecule?
32 ATP.
47
Fill in the blank: The enzyme _______ catalyses the combination of ribulose bisphosphate with carbon dioxide in the light-independent reaction.
rubisco
48
True or False: Glycolysis requires oxygen to occur.
False
49
What happens to hydrogen atoms during oxidative phosphorylation?
Hydrogen atoms split into protons and electrons.
50
What is the function of ATP synthase?
Catalyses the phosphorylation of ADP to produce ATP.
51
What is the total ATP yield from one reduced NAD?
2.5 ATP
## Footnote
This is used in the context of cellular respiration.
52
What is the total ATP yield from one reduced FAD?
1.5 ATP
## Footnote
This is used in the context of cellular respiration.
53
What are the two main types of respiration substrates besides sugars?
Lipids and proteins
## Footnote
These can be oxidized by cells to release energy.
54
What are the products of lipid respiration?
Glycerol and fatty acids
## Footnote
Glycerol enters glycolysis and fatty acids become acetyl CoA.
55
What is the process by which proteins are broken down for energy?
Hydrolysis into amino acids and deamination
## Footnote
This prepares them for entry into the respiratory pathway.
56
What happens to pyruvate in anaerobic respiration in animals?
Converted to lactate
## Footnote
This occurs to regenerate NAD during oxygen debt.
57
What is the equation for the conversion of pyruvate to lactate?
Pyruvate + reduced NAD → lactate + oxidised NAD
## Footnote
This reaction occurs in anaerobic respiration.
58
What is the byproduct of fermentation in plants and microorganisms?
Ethanol and carbon dioxide
## Footnote
This occurs when pyruvate is decarboxylated.
59
What is the main difference in ATP production between aerobic and anaerobic respiration?
Aerobic respiration produces more ATP
## Footnote
Anaerobic respiration yields only 2 ATP from glycolysis.
60
What is GPP?
Gross Primary Production
## Footnote
It is the total quantity of chemical energy produced by plants.
61
What is NPP?
Net Primary Production
## Footnote
It is the chemical energy store left after respiratory losses.
62
How much of the sun's energy is typically converted into organic matter by plants?
1% - 3%
## Footnote
Most energy is lost through reflection, absorption, or not reaching chlorophyll.
63
What is the main role of saprobionts in an ecosystem?
Decomposing complex materials in dead organisms
## Footnote
They help recycle nutrients back into the ecosystem.
64
What defines a food chain?
A feeding relationship between producers and consumers
## Footnote
It illustrates how energy flows through an ecosystem.
65
What is the role of consumers in an ecosystem?
Heterotrophs that obtain energy by consuming other organisms
## Footnote
They can be primary, secondary, or tertiary consumers.
66
What is biomass?
The total mass of living material in a specific area
## Footnote
It can be measured in terms of dry mass or mass of carbon.
67
What is bomb calorimetry used for?
Estimating the chemical energy stored in dry biomass
## Footnote
It involves burning a sample in pure oxygen and measuring heat released.
68
What does the efficiency of energy transfer between trophic levels generally indicate?
Energy decreases as one moves up a food chain
## Footnote
Typically, only 10% of energy is transferred to the next trophic level.
69
What practices can increase energy transfer efficiency in farming?
Restrict movement, control feeding, exclude predators
## Footnote
These practices reduce energy loss and increase biomass.
70
What is the equation for net production in consumers?
N = I - (F + R)
## Footnote
Where I is ingested energy, F is energy lost in faeces, and R is respiratory losses.
71
What is the significance of primary productivity?
It quantifies the rate of energy production in an ecosystem
## Footnote
It can be measured as GPP or NPP.
72
What are icides?
Kill insect pests that eat and damage crops, increasing NPP.
73
What do herbicides do?
Kill weeds, removing competition with crops for sunlight.
74
What are biological agents in pest control?
Include parasites and pathogenic bacteria/viruses that reduce pest populations.
75
What is saprobiont nutrition?
Obtaining nutrients from dead organic matter and animal waste using extracellular digestion.
76
Define mycorrhizae.
Symbiotic relationships between fungi and plant roots.
77
What is symbiosis?
When two species live closely together, with one or both depending on the other.
78
What is the sequence of nutrient cycles?
Producers take up nutrients, incorporate them, consumers eat producers, and decomposers release nutrients.
79
What role do saprobionts play in ecosystems?
They break down dead organic matter, releasing nutrients for reuse.
80
How do saprobionts break down waste?
By secreting enzymes for extracellular digestion and absorbing soluble nutrients.
81
What is the importance of saprobionts?
They ensure nutrients are released for reuse; without them, nutrients remain locked in complex molecules.
82
What is the role of mycorrhizae?
Increase surface area for absorption of water and minerals, aiding plant growth.
83
What is nitrogen fixation?
Conversion of nitrogen gas into nitrogen-containing compounds like ammonia.
84
What are the two types of nitrogen-fixing bacteria?
* Free-living nitrogen-fixing bacteria * Mutualistic nitrogen-fixing bacteria.
85
What is ammonification?
Conversion of organic nitrogen-containing compounds to ammonia and ammonium ions.
86
Define nitrification.
Conversion of ammonium ions to nitrite ions and then to nitrate ions.
87
What is denitrification?
Conversion of nitrates in the soil to nitrogen gas.
88
Why is denitrification problematic?
It reduces the availability of nitrogen-containing compounds for plants.
89
What is required for the phosphorus cycle?
Phosphorus is needed for nucleic acids, ATP, and phospholipids.
90
How do plants assimilate phosphate ions?
Through roots from soil, enhanced by mycorrhizae.
91
What happens to excess phosphate ions from animals?
They are lost in waste products to the soil.
92
What are the effects of harvesting crops on mineral ions?
Minerals are removed from the field, preventing their return to the soil.
93
What do fertilizers do?
Replenish lost mineral ions, increasing productivity.
94
What are the two types of fertilizers?
* Natural * Artificial.
95
What are the advantages of natural fertilizers?
* Less soluble, released slowly * Improves soil structure.
96
What are the disadvantages of artificial fertilizers?
* More soluble, can lead to leaching * Expensive.
97
How do fertilizers increase productivity?
Provide essential minerals for plant growth, enhancing photosynthesis.
98
What are some effects of nitrogen-containing fertilizers?
* Reduced species diversity * Leaching * Eutrophication.
99
What is leaching?
Removal of nutrients from soil by rain or irrigation.
100
What factors increase the likelihood of leaching?
* Applied before heavy rainfall * Use of chemical fertilizers.
101
What are the harmful effects of leached nitrate ions?
Can contaminate drinking water and affect oxygen transport in babies.
102
Define eutrophication.
Natural process where nutrient enrichment leads to increased plant growth.
103
What is the effect of leached nitrate ions on freshwater lakes?
They can lead to eutrophication and have a harmful effect on humans if the water is a source of drinking water.
## Footnote
Very high nitrate ion concentrations in drinking water can prevent efficient oxygen transport in babies and a link to stomach cancer in humans has been suggested.
104
Define eutrophication.
A natural process by which nutrient concentrations increase in bodies of water, stimulating the growth of algae.
105
What causes the increase in mineral concentrations during eutrophication?
Leaching from fertilised fields.
106
What is an algal bloom?
A dense surface layer of algae that absorbs light and prevents it from penetrating to lower depths.
107
What happens to plants and algae at lower depths during eutrophication?
They cannot photosynthesise due to lack of light and eventually die.
108
What is the role of saprobiontic bacteria in eutrophication?
They feed on dead organisms, leading to a rise in their populations.
109
What is the consequence of saprobiontic bacteria requiring oxygen?
The concentration of oxygen in the water is reduced.
110
What happens to aerobic organisms, such as fish, during eutrophication?
They die due to a lack of oxygen.
111
What occurs when aerobic organisms die in a eutrophic environment?
There is less competition for anaerobic organisms, whose populations then rise.
112
What do anaerobic organisms release as they decompose dead material?
More nitrates and some toxic wastes, such as hydrogen sulphide.
113
Fill in the blank: Eutrophication results in the _______ of water.
putrid
114
True or False: Eutrophication is solely beneficial for aquatic ecosystems.
False
