Topic 4 - Ecology Flashcards
(126 cards)
1
Q
Species
A
Proposed by Ernst Mayr, the biological species concept defines a species as organisms that can (actually or potentially) interbreed with each other to produce fertile offspring and cannot breed with others. In other words, the organisms of the species are reproductively isolated.
2
Q
Describe limitations of the biological species concept.
A
- Cannot test the reproductive isolation of fossils which must be classified into species based on morphology.
- Even for living species, it is hard to determine if populations are reproductively isolated especially if they are geographically isolated.
- Many species, especially prokaryotes, reproduce asexually and must be classified based on morphology and/or biochemical characteristics.
3
Q
Define “reproductive isolation.”
A
Reproductive isolation is the inability of a species to interbreed successfully with other species due to geographical, behavioral, physiological, or genetic barriers.
4
Q
Define “population.”
A
A population is organisms of the same species that live in a particular geographic area at the same time.
5
Q
Define “speciation.”
A
Speciation is the process by which populations evolve to become distinct species no longer capable of interbreeding with each other to produce fertile offspring.
6
Q
Outline how reproductive isolation can lead to speciation.
A
- Geography, changes in behavior or polyploidy can cause reproductive isolation between populations, isolating the gene pools
- Natural selection acts on the isolated populations independently
- The populations diverge to the point of no longer being able to interbreed with each other to produce fertile offspring, forming two species
7
Q
Define “autotroph.”
A
An autotroph is an organism capable of making energy-containing organic molecules from inorganic sources via photosynthesis (involving light energy) or chemosynthesis (involving chemical energy). Autotrophs are the producers in a food chain, such as plants or algae.
8
Q
Define “heterotroph.”
A
A heterotroph is an organism that is unable to synthesize its own organic compounds from inorganic sources, and as a result must feed on organic matter produced by, or available in, other organisms.
9
Q
Describe the feeding behaviors of consumers.
A
Consumers are organisms that need to eat food to obtain their energy. All heterotrophs are consumers.
10
Q
List three example consumer organisms.
A
Any organism that is not an autotroph (producer) is a consumer. In this food web, all organisms besides the phytoplankton and seaweed are consumers.
11
Q
Describe the feeding behaviors of detritivores.
A
Detritivores are heterotrophs that obtain nutrients by consuming detritus. Detritus is particulate organic material such as the bodies or fragments of dead organisms and/or fecal material.
12
Q
List two example detritivore organisms.
A
Some example detritivores include earthworms, millipedes, dung beetles, sea cucumbers and fiddler crabs.
13
Q
Describe the feeding behaviors of saprotrophs.
A
Saprotrophs live on dead organic matter and feed by a process in which dead or decaying organic material is extracellularly digested (outside of the cell) by a variety of enzymes that are excreted by the organism. After digestion, the nutrients are then absorbed into the organism.
14
Q
Explain the role of saprotrophs in an ecosystem.
A
In the ecosystem, saprotrophs recycle nutrients by breaking down organic material into inorganic material. Saprotrophs improves soil fertility by returning nutrients (such as minerals, nitrates, phosphates) to the environment.
Saprotrophs release heat energy that in turn accelerates decomposition by warming the soil.
15
Q
List two example saprotroph organisms.
A
Some example saprotrophs include fungi and soil bacteria.
16
Q
Define “community.”
A
A community is all the populations of various species living and interacting in a common location.
17
Q
Give an example of a community of organisms.
A
A tropical forest of trees and undergrowth plants, inhabited by animals and rooted in soil containing bacteria and fungi, constitutes a biological community.
18
Q
Define “abiotic.”
A
Abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors such as climate and geology can determine which species of organisms will survive in a given environment.
19
Q
Define “ecosystem.”
A
An ecosystem is the interaction of the community of living organisms with the abiotic components of their environment. The biotic and abiotic components are of an ecosystem are linked together through nutrient cycles and energy flows.
20
Q
Define “nutrient.”
A
Nutrients are molecules required by an organism for growth, repair, and normal metabolism.
21
Q
List the common nutrients needed by organisms.
A
Macronutrients (carbohydrates, fats, proteins and water) are needed in large amounts and are used primarily to generate energy or to incorporate into tissues for growth and repair.
Micronutrients (minerals and vitamins) are needed in smaller amounts and often have subtle biochemical and physiological roles in cellular processes.
22
Q
Outline how nutrients enter living systems.
A
Through a nutrient cycle a nutrient is able to move from inorganic matter back into a living system. In this example, the process is initiated by an autotroph which synthesizes organic molecules which then move through food web pathways. Eventually the nutrient convert back into inorganic nutrients through metabolism or decomposition.
23
Q
State that chemical elements can be recycled but energy cannot.
A
Chemical nutrients and energy tend to flow in the same direction for most of an ecosystem (from autotrophs to heterotrophs). The big difference is that the chemical nutrients can be recycled in the ecosystem while the energy is ultimately lost from the ecosystem to the universe at large.
24
Q
Outline the generalized flow of nutrients between the abiotic and biotic components of an ecosystem.
A
Elements such as carbon, nitrogen, oxygen, and hydrogen are moved through biotic components of an ecosystem through food chains and recycled through abiotic environments including the atmosphere, water, and soil.
25
Define "sustainability."
Sustainability is the capacity of ecosystems to maintain their essential functions and processes, over time.
26
Give an example of an unsustainable practice.
Unsustainable practices are not able to be maintained at the current rate or level.
Examples include:
Pollution and contamination of air, land, and water.
Deforestation.
Soil degradation and erosion.
Wasteful consumption of water.
27
Outline three requirements of a sustainable ecosystem.
Sustainable ecosystems require nutrient availability , an ability to detoxify waste products and a supply of energy.
28
Use a dichotomous key to identify the mode of nutrition of an organism.
A dichotomous key is a tool that allows the user to determine the identity of an organism by following a series of steps.
29
Outline why sampling must be random.
In ecology research it is very difficult to count/measure all individuals in a population, community or ecosystem. Random sampling eliminates bias and allows researchers to make generalizations about a larger system, making the assumption that these samples are representative of the ecosystem in general.
30
Explain methods of random sampling, including the use of a quadrat.
In quadrat sampling, a number of random samples are taken from around the habitat using a standard sampling unit. Quadrats normally consist of a square frame. The frame is placed (on the ground or on whatever is being investigated) and the animals, and/ or plants inside it counted, measured or collected. This is done many times at different points within the habitat to give a large number of different samples.
31
Use a contingency table to complete a chi-square test of association.
The chi-square test of association is used to determine whether there is a significant association between the two species within a habitat. The data is displayed in a contingency table where each row represents a category for one species and each column represents a category for the other species.
32
Calculate a chi-square statistic based on observed and expected values.
1. Calculate the expected values for the two species, assuming the species are randomly distributed with respect to each other. Expected frequencies = (row total X column total) / grand total
2. Apply the formula to calculate the value of the Chi-Square test of Independence
3. The calculated X2 value is than compared to the "critical value X2" found in an X2 distribution table. The X2 distribution table represents a theoretical curve of expected results. The expected results are based on DEGREES OF FREEDOM. DF = (rows-1)(columns-1)
33
State the null and alternative hypothesis of statistical tests.
Null hypothesis: Assumes that there is no association between the two variables.
Alternative hypothesis: Assumes that there is an association between the two variables.
34
Determine if the null hypothesis is supported or rejected given a critical value and a calculated statistic.
If the calculated value is lower than the critical value at the 0.05 level of significance, accept the null hypothesis and conclude that there is NO significant association between the variables.
If the calculated value is higher than the critical value at the 0.05 level of significance, reject the null hypothesis and conclude that there IS a significant association between the variables.
35
State the minimum acceptable significance level (p value) in published research.
In the majority of analyses, a p value of 0.05 is used as the cutoff for significance. If the p-value is less than 0.05, we reject the null hypothesis that there's no difference between the means and conclude that a significant difference does exist.
36
Define "p-value" in relation to tests of statistical significance.
The significance level, p, is the probability of obtaining a result at least as extreme, given that the null hypothesis were true.
A significance level of 0.05 indicates a 5% risk of concluding that a significant result exists when there actually isn't one..
37
Explain the meaning of a "statistically significant" result.
A "statistically significant" result is one in which there is a very low probability (usually less than 5%) that the observed effect would have occurred due to sampling error alone.
38
Define "mesocosm."
A mesocosm is an experimental model ecosystem used to investigate ecosystems under controlled conditions.
39
List three example mesocosms.
Mesocosms can take many shapes and forms, such as:
1. small sealed containers with organisms inside it
2. fenced enclosures in fields or aquatic areas
3. large tanks with inputs and outputs that mimic environmental conditions.
40
State the trend found in the nutritional patterns of plants and algae.
The majority of plants and algae are autotrophs capable of making their own carbon compounds by photosynthesis.
41
Describe the discrepancy in the nutritional pattern of parasitic plants and algae.
There are a few types of plants and algae that do not perform photosynthesis and instead are parasitic on other plants, obtaining their nutritional requirement from another living plant.
Parasitic plants have modified roots which penetrates the host plants, providing them with the ability to extract water and nutrients from the host.
42
State how energy in carbon compounds enters most biological communities.
In most ecosystems, chemical potential energy stored in carbon compounds enters biological communities through photosynthesis in producers.
43
List three groups of autotrophs.
Autotrophs are organisms that produces complex organic compounds from inorganic substances, generally using energy from light or inorganic chemical reactions.
Common autotrophs are:
-plants
-algae
-cyanobacteria
44
Outline how light energy is converted to chemical energy.
Light energy is converted to chemical energy through photosynthesis. Producers absorb wavelengths of light using photosynthetic pigments and convert this light energy into chemical energy.
45
Define "food chain."
A food chain is a sequence of organisms through which nutrients and energy pass as one organism eats another. Food chains show which organisms eats which organism. Food chains always begin with a producer and follow the flow of energy through trophic levels.
46
Define "food web."
A food web represents the interconnected feeding relationships within an ecological community.
47
State the meaning of the arrow in a food web or chain.
Arrows in food chains and webs represent the flow of energy and nutrients through the trophic levels.
48
Outline the flow of energy through a food chain.
1. Light energy is converted by an autotrophs to chemical energy stored in carbon compounds (such as glucose) through photosynthesis.
2. Energy is transferred to other organisms through feeding; producers are eaten by primary consumers, these by secondary consumers, these by tertiary consumers...
3. Cellular respiration releases energy from the carbon compounds to produce ATP for use by organisms for metabolism, growth, repair, and/or movement
4. Approximately 90% of the energy at each trophic level is lost as heat, biomass not consumed (i.e. bones/hair) or biomass lost as waste (i.e. in feces/urine)
Energy is NOT recycled!
49
Draw a food chain, labeling the producer, primary consumer, secondary consumer and tertiary consumer.
When drawing a food chain, begin with a producer. Draw an arrow to the organism(s) that eats the producer, called the primary consumer. Draw additional organisms and arrows to represent the chain of feeding, from the primary consumer to the secondary consumer and from secondary consumer to the tertiary consumer.
50
List three reasons why living organisms need energy for cell activities.
Maintaining a living system requires an input of energy for cell activities such as synthesizing large molecules (such as DNA and proteins), active transport of molecules and ions across the cell membrane, movement of structures within the cell (such as vesicles and chromosomes) and contraction of proteins (such as during cytokinesis).
51
State the function of ATP.
Adenosine triphosphate (ATP) is a nucleotide that functions as the main source of energy for most metabolic processes. ATPs are consumed by energy-requiring (endergonic) processes and produced by energy-releasing (exergonic) processes in the cell.
52
Outline how ATP is formed, referencing exothermic and endothermic reactions.
Formation of ATP:
ADP + Pi --> ATP + H2O
(this reaction is endothermic, with the energy input coming from the oxidation of carbon compounds such as carbohydrates and lipids)
Hydrolysis of ATP
ATP + H2O --> ADP + Pi
(this reaction is exothermic)
53
Outline the reason why respiration releases heat.
Heat energy is released as glucose burns. This is combustion. During cell respiration glucose is broken down gradually by a series of reactions, each catalysed by a different enzyme. This releases energy in small amounts so that it can be used by cells.
However, metabolism is far from efficient at capturing the energy in glucose in the form of ATP. A large fraction of the energy is lost as heat in the process of making ATP.
54
Outline the energy conversions performed by living organisms.
Living organisms can perform various energy conversions:
Light energy -> chemical energy (photosynthesis)
Chemical energy -> kinetic energy (muscle contraction)
Chemical energy -> electrical energy (neuron action potential)
Chemical energy -> heat energy (cell respiration)
55
State the reason why heat created by living organisms is eventually lost from the ecosystem.
All energy released by metabolism for use in cell activities will ultimately be lost from an ecosystem because living organisms cannot turn this heat into other forms of usable energy.
56
Define "biomass."
Biomass is the mass of living biological organisms in a given area or ecosystem at a given time.
57
Define "trophic level."
A trophic level is *the group of organisms within an ecosystem which occupy the same level in a food chain." The first level contains the producers. The producers are consumed by the second-trophic level organisms—the herbivores (aka primary consumers). At the third trophic level, secondary consumers eat the herbivores; and at the fourth trophic level, tertiary consumers eat the secondary consumers. These categories are not strictly defined, as many organisms feed on several trophic levels. A separate trophic level, the decomposers (saprotrophs), consists of organisms such as bacteria and fungi that break down dead organisms and waste materials into nutrients usable by the producers.
58
State the unit used for communicating the energy in each trophic level of a food chain.
Energy flow in an ecosystem is measured as energy per unit area per unit time:
kJ m-2 yr-1
"kilojoules per square meter per year"
kJ = kilojoules, a measure of energy
m-2 = square meter; a measure of area
yr-1 = year; a measure of time
59
Outline three reasons why the amount of energy decreases at higher trophic levels.
Energy decreases as it moves up trophic levels because energy is lost as metabolic heat at each trophic level. Additionally, some chemical energy is excreted in feces at each trophic level. Lastly, not all of the biomass at each level is consumed during feeding, the unconsumed biomass is a source of loss of chemical energy from the trophic level.
60
State the average amount of energy passed through each trophic level of a food chain.
Only a fraction of the energy available at one trophic level is transferred to the next trophic level; the fractions can vary between 1-15%, with an average value of 10%.
61
Describe the shape of a pyramid of energy.
An energy pyramid is a graphical depiction of energy flow in a community. The different levels represent different trophic levels, with producers at the bottom. The energy pyramid shape shows how the amount of useful energy that enters each trophic level — chemical energy in the form of food — decreases as it is used by the organisms in that level.
The top trophic level is the smallest because only part of the energy in one trophic level will become part of the next trophic level.
62
Draw a pyramid of energy given data for an ecosystem.
Energy pyramids should be drawn as stepped, not pyramidal.
Each bar of the energy pyramid should be labeled with the trophic level it represents and the relative amount of energy in the trophic level..
The width of the bars should substantially decrease at each trophic level*(at least 1/5), to depict the average 10% of energy moved between trophic levels.
63
Explain why there is a limited number of organisms in a food chain.
Because only a small proportion (10 %) of energy can pass from one trophic level to the next, the consumers at the top of an energy pyramid have much less energy available to support them than those closer to the bottom.
The amount of useful energy left can't support another level. There is not enough energy for a 4th/5th/later stages of a food chain.
Most of the energy that enters a community is ultimately lost to the living world as heat
released by cell respiration, biomass not consumed (i.e. bones/hair) or biomass lost as waste (i.e. in feces/urine).
64
Define "autotroph."
An autotroph is *an organism capable of making energy-containing organic molecules from inorganic sources* via photosynthesis (involving light energy) or chemosynthesis (involving chemical energy).
65
State the molecular formula for carbon dioxide.
Carbon dioxide = *CO₂*
One carbon atom with double bonds to two oxygen atoms.
66
State the role of photosynthesis in the carbon cycle.
Autotrophs take in carbon from the atmosphere in the form of CO₂. They then use the carbon atoms from the CO₂ in the process of photosynthesis to make sugars, proteins and lipids for their growth.
Photosynthesis *converts inorganic carbon molecules into organic carbon molecules.*
67
State the molecular formula for the hydrogen carbonate ion.
Hydrogen carbonate ion=
Bicarbonate=
HCO₃⁻.
68
Outline the process that converts carbon dioxide to hydrogen carbonate ion in water.
CO₂ diffuses into water. Some will remain as a dissolved gas. The remainder will combine with water to form carbonic acid (CO₂ + H₂O ⇄ H₂CO₃) which dissociates to form hydrogen and hydrogen carbonate ions (H⁺ and HCO₃⁻).
69
Explain the reduction of the pH in water when carbon dioxide is added.
When CO₂ combines with H₂O, hydrogen and hydrogen carbonate ions (H⁺ and HCO₃⁻) are formed. The increased [H⁺] will cause a reduction in the pH of the solution.
Reduced pH = more acidic
70
Define "diffusion."
Diffusion is the net movement of particles down their concentration gradient (from areas of higher concentration to areas of lower concentration).
71
Outline the role of diffusion in the carbon cycle.
CO₂ diffuses into autotrophs from the atmosphere or water. Without diffusion of CO₂, autotrophs would not have a carbon source for performing photosynthesis.
A waste product of cellular respiration, CO₂ diffuses out of living things to the atmosphere or water.
72
State the role of respiration in the carbon cycle.
All living things respire, the metabolic process of converting biochemical energy from nutrients into adenosine triphosphate (ATP) for cellular work. CO₂ is a waste product of respiration.
Respiration converts organic carbon molecules into inorganic carbon molecules which then diffuse into water or the atmosphere.
73
State the molecular formula for methane.
Methane=
CH₄.
74
Outline the role of methanogenic archaea in the transformation of organic material into methane.
Methanogenic archaeans are microorganisms that produce methane as a metabolic byproduct in anaerobic conditions. The methane produced will either accumulate underground (forming natural gas) or diffuse into the atmosphere.
75
Define "oxidation."
Oxidation is the gain of oxygen or loss of a hydrogen in a "redox" reaction.
76
State the formula for the oxidation of methane to carbon dioxide that occurs in the atmosphere.
In the atmosphere, methane (CH₄) is oxidized (gains oxygen and loses hydrogens) when it reacts with atmospheric oxygen (O₂). The result is carbon dioxide and water vapor.
CH₄ + 2O₂ → CO₂ + 2H₂O
77
Define "decomposition."
Decomposition is the process of complex, carbon compounds in dead organisms, urine and faeces being broken down into simpler carbon compounds by bacteria or fungi.
78
Define "peat."
Peat is a brown deposit resembling soil, formed by the partial decomposition of organic matter in wet acidic conditions (such as in bogs).
79
Outline formation of peat.
Peat forms when organic material (mostly plants/Sphagnum moss) does not fully decompose.
Peat forms in in acidic, waterlogged and/or anaerobic conditions where decomposers (such as bacteria, fungi and other saprotrophs) are inhibited.
80
Define "fossilization."
If conditions are not favourable for the process of decomposition, dead organisms decay slowly or not at all. These organisms build up and, if compressed over millions of years, can form fossil fuels (coal, oil or gas).
81
Outline formation of coal.
Coal forms from peat over long periods of time. Heat and pressure produce chemical and physical changes in the peat layers which force out oxygen and leave rich carbon deposits called coal.
82
Outline formation of oil and natural gas.
All of the oil and gas available today began as microscopic plants and animals living in the ocean millions of years ago. As these microscopic plants and animals lived, they stored carbon molecules in their bodies. When they died, they sank to the bottom of the sea. Over millions of years, layer after layer of sediment were formed. As they became buried ever deeper, heat and pressure began to rise. The amount of pressure and the degree of heat, along with the type of biomass, determines if the material becomes oil or natural gas. The gas or oil then accumulates in tiny pores in the surrounding rock.
83
Outline the role of combustion in the carbon cycle.
Combustion occurs when any organic material is reacted (burned) in the presence of oxygen to give off the products of carbon dioxide and water. In the carbon cycle, combustion converts carbon stored in organic molecules (biomass, coal, gas and oil) to atmospheric CO₂.
84
State the products of a combustion reaction.
Combustion occurs when a organic molecule reacts with oxygen to produce carbon dioxide and water.
85
State sources of fuel for a combustion reaction.
Combustion reactions are commonly referred to as "burning." Biomass (such as wood), coal, gas and oil are common fuel sources in combustion reactions.
86
State the molecular formula for calcium carbonate.
The calcium carbonate chemical formula is CaCO₃.
87
State that hard shells, such as in mollusk and coral, are made of calcium carbonate.
Hard shells are the exoskeletons of corals and mollusks such as snails, clams and oysters. The shells are composed mostly of calcium carbonate, CaCO₃.
88
Outline the role of lithification in the carbon cycle.
Lithification is the compaction of sediments into rocks through compaction and cementation. In the carbon cycle, lithification creates limestone.
89
Outline the formation of limestone.
Limestone is primarily composed of calcium carbonate (CaCO₃). It is usually an organic sedimentary rock that forms from the accumulation of shell, coral, algal, and fecal debris in shallow, calm, warm marine waters.
90
Define "carbon cycle."
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere (living things), pedosphere (soil), geosphere (rocks), hydrosphere (water), and atmosphere of the Earth.
91
Define "flux" as related to the carbon cycle.
A carbon flux is the exchange of carbon between Earth's carbon pools.
92
List flux processes in the carbon cycle.
Photosynthesis
Respiration
Decomposition
Diffusion
Lithification
Combustion
Fossilization
Feeding
93
Define "pool" as related to the carbon cycle.
Carbon pools are locations or systems that have the capacity to both take in and release carbon.
94
List pools of carbon in the carbon cycle.
Biosphere (living things, terrestrial and aquatic)
Pedosphere (soil)
Geosphere (rocks and Earth's crust)
Hydrosphere (water, mostly ocean)
Atmosphere
Fossil fuels
95
State the unit of measure for carbon flux values.
Global carbon fluxes are estimated in gigatonnes (1 gigatonne = 1 billion metric tonnes).
96
Sketch a graph of the annual fluctuation in atmospheric carbon dioxide concentration.
Sinusoidal shape with a peak in May and a trough in October.
Axis labeled:
X axis = month
Y axis = Atmospheric CO₂ level (ppm)
97
Explain the annual fluctuation in atmospheric carbon dioxide concentration in the northern hemisphere.
The annual, seasonal fluctuations of CO₂ levels are caused by increased photosynthesis during Northern hemisphere spring/summer.
Photosynthesis uses CO₂;
lowering carbon dioxide level in atmosphere during the spring and summer months.
98
Draw a diagram of the terrestrial carbon cycle.
CO₂ in atmosphere linked to producer (plant) with an arrow labeled photosynthesis;
Producer linked to consumer (animal) with an arrow labeled feeding;
Producer and consumer linked to CO₂ in the atmosphere with an arrow labeled (cell) respiration;
Producer and consumer linked to decomposers (bacteria or fungi) with an arrow labeled decomposition;
Decomposers linked to CO₂ in the atmosphere with an arrow labeled cell respiration;
Producer linked to CO₂ in the atmosphere with an arrow labeled combustion;
Producers, consumers and decomposers linked to fossil fuels (coal, oil, natural gas) with arrow labeled fossilization;
Fossil fuels linked to CO₂ in the atmosphere with an arrow labeled combustion;
Methanogenic bacteria linked to methane in the atmosphere with an arrow labeled anaerobic respiration;
Methane linked CO₂ in the atmosphere with an arrow labeled oxidization;
99
Explain why accurate measurements of carbon dioxide and methane in the atmosphere are important.
It is important to make observations and collect data regarding greenhouse gas levels (such as CO₂ and methane). The information helps scientists understand trends and test whether actions to reduce greenhouse gases are working.
100
Outline how data on concentration of atmospheric carbon dioxide and methane are collected.
Scientists measure the amount of greenhouse gases in the atmosphere in several ways. They use satellites and other instruments to measure the amount of greenhouse gases in the air all around the world. They also collect samples of air from specific places and then analyze these samples in a laboratory.
We also have clues about the levels of greenhouse gases that existed in the past. For example, ancient air bubbles trapped deep in the ice of Greenland and Antarctica reveal how much atmospheric CO₂ was present long ago.
101
List greenhouse gases found in the atmosphere.
A greenhouse gas is a gas that absorbs and emits longwave radiation (heat). Greenhouse gases cause the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide and ozone.
102
State the sources of CO2 in the atmosphere.
Carbon dioxide is added to the atmosphere naturally when organisms respire or decompose, carbonate rocks are weathered, forest fires occur, and volcanoes erupt.
Carbon dioxide is also added to the atmosphere through human activities, such as the burning of fossil fuels and forests and the production of cement.
103
State the sources of water vapor in the atmosphere.
The water in the atmosphere is due to evaporation of water during the water cycle. In the atmosphere, water exists as a gas (water vapor from evaporation), as a liquid (droplets of rain), and as a solid (snow and ice).
104
Define "greenhouse effect."
The greenhouse effect is the natural process by which radiation (heat) is trapped by a planet's atmosphere, warming the planet's surface to a temperature above what it would be without its atmosphere.
105
Outline the mechanism by which greenhouse gases trap heat in the atmosphere.
Solar energy absorbed at Earth's surface is radiated back into the atmosphere as heat.
A layer of greenhouse gases in the atmosphere absorb the heat and radiate it back to the Earth's surface.
106
State the sources of nitrous oxide gas in the atmosphere.
Human activities such as agriculture, fuel combustion, wastewater management, and industrial processes are increasing the amount of nitrous oxide (N2O) gas in the atmosphere. Nitrous oxide is also naturally present in the atmosphere as part of the Earth's nitrogen cycle, and has a variety of natural sources.
107
State the sources of methane in the atmosphere.
Methane (CH4) is found in very small quantities in the atmosphere but is able to make a big impact on warming. Human activities emitting methane include leaks from natural gas systems and the raising of livestock. Methane is also emitted by natural sources such as natural wetlands and melting permafrost.
108
State two factors that determine the warming impact of a greenhouse gas.
1. Ability to absorb longwave radiation (only certain gases in the atmosphere have the ability to trap long wave radiation and therefore act as a greenhouse gas).
2. Abundance of the gas in the atmosphere (the amount of a particular gas in the atmosphere).
109
State two variables that determine the concentration of a gas in the atmosphere.
1. Rate of release of the gas into the atmosphere.
2. How long the gas persists in the atmosphere once it is there.
110
Compare how long water, methane and CO2 remain in the atmosphere, on average.
There are several processes that remove CO2 from the atmosphere. Most dissolves into the ocean over a period of 20-200 years. The rest is removed by slower processes that take up to hundreds of thousands of years, including chemical weathering and rock formation. This means that once in the atmosphere, carbon dioxide can continue to affect climate for thousands of years.
Methane is mostly removed from the atmosphere by chemical reaction, persisting for about 12 years.
Water vapour has a very short atmospheric lifetime, of the order of hours to days, because it is rapidly removed as rain and snow.
111
State that the Earth absorbs shortwave energy from the sun and re-emits longer wavelengths.
Solar energy enters Earth's atmosphere as shortwave radiation in the form of ultraviolet (UV) rays and visible light. Once in the Earth's atmosphere, clouds and the surface absorb the solar energy. The ground heats up and re-emits energy as longwave radiation in the form of infrared rays.
112
Compare wavelengths of UV, visible and infrared radiation.
Electromagnetic energy travels as waves that vary in wavelength. Infrared radiation, what we experience as heat, has a longer wavelength than visible light. Ultraviolet has shorter wavelengths than visible light.
113
Explain the greenhouse effect, with reference to shortwave radiation from the sun, longwave radiation from the Earth and the effects of greenhouse gases.
When the Sun's shortwave energy reaches the Earth's atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated as longwave radiation from the Earth's surface. Greenhouse gases in the atmosphere absorb some of the longwave radiation, which makes the atmosphere and Earth's surface warmer.
114
Explain why water vapor, carbon dioxide, methane and nitrous oxide are greenhouse gases.
Water vapor, CO2, methane and N2O are greenhouse gases because they are able to absorb most of the Earth's emitted longwave infrared radiation, which heats the atmosphere.
Other atmospheric gases (such as N2 and O2) do not interact with longwave radiation, and therefore have no consequence for the greenhouse effect.
115
Explain why atmospheric greenhouse gas concentration would logically impact global temperatures.
The amount of greenhouse gases in the atmosphere is directly related to the temperature of the atmosphere. If the concentration of any of the greenhouse gases rises, more longwave radiation (heat) will be captured by the atmosphere leading to an increase in average global temperatures.
116
Outline the effect of greenhouse gas concentration on climate, specifically location and frequency of of rain and frequency of severe storms.
Higher average global temperatures are worsening many types of disasters, including storms, heat waves, floods, and droughts. A warmer climate creates an atmosphere that can collect, retain, and drop more water, changing weather patterns in such a way that wet areas become wetter and dry areas drier.
117
Define "enhanced greenhouse effect."
The disruption to Earth's climate equilibrium caused by the increased concentrations of greenhouse gases has led to an increase in the global average surface temperatures. This process is called the enhanced greenhouse effect.
118
State the atmospheric CO2 concentration prior to the industrial revolution.
Before the Industrial Revolution, atmospheric levels of CO2 were around 280 parts per million. In 2013, the Mauna Loa observatory in Hawaii, which has been measuring atmospheric CO2 levels since 1958, recorded the milestone value of 400 parts per million of CO2 in the atmosphere, a level not seen since around 35 million years ago. The value continues to rise.
119
Outline the impact of the industrial revolution on atmospheric greenhouse gas concentration.
The Industrial Revolution brought new industrial processes, an increase in the burning of fossil fuels, more extensive agriculture, and a rapid increase in the world's population. This rapid increase in human activity led to the emission of significant amounts of greenhouse gases into the atmosphere.
120
Describe the correlation between atmospheric CO2 concentrations since the industrial revolution and global temperatures.
There is a strong positive correlation between industrial processes (and the burning of fossil fuels) and the rising atmospheric concentrations of CO2.
In turn, the increase in atmospheric CO2 concentration correlates with an increase in average global temperature.
While correlation doesn't equal causation, there is substantial and growing evidence to suggest that CO2 emissions are linked to global average temperature increases.
121
Explain how historical temperature data has been collected.
Direct measurements of atmospheric gases have been made over the past 50 years. For historical data, analysis of air bubbles trapped in ancient ice, show that levels of carbon dioxide, methane, nitrous oxide and halocarbons are increasing.
The Vostok ice core (from Antarctica) is one of the longest drilled, with ice dated to 420,000 years old. By analyzing the gas bubbles trapped in ice, historical CO2 levels and air temperatures can be deduced.
122
Using ice core data, outline the correlation between atmospheric CO2 concentration and global temperatures.
Scientists can study Earth's climate as far back as 800,000 years by drilling core samples from deep underneath the ice sheets of Greenland and Antarctica. Detailed information on air temperature and CO2 levels is trapped in these specimens. Current polar records show a direct relationship between atmospheric carbon dioxide and global temperature.
123
Outline reasons why there is vigorous debate around the claim that human activities are causing climate change.
The causes and effects of climate change have stirred vigorous debate because:
1. There is a degree of uncertainty in mathematical models used to predict consequences.
2. Climate patterns are complex with many variables.
3. Possible solutions to climate change will cost money and require government regulation.
4. Economic dependence on a fossil fuel based economy.
5. Correlation does not imply causation.
124
Outline the effect of atmospheric CO2 concentration on ocean pH.
Atmospheric CO2 dissolves into ocean water. The CO2 reacts with water molecules (H2O) to form carbonic acid (H2CO3). This compound then breaks down into a hydrogen ion (H+) and bicarbonate (HCO3-). The presence of all the hydrogen ions is what decreases the pH, or acidifies the ocean.
125
Describe the impact of lower ocean pH on animals that make skeletons from calcium carbonate.
Many marine organisms (such as coral, oysters, clams and snails) combine calcium and carbonate to form hard shells and skeletons out of the mineral calcium carbonate, CaCO3. Increased acidity slows the growth of calcium carbonate structures, and under severe conditions, can dissolve structures faster than they form.
126
Outline ways by which claims can be evaluated for truth.
Not only is climate science very complex, but it has also been targeted by deliberate obfuscation campaigns. Claims must be evaluated for truth.
Here are some questions to ask when evaluating claims:
1. Is there evidence to back up the claim?
2. Is the evidence based on a large sample of observations or just a few isolated incidents?
3. Are the claims supported by multiple lines of evidence?
4. Does the scientific community find the evidence convincing?
