Module 1 Flashcards
Learn and focus on key concepts
1
Q
What is ecology?
A
The study of the relationships between organisms and their interactions with both the living (biotic) and nonliving (abiotic) parts of their environment.
2
Q
What does the term “species” mean in ecology?
A
A group of similar organisms that can interbreed and produce fertile offspring.
3
Q
How is a “population” defined in ecological terms?
A
A group of individuals of the same species living in a particular area.
4
Q
What is a “community” in an ecological context?
A
An assemblage of populations of different species living and interacting in the same area.
5
Q
Define “ecosystem”
A
A system comprising a community of organisms along with the physical environment with which they interact.
6
Q
What is Liebig’s law of the minimum?
A
It states that an organism’s growth is limited by the scarcest resource (the limiting factor) relative to its needs.
7
Q
What are tolerance limits?
A
The maximum and minimum levels of an environmental factor that an organism can tolerate; conditions beyond these limits prevent survival.
8
Q
Define “habitat”
A
The physical location or environment where an organism lives.
9
Q
What is an ecological “niche”?
A
the role a species plays in its community—including its habitat, resource use, and interactions with other species.
10
Q
How do habitat and niche differ?
A
A habitat is where an organism lives, while a niche describes how that organism uses the environment and interacts with others.
11
Q
What is a fundamental niche?
A
The full range of environmental conditions under which a species can survive and reproduce in the absence of competitors or predators.
12
Q
What is a realized niche?
A
The portion of the fundamental niche actually occupied by a species when biotic interactions (like competition) are present.
13
Q
Define “biome”
A
A large ecological area defined by its climate, soil, and the types of plants and animals adapted to that environment.
14
Q
What is an ecotone?
A
A transitional zone between two ecological communities that often contains species characteristic of both, sometimes with increased diversity due to the edge effect.
15
Q
What are abiotic factors?
A
Nonliving, chemical, physical components of the environment
such as temperature, pH, moisture, light, and soil composition.
16
Q
What are biotic factors?
A
The living components of an environment, including plants, animals, fungi, and microorganisms.
17
Q
What is “zonation” in an ecosystem?
A
The horizontal distribution or pattern of species or different communities or ecosystems along an environmental gradient.
18
Q
A
19
Q
Define “stratification”
A
The vertical layering of organisms in an ecosystem, as seen in forests where species occupy different canopy levels.
20
Q
What is ecological succession?
A
The gradual change in species composition and community structure over time in an ecosystem.
21
Q
How do primary and secondary succession differ?
A
Primary succession begins on a lifeless surface (no soil), whereas secondary succession occurs in areas where a disturbance has occurred but soil remains.
22
Q
What is competition in ecology?
A
An interaction where organisms vie for the same limited resources (food, space, mates), reducing the availability for others.
23
Q
Explain the competitive exclusion principle
A
Two species competing for the same limited resource cannot coexist indefinitely; one will eventually outcompete the other.
24
Q
What is resource partitioning?
A
The division of resources among species to lessen competition and allow coexistence.
25
What is the difference between intraspecific and interspecific competition?
Intraspecific competition occurs among individuals of the same species, whereas interspecific competition occurs between individuals of different species.
26
How do predator–prey interactions affect population dynamics?
Increases in prey can lead to increases in predator numbers; as predators become more abundant, they reduce the prey population, creating dynamic fluctuations.
27
What is exploitative competition?
Competition where individuals indirectly compete by consuming a shared resource, thereby reducing its availability to others.
28
What is interference competition?
Direct competition where individuals physically interact or interfere with each other’s access to resources often through aggression or territoriality.
29
Define symbiosis
A close, long-term interaction between individuals of two or more different species.
30
What is mutualism?
A symbiotic relationship where both species benefit from the interaction.
31
Give an example of mutualism
Cattle egrets feeding on ticks on cattle or bees pollinating flowers while obtaining nectar.
32
What is commensalism?
A symbiotic relationship where one species benefits and the other is neither harmed nor helped significantly.
33
Provide an example of commensalism
Orchids growing on trees to obtain water droplets without affecting the tree.
epiphytes
remora and sharks
34
What is parasitism?
symbiotic relationship where one species benefits at the expense of the host, often causing harm.
35
Provide an example of parasitism
Aphids feeding on plant sap, potentially damaging the plant.
love plant
ringworm
ticks
36
What is the carbon cycle?
The process by which carbon is exchanged among the atmosphere, oceans, soil, and living organisms.
37
Why is carbon important in ecosystems?
It is a structural component of organic molecules and an essential element in energy storage and climate regulation.
38
How do plants contribute to the carbon cycle?
Through photosynthesis, plants take in CO₂ and convert it into organic compounds.
39
What is respiration in the carbon cycle?
The process by which organisms convert organic matter into energy, releasing CO₂ back into the atmosphere.
40
How does combustion affect the carbon cycle?
Burning fossil fuels releases stored carbon as CO₂, increasing atmospheric greenhouse gases.
41
What role does decomposition play in the carbon cycle?
Decomposers break down dead organic matter, releasing carbon back into the environment as CO₂ or methane.
42
What is the nitrogen cycle?
The series of processes by which nitrogen is converted into different chemical forms and cycled between the atmosphere, soil, and living organisms.
43
Explain nitrogen fixation
The conversion of atmospheric nitrogen (N₂) into ammonia (NH₃) or ammonium (NH₄⁺) by bacteria or through lightning.
44
Ammonification (happens twice, second time restarting the cycle)
the process where organic nitrogen compounds from dead organisms, plant matter or waste products is converted by microorganisms such as bacteria and fungi into simpler inorganic forms predominantly ammonia (NH3) and then ammonium ions (NH4+). This inorganic nitrogen is then available for uptake by plants and other microorganisms.
45
What is nitrification?
A two-step aerobic process where ammonia is oxidized first to nitrite (NO₂⁻) by bacteria such as Nitrosomonas, then to nitrate (NO₃⁻) by Nitrobacter. Nitrifying bacteria is very important, converting ammonia into a form plants can easily absorb.
46
Assimilation
the stage where plants and animals take up and incorporate inorganic nitrogen compounds, such as nitrate ions (NO3-) and ammonium ions (NH4+) , into their biological tissues to build proteins and nucleotides, amino acids. Plants absorb inorganic nitrogen compounds through roots and incorporate them into their organic molecules e.g. amino blah.
Animals obtain nitrogen by eating plants and animals when digesting them, breaking down then used
47
Define denitrification
The process by which denitrifying bacteria convert nitrates back into nitrogen gas (N₂) or nitrous oxide (N₂O), releasing them into the atmosphere.
48
How do human activities impact the nitrogen cycle?
Through the use of fertilizers, fossil fuel combustion, and habitat alteration, which can increase the availability of nitrogen compounds and lead to pollution.
49
What makes the phosphorus cycle unique?
It is a sedimentary cycle with no significant gaseous phase; phosphorus is mainly transported in aqueous form.
50
Why is phosphorus a limiting nutrient in aquatic ecosystems?
Low phosphorus levels can restrict plant growth, while excessive amounts can trigger eutrophication.
51
What is eutrophication?
The over-enrichment of water bodies with nutrients, leading to excessive algal growth and oxygen depletion.
52
How do human activities contribute to eutrophication?
Agricultural runoff, sewage, erosion(phosphate rocks can be broken down into smaller particles) and industrial waste add high levels of phosphates and nitrates to aquatic systems.
53
What are the ecological effects of eutrophication?
Algal blooms, reduced oxygen levels, fish kills, increased water turbidity, and altered species composition.
54
What is the water (hydrologic) cycle?
The continuous movement of water on, above, and below the Earth's surface through evaporation, condensation, precipitation, and runoff.
55
Describe evaporation
The process in which water transforms from a liquid to a gaseous state, driven by the sun’s heat.
56
What happens during condensation?
Water vapor cools and condenses into tiny droplets, forming clouds or fog.
57
Define precipitation
The process by which condensed water falls from the atmosphere as rain, snow, sleet, or hail.
58
What is runoff?
The movement of water over the Earth's surface that eventually enters streams, rivers, or lakes.
59
Explain infiltration
The process by which water soaks into the ground, replenishing aquifers.
An aquifer is an underground layer of water-bearing material, consisting of permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt)
60
What is transpiration?
The release of water vapor from plants after absorbing it through their roots.
61
What is a food chain?
A linear sequence in which each organism feeds on the one before it, starting with producers.
62
What is a food web?
A complex network of interconnected food chains in an ecosystem.
63
Define trophic levels
The hierarchical levels in an ecosystem, beginning with producers and moving to various levels of consumers.
64
What is the “10% rule” in energy transfer?
Only about 10% of the energy from one trophic level is transferred to the next; the rest is lost as heat or used in metabolism.
65
What are ecological pyramids?
Graphical representations that show the distribution of energy, biomass, or numbers of organisms across trophic levels.
66
How does biomagnification occur?
Pollutants accumulate and increase in concentration as they move up the food chain.
67
What is bioaccumulation?
The buildup of substances, such as toxins, in an organism over time.
68
Define primary productivity
The rate at which producers convert solar energy into chemical energy through photosynthesis.
69
What is gross primary productivity (GPP)?
The total rate of energy capture and biomass production by autotrophs.
70
Define net primary productivity (NPP)
The rate of biomass production after subtracting the energy used in respiration (NPP = GPP – respiration).
71
What does a pyramid of energy represent?
A graphical depiction of the energy available at each trophic level, always upright due to energy loss between levels.
72
Why is population sampling important in ecology?
It helps estimate the types, abundance, and distribution of species within a habitat.
73
What is random sampling?
A method where samples are taken at random locations to avoid bias and obtain a representative sample.
74
Describe systematic sampling
A method that involves taking samples at fixed intervals or along a transect to capture spatial patterns.
75
What is stratified sampling?
Dividing a study area into distinct sections (strata) and sampling each separately to account for variability.
76
What is a transect?
A straight line along which samples are taken to study changes in species composition over a gradient.
77
How does a line transect differ from a belt transect?
A line transect records species along a line, whereas a belt transect covers a specified width along the line to assess abundance.
78
What is quadrat sampling?
A method using a frame of known area (a quadrat) to sample a small, representative area for estimating species density, frequency, or cover.
79
How is percentage cover determined in quadrat sampling?
By estimating the proportion of the quadrat’s area that is occupied by a species.
80
What is the mark-release-recapture method?
A technique for estimating population size by marking individuals, releasing them, and later recapturing a sample to count marked versus unmarked individuals.
81
What assumptions are made in mark-release-recapture?
Assumptions include: marked individuals mix evenly with unmarked ones, marks are not lost, marking does not affect behavior, capture probabilities are equal, and the population is closed during sampling.
82
Provide an example calculation using mark-release-recapture
If 10 individuals are marked, and in a later sample of 20, 4 are marked, the estimated population is (10 × 20) ÷ 4 = 50.
83
What is ecological succession?
The gradual process of change in species composition in a community over time.
84
Differentiate between primary and secondary succession
Primary succession starts on barren surfaces (no soil), whereas secondary succession occurs in areas with existing soil following a disturbance.
85
What is a climax community?
A stable, self-sustaining community that results from the final stage of succession.
86
What factors can trigger ecological succession?
Catastrophic events, seasonal changes, and ongoing interactions among species.
87
How can human activities influence succession?
Through disturbances like deforestation, agriculture, and urbanization that reset or alter successional stages.
88
Who proposed the idea that a single limiting factor determines species distribution?
Justus von Liebig (1840).
89
What did Victor Shelford add to the concept of species tolerance?
He explained that each environmental factor has maximum and minimum tolerance limits that determine species survival.
90
What is the “edge effect” in ecotones?
The phenomenon where species diversity and population density are higher at the boundary between two ecological communities.
91
Give an example of resource partitioning among similar species
Cormorants and shags partition resources by differing in feeding strategies and breeding sites along coastal areas.
92
What role do decomposers play in the carbon cycle?
They break down dead organic matter, recycling carbon back into the ecosystem.
93
How does nitrification benefit plants?
By converting ammonia into nitrates, which are more easily absorbed by plant roots.
94
Why is phosphorus re-entry into the terrestrial environment a slow process?
Because most phosphorus is locked in sedimentary rocks and is released slowly through weathering and geological processes.
95
What effect does un-ionised ammonia (NH₃) have on aquatic life?
It is highly toxic to fish, especially at higher pH levels.
96
How do terrestrial and aquatic ecosystems differ in their biomass pyramids?
Terrestrial ecosystems typically have upright pyramids (more biomass in producers), while aquatic ecosystems may have inverted biomass pyramids due to rapid turnover of primary producers.
97
What are the three types of ecological pyramids?
Pyramid of numbers, pyramid of biomass, and pyramid of energy.
98
Why is measuring abiotic factors at the microhabitat level important?
It helps link the distribution and abundance of organisms to specific environmental conditions.
99
What is an advantage of random sampling?
It minimizes observer bias and provides a representative sample in uniform habitats.
100
What is the formula used in mark-release-recapture studies?
N = (Number marked in first sample × Total caught in second sample) ÷ Number of marked recaptured.
101
In mark-release-recapture, if 10 individuals are marked and 20 are recaptured with 4 marked, what is the estimated population size?
50, since (10 × 20) ÷ 4 = 50.
102
What are pioneer species?
The first species to colonize barren or disturbed environments during primary succession.
103
How does secondary succession differ from primary succession?
Secondary succession occurs in areas where soil is present following a disturbance, whereas primary succession starts on new, lifeless surfaces.
104
What defines a climax community?
A mature, stable community that has reached equilibrium after successive stages of succession.
105
What are carbon sinks?
Reservoirs (like forests, oceans, and soils) that absorb more carbon than they release, helping regulate atmospheric CO₂.
106
Why are carbon sinks crucial for the carbon cycle?
They maintain a balance in atmospheric carbon dioxide levels, mitigating climate change.
107
How is net primary productivity (NPP) calculated?
NPP = Gross Primary Productivity (GPP) minus the energy used in respiration.
108
Why is NPP an important measure in ecosystems?
It represents the amount of energy stored as biomass that is available to consumers.
109
What is secondary productivity?
The rate at which consumers convert food energy into biomass.
110
What is a quadrat in ecological studies?
A frame of known area used to sample and estimate the abundance or cover of species.
111
What are frame quadrats and point quadrats?
Frame quadrats isolate a fixed area for measurement; point quadrats record presence/absence at specific points.
112
What does “percentage cover” measure?
The proportion of a quadrat’s area occupied by a species.
113
What does “percentage frequency” measure?
The proportion of sampled quadrats in which a species appears.
114
What concept is illustrated by a figure showing tolerance limits?
The range over which an organism can survive, with zones of optimal conditions and intolerance beyond certain limits.
115
What does a figure depicting predator–prey interactions show?
How fluctuations in prey populations affect predator numbers and vice versa.
116
Summarize the competitive exclusion principle
Two species competing for the same limited resource cannot coexist indefinitely; one will outcompete the other.
117
Why are ecotones significant for conservation?
They facilitate species and nutrient exchange between communities and often harbor higher biodiversity.
118
How do human activities affect the carbon cycle?
By burning fossil fuels and deforestation, humans release excess CO₂, enhancing the greenhouse effect.
119
In what ways do fertilizers impact the nitrogen and phosphorus cycles?
They add high levels of nutrients to ecosystems, potentially leading to nutrient imbalances and eutrophication.
120
What are some consequences of eutrophication?
Algal blooms, oxygen depletion, fish kills, increased turbidity, and shifts in species composition.
121
Why are decomposers essential in ecosystems?
They break down dead organic matter, recycling nutrients and completing energy flow cycles.
122
Why is it more energy efficient for humans to eat plants directly rather than animals?
Because energy is lost at each trophic level; consuming plants retains more of the original solar energy captured in photosynthesis.
123
What does the “10% rule” signify in energy transfer?
Only about 10% of the energy at one trophic level is passed on to the next.
124
What is population density?
The number of individuals per unit area or volume within a habitat.
125
How does frequency differ from density in quadrat sampling?
Frequency measures the number of quadrats in which a species appears; density measures the number of individuals per area.
126
What challenges arise when sampling mobile organisms?
Their movement can make them less visible or cause uneven capture, necessitating methods like mark-release-recapture.
127
How can unbiased sampling be ensured?
By using random or systematic sampling methods and accounting for spatial variability.
128
What instruments might be used to measure dissolved oxygen (DO) in water?
DO meters or the Winkler titration method.
129
What does water conductivity measure?
The water’s ability to conduct electrical current, which relates to the concentration of dissolved ions.
130
Why are environmental indicators important?
Certain species’ presence or absence can signal the health or quality of an ecosystem.
131
How do vertical stratification and horizontal zonation differ?
The layering of organisms at different heights within an ecosystem vs the spatial distribution of species along environmental gradients on the ground.
132
What factors contribute to vertical stratification in a forest?
Differences in light availability, species height, and canopy structure.
133
What is the advantage of systematic sampling?
It provides evenly distributed samples across a study area to detect spatial gradients.
134
What is the advantage of stratified sampling?
It ensures that different habitat areas (strata) are adequately represented.
135
What triggers primary succession?
The formation of new, barren surfaces (e.g., after a volcanic eruption or glacier retreat).
136
What typically triggers secondary succession?
Disturbances such as fires, floods, or human activities that disrupt but do not destroy soil.
137
What makes an ecosystem self-sustaining?
A balanced interaction of biotic and abiotic factors that allows it to persist and recover from disturbances.
138
What is a pyramid of numbers?
A graphical representation of the number of individuals at each trophic level.
139
What is a pyramid of biomass?
A representation showing the total biomass of organisms at each trophic level.
140
What is a pyramid of energy?
A diagram showing the amount of energy available at each trophic level
141
How does water temperature affect aquatic organisms?
It influences metabolic rates and enzyme activity; most organisms have a specific temperature range for optimal function.
142
Why does water temperature generally decrease with depth?
Because less sunlight penetrates deeper water, reducing the energy available for heating.
143
Can two species have identical ecological niches?
No; even if they share a habitat, subtle differences in resource use and behavior allow them to coexist.
144
What is resource partitioning and why is it important?
It is the division of resources among species to reduce direct competition, promoting co-existence
145
What is measured by population density?
The number of individuals per unit area or volume in a habitat.
146
How does frequency in quadrat sampling differ from density?
Frequency counts the proportion of quadrats where a species occurs, while density counts individuals per unit area.
147
What does bioaccumulation refer to?
The buildup of substances, like toxins, in an organism over time.
148
What is biomagnification?
The increasing concentration of pollutants in organisms at successively higher trophic levels.
149
What is the “edge effect” in ecotones?
Enhanced species diversity and density at the boundary between two ecological communities.
150
How is chlorophyll used in estimating primary productivity?
Chlorophyll measurements indicate the biomass of photosynthetic organisms and thus the rate of energy capture.
151
What is a line transect used for?
Recording species presence along a straight line to detect changes along an environmental gradient.
152
How does a belt transect differ from a line transect?
A belt transect covers a specified width along a line, allowing estimation of species abundance as well as presence.
153
What is carrying capacity?
The maximum number of individuals that an environment can sustainably support.
154
How does intraspecific competition affect carrying capacity?
It limits individual growth and reproduction as resources become scarce
155
How do decomposers affect soil fertility?
By breaking down dead organic matter, they release nutrients back into the soil.
156
What gases are typically released during decomposition?
Carbon dioxide and, under anaerobic conditions, methane.
157
What is the typical effect of a predator on a prey population?
Predators reduce the prey population, helping regulate its size i.e. population control.
158
How does an increase in prey affect predator numbers?
It generally leads to an increase in the predator population due to more available food.
159
What happens when the predator population grows too high?
Overpredation can cause a decline in prey numbers, which may later reduce the predator population. (an example of population dynamics)
160
Provide an example of intraspecific competition
During the breeding season (rut), male deer (bucks) will often fight, engage in elaborate displays, or use physical dominance to secure access to females for mating.
Plants Competing for Sunlight: In a dense forest, trees of the same species might compete for sunlight, affecting their growth and reproductive ability.
Robins Competing for Territory: Robins will defend a specific territory and will not allow other robins in that area, leading to conflict and even fights.
Clownfish Competing for breeding sites: Clownfish, like many species, will compete with conspecifics for limited resources like breeding sites.
161
Provide an example of interspecific competition
Woodpeckers and squirrels frequently compete for nesting sights in the same holes in trees, whereas African savanna lions and cheetahs struggle for the same antelope and gazelle food.
Sharks, dolphins, and seabirds in an ocean ecosystem might all eat the same type of fish, resulting in competition for that food source.
Goats and native deer on an island competing for the same plant resources can lead to the decline of one species.
An example of interspecific competition is two different species of trees in a forest competing for sunlight, where the taller trees absorb more sunlight, limiting the resources available to the shorter trees.
162
How does biodiversity contribute to ecosystem services?
Greater diversity enhances resilience and provides multiple functions like pollination, nutrient cycling, and climate regulation.
163
How are fossil fuels related to the carbon cycle?
They are formed from ancient organic matter; burning them releases stored carbon as CO₂.
164
What is one environmental consequence of burning fossil fuels?
Increased atmospheric CO₂ levels, contributes to global warming
165
Write the basic equation for photosynthesis
6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.
166
Why is photosynthesis critical in the carbon cycle?
It removes CO₂ from the atmosphere and converts it into organic matter for the food chain.
167
Write the basic equation for aerobic respiration
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy.
168
What role does respiration play in the carbon cycle?
It releases CO₂ back into the atmosphere as organisms break down glucose for energy.
169
How does lightning contribute to nitrogen fixation?
It breaks the triple bond of N₂, allowing nitrogen to combine with oxygen and form nitrogen oxides that dissolve in rainwater.
170
What is one effect of agricultural runoff on aquatic systems?
It can cause eutrophication due to excess nutrients.
171
How do fertilizers alter natural nutrient cycles?
They add high levels of nitrogen and phosphorus, potentially disrupting ecosystem balances.
172
Why is CO₂ considered a greenhouse gas?
It traps heat in the atmosphere by absorbing infrared radiation
173
What happens when greenhouse gas concentrations increase?
They enhance global warming and lead to climate change.
174
What does the base of an energy pyramid represent?
The primary producers that capture solar energy through photosynthesis.
175
How does decomposition affect the carbon cycle?
It releases carbon from dead organic matter back into the atmosphere as CO₂ or methane.
176
How does decomposition enhance soil fertility?
By recycling nutrients from dead material into forms that plants can reuse.
177
178
What influences the biotic environment?
Factors such as tolerance ranges, limiting factors, and ecological niches
## Footnote
These factors determine how organisms interact within their ecosystem.
