Energy Flow In Ecosystems
What is the primary energy source for producers?
Solar energy from the sun
What is a biogeochemical cycle?
The movement of an element between living and nonliving forms and locations in the biosphere. (Water, Phosphorous, Carbon Cycles, etc)
What is dissolved oxygen (DO)?
The amount of oxygen available in water for aquatic organisms.
What is the tragedy of the commons?
When individuals overuse a shared resource, leading to its depletion.
What is resource partitioning?
When species divide resources to reduce competition.
What is photosynthesis?
It’s the process where plants convert carbon dioxide and sunlight into glucose (sugar) and oxygen.
What is the major reservoir in the hydrologic cycle?
The ocean
What is genetic diversity?
The variety of inherited traits within a species.
Why did finches on the Galápagos Islands evolve to be specialists?
Limited food sources forced them to adapt to specific diets.
What are pioneer species?
First species to colonize new or disturbed environments (e.g., lichens, mosses).
What are regulating services?
Natural processes that help regulate the environment (e.g., flood control, climate regulation).
Which has more offspring, r-selected or K-selected species
r-selected species.
What is primary productivity?
The rate at which solar energy is converted into organic compounds via photosynthesis.
What step moves nitrogen from the atmosphere into the soil?
Nitrogen fixation
What is the main source of DO in the ocean?
Phytoplankton through photosynthesis
What does “impervious” mean, and how does it relate to runoff?
It means fluid cannot pass through; it increases runoff.
Why is competition considered a negative interaction for both species involved?
Because both species expend energy and resources fighting for the same limited resource, which reduces their chances of survival and reproduction (– / – interaction).
What is the equation for net primary productivity (NPP)?
What is infiltration, and why is it important?
Infiltration is the process where water soaks into the ground; it replenishes groundwater and supports vegetation growth.
What can happen to populations with low genetic diversity?
They are more susceptible to disease and unpredictable events.
Why are small island populations more prone to extinction?
They are more vulnerable to unpredictable events and have limited genetic variation.
What is primary succession?
Succession starting from bare rock or lifeless area with no soil.
Name one example of a provisioning service.
Food, raw materials, fresh water, or medicinal resources.
Which type provides more parental care: r-selected or K-selected?
K-selected species.
In an ecosystem where producers create 65,000 kcal, how much energy reaches tertiary consumers?
65,000 → 6,500 (primary) → 650 (secondary) → 65 kcal (tertiary; 10% rule at each level)
What are the major reservoirs for the nitrogen and carbon cycles?
Nitrogen: Atmosphere
Carbon: Limestone, sedimentary rocks, old forests, fossil fuels
Where in the ocean are phytoplankton most abundant, and why?
In the upper layers of the ocean where sunlight is available for photosynthesis.
List 3 human activities that increase carbon in the atmosphere.
Burning fossil fuels
Deforestation
Waste/trash incineration
Explain how predator-prey relationships help maintain ecosystem stability.
Predators control prey populations, preventing overgrazing or resource depletion, which helps maintain balance in the ecosystem and supports biodiversity.
What happens during cellular respiration?
Glucose is broken down to release energy, producing carbon dioxide and water as byproducts.
How does urban development affect the water cycle?
Urban areas have many impervious surfaces (like concrete), which reduce infiltration and increase runoff and flooding.
What is carrying capacity?
The number of organisms a region can support without environmental degradation.
What type of island has the highest species richness?
Large islands close to the mainland.
What is secondary succession?
Succession that occurs in areas where soil and nutrients remain after disturbance.
Name one example of a cultural service.
Recreation or ecotourism.
Fill in the survivorship curve types: (K/r-selected) (Type I, II, III)
Wolves
Rabbits
Mosquitoes
Wolves: K-selected, Type I
Rabbits: r-selected, Type III
Mosquitoes: r-selected, Type III
Why do trophic pyramids rarely extend beyond tertiary consumers?
Because only ~10% of energy is passed on at each level, too little energy remains to support higher levels.
How is nitrogen returned to its largest reservoir?
Through denitrification, where bacteria convert nitrogen compounds into atmospheric nitrogen.
Does the open ocean have high or low net primary productivity, and why?
Low, due to nutrient limitations, but the vast area supports many producers.
List 2 long-term CARBON sinks other than fossil fuels.
Old-growth forests
Limestone/sedimentary rocks
What is the function of bacteria in the nitrogen cycle?
They fix nitrogen, nitrify ammonia, and denitrify compounds back to atmospheric N₂.
How do photosynthesis and respiration form a cycle in the carbon cycle?
Plants take in CO₂ during photosynthesis to make glucose; organisms release CO₂ back into the atmosphere through respiration.
Describe the role of transpiration in the water cycle.
Plants release water vapor through their leaves, contributing to the movement of water back into the atmosphere.
Why does a population experience dieback after an overshoot?
Resource depletion leads to famine, disease, or conflict, causing population decline.
Classify the following species as a generalist or a specialist:
Panda
Raccoon
Salamander
Deer
Panda: Specialist
Raccoon: Generalist
Salamander: Specialist
Deer: Generalist
Describe the difference between early and late stages of succession.
Early: mosses, lichens, grasses
Late: shrubs, trees
Carbon storage (Regulating, Provisioning, Cultural, etc)
Regulating
Describe characteristics of r-selected species.
Small, many offspring, little to no parental care, short life span.
A pine forest has an NPP of 25,000 kcal/m²/yr and plant respiration is 200,000 kcal/m²/yr. What is the GPP?
GPP = NPP + R = 25,000 + 200,000 = 225,000 kcal/m²/yr
How does the phosphorus cycle differ from the nitrogen cycle?
The phosphorus cycle does not involve a gaseous phase, while nitrogen does.
Where is most of Earth's freshwater stored?
In ice caps and glaciers
How does infiltration promote vegetation growth?
It increases soil moisture availability, supporting plant growth.
List the full nitrogen cycle in 5 steps.
Nitogen Fixation → ammonia
Nitrification → nitrates
Assimilation → plants use it, absorb nutrients
Decomposition → nitrogen returns
Denitrification → atmospheric nitrogen
How does deforestation affect the balance between photosynthesis and respiration in the carbon cycle?
Deforestation reduces the number of trees available to absorb CO₂ via photosynthesis, while decaying trees release more CO₂, increasing atmospheric carbon levels.
How can climate change affect the global water cycle?
Climate change can alter precipitation patterns, increase evaporation rates, melt ice caps (reducing freshwater storage), and intensify extreme weather events like droughts and floods, disrupting the balance of the water cycle.
Why is high genetic diversity important for species survival in a changing environment?
It increases the chances that some individuals will have traits allowing them to adapt to changes, such as disease, climate shifts, or habitat loss, which helps the species survive over time.
Why are specialists more vulnerable to environmental changes than generalists?
Because they rely on a narrow range of resources or conditions and cannot easily adapt.
Name 2 natural and 1 human-caused event that can trigger succession.
Natural (primary): volcanic eruption, glacier retreat
Human (secondary): clearcutting or human-caused forest fire
Ecotoursim (Regulating, Provisioning, Cultural, etc)
Cultural
What type of survivorship curve do K-selected species follow?
Type I, because most individuals live long lives with few dying young due to high parental care.