BIOL 314 Chapter 20-23 Flashcards

Questions and Answers

Define gross primary production (GPP) and net primary production (NPP).

Gross primary production is the amount of energy that autotrophs capture by photosynthesis and chemosynthesis per unit of time. Net primary production is the amount of energy per unit of time that producers capture by photosynthesis and chemosynthesis minus the amount they use in cellular respiration.

How does NPP vary with latitude?

Terrestrial NPP is highest in the tropics and declines in the north and south.

What is 'secondary production' and how is it related to heterotroph physiology?

Secondary production is energy derived from the consumption of organic compounds produced by other organisms. Heterotrophs obtain their energy in this manner.

Define allochthonous and autochthonous inputs to ecosystems, and give an example of each.

Allochthonous inputs are external energy inputs, such as plant leaves and dissolved organic matter. Autochthonous inputs are energy produced by autotrophs within the system, such as green plants and algae. Signup and view all the answers

What is a trophic pyramid?

A trophic pyramid is a conceptual representation of trophic relationships in an ecosystem that shows the amount of energy or biomass at each trophic level. Signup and view all the answers

What is 'trophic efficiency'?

Trophic efficiency is defined as the amount of energy at one trophic level divided by the amount of energy at the trophic level immediately below it. Signup and view all the answers

How can biomass pyramids be inverted in aquatic ecosystems?

In aquatic ecosystems, high consumption rates and short life spans of phytoplankton can lead to a biomass pyramid that is inverted relative to the energy pyramid. Signup and view all the answers

What is the difference between 'bottom-up' and 'top-down' control of trophic cascades?

Bottom-up control is determined by energy input via NPP, while top-down control is governed by consumption rates at higher trophic levels. Signup and view all the answers

Describe three factors that might affect the number of trophic levels in an ecosystem.

<ol> <li>The amount of energy entering through primary production, 2) Frequency of disturbances or agents of change, and 3) The physical size of the ecosystem.</li> </ol> Signup and view all the answers

What is meant by 'net interaction strength'?

Net interaction strength measures the effect of one species' population on the size of another species' population, including both direct and indirect effects. Signup and view all the answers

How is community or ecosystem stability affected by food web complexity?

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Define nitrification and denitrification.

Nitrification is the process where nitrifying bacteria convert ammonia and ammonium into nitrate under aerobic conditions. Denitrification is where certain bacteria convert nitrate into nitrogen gas and nitrous oxide under hypoxic conditions. Signup and view all the answers

What is a nutrient cycle?

A nutrient cycle is the movement and exchange of organic and inorganic matter back into the production of living matter. Signup and view all the answers

Why do different nutrients cycle at different rates?

Different nutrients cycle at different rates depending on the element in question and the ecosystem, with limiting nutrients cycling more rapidly. Signup and view all the answers

What is meant by a 'nutrient spiral' in an aquatic ecosystem?

A nutrient spiral refers to the cycling of nutrients as water moves downstream, leading to repeated spirals of nutrient uptake and release. Signup and view all the answers

What does it mean to say that conservation biology is a value-based discipline?

It means that science is influenced by human values and takes place within a larger social context. Signup and view all the answers

What is meant by the 'background' extinction rate?

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What is 'taxonomic homogenization'?

Taxonomic homogenization is the worldwide reduction of biodiversity due to the spread of non-native and native generalists alongside declining native specialists. Signup and view all the answers

Study Notes

Gross and Net Primary Production

Gross primary production (GPP) refers to total energy captured by autotrophs through photosynthesis and chemosynthesis over time.
Net primary production (NPP) is the energy left after autotrophs use some for cellular respiration, measuring the energy available for consumers.

NPP Variability

NPP is highest in tropical regions and decreases towards the poles.
Yearly variations in NPP can indicate ecosystem health, indicating potential impacts from environmental stresses like drought or acid rain.
NPP is connected to the global carbon cycle.

Secondary Production and Heterotrophs

Secondary production is the energy obtained from consuming organic compounds produced by other organisms (heterotrophs).
Heterotrophs are categorized based on their food sources.

Ecosystem Input Types

Allochthonous inputs are external energy sources, such as plant material in aquatic ecosystems.
Autochthonous inputs are energy produced within the ecosystem by autotrophs, like green plants and algae.
Example: Bear Brook relies heavily on allochthonous inputs, while Mirror Lake capitalizes on autochthonous energy.

Trophic Pyramid and Efficiency

A trophic pyramid illustrates energy or biomass levels across trophic layers, reflecting energy flow in ecosystems.
Trophic efficiency is energy at one level divided by the energy at the level below, accounting for consumption and assimilation rates.

Inverted Biomass Pyramids

In many aquatic ecosystems, primary producers (phytoplankton) may have shorter life spans, resulting in inverted biomass pyramids where heterotrophs outweigh autotrophs by biomass, though autotrophs produce more energy.

Trophic Cascade Controls

Bottom-up control is influenced by NPP and resource availability, dictating energy flow upward through trophic levels.
Top-down control focuses on consumption by predators affecting lower trophic levels' biomass and composition, leading to simultaneous operation of both control types in ecosystems.

Trophic Levels Influences

Trophic levels depend on energy input through primary production.
Disturbances, including diseases, influence population sustainability of higher predators.
Ecosystem size affects biodiversity; larger areas may support more trophic levels due to larger populations.

Net Interaction Strength

Describes the impact of one species on another’s population, capturing direct and indirect effects within food webs.
Understanding interaction strengths aids in research and conservation efforts by clarifying key ecological links.

Food Web Complexity and Stability

Complexity in food webs can enhance community stability, providing resilience against disturbances through interconnected species interactions.

Nutrification Processes

Nitrification converts ammonia and ammonium to nitrate via nitrifying bacteria in aerobic conditions.
Denitrification transforms nitrate back into nitrogen gas, facilitating nitrogen cycle completion under hypoxic conditions.

Nutrient Cycle Definition

Nutrient cycles represent the exchange and movement of organic and inorganic matter, regulated by food webs and influenced by climate conditions.
Nutrients vital for primary productivity cycle faster than those that are not limiting.

Nutrient Spiral in Aquatic Ecosystems

Describes the upstream-downstream cycling of nutrients, characterized by repeated nutrient absorption and release along water flow.

Conservation Biology's Value Basis

Conservation biology reflects human values and operates within societal contexts, requiring transparency about the values inherent in conservation practices.

Background Extinction Rate

Refers to the natural rate of extinction over geological time, with current extinction rates greatly elevated compared to historical background levels.

Taxonomic Homogenization

Describes the global decline in biodiversity from the spread of non-native species, leading to reduced native specialists and increased presence of generalists.

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Description

Explore key concepts in chapters 20 to 23 of BIOL 314, focusing on gross primary production (GPP) and net primary production (NPP). This quiz will help reinforce your understanding of energy capture in ecosystems and how various factors like latitude influence these processes.