Ecology and Ecosystems Overview

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Questions and Answers

What is the best definition of ecology?

The relationships of organisms and their environment. (correct)

The study of physical laws governing organisms.

The study of organisms without considering their environment.

The analysis of the chemical composition of living organisms.

What term describes the factors that are not living but influence organisms?

Ecosystem factors

Abiotic factors (correct)

Biotic factors

Environmental factors

Which of the following best describes the function of an ecosystem?

Changes in biodiversity and abiotic components.

Productivity, nutrient changes, energy flow, and water flow. (correct)

Only the flow of water and nutrients.

The rate of increase in biodiversity.

What adaptation do mangrove trees have to survive in their salty environment?

They secrete salt onto their leaves. Signup and view all the answers

Which factor is known as a limiting factor in ecosystem productivity?

Phosphorus availability Signup and view all the answers

What distinguishes a fundamental niche from a realized niche?

The realized niche is observed in nature, while the fundamental niche is theoretical. Signup and view all the answers

What is a chronic stressor in an ecosystem?

A long-term environmental influence. Signup and view all the answers

What role do pneumatophores play in the survival of mangrove trees?

They allow the tree to take in oxygen during high tide. Signup and view all the answers

What are the effects of stressors on ecosystems?

Decrease in productivity and loss of diversity Signup and view all the answers

Which of the following is an example of a natural stressor?

Severe windstorm Signup and view all the answers

What does the first law of thermodynamics state?

Energy input must equal energy output Signup and view all the answers

What is true about net primary production (NPP)?

NPP equals GPP minus respiration by autotrophs Signup and view all the answers

Which of the following factors does not contribute to climatic stress?

Heavy metal toxicity Signup and view all the answers

Biomagnification is primarily a concern because it leads to:

High concentrations of toxins in top predators Signup and view all the answers

The primary source of energy in most ecosystems is:

Solar radiation Signup and view all the answers

Which statement accurately describes anthropogenic stressors?

They are a result of human activities Signup and view all the answers

Which of the following ecosystems is likely to have the highest net primary productivity?

Tropical rainforest Signup and view all the answers

What is a consequence of energy transformations according to the second law of thermodynamics?

They increase entropy in the universe Signup and view all the answers

What typically happens in an open population regarding population dynamics?

Population size is affected by births, deaths, and migration. Signup and view all the answers

Which statement accurately describes nitrogen fixation?

It is a critical process for providing usable nitrogen to plants. Signup and view all the answers

What is the main limitation of phosphorus in aquatic ecosystems?

Phosphorus can often limit growth due to its scarcity in lakes. Signup and view all the answers

What describes the process of biomagnification?

Chemicals accumulate in higher concentrations within top predators. Signup and view all the answers

In logistic growth, what does the carrying capacity (K) represent?

The maximum population limited by environmental resources. Signup and view all the answers

Which of the following is NOT a way nitrogen is fixed in the environment?

Through volcanic activity. Signup and view all the answers

What role do animals play in the phosphorus cycle?

Animals transport phosphorus as biovectors. Signup and view all the answers

What is a characteristic of exponential population growth?

Resources rapidly become limited, leading to competition. Signup and view all the answers

Study Notes

Ecology

Study of organism-environment relationships, a systematic and quantitative field.

Environmental Factors

Abiotic factors: Influence organisms (temperature, moisture, nutrients, radiation, wind, water currents, fire, toxins).
Biotic factors: Influence organisms through interactions like competition, herbivory, predation, parasitism, disease, mutualism.

Ecosystems

Fundamental unit in ecology.
Include abiotic and biotic components.
Range from large (biosphere) to small (pitcher plant).
Described by productivity, nutrient changes (e.g., nitrogen fixation), energy flow, and water flow.

Mangroves

Brackish water ecosystem of mangrove trees.
Adapted to intertidal zones (mixing of salt and fresh water).
Salt tolerance: Excrete salt through leaves, utilize pneumatophores (lung roots) for oxygen in high tides, filter water through roots absorbing nutrients and eliminating unwanted elements.
Seed dispersal: Carried by high tides.

Limiting Factors

Often, mineral nutrients limit ecosystem productivity.
Limiting factor: resource with lowest availability relative to need.
Phosphorus often limits lake productivity, excess can lead to eutrophication.
Growth depends on the scarcest resource.

Niche

All environmental factors restricting a species' distribution, growth, reproduction.
Physical space occupied by an organism or species.
Fundamental niche: Complete range of conditions for a species to survive without competition.
Realized niche: Observed resource use in nature, affected by environmental restrictions.

Stressors

Chronic stressors: Long-term influence (e.g., water nutrient levels).
Disturbance stressors: Powerful, short-lived events (e.g., storms, fire).
Natural stressors: Present for long time periods.
Anthropogenic stressors: Human-created.
Types: Climatic (temperature, radiation, wind, moisture), chemical (toxicity), wildfire, physical (volcanic eruption), biological (inter-organism interaction).
Effects: Decreased productivity, increased mortality, reproductive failure.
Species response: Sensitive species replaced by tolerant ones; loss of top predators and large-bodied species; reduced species diversity.

Ecological Energetics

Ecosystems are open systems needing continuous energy input.
Primary source: Solar radiation.
Amount & transmission: Varies with latitude.
Photosynthesis: Uses visible light, autotrophs fix energy.
Energy flow: Organisms use fixed solar energy for processes, release as heat.
This is how most ecosystems operate using solar energy utilized by autotrophs. Stored energy can be stored for extended periods (peat, fossil fuels).

Thermodynamics

First Law: Energy transformation, not creation or destruction. Input = stored + output.
Second Law: Natural processes only increase universe's entropy. Energy for order requires energy transformations are never fully efficient.
Life: Needs continual energy input, primarily solar.

Greenhouse Gases

Natural greenhouse gases (CO2, water, methane) absorb infrared radiation, re-radiating it.
Thermal blanket effect: Warms Earth's average temperature (from -18°C to +15°C).
Human activities (fossil fuel combustion, deforestation, agriculture) increase concentrations of these gases.

Ecological Productivity

Rate at which energy is fixed (autotrophs) and biomass accumulates.
Measured in dry weight per area (t/ha or tons/ha), per unit time (e.g. t/ha/year).
Gross Primary Production (GPP): Total solar energy fixed.
Respiration (R): Energy autotrophs use for metabolism.
Net Primary Production (NPP): GPP minus respiration (NPP = GPP - R).
Low NPP in open oceans (low nutrient availability); High NPP in reefs and estuaries.

Biomagnification

Humans introduce unnatural substances (organochlorides, DDT, mercury).
Bioaccumulation in food chains, dramatic effects on top predators, e.g., DDT affected hawks and eagles.

Cycles

Carbon cycle: Fixation through photosynthesis, release through decomposition and respiration. Storage in biomass, eventually fossil fuels.
Methane production: By bacteria, fossil fuel combustion, and autotrophs.
Nitrogen cycle: Often a growth limitation. Nitrogen fixation converts N2 (atmospheric nitrogen) to usable forms. Natural and industrial fixation. Rhizobium and Bradyrhizobium bacteria in root nodules.
Phosphorus cycle: Essential for cells and biomolecules. Limited in lakes, primarily in sediments. One-way transport from land to oceans, with biovectors (birds, fish).
Sulfur cycle: Important for proteins and other chemicals. Volcanic emissions, bacterial production, human impact through fossil fuel combustion and ore smelting.

Population Ecology

Study of population dynamics and environment interactions. Populations can increase or decrease in short term and long term.
Closed population: Nt+1 = Nt + (B-D).
Open population: Nt+1 = Nt + (Bt - Dt) + (It - Et).

Population Growth

Exponential growth: Resources eventually limit growth with increased competition.
Logistic growth: Carrying capacity (K) is the maximum sustainable population size in an environment where N (population size) = K in equilibrium. When N < K populations grow, and when N > K populations shrink down until N = K.

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Description

Explore the fundamental concepts of ecology, including the intricate relationships between organisms and their environment. This quiz covers various environmental factors, ecosystems, and specific habitats like mangroves, emphasizing both biotic and abiotic influences. Test your understanding of how these elements interact within the ecological framework.