lecture 4: Ecosystems, Services and Threats – Lecture 4 Review

What does ecology study?

The connections and interactions among living organisms and between organisms and their environment.

From which Greek word is “ecology” derived and what does it mean?

It comes from the Greek word “oikos,” meaning house or place to live.

List the typical hierarchy of biological organization from smallest to largest.

Organism → Population → Community → Ecosystem → Biosphere.

Which group of organisms ‘rules the world’ according to the lecture?

Microorganisms (microbes).

Give two reasons why microbes are essential for life on Earth.

They help digest food and cleanse water (they also act as natural pesticides and drive nutrient cycles).

Define a biological population.

A group of individuals of the same species living in the same habitat at the same time.

Why is genetic diversity within a population important?

It provides the raw material for natural selection and helps populations adapt to changing conditions.

What is an ecological community?

A collection of interacting populations living in the same area.

How does an ecosystem differ from a community?

An ecosystem includes the community plus all non-living (abiotic) components such as air, water, and minerals.

Name three major parts of Earth’s life-support system highlighted in the lecture.

Atmosphere, Geosphere, and Hydrosphere/Biosphere (life layer).

Which two atmospheric layers were specifically mentioned?

Troposphere and Stratosphere.

List four components of the geosphere identified in the notes.

Crust, Lithosphere, Upper Mantle, Asthenosphere (also Lower Mantle and Core).

State the three factors that sustain life on Earth.

One-way flow of high-quality energy, cycling of essential matter, and gravity.

What term is used for organisms that make their own food from sunlight?

Producers (autotrophs).

Define decomposers and give two examples.

Organisms that break down dead material and recycle nutrients; examples: bacteria and fungi.

What rule of thumb describes the drop in usable energy at each trophic level?

The 10 percent rule—only about 10 % of energy is transferred to the next level.

Why are food webs considered better models than simple food chains?

Because real ecosystems have many interconnected feeding relationships rather than a single linear path.

State the Limiting Factor Principle.

Too much or too little of any single abiotic factor can limit or prevent the growth of a population.

Give three abiotic factors mentioned that can limit aquatic populations.

Precipitation, dissolved oxygen (DO), and salinity.

List the five dimensions of biodiversity discussed.

Genetic, Species, Ecological, Functional, and Structural diversity.

Differentiate between a biome and an aquatic life zone.

A biome is a terrestrial region with a specific climate and life forms, while an aquatic life zone refers to freshwater or marine regions characterized by their organisms and abiotic conditions.

What does NPP stand for and why is it important?

Net Primary Productivity; it sets the energy budget that supports all consumers in an ecosystem.

Roughly what percentage of Earth’s total NPP do humans use or appropriate?

About 27 percent of global NPP (10–55 % of terrestrial NPP).

Give two critical ecological functions of soil.

Provides nutrients for plant growth and acts as Earth’s primary filtration system for water.

Why is soil considered a renewable resource only at a slow rate?

Because soil formation takes hundreds to thousands of years compared to the rate of erosion and degradation.

Name three physical properties used to classify soil types.

Texture, Porosity, and Permeability.

Identify the five major biogeochemical cycles discussed.

Water (Hydrologic), Carbon, Nitrogen, Phosphorus, and Sulfur cycles.

Cite one human action that increases surface runoff in the water cycle.

Covering land with crops, buildings, or pavement (deforestation and filling wetlands also increase runoff).

What major human activities add excess CO₂ to the atmosphere in the carbon cycle?

Burning fossil fuels and deforestation.

Which biogeochemical cycle converts atmospheric nitrogen into forms usable by plants?

The Nitrogen cycle.

What is GIS and why is it important to ecology?

Geographic Information Systems; they analyze spatial ecological data using remote sensing, field studies, and satellite information.

List any three data sources that feed into GIS analyses mentioned in the lecture.

Remote sensing data, satellite data, and field studies (plus geographic coordinates).

Outline the first two steps in systems analysis described in the notes.

Systems Measurement (define objectives, inventory variables, obtain baseline data) followed by Data Analysis (statistical analysis, identify significant interactions).

What is the ultimate purpose of system optimization in ecological modeling?

To evaluate and choose the best strategies for achieving defined ecological or management objectives.

Summarize the lecture’s main conclusion about ecological systems.

Ecology studies interactions among life and environment; nutrients cycle, energy flows, and organisms are limited by environmental conditions and trophic level.