Download 3-1 What is Ecology? • Cells Are the Basic Units of Life: • All living

3-1 What is Ecology?
• Cells Are the Basic Units of Life:
• All living things are composed of cells (Cell Theory)
• Eukaryotic (Nucleus) vs Prokaryotic (No Nucleus)
Ex. Human Cells
Ex. Bacteria
• Ecology – The study of how organisms interact with their living (biotic) and
non-living (abiotic) parts of their environments.
Biosphere
Parts of the earth's air, water, and
soil where life is found
Ecosystem
A community of different species
interacting with one another and with their
nonliving environment of matter and energy
Community
Populations of different species living in a
particular place, and potentially interacting
with each other
Population
A group of individuals of the same species
living in a particular place
Organism
Cell
Molecule
Atom
An individual living being
The fundamental structural and functional
unit of life
Chemical combination of two or more atoms
of the same or different elements
Smallest unit of a chemical element that
exhibits its chemical properties
Stepped Art
Fig. 3-3, p. 52
• 3-2 What Keeps Us and Other
Organisms Alive?
• The Earth’s Life-Support System Has
Four Major Components:
• Atmosphere (air)- a thin spherical
envelope of gases surrounding the
earth’s surface.
* Includes: troposphere,
stratosphere
• Hydrosphere (water) – all of the
water on or near the earth’s surface.
• Geosphere (rock, soil, sediment) earth’s intensely hot core, thick mantle
of rock, and a thin outer crust.
• Biosphere (living things) – the
parts of the atmosphere, hydrosphere,
and geosphere where life exists.
* The goal of Ecology is to understand
the interactions in this thin layer of air,
water, soil and organisms!
• Life Exists on Land and in Water
• Biomes – the terrestrial (land) portion of the biosphere; large regions with
distinct climates and certain species adapted to them.
• Aquatic Life Zones – freshwater (lakes or streams); 2% of surface of earth &
ocean or marine (coral reefs and coastal estuaries); 71 % of surface.
• Three Factors Sustain Life on Earth:
• One-Way Flow of High-Quality Energy –
•sun Æ through living things Æ into environ. (heat; low-quality) Æ
back to space as heat.
• Cycling of Matter or Nutrients - Nutrient Cycles, Biogeochemical Cycles
& Law of Conservation of Matter.
• Gravity – allows the planet onto its atmosphere & enables cycling of
chemicals.
• What Happens to Solar Energy Reaching the Earth?
• Natural Greenhouse Effect - 1% of the solar energy reaches Earth’s
surface.
* Most of it is reflected back up through lower atmosphere where it
reaches greenhouse gases (water vapor, CO2, methane, nitrous oxide &
ozone). This causes gases molecules to vibrate and release infrared
radiation that warms the lower atmosphere.
• 3-3 What Are the Major Components of an Ecosystem?
• Ecosystems Have Living and Nonliving Components:
• Abiotic = nonliving; water, soil, air, nutrients, etc…
• Biotic = living and once living biological components.
• Range of Tolerance - organisms tolerance to physical or chemical
environment. Example
• Several Abiotic Factors can Limit Population Growth:
• Limiting Factors - (Limiting Factor Principle) = too much or too little of
any abiotic factor can limit or prevent growth of a population, even if all other
factors are at or near the optimal range of tolerance.
•Ex. Lack of water in a desert limits plant growth.
• Producer & Consumers Living Parts of Ecosystems:
• Trophic Level = feeding level in an ecosystem.
• Producers (autotrophs) - make nutrients they need by photosynthesis
or chemosynthesis
• Consumers (heterotrophs) - obtain nutrients by feeding on other
organisms.
* Primary Consumers (herbivores)
* Secondary Consumers & Third/Higher level (carnivores &
omnivores)
* Decomposers (bacteria + fungi)
* Detritivores (mites, earthworms, vultures, anything feeding on
detritus)
• Energy processes: (Making ATP)
• aerobic respiration (cellular respiration) & anaerobic (fermentation)
- uses oxygen
- does not use oxygen
3-4 What Happens to Energy in an Ecosystem?
• Energy Flows through Ecosystems in Food Chains & Food Webs
* Arrows
represent flow of
Energy!
• Usable Energy Decreases with Each Link in a Food Chain or Web
• Ecological Efficiency – % of usable chemical energy transferred as
biomass from one trophic level to the next.
• Ranges from 2% to 40% depending on organism; avg = 10%
• Pyramid of Energy Flow
• Some Ecosystems Produce Plant Matter Faster than Others Do.
• Gross Primary Productivity (GPP) - rate at which an ecosystem’s
producers convert solar energy into chemical energy (biomass).
• Net Primary Productivity (NPP) = NPP = GPP – R
R = energy used in respiration
3-5 What Happens to Matter in an Ecosystem?
• Nutrient Cycles & Biogeochemical Cycles:
* Consists of: water, nitrogen, carbon, phosphorus & sulfur cycles
• Water Cycle (Hydrologic Cycle):
• Carbon Cycle:
• Nitrogen Cycle:
• Phosphorus Cycle:
• Sulfur Cycle:
3-6 How Do Scientists Study Ecosystems?
• Some Scientists Study Nature Directly
• Field Research - involves observing and
measuring the structure of natural
ecosystems and what happens to them.
• Some Scientists Study Ecosystems in the
Lab
• Lab research – set up, observe,
measurements of model ecosystems and
populations under lab conditions.
•Ex. Examining bacteria growth in
culture tubes.
• Some Scientists use Models to Simulate Ecosystems
• Ex. Computer models or simulations to calculate possible changes.
• We Need to Learn More about the Health of the World’s Ecosystems
• According to 2005 study by Millenium Ecosystem Assessment; “ Scientists
have less than half of the basic ecological data they need to evaluate the
status of ecosystems of the U.S.”
• Even fewer for that of the World!