Chapter 3. Ecology!

Honors Biology

3.1 What is Ecology?Interactions and Interdependence

Ecology – the scientific study of interactions among organisms.

Biosphere – contains the combined portions of the planet in which all life exists, including land, water, and air or atmosphere (8 km above the Earth’s surface and 11 km below the surface of the ocean.

3.1 What is Ecology?Levels of Organization

Species – a group of organisms so similar to one another that they can breed and produce fertile offspring.

Populations – groups of individuals that belong to the same species and live in the same area.

Communities – assemblages of different populations that live together in defined area.

Ecosystem – a collection of all the organisms that live in a particular place, together with their nonliving, or physical, environment.

Biomes – a group of ecosystems that have the same climate and similar dominant communities.

The highest level is the biosphere. Let’s turn to page 100…

3.1 What is Ecology?Levels of Organization - Review

1.Can a group of rabbits and a group of field mice make up the same population in an ecosystem?

2. Could a biome in Brazil near the equator be the same biome as a biome in Northern Canada? Explain. PG 64

3.1 What is Ecology?Ecological Methods

Ecologists use a wide range of tools and techniques to study the living world.

Observing The first step in asking an

ecological question. Experimenting

Used to test hypothesis Modeling

Mathematical formulas based on data collection, can be tested further.

3.1 What is Ecology?Ecological Methods

Ecological Methods

Chemical Testing

Sites

Computer/Calculators

Written Record

Magnifying Tools

Measuring Tools

Observation Experiment Model BuildingField site Experimental plots,

field sites, laboratoryMany sites for datacollecting

Tapes, compass,Global PositioningSystem, thermometer,sensors

Tapes, compass,Global PositioningSystem, thermometer,sensors

Aerial views, GlobalPositioning System,weather balloons

Binoculars, microscope,telescope

Binoculars, microscope,telescope

Satellite images

Notes, automated datastorage

Notes, automated datastorage

Automated data storage

Test kits Test kits Large database,multiple sensors

Mathematical analysisand graphics, statistics

Mathematical analysisand graphics, statistics

Mathematical analysisand graphics, statistics,simulations

Assessment

1. What are the six different major levels of organization from smallest to largest, that ecologist commonly study?

2. Is weather a biotic or abiotic factor?3. Describe the three basic methods of

ecological research. 4. Why is modeling used to describe

ecological phenomenon?

Assessment Answers

1. Individual, population, community, ecosystem, biome, biosphere

2. Abiotic3. Observation, Experimentation, Modeling 4. Phenomenon- a situation that is observed to

exist or happen whose cause or explanation is unclear- We use models to try to understand what is actually going on.

1. Ex. Migration of animals.

3.2 Energy FlowProducers

Sunlight is the main energy source for life on Earth.

Less than 1% of the sun’s energy is used by living organisms

Some types of organisms rely on the energy stored in inorganic chemical compounds

Only plants, some algae, and certain bacteria can capture energy from sunlight or chemicals and use that energy to produce food. They are called autotrophs.

Autotrophs are also referred to producers.

3.2 Energy FlowEnergy From the Sun

The best known autotrophs are ones that use photosynthesis.

Photosynthesis – autotrophs that use light energy to power chemical reactions that convert carbon dioxide and water into oxygen and energy rich carbohydrates such as sugars and starches.

Carbon dioxide + Water Carbohydrates + OxygenLight Energy

3.2 Energy FlowEnergy From the Sun

1. Which element does each letter in the formula stand for?

2. Why are the numbers needed in the equation?

Carbon dioxide + Water Carbohydrates + Oxygen

Light Energy

6CO2 + 6H20 C6H12O6 + 6O2

3.2 Energy FlowLife Without Light

Some autotrophs can produce food in the absence of light.

Chemosynthesis – when organisms use chemical energy

Example. Some Bacteria.

3.2 Energy FlowConsumers

Organisms that rely on other organisms for their energy and food supply are called heterotrophs.

Heterotrophs are called consumers.

There are many types of heterotrophs: Herbivores (eat only plants) Carnivores (eat animals) Omnivores (eat both plants and

animals) Detritivores (feed on plant and

animal remains and other dead matter)

Decomposers (break down organic matter. How can we categorize crabs?

3.2 Energy FlowFeeding Relationships

Energy flows through an ecosystem in one direction from the sun or inorganic compounds to autotrophs (producers) and to various heterotrophs (consumers)

3.2 Energy FlowFood Chains

Food chain – a series of steps in which organisms transfer energy by eating or being eaten.

Ex. Prairie: grass being eaten by an antelope being eaten by a coyote.

Ex. Marine: microscopic algae being eaten by zooplankton being eaten by a herring being eaten by a squid being eaten by a shark.

3.2 Energy FlowFood Webs

In most ecosystems, feeding relationships are more complex than a food chain.

Most producers complete their life cycles and die, then decompose.

Decomposers covert dead plant matter to detritus, which are eaten by detritivores.

When the feeding relationships among the various organisms form a network of complex interactions, it is described as a food web.

Ex. Salt-marsh community

3.2 Energy FlowTrophic Levels

Each step in a food chain or food web is called a trophic level.

1. Producers2. Consumers3. Consumers 4. Consumers Each consumer

depends on the trophic level below it.

3.2 Energy FlowEcological Pyramids

Ecological pyramid – a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or a food web.

Three types: energy pyramids, biomass pyramids, and pyramids of numbers.

3.2 Energy FlowEcological Pyramids

Energy PyramidShows the relative amount of energy available at each trophic level. Organisms use about 10 percent of this energy for life processes. The rest is lost as heat.

Biomass PyramidRepresents the amount ofliving organic matter at each trophic level. Typically, thegreatest biomass is at the base of the pyramid.

Pyramid of NumbersShows the relativenumber of individualorganisms at eachtrophic level.

3.2 Energy FlowEcological Pyramids – Make

Connections The amount of energy available in food is measured in calories. One

calorie is the amount of energy needed to raise the temperature of 1 gram of water 1oc. Scientists usually refer to the energy content of food in units of kilocalories. One kilocalorie equals 1000 calories. A kilocalorie is also expressed as a Calorie, with a capital C.

Suppose, that the base of this energy pyramid consists of plants that contain 450,000 Calories of food energy. If all the plants were eaten by mice and insects, how much food would be available to those first level consumers?

If all the mice and insects were eaten by snakes, how much food energy would be available to snakes?

If all the snakes were eaten by a hawk, how much food energy would be available to the hawk?

How much food energy would the hawk use for its body processes and lose of heat?

How much food would be stored in the hawk’s body?

3.2 EcologySection Assessment

1. Solar energy is harnessed by autotrophs that conduct photosynthesis. Chemical energy – the energy within the chemical bonds of inorganic molecules – is harnessed by autotrophs that conduct chemosynthesis.

2. Students should describe a one-way flow of energy from autotrophs (producers) to consumers – first herbivores, then carnivores and/or omnivores.

3. In general, about 10 percent.4. The autotroph is the producer, and it is eaten by the

herbivore. The herbivore is then eaten by the omnivore.

5. Students’ pyramids should show 100% of energy available at the first (producer) level, 10% at the second level, 1% at the third level, 0.1% at the fourth level, and 0.01% at the fifth level.

3.3 Cycles of MatterRecycling in the Biosphere

Energy is crucial to an ecosystem.

Organisms need more than energy, they need water, minerals, and other life sustaining compounds.

In most organisms, 95% of the body is made up of just four elements: oxygen, carbon, hydrogen, and nitrogen.

3.3 Cycles of MatterRecycling in the Biosphere

Matter is recycled within and between ecosystems.

Elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another through biogeochemical cycles.

Matter can cycle through the biosphere because biological systems do not use up matter, they transform it.

3.3 Cycles of MatterWater Cycle

All living things require water to survive.

Evaporation – the process by which water changes form liquid form to an atmospheric gas.

Transpiration – the process by which water enters the atmosphere by evaporating from the leaves of plants.

CondensationPrecipitation

Runoff

Seepage

RootUptake

TranspirationEvaporation

What are some forms of precipitation?

3.3 Cycles of MatterNutrient Cycles

“Every living organism needs nutrients to build tissues and carry out essential life functions. Like water, nutrients are passed between organisms and the environment through biogeochemical cycles.”

The food you eat provides energy and chemicals that keep YOU alive.

Nutrients – all the chemical substances that an organism needs to sustain life. (“building blocks”)

3.3 Cycles of MatterCarbon Cycle

Biological processes, such as photosynthesis, respiration, and decomposition, take up and release carbon and oxygen.

Geochemical processes, such as erosion and volcanic activity, release carbon dioxide to the atmosphere and oceans.

Mixed biogeochemical processes, such as the burial and decomposition of dead organisms and their conversion under pressure into coal and petroleum (fossil fuels), store carbon underground.

Human activities, such as mining cutting, and burning forest and fossil fuels, release carbon dioxide into the atmosphere.

CO2 inAtmosphere

CO2 in Ocean

3.3 Cycles of MatterThe Nitrogen Cycle

All organism need nitrogen to make amino acids.

N2 makes up 78% of Earth’s atmosphere.

Ammonia (NH3), nitrate ions (NO3-), and nitrite ions (NO2-) found in waste products and dead or decaying matter.

Only certain bacteria can use nitrogen directly

Nitrogen Fixation – convert nitrogen gas into ammonia, then to nitrite or nitrates

Denitrification – covert nitrates into nitrogen gas, releasing back into the atmosphere.

N2 in Atmosphere

NO3-

and NO2-

NH3

3.3 Cycles of MatterThe Phosphorus Cycle

Phosphorus is an important component of DNA and RNA.

Does not enter the atmosphere, remains on land in rock and soil and ocean sediments.

Plants absorb phosphate from the soil or from water and binds the phosphate into organic compounds.

Moves through the food web from producers to consumers

3.3 Cycles of MatterNutrient Limitation

Primary productivity - the rate at which organic matter is created by producers (affected by available nutrients).

When an ecosystem is limited by a single nutrient that is scarce or cycles slowly, this is called the limiting nutrient.

Fertilizers contain: nitrogen, phosphorus, and potassium.

Algal bloom – an immediate increase in the amount of algae and other producers.

3.3 Cycles of MatterSection Assessment

1. Unlike the one-way flow of energy, matter is recycled within and between ecosystems.

2. To build tissues and carry out life functions.3. A good response should describe the different forms

of nitrogen as well as explain bacterial nitrogen fixation and denitrification.

4. If a nutrient is in short supply, it will limit an organism’s growth.

5. If vast areas of forest were cleared, less carbon dioxide would be removed from the atmosphere by plants.

6. When an aquatic ecosystem receives a large input of a limiting nutrient, the result is often an algal bloom. Algal blooms can sometimes disrupt the equilibrium of an ecosystem by producing more algae than consumers can eat.