Chapter 3What is Ecology?

• Prentice Hall

• P.60-85

Chapter 3 What is Ecology ? SOL 9

• The branch of biology that developed from natural history is called ecology.

• Ecology is the study of interactions that take place between organisms and their environment.

What is ecology?What is ecology?

The Biosphere

• The biosphere is the portion of Earth that supports living things.

• It extends from high in the atmosphere to the bottom of the oceans.

The nonliving environment: Abiotic factors

• The nonliving parts of an organism’s environment are the abiotic factors.

• Examples: air currents, temperature, moisture, light, and soil.

The living environment: Biotic factors

• A key consideration of ecology is that living organisms affect other living organisms

• All the living organisms that inhabit an environment are called biotic factors.

• All organisms depend on others directly or indirectly for food, shelter, reproduction or protection.

Levels of Organization

• Ecologists study individual organisms, interactions among organisms of the same species, interactions among organisms of different species, as well as the effects of abiotic factors on interacting species.

• Ecologists have organized the living world into levels– the Organism by itself (species), – Population- all members of one species in an area– Community- all populations in a given area– Ecosystem- community + the nonliving factors (ABIOTIC)– Biome –ecosystems with similar climate and similar

dominant communities– Biosphere – biotic + abiotic factors of the entire Earth

Levels of Organization

Ecological Methods

• Observing – use of one or more of the senses to gather information

• Experimenting –testing hypotheses either in the lab or in the field

• Modeling – involves constructing a representation of an object, a system or a process that helps show relationships among data = an explanation supported by data

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

Ecological research

• Ecologists obtain quantitative data by making measurements and carrying out controlled experiments in the field and in the laboratory.

Question 1 The study of interactions that take place

between organisms and their environment is __________.

D. biology

C. ecology

B. symbiosis

A. abiosis

The answer is C. Ecology is a branch of biology that developed from natural history.

Question 2 Which of the following is a biotic factor?

D. light

C. earthworm

B. soil

A. moisture

The answer is C. Biotic factors are all the living organisms that inhabit an environment.

Question 3A(n) __________ is a group of organisms, all of the same species, which interbreed and live in the same place at the same time.

D. habitat

C. ecosystem

B. population

A. biological community

The answer is B. Communities and ecosystems are comprised of more than one species. Habitat refers to the place an organism lives.

Question 4

Which type of organism consumes both plant and animal products?

D. omnivore

C. predator

B. carnivore

A. herbivore

The answer is D. Humans are omnivores and eat a variety of foods that include both plant and animal materials. The figure shows recommended food servings for good health.

Energy Flow

• All organisms need energy for life activities

• This energy comes from their food.

• Consumption of food is an energy transfer

• Food Chains

• Food Webs

The producers: Autotrophs

• The ultimate source of the energy for life is the sun.

• Plants use the sun’s energy to manufacture food in a process called photosynthesis.

Chemosynthesis – use chemical energy to produce food instead of light

Life Without Light

The producers: Autotrophs

• An organism that uses light energy or energy stored in chemical compounds to make energy-rich compounds is a producer, or autotroph

• Other organisms in the biosphere depend on autotrophs for nutrients and energy. These dependent organisms are called consumers or heterotrophs

The consumers: Heterotrophs

• An organism that cannot make its own food and feeds on other organisms is called a heterotroph

• A heterotroph that feeds only on plants is an herbivore.• Some heterotrophs eat other heterotrophs. Animals

such as lions that kill and eat only other animals are carnivores.

• Detritivores- eat dead plants and animals (detritus)– Ex: mites, earthworms, snails, crabs

• Some organisms, such as bacteria and fungi, are decomposers. Decomposers break down the complex compounds of dead and decaying plants and animals into simpler molecules that can be more easily absorbed.

Producers: organisms that make their own food

Herbivore: animal that eats plants (Primary Consumer)

Carnivore: animal that eats other animals(Secondary consumer, Tertiary consumer, Quaternary consumer etc)

Decomposer: an organism that feeds on dead organic material

Detritivore (Scavenger): consumer that feeds on remains of dead organisms

Flow of Matter and Energy in Ecosystems

• A food chain is a simple model that scientists use to show how matter and energy move through an ecosystem.

• In a food chain, nutrients and energy move from autotrophs to heterotrophs and, eventually, to decomposers.

• A food chain is drawn using arrows to indicate the direction in which energy is transferred from one organism to the next.

• Most food chains consist of two, three, or four transfers.

• The amount of energy remaining in the final transfer is only a portion of what was available at the first transfer.

• A portion of the energy is given off as heat at each transfer.

Simple Food Chain

Trophic levels represent links in the chain

• Each organism in a food chain represents a feeding step, or trophic level, in the passage of energy and materials

• Primary Consumer (Herbivore)(first order heterotroph) is an organism that feeds on plants, such as a grasshopper.

• Secondary Consumer (Carnivore) (A second order heterotroph) is an organism that feeds on a first order heterotroph.

• A food chain represents only one possible route for the transfer of matter and energy through an ecosystem.

Food web

A food web, shows all the possible feeding relationships at each trophic level in a community.

Ecological Pyramids

• An ecological pyramid – shows the amount of energy or matter in an ecosystem.– Shows relative amounts of energy or matter contained in

each trophic level

• The base of the ecological pyramid represents the autotrophs, or first trophic level. Higher trophic levels are layered on top of one another.

• Three different types of Ecological Pyramids:– 1. Energy– 2. Biomass– 3. Pyramid of Numbers

Energy pyramids

• The pyramid of energy illustrates that – the amount of available energy decreases at

each succeeding trophic level.

– the total energy transfer from one trophic level to the next is only about ten percent because1. organisms fail to capture and eat all the food energy available at the trophic level below them.2. They use much of the energy for life processes3. Some of the energy is released as heat

Pyramid of EnergyPyramid of Energy

Pyramid of BiomassPyramid of Biomass

• A Pyramid of Biomass is the total weight of living matter at each trophic level.

1 kilogram of human tissue

10 kilograms of beef

100 kilograms of grain

Biomass Pyramid

Pyramids of NumbersPyramids of Numbers• A pyramid of numbers shows that population

sizes decrease at each higher trophic level.

Fox (1)

Birds (25)

Grasshoppers (250)

Grasses (3000)

Which of the following is a producer?

Question 5

D. herbivore

C. decomposer

B. heterotroph

A. autotroph NucleusChloroplast

Mitochondrion

Eyespot

FlagellumPellicle

Contractile vacuole

The answer is A. Organisms that make energy-rich compounds are producers, or autotrophs.

NucleusChloroplast

Mitochondrion

Eyespot

FlagellumPellicle

Contractile vacuole

In a food chain, nutrients and energy move from __________ to __________.

Question 6

D. decomposers, autotrophs

C. heterotrophs, autotrophs

B. autotrophs, heterotrophs

A. autotrophs, autotrophs

The answer is B. The first level in all food chains is made up of producers.

berries → mice → black bear

A model of all the possible feeding relationships at each trophic level in a community is a(n) __________.

Question 7

D. food web

C. food matrix

B. food chain

A. food pathway

The answer is D. A food web is a more realistic model than a food chain, because most organisms depend on more than one other species for food.

Question 8

Which of the following models best illustrates heat released at each trophic level of an ecosystem?

D. pyramid of biomass

C. pyramid of energy

B. food web

A. food chain

Pyramid of Energy

Heat

Heat

Heat

Heat

0.1% Consumers

1% Consumers

10% Consumers

100% Producers

Parasites, scavengers, and

decomposers feed at each

level.

The answer is C. The pyramid of energy shows energy available. Organisms at each trophic level use some energy in food for metabolism and some is given off as heat. The total amount of energy remains the same in accordance with the law of conservation of energy.

Question 9

Compare the amount of energy available in the biosphere to the amount of matter here.

Both energy and matter are conserved: they may be transformed, but are not destroyed. However, sunlight is the primary source of all the energy utilized and transferred in the biosphere. It is always being replenished by the sun.

In contrast, there is a finite amount of matter in the biosphere, which is cycled and not replenished.

ANSWER

Cycles in Nature

• Matter, in the form of nutrients, moves from one organism to another and from one part of the biosphere to another through biogeochemical cycles,

• Matter is cycled and is not replenished like the energy from sunlight. There is a finite amount of matter.

Major Processes in Water Cycle

• 1. Precipitation- water vapor condensing and falling from the atmosphere

• 2. Evaporation – liquid water changing to a gas

• 3. Transpiration- water evaporating from plants

The cycling of water is driven by heat from the sun

Condensation

Seepage

Runoff

Precipitation

TranspirationEvaporation

RootUptake

The Water Cycle

The Water CycleThe Water Cycle

• In the water cycle, water is constantly moving between the atmosphere and Earth.

Precipitation

Evaporation

Groundwater

Transpiration

Evaporation

Condensation

Oceans

Runoff

Water Cycle

Carbon Cycle• Carbon and Oxygen combine to form Carbon

Dioxide.

• Plants use Carbon Dioxide during photosynthesis to produce sugars.

• Plants use sugars for plant growth & respiration

• Herbivores eat plants, and incorporate molecules into their structures.

• Respiration breaks down sugars releasing CO2 and water back into the atmosphere.

Carbon CycleMajor Processes are:

1. Photosynthesis:

6 CO2 + 6 H2O C6H12O6 + 6 O2.

Carbon Dioxide Water Glucose Oxygen2. Respiration:

C6H12O6 + 6 O2 6 CO2 + 6 H2O

Glucose Oxygen Carbon Dioxide Water

Carbon Cycle

Nitrogen Cycle

• Relies heavily on bacteria

• Atmosphere major reservoir-78% N2

• Nitrogen found in proteins and DNA, RNA

• Plants need nitrogen in the form of nitrate ( NO3)

• Animals get nitrogen from proteins in their food

Bacteria of the Nitrogen Cycle

1. Nitrogen-fixing bacteria -convert N2 in air to nitrates that plants can absorb and use– Symbiotic with legumes-found in nodules in

roots of peas, beans, and clover

2. Bacteria of Decay - Decomposers- convert

nitrogenous wastes into ammonia (NH3)

3. Nitrifying bacteria – convert ammonia to nitrates

4. Denitrifying bacteria – break down nitrogen compounds into free nitrogen which returns to the atmosphere

The nitrogen cycle• In the nitrogen cycle, nitrogen is converted from

a gas to compounds important for life and back to a gas.

N2 in Atmosphere

NO3 & NO2NH3

Nitrogen Cycle

Phosphorus Cycle• Main abiotic reservoir for phosphorus is

rock• Weathering of rock adds phosphorus to soil• Plants absorb phosphates from soil and

build organic compounds (ATP, DNA, bones)

• Animals eat plants –incorporate phosphates in to animal compounds

• Is not cycled in the atmosphere!

Phosphorus Cycle

Nutrient Limitation

• Primary productivity = rate at which organic matter is created by producers

• Limiting nutrient – a needed nutrient is in short supply- will affect growth and reproduction of organisms

• Open Oceans – nutrient poor– Sea Water contains 0.00005% Nitrogen (1/10,000 of

amount usually found in soil)• Algal bloom – sudden increase in limiting factor

causes sudden large increase in population of algae

Chlorella Algae

Question 10

Which of the following does not cycle into the atmosphere?

D. water

C. carbon

B. nitrogen

A. phosphorus

The answer is A. Phosphorus moves between the living and nonliving parts of the environment, but does not enter the atmosphere as a gas.

Question 11

How does water on Earth's surface get back into the atmosphere?

Precipitation

EvaporationRunoff

Groundwater

TranspirationEvaporation

Condensation

Oceans

The processes of evaporation of water in lakes and oceans and transpiration by plants both put water vapor into the air.

Precipitation

EvaporationRunoff

Groundwater

TranspirationEvaporation

Condensation

Oceans

ANSWER