It is morning in the tropical valley. Birds call, insects buzz, and raindrops rattle onto huge, shiny leaves and drip to the ground. The crab spider sits on a purple orchid, waiting. Soon, the orchids’s sticky stamens attract a fly. The fly begins to feed on the nectar, but its meal is brief. In a flash, the spider pounces. The fly becomes food for the spider. How are the fly, the spider, the orchid, and the rain connected?

What is ecology?

• the study of how organisms interact with the living and nonliving things that surround them

Environment is every living and nonliving thing that surrounds them.

What is an ecosystem?

• ecological system

• any portion of the environment

• made up of living(biotic factors) and nonliving things (abiotic factors)

Important terms to remember...

• habitat - the specific environment that is “home” to most species

examples: oceans, forests, streams, fields, deserts

• population - all the organisms of a species that live in the same area

• community - combination of all different populations

• biosphere - the biologically inhabited portions of the planet

-all of Earth’s ecosystem

- includes all the water, land, and air

Two types of resources:

unlimited (infinite) resources

• could result in living things producing population of unlimited size

limited (finite) resources

• could result in organisms competing with one another

Environmental limits of population size:

Competition

- the struggle for resources among organisms

Limiting factors

- factors in the environment that limit the size of population

• Relationship between predators and prey

predators - organisms which kill and eat other organisms

prey - organisms which are killed

• carrying capacity

- the number of organisms of any single species that an ecosystem can support

- determined not only by the available energy, water, oxygen, and minerals, but also by the interactions of organisms

How much have you learned?

1. All of the Earth’s water, land, and atmosphere within which life exists is known as

A. a population

B. an ecosystem

C. the biosphere

D. a biotic community

2. In the biosphere, what are some of the major abiotic factors that determine the distribution and types of plant communities?

A. temperature, sunlight, and rainfall

B. humidity, location, and humans

C. soil type, soil bacteria, and soil water

D. insects, carbon dioxide, and nitrogen in the air

3. The fact that an organism cannot live without interacting with its surrounding is a basic concept in the field of study known as

A. ecology

B. evolution

C. behavior

D. technology

4. When two different species live in the same area and use the same limited resources, which of the following will occur?

A. competition

B. succession

C. parasitism

D. industrialization

5. The graph below shows the changes in two populations of herbivores in a grassy field. A possible reason for these changes is that

A.all of the plant populations in this habitat decreased

B. population B competed more successfully for food than population A

C. A produced more offspring than B did

D. A consumed members of B

6. Base your answer to the two graphs below.

The appearance of the greatest percentage of white mice occurred

A. before the maximum number of days of snow cover

B. at the same time as the maximum number of days of snow cover

C. after the maximum number of days of snow cover

D. both before and after the maximum number of days of snow cover

7. Which statement is supported by the data in the graphs?

A. The percentage of brown mice was greatest during the years of longest snow cover.

B. The percentage of mice with white fur was greatest during the years of longest snow cover.

C. The actual number of white mice was just greatest during the years of least snow cover.

D. The actual number of

brown mice was greatest

during the years of longest

snow cover

8. Which term includes all of the interactions that occur between the organisms and the physical factors in a pond environment?

A. population

B. ecosystem

C. abiotic

D. competition

9. The amount of salt in the air and water of coastal areas determines which species can exist there. In these areas, salt function as a

A. source of energy

B. biotic factor

C. food source

D. limiting factor

The Biosphere• the portion of the earth in which living things

exist• a thin zone compared to the diameter of the earth• about 20 kilometers in thickness• extends from the ocean floor to the highest point

in the atmosphere• composed of the lithosphere, hydrosphere, and

atmosphere

Two types of organisms in the biosphere:

1. Autotrophs(self-feeders) or producers• are organisms that make their own food• most carry on photosynthesis• directly or indirectly, provide food to

heterotrophs

2. Heterotrophs - acquire food by consuming other organisms - consumers

herbivores - animals that feed only on plants

carnivores - animals that feed on other animalsomnivores - are animals that feed on both

plants and animals

saprobes - organisms that obtain nutrients by breaking down the remains of

dead plants and animals

- decomposers

A herbivore...

Symbiotic Relationships

• relationships in which two different organisms live in close association with each other to the benefit of at least one of them

• three types: mutualism

commensalism

parasitism

mutualism - both organisms benefit from their association

commensalism - one organism benefits from a symbiotic relationship,

and the other is not affected

parasitism - one organism benefits from a symbiotic relationship,

and the other is harmed

parasite - the organism that benefits

host - the organism that is harmed

Energy Flow Through an Ecosystem

• Organisms use solar energy stored in food to power life processes.

• Energy loss occurs because the organism is continually breaking the chemical bonds in food to use the energy to live.

• Much of the energy converted to heat that is lost to the environment.

Energy Pyramid

Recycling and Reusing Materials

How much have you learned?1. An earthworm lives and reproduces in the soil.

Through its feeding, excretion, and tunneling activities, the worm adds nutrients and allows air to enter the soil. Together, these statements describe the earthworm’s

A. habitat

B. nutrition

C. niche

D. environment

2. Among the populations of any natural community, the basic food supply is always a critical factor because it is

A. produced by all organisms of the community

B. synthesized from oxygen

C. a means of transferring energy

D. present in surplus amounts

3. A consumer-producer relationship is best illustrated by

A. foxes eating mice

B. leaves growing on trees

C. rabbits eating clover

D. fleas living on a cat

4. Which organism in the food chain below can transform light energy into chemical energy?

rosebush beetle spider toad snake

5. Which group of organisms is not represented in the diagram below?

A. consumers

B. carnivores

C. producers

D. decomposers

6. Which organisms are chiefly responsible for the recycling of dead matter?

A. parasites

B. viruses

C. decomposers

D. producers

7. In a natural community in New York State, the producer organisms might include

A. bacteria, fungi, and viruses

B. deer, rabbits, and squirrels

C. grasses, maple trees, and weeds

D. trout, peas, and earthworms

8. In a food chain consisting of photosynthetic organisms, herbivores, carnivores, and organisms of decay, the principal function of the photosynthetic organisms is to

A. capture energy from the environment

B. provide material for decay

C. prevent erosion of the topsoil

D. release energy from organic compounds

9. A characteristic shared by the both predators and parasites is that they

A. feed on decomposing plant material

B. capture and kill animals for food

C. live inside their hosts

D. attack a living source

10. As you drive down the highways, you may see crows feeding on dead animals. As a result of this nutritional pattern, crows may be classified as

A. scavengers

B. predators

C. herbivores

D. producers

11. In the following diagram of a food chain, what do the arrows indicate?

A. the direction in which organisms move in the environment

B. the direction of energy flow through a series of organisms

C. the order of importance of the organisms

D. the return of chemical substances to the environment

12. When the food relationships in a habitat are illustrated by means of a diagram, the result is always a complicated weblike pattern. This is due to the fact that

A. many consumers are adapted to use more than one food source

B. producer organisms always outnumber the consumer organisms

C. matter is lost in an ecosystem as it moves from producers to consumers

D. both producers and consumers require oxygen for metabolic processes

13. Although three different butterfly species all inhabit the same flower garden in an area, competition between the butterflies rarely occurs. The most likely explanation for this lack of competition is that the butterflies

A. occupy different niches

B. have a limited supply of food

C. share food with each other

D. are able to interbreed

14. Decomposition and decay of organic matter are accomplished by the action of

A. green plants

B. bacteria and fungi

C. viruses and algae

D. scavengers

15. Organisms that eat goats obtain less energy from the goats than the goats obtain from the plants they eat. This is because the goats

A. pass on most of the energy to their offspring

B. convert solar energy to food energy

C. store all their energy in milk

D. use energy for their own metabolism

What is biodiversity?

• a measurement of the degree to which species vary within an ecosystem

• strongly connected with the stability of the ecosystem

• loss or decline upsets stability of the ecosystem

Attempts are being made to breed this black-footed ferret, an endangered animal in captivity so they can be introduced in the wild.

Biodiversity in Danger1. How many species may become extinct by the end of

the 20th century?

2. Why did the researchers say that the ecosystems are in the opening stages of an extinction episode?

3. What could be the primary cause of the decline in diversity?

4. How did habitat destruction cause a decline in biodiversity?

5. Why are the roles that microorganisms, plants, and animals play within the ecosystem important?

Ecological Succession• series of changes by which one habitat

changes into another

• each community causes modifications to its environment

• modifications result in changes that make it more suitable for another community

• climatic changes, natural disasters, and activities of animals alter stable ecosystems

Two Commonly Observed Patterns of Succession

• A community of mostly bare rock will gradually accumulate soil, leading to a progression of vegetation types from grasses to shrubs, and eventually forest.

• The change from a lake community to a forest

Human Impact on the Ecosystems

Human Ecology

• deals with the relationship between humans and their environment

Two Types of Resources• Renewable resources

- resources that can be replaced

- solar energy, air, water, soil, living things, food supply

• Nonrenewable resources

- once used, can not be replaced

- fossil fuels, coal, oil, natural gas, metals, minerals

Renewable Resources

Nonrenewable Resources

Preserving Our ResourcesThe 3 R’s

• REDUCE

• REUSE

• RECYCLE

How Individuals Can Preserve Resources

Causes of Environmental Damage

Thinking critically...

Human Population Growth

• most serious environmental problems related to growth in human population

• 1850: 1 billion

• 1930: 2 billion

• mid 1970’s: 4 billion

• 1990: 5.1 billion

• 2000: 6.2 billion

Disruption of the Ecosystem

• Urbanization

- shift from rural (farming) areas to cities

- results in the destruction of farmlands

- destroyed or endangered other ecosystems

Industrialization

• the development of an economy in which machines produce many of the products people use

• may add to quality of life, but can harm the environment

• contributes to pollution of air and water

• increase demand for energy, water, and other resources

Deforestation

• the destruction of forests resulting from human activity

• can provide people with land for farming and places to live

• causes widespread habitat destruction

Poor Farming Practices

• Overfarming and overgrazing

•Misuse of Pesticides

- indiscrimate use caused contamination of the air and water

- disrupted food chains by killing organisms that are not pests

Pollution

• adding anything to the environment or affecting the environment in a way that makes it less fit for living things

• processes or changes that are likely detrimental or damaging to the ecosystems

• a harmful change in the chemical makeup of the soil, water, or air

Some Forms of Pollution• Water Pollution

Sources of pollution:

1. organic wastes

2. inorganic chemicals

3. disease-causing microorganisms

4. changes in water temperature

5. oil spills

6. radioactive wastes

Water Pollution

• Air Pollution

Some air pollutants:

1. aerosols

- natural (smoke, dust)

- artificial ( hair spray, air freshener)

2. gases (SO2, H2S, CO, NO, NO2)

Global Warming

Carbon dioxide in the atmosphere from 1750

Ozone Depletion

•Land Pollution

- caused by many tons of solid waste, or refuse everyday

Two ways of disposing waste or refuse:

1. Sanitary landfills

2. Incineration (burning)

Natural Processes in the Ecosystem

Soil Formation• weathering which breaks down rocks

• accumulation of organic materials from decaying plants and animals

The Water Cycle

• almost entirely a physical process• consists of the following processes:

- evaporation from the surface of land and water

- transpiration from the leaves of plants

- condensation

- precipitation

The Water Cycle

The Nitrogen Cycle• atmosphere composed of almost 80% nitrogen

gas(N2)

• cannot be used by organisms as N2

• important component of amino acids, which form proteins, and nucleotides, which form nucleic acids

• plants use nitrogen in two inorganic forms: ammonia (NH3) and nitrate(NO3

-)

The Nitrogen Cycle

Nitrogen-fixing

bacteria in

root nodules

of a legume

The Carbon and Oxygen Cycles

Carbon dioxide(CO2):

• makes up 0.03% of the atmosphere• also found dissolved in the waters of the earth• incorporated into organic compounds during

photosynthesis• released when remains of dead plants and

animals decompose

Oxygen (O2):

• makes up about 20% of the earth’s atmosphere

• formed from the splitting of water into hydrogen and oxygen during photosynthesis

• used by animals and plants in cellular respiration

The Carbon and Oxygen Cycle

Waste Removal and the Recycling of Nutrients• nutrients transported from one organism to

another through the food chains

• those not released in the atmosphere are contained in the dead bodies and wastes of organisms

• nutrients restored through break down of wastes and dead bodies of organisms by decomposers

How much have you learned?

1. The members of an animal community are usually similar in

A. size

B. structure

C. food requirements

D. environmental requirements

2. Which ecological principle is best illustrated by the following diagram?

A. In an ecosystem, material is cycled among the organisms and the environment

B. In an ecosystem, the number of producers and consumers are equal

C. Competition within a species results in natural selection

D. An ecosystem requires a constant source of energy

3. When a stable forest community is destroyed by fire, the community usually is

A. not restored

B. restored in a series of successive changes

C. restored only if humans reforest the area

D. changed into a permanent grassland

4. An overpopulation of deer in certain area will most likely lead to

A. a decrease in the number of predators of the deer

B. an increase in the number of autotrophs available for food

C. a decrease in the incidence of disease

D. an increase in competition between the deer

5. A farmer abandons one of his fields, and over the years, he notices that one field community is replaced by another. This replacement represents part of

A. a food chain

B. an abiotic community

C. an energy pyramid

D. an ecological succession

6. An ecosystem such as an aquarium, is self-sustaining if it involves the interaction between organisms, a flow of energy, and the presence of

A. an equal number of plants and animals

B. more animals than plants

C. material cycles

D. organisms undergoing succession

7. In order to be self-sustaining, an ecosystem must contain

A. a large number of organisms

B. a warm, moist environment

C. a constant source of energy

D. organisms that occupy all niches

8. Which type of organisms must be present in an ecosystem if the ecosystem is to be maintained?

A. producers and carnivores

B. producers and decomposers

C. carnivores and decomposers

D. herbivores and carnivores

9. Producer organisms function to

A. store more energy than they use it

B. use more energy than they store

C. store energy but not use it

D. use energy but not store it

10. Which foods are derived from organisms that occupy the same level that contains the greatest amount of energy in an energy pyramid?

A. bread and tomatoes

B. shrimp and rice

C. hamburger and French fries

D. chicken and lettuce

11. Which organism shown in the food web below would most likely be adversely affected by a continuous decrease in the population of mice?

A. grass C. crickets

B. elk D. hawks

12. Which pair of terms would most likely apply to the same organism?

A. heterotroph and herbivore

B. heterotroph and autotroph

C. autotroph and parasite

D. producer and predator

13. In the following diagram of a food web, which organisms are most likely to be competitors?

A. (A) and (C)

B. (B) and (D)

C. (B) and (C)

D. (D) and (E)

14. In the following food chain, which are the most abundant organisms?

corn plants - field mice - garter snakes - red-tailed hawks

A. corn plants

B. field mice

C. garter snakes

D. red-tailed hawks

15. Which relationship can be correctly inferred from the data present?

A. As sewage waste increases, the oxygen content decreases

B. As sewage waste increases, the oxygen content increases

C. As oxygen content decreases, the carp population decreases

D. As oxygen content decreases, the trout population increases

16. The grasshoppers, spiders, shrews, and other organisms, along with the soil minerals, amount of rainfall, and other factors, constitute

A. an ecosystem

B. a species

C. a biosphere

D. a food web

17. Which of the following is a renewable resource?

A. wood

B. oil

C. iron

D. coal

18. The best way to ensure that there will be enough aluminum for all future needs is to

A. dig more mines and process more aluminum

B. buy more aluminum from other countries and save our own

C. recycle and reuse aluminum

D. increase space exploration and search for new sources of aluminum

19. Some ecologists are concerned that the human population has outgrown the capacity of many of Earth’s ecosystems. The natural limiting factor that will more likely prevent further human population growth in many parts of the world is

A. habitat destruction

B. political intervention

C. food supply

D. social intervention

20. Ladybugs were introduced as predators into an agricultural area of the United States to reduce the number of aphids feeding on grain crops. This action is an example of

A. preservation of endangered species

B. conservation of natural resources

C. protection of watershed areas

D. use of a nonchemical means of insect control

21. An example of a human activity that has had a positive effect on the environment is the

A. disruption of natural habitats through deforestation

B. capture and sale of rare South American birds

C. use of reforestation to control erosion

D. hunting of endangered species of animals

22. The trees in forest aid in reducing flood damage chiefly because their

A. branches store water in the form of sap

B. leaves absorb moisture from the air

C. root systems hold the soil in place

D. stems serve to store food

23. A method of agriculture presently used in many regions of the world where one crop is grown on many acres of land has created serious insect problems. This is primarily because this method

A. increase soil erosion

B. provides concentrated areas of one kind of food for insects

C. increases the effectiveness of insecticides used over long periods of time

D. involves the growing of crops in former desert areas

24. Refer to the chart below, which illustrates some methods of pest control.

One likely effect of using these methods of pest control will be to

A. prevent the extinction of endangered species

B. increase water pollution

C. reduce pesticide contamination of the environment

D. Harm the atmosphere

25. Today’s lifestyles have led to increased demands for disposable products. The packaging of these products has caused environmental problems most directly associated with

A. food web contamination

B. atmosphere depletion

C. solid waste disposal

D. the use of nuclear fuels

26. Which action that humans take in attempting to solve ecological problem has had the most negative effect?

A. seeking better means of birth control in the human population

B. applying scientific farming techniques

C. producing stronger and more effective pesticides

D. developing new techniques for the disposal of sewage and industrial chemical wastes

27. DDT is an insecticide that accumulates in the fatty tissues of animals and is transferred through food chains. Its concentration increases at each link of a food chain. Which organism in a food chain is most likely to accumulate the highest concentration of DDT?

A. rabbit (a herbivore)

B. corn (a producer)

C. field mouse (a consumer)

D. owl (a predator)

28. A desired outcome derived from an understanding of the principles of ecology would be

A. the elimination of most predatory species

B. an increase in world human population

C. a decrease in disruption of existing wildlife habitats

D. an increase in the amount of industrialization

29. Modern methods of agriculture have contributed to the problem of soil depletion because many of these methods

A. require smaller amounts of mineral and fertilizer application

B. interfere with the natural cycling of elements

C. use many varieties of cloned plants

D. depend on the practice of planting and harvesting

30. The decline and extinction of many predatory animal species is most probably the result of

A. an overabundance of prey species

B. the introduction of a new species of animal into an area

C. the disruption of natural food chains

D. the decreased use of chemical pesticides