Chapter 3

Basic Needs of Living Things

Ecology

• the study of all processes influencing the distribution and abundance of organisms

• Interactions between living things and the environment

The hierarchy of life

Species

• Species: the different kinds of living things in a community – All individuals are like one another, but are

distinct from other groups

It is hard to define a species

• All members that can interbreed and produce fertile offspring – Members of different species generally do not

breed

• New species arise due to evolution – Species classifications are changed to reflect

this

Populations and biotic communities

• Population: a number of individuals that make up the interbreeding, reproducing group – It refers only to individuals of a species in an area – For example, gray wolves in Yellowstone National

Park– A species would be all gray wolves in the world

• A biotic community (biota): the grouping of populations in a natural area – Includes all vegetation, animals, and microscopic

organisms

Biotic community

• The grouping of populations in a natural area – Includes all vegetation, animals, and microscopic

organisms

• The biotic community is determined by abiotic (nonliving chemical and physical) factors – Water, climate, salinity, soil

• A community is named for its plants – Vegetation strongly indicates environmental

conditions

Species within a biotic community

• Species in a community depend on each other – The plant community supports the animals

• Populations of different species within a biotic community constantly interact – With each other and with the abiotic

environment

Predictable vegetation

Winter in the forest

Ecosystems

• Ecosystem: an interactive complex of communities and the abiotic environment affecting them within an area – A forest, grassland, wetland, coral reef – Humans are part of ecosystems

Ecosystems

• Ecosystems lack distinct boundaries and are not isolated– Species can occupy multiple ecosystems and

migrate between them

• Ecotone: a transitional region between ecosystems– Shares species and characteristics of both– May have more or fewer species than the

ecosystems

Ecotones

Ecotones

Landscapes and biomes

• Landscape: a cluster of interacting ecosystems

• Biome: a large area of Earth with the same climate and similar vegetation – For example, grasslands can be predicted by

rainfall and temperature – Boundaries grade into the next biome

• Biomes describe terrestrial systems – Aquatic and wetland ecosystems are determined

by depth, salinity, and permanence of water

• Biosphere one huge system formed by all living things

Environmental factors

• Organisms live in the environment with physical, chemical, and biological biotic or abiotic factors

• Condition: any factor that varies in space and time but is not used up (temperature, wind, pH, salinity)

• Resource: any factor consumed by organisms– Water, nutrients, light, oxygen, food, space

Factors

• A factor can be both a condition and resource– Plants use water as a resource, but pond

water is a condition

• Factors determine whether a species occupies an area

Optimums, zones of stress, limits of tolerance

• Different species thrive with different levels of factors

• For every factor there is an optimum– A certain level where organisms grow or

survive best– Organisms do less well at higher or lower

levels – They do not survive at extremes

Range of Tolerance

• Range of tolerance: the entire range allowing any growth

• Limits of tolerance: the high and low ends of the range of tolerance

• Zones of stress: between the optimal range and high or low limit of tolerance

Survival curve

Law of limiting factors

• Limiting factor: any factor that limits growth

• Law of limiting factors: any factor outside the optimal range will cause stress and limit growth, reproduction, and survival of a population

Limiting Factors

• Limiting factors may be a problem of too much or too little– They can change over time (e.g., temperature

vs. nutrients)– The ultimate limiting factor: an organism’s

genetic potential

• Synergistic effects (synergisms): factors (e.g., pollution) that interact to cause a greater effect than expected

Habitat

• Habitat: the place—defined by the plant community and physical environment—where a species is adapted to live– A deciduous forest, swamp, etc. – Microhabitat: puddles, rocks, holes in tree

trunks

Niche

• Niche: the sum of all conditions and resources under which a species can live – What the animal eats, where it feeds and

lives, how it responds to abiotic factors

• Species coexist in an area but have separate niches – Reducing competition by using different

resources– Resource partitioning

Matter in living and nonliving systems

• Organisms take in matter and energy from the environment to grow and function

• Matter: anything that occupies space and has mass – All solids, liquids, and gases– All living and nonliving things – Is composed of atoms

Atoms

• Atoms: the building blocks of all matter – Elements: 94 naturally occurring kinds of atoms – Made of protons, neutrons, electrons

• Chemical reactions rearrange atoms to form different kinds of matter

• Law of Conservation of Matter: atoms do not change and are not created or destroyed

• Nuclear reactions split atoms – This is very rare and is not a chemical reaction

Molecules and compounds

• Molecule: two or more atoms of the same or different kinds– Bonded in a specific way– Properties depend on how atoms are bonded

– Oxygen: O2

• Compound: two or more different kinds of atoms– Water: H2O (it is also a molecule)

• The cycle of growth, reproduction, death, and decay is a continuous process– Molecules and compounds are used, assembled, and

disassembled repeatedly

The four spheres of Earth’s environment

The atmosphere

• Atmosphere: the thin layer of gases separating Earth from outer space– Oxygen (O2), nitrogen (N2), carbon dioxide

(CO2)

– Plus water vapor and other gases

• Plants take in carbon dioxide through leaves– Animals take in oxygen through lungs, gills, or

skin

The major gases of clean, dry air

The hydrosphere

• The source of water• Hydrogen bonding: a weak attraction that

joins hydrogen atoms to an oxygen atom in a different molecule

• Water undergoes melting and evaporation– Sublimation: water goes from solid directly

into the air

Water and its three states

The lithosphere

• Mineral: a naturally occurring solid made by geologic processes– A hard, crystalline structure of a given

chemical composition

• Rocks: made of small crystals of two or more minerals– Soil: particles of many different minerals

Minerals

Organic compounds

• An organism’s body is composed of large compounds

• These compounds contain six key elements– Carbon (C), hydrogen (H), oxygen (O), nitrogen

(N), phosphorus (P), and sulfur (S)

• Organic compounds: chemical compounds making up tissues of living organisms– Very large, complex molecules– Mainly carbon, hydrogen, and oxygen

Energy basics

• Kinetic energy: energy in action or motion– Light, heat, physical motion, electrical current

• Potential energy: energy in storage (e.g., gasoline)

- Chemical energy: potential energy

contained in chemicals and fuels

• Energy can be changed from one form to another – Potential to kinetic energy– Kinetic to potential energy (e.g., charging a battery)

Forms of energy

Energy conversions

Units of energy

• Calorie: the amount of heat required to raise the temperature of 1 gram of water 1 degree Celsius– 1 kilocalorie = 1,000 calories

• Temperature: measures the molecular motion in a substance– Caused by kinetic energy

• Movement of matter requires energy absorption or release– Change in matter cannot be separated from its

change in energy

Laws of thermodynamics

• First Law of Thermodynamics (Law of Conservation of Energy): energy is neither created nor destroyed – But it may be converted from one form to another

• Second Law of Thermodynamics: usable energy is lost in any energy conversion

• Entropy: a measure of the degree of disorder in a system– Without energy input, everything goes toward increasing entropy– Increasing disorder releases heat from the system

• To gain potential energy, energy must come from somewhere– Energy lost is greater than the energy gained

Entropy

Storage and release of potential energy

Energy changes in organisms

• Breaking bonds in molecules releases energy to do work

• Oxidation: a loss of electrons– Usually accomplished by the addition of oxygen

(which causes burning)

• Inorganic compounds are nonflammable – They have low potential energy

• Production of organic material from inorganic material represents a gain in potential energy– Breakdown of organic material releases energy

Producers make organic molecules

• Producers: make high-potential-energy organic molecules from low-potential-energy raw materials (CO2, H2O, N, P)– Chlorophyll in plants absorbs kinetic light energy to

power the production of organic molecules• Green plants use the process of photosynthesis to

make – Sugar (glucose—stored chemical energy)– Using inputs of carbon dioxide, water, and light energy– Releasing oxygen as a by-product

Producers make organic molecules

• Green plants use the process of photosynthesis to make – Sugar (glucose—stored chemical energy)– Using inputs of carbon dioxide, water, and light

energy– Releasing oxygen as a by-product

• 6 CO2 + 6 H2O C6H12O6 + 6 O2

Producers as chemical factories

Within the plant

• Glucose serves three purposes– It is the backbone for all other organic molecules– It provides energy to run cell activities (e.g.,

growth)– It is stored for future use (as starch in potatoes,

grains, seeds) • Each stage of the process uses enzymes:

proteins that promote the synthesis or breaking of chemical bonds

Cell respiration

• Consumers: organisms that live on the production of others– Obtain energy from feeding on and breaking down

organic matter made by producers

Cell respiration

• Respiration: organic molecules are broken down inside each cell – Produces energy for the cell to use– The reverse of photosynthesis– Oxygen is consumed– Occurs in plants and animals

• C6H12O6 + 6 O2 6 CO2 + 6 H2O

Cellular respiration is not 100% efficient

• In keeping with the Second Law of Thermodynamics– Cell respiration is only 40–60% efficient– The rest of the energy is released as waste (body)

heat• Consuming more calories than your body needs

converts calories to fat and results in weight gain• Stored energy can be released from food without

oxygen– Anaerobic respiration (fermentation) is less

efficient

The cycling of matter in ecosystems

• Biogeochemical cycles: circular pathways of elements involving biological, geological, and chemical processes

The Carbon Cycle

• The carbon cycle: starts with the reservoir of carbon dioxide in the air– Becomes organic molecules in organisms– Carbon is respired by plants and animals into the

air or is deposited in soil

• Photosynthesis in oceans moves CO2 from seawater into organisms – Respiration returns inorganic carbon to seawater

Means of nitrogen fixation

• Bacteria (genus Rhizobium) live in legume root nodules

• The legume provides the bacteria a place to live and food– It receives a source of nitrogen in return– Nitrogen enters the food chain from the

legumes

Three other processes “fix” nitrogen

Atmospheric nitrogen fixation: lightningIndustrial fixation: in fertilizer manufacturingCombustion of fossil fuels: oxidizes nitrogen

• Industrial fixation and fossil fuels release nitrogen oxides, which are converted to nitric acid (acid precipitation)

Nitrogen fixation

A ______ is a certain number of individuals that make up an interbreeding, reproducing group within a given area.

a. speciesb. populationc. organismd. cell

Review Question-1

A ______ is a certain number of individuals that make up an interbreeding, reproducing group within a given area.

a. speciesb. populationc. organismd. cell

Review Question-1 Answer

All the ecosystems of the Earth are interconnected and form one huge system called the

a. ecotone.b. landscape.c. biome.d. biosphere.

Review Question-2

All the ecosystems of the Earth are interconnected and form one huge system called the

a. ecotone.b. landscape.c. biome.d. biosphere.

Review Question-2 Answer

The basic building blocks of all matter are

a. atoms.b. molecules.c. compounds.d. matter.

Review Question-3

The basic building blocks of all matter are

a. atoms.b. molecules.c. compounds.d. matter.

Review Question-3 Answer

Organic compounds usually contain the following six key elements:

a. helium, oxygen, hydrogen, magnesium, plutonium, and nitrogen.

b. carbon, plutonium, helium, nitrogen, sulfur,and magnesium.

c. carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur.

d. gold, silver, magnesium, chromium, iron,and sulfur.

Review Question-4

Organic compounds usually contain the following six key elements:

a. helium, oxygen, hydrogen, magnesium, plutonium, and nitrogen.

b. carbon, plutonium, helium, nitrogen, sulfur,and magnesium.

c. carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur.

d. gold, silver, magnesium, chromium, iron,and sulfur.

Review Question-4 Answer

Entropy is a measure of the degree of _____ in a system.

a. orderb. disorderc. lightd. oxygen

Review Question-5

Entropy is a measure of the degree of _____ in a system.

a. orderb. disorderc. lightd. oxygen

Review Question-5 Answer

According to Fig. 3-5, the range of tolerance for the species is

a. 8-18 degrees Celsius.b. 8-38 degrees Celsius.c. 20-28 degrees Celsius.d. 29-38 degrees Celsius.

Interpreting Graphs and Data-1

According to Fig. 3-5, the range of tolerance for the species is

a. 8-18 degrees Celsius.b. 8-38 degrees Celsius.c. 20-28 degrees Celsius.d. 29-38 degrees Celsius.

Interpreting Graphs and Data-1 Answer

According to Fig. 3-8, when water undergoes sublimation, it moves from the _____ state to the _____ state.

a. solid; gasb. solid; liquidc. gas; solidd. liquid; gas

Interpreting Graphs and Data-2

According to Fig. 3-8, when water undergoes sublimation, it moves from the _____ state to the _____ state.

a. solid; gasb. solid; liquidc. gas; solidd. liquid; gas

Interpreting Graphs and Data-2 Answer

All of the following are examples of potential energy except

a. batteries.b. firewood.c. gasoline.d. light.

Thinking Environmentally-1

All of the following are examples of potential energy except

a. batteries.b. firewood.c. gasoline.d. light.

Thinking Environmentally-1 Answer

The Second Law of Thermodynamics states: “In any energy conversion, some of the usable energy is always lost.” Underlying the loss of usable energy to heat is

a. the Law of Gravity.b. the process of photosynthesis.c. the Law of Independent Assortment.d. the principle of entropy.

Thinking Environmentally-2

The Second Law of Thermodynamics states: “In any energy conversion, some of the usable energy is always lost.” Underlying the loss of usable energy to heat is

a. the Law of Gravity.b. the process of photosynthesis.c. the Law of Independent Assortment.d. the principle of entropy.

Thinking Environmentally-2 Answer