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: lightning
Industrial fixation: in fertilizer manufacturing
Combustion of fossil fuels: oxidizes nitrogen
• Industrial fixation and fossil fuels release
nitrogen oxides, which are converted to nitric
acid (acid precipitation)
Nitrogen fixation
Review Question-1
A ______ is a certain number of individuals that
make up an interbreeding, reproducing group within
a given area.
a. species
b. population
c. organism
d. cell
Review Question-1 Answer
A ______ is a certain number of individuals that
make up an interbreeding, reproducing group within
a given area.
a. species
b. population
c. organism
d. cell
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
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-3
The basic building blocks of all matter are
a. atoms.
b. molecules.
c. compounds.
d. matter.
Review Question-3 Answer
The basic building blocks of all matter are
a. atoms.
b. molecules.
c. compounds.
d. matter.
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
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-5
Entropy is a measure of the degree of _____ in a
system.
a. order
b. disorder
c. light
d. oxygen
Review Question-5 Answer
Entropy is a measure of the degree of _____ in a
system.
a. order
b. disorder
c. light
d. oxygen
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. 3-5, 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-2
According to Fig. 3-8, when water undergoes
sublimation, it moves from the _____ state to the
_____ state.
a. solid; gas
b. solid; liquid
c. gas; solid
d. liquid; gas
Interpreting Graphs and Data-2 Answer
According to Fig. 3-8, when water undergoes
sublimation, it moves from the _____ state to the
_____ state.
a. solid; gas
b. solid; liquid
c. gas; solid
d. liquid; gas
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
All of the following are examples of potential energy
except
a. batteries.
b. firewood.
c. gasoline.
d. light.
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
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.