Download Ch. 3 Ecology: basic needs of living things

CHAPTER 3
Basic Needs of
Living Things
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Organisms in their environment
• Ecology: the study of all processes influencing
• The distribution and abundance of organisms
• Interactions between living things and the environment
• Understanding ecological terms and concepts helps
us see how environmental changes affect living
things
• Ecology is a hierarchy of studies
• Scientists operate at different scales and ask different
questions
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The hierarchy of life
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What is Life?
• All life shares a set of basic
characteristics
• Made of cells that have highly
organized internal structure and
functions
• Characteristic types of
deoxyribonucleic acid (DNA)
molecules in each cell
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Species
• Species: the different kinds of living things in a
community
• All individuals are like one another, but are distinct
from other groups
• Species are grouped into genera
• Which are grouped into families, orders, classes,
phyla, kingdoms, and domains
• The official species name is Latin and has two parts
• The genus name and species descriptive term
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It is hard to define a species
• All members that can interbreed and produce fertile
offspring
• Members of different species generally do not breed
• This definition does not work for organisms that do
not mate to produce offspring
• Scientists use other classification methods
• New species arise due to evolution
• Species classifications are changed to reflect this
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• 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
• Genetic diversity
• In most natural
populations individuals
vary slightly in their
genetic makeup.
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Community
• The biotic (living) 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 in a community depend on each other
• Populations of different species within a biotic
community constantly interact
• With each other and with the abiotic environment
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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 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
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Ecotones
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Biomes
• 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
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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: 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
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Survival curve
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A fundamental biological principle
• Every species has an optimum range, zones of
stress, and limits of tolerance for every abiotic factor
• These characteristics vary between species
• Some species have a broad range
• Other species have a narrower range
• The range of tolerance for a factor affects an
organism’s growth, health, survival, reproduction
• The population density of a species is greatest
where all conditions are optimal
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Habitat and niche
• 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: 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
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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
6 CO2 + 6 H2O
C6H12O6 + 6 O2
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Producers as chemical factories
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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
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Consumers:
• Consumers: organisms that live on the production
of others
• Obtain energy from feeding on and breaking down
organic matter made by producers
• 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
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Consumers
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Consumers: Eating and Recycling to
Survive
• Consumers (heterotrophs) get their food by eating
or breaking down all or parts of other organisms
or their remains.
• Herbivores
• Primary consumers that eat producers
• Carnivores
• Secondary consumers eat primary consumers
• Third and higher level consumers: carnivores that
eat carnivores.
• Omnivores
• Feed on both plant and animals.
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Decomposers and Detrivores
• Decomposers: Recycle nutrients in ecosystems.
• Detrivores: Insects or other scavengers that feed on
wastes or dead bodies.
Figure 3-13
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Cellular respiration is not 100%
efficient
• Animals have respiratory organs to obtain oxygen
• Carbon dioxide is eliminated through the lungs
• Many aquatic places are severely oxygen limited
• 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
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One-way flow of energy
• Most solar energy entering ecosystems is absorbed
• Heats the atmosphere, oceans, and land
• 2–5% is passed through plants to consumers
• All energy eventually escapes as heat
• Entropy is increased
• Re-radiated into space
• Energy flows in a one-way direction through
ecosystems
• Light from the Sun is nonpolluting and nondepletable
• (In contrast, nutrients are recycled and continually
reused)
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Trophic levels (position that an
organism occupies in a food chain)
• During photosynthesis, plants use the Sun’s
energy
• Producing chemicals from carbon dioxide and water
• Plants are eaten by predators (a grasshopper,
mouse, etc.)
• These animals are eaten by other predators
• Food chain: describes where energy and nutrients
go as they move from one organism to another
• Energy moves “up” the food chain
• Not all energy and nutrients are passed to other
levels
• Food web: interconnection of food chains to form
complex webs of feeding relationships
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Food webs
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Trophic categories
• Autotrophs: produce organic material from
inorganic constituents through the use of an
external energy source
• Also referred to as producers
• Green plants, some single-celled organisms and
bacteria
• Heterotrophs: must consume organic material
to obtain energy
• Consumers: eat living prey
• Decomposers: scavengers, detritus feeders,
chemical decomposers eat dead organic material
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Consumers
• Organisms feed on organic matter for energy
• Animals, fungi (mushrooms, mold, etc.), most bacteria
• Range in size from plankton to blue whales
• Divided into subgroups according to their food
source
• Primary consumers (herbivores): feed on
producers
• Secondary consumers: feed on primary consumers
• Third (tertiary), fourth (quaternary), or higher levels
• Carnivores: secondary or higher-order meat eaters
• Omnivores: feed on both plants and animals
• Animals can occupy various levels, depending on
the food
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A grassland food chain
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Decomposers
• Detritus: dead plant material (leaves, etc.), fecal
wastes, dead bodies
• Most energy in an ecosystem goes through this
food web
• Detritus is organic and high in potential energy for
• Decomposers
• Scavengers (vultures): break down large pieces of
matter
• Detritus feeders (earthworms): eat partly
decomposed matter
• Chemical decomposers (fungi and bacteria): break
down matter on the molecular scale
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Detritus food web
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Decomposers act like any other
consumer
• Some decomposers (e.g., termites) digest woody
material
• They have a mutualistic, symbiotic relationship with
decomposer microorganisms in their guts
• Most decomposers use oxygen for cell respiration
• Some decomposers (bacteria and yeasts) partially
break down glucose in the absence of oxygen
(fermentation)
• Results in ethyl alcohol, methane gas, acetic acid
• Anaerobic (oxygen-free) respiration: in sediments
of lakes, marshes, swamps, and animal guts
• Cattle and their fermenting bacteria release methane
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The flow of energy in ecosystems
• In most ecosystems, sunlight is the initial source
of energy
• Primary production (production of organic
molecules) is only 2% of the incoming solar
energy
• Although small, it’s enough to fuel all life
• Standing-crop biomass: the actual biomass of
primary producers in an ecosystem at any given
time
• Not always a good measure of productivity
• Biomass and primary production vary greatly
• Forests have large biomass
• Grasslands have high primary production
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Energy pyramids on Wednesday,
now… continue with population
dynamics
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Ecological pyramids
• The standing crop, productivity, number of
organisms, etc. of an ecosystem can be
conveniently depicted using “pyramids”, where the
size of each compartment represents the amount of
the item in each trophic level of a food chain.
carnivores
herbivores
producers
• Note that the complexities of the interactions in a food web are not
shown in a pyramid; but, pyramids are often useful conceptual devices-they give one a sense of the overall form of the trophic structure of an
ecosystem.
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Limits on trophic levels
• Terrestrial ecosystems usually have three or four
trophic levels
• Marine systems sometimes have five
• Biomass: the total combined (net dry) weight of
organisms
• Each higher trophic level has about 90% less biomass
• One acre of grassland has 907 kg (2,000 lbs)
• It has 90.7 kg (200 lbs) of herbivores
• It has 9.7 kg (20 lbs) of primary carnivores
• Biomass pyramid: the different levels of producer
and consumer mass
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A biomass pyramid
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Pyramid of biomass
• A pyramid of biomass indicates how much biomass
(take all the organisms of a level, dry, and weigh) is
present in each trophic level at any one time.
• g m-2 yr -1
biomass of carnivores
biomass of herbivores
biomass of producers
(at one point in time)
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Pyramid of energy
• A pyramid of energy depicts the energy
flow, or productivity, of each trophic
level.
• Due to the Laws of Thermodynamics,
each higher level must be smaller than
lower levels, due to loss of some energy
as heat (via respiration) within each
Energy flow in :
level.
• J m-2 yr-1
carnivores
herbivores
producers
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Pyramid of numbers
• A pyramid of numbers indicates the
number of individuals in each trophic
level.
•
• Since the size of individuals may vary widely and
may not indicate the productivity of that individual,
pyramids of numbers say little or nothing about the
amount of energy moving through the ecosystem.
# of carnivores
# of herbivores
# of producers
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Pyramid of yearly biomass production
• If the biomass produced by a trophic level is
summed over a year (or the appropriate complete
cycle period), then the pyramid of total biomass
produced must resemble the pyramid of energy flow,
since biomass can be equated to energy.
Yearly biomass production
(or energy flow) of:
carnivores
herbivores
producers
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Energy flow and efficiency
• There is a huge inefficiency at each trophic level
• Only a small fraction of energy is passed on when
energy flows from one trophic level to the next
• Much of the biomass is not consumed by herbivores
• Some food is used as energy to fuel the hetrotroph’s
cells and tissues
• Some food is not digested and is excreted as waste
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Inefficiency at trophic levels
• Individuals at higher levels represent a greater
amount of the Sun’s energy for the same amount
of body tissue
• More energy is needed to produce a top-order
consumer than a producer
• It takes more time, water, and resources to
produce a top-order consumer
• Some materials are hard to excrete (e.g.,
chemicals in fat)
• They biomagnify as you go up the food chain
• They bioaccumulate (build up in tissues)
• DDT
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Aquatic systems
• These systems go through the same process as
terrestrial ecosystems, with two major differences
• Less energy is required in aquatic systems
• More cold-blooded animals, which require less energy
• Less energy is needed to support body weight in
water
• With less energy needed at each level
• More energy is available to the next level
• Food chains can be longer
• Aquatic systems may have a reversed biomass
pyramid
• Larger, older fish eat algae that turn over rapidly
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A reverse pyramid in aquatic systems
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CHAPTER 3
Basic Needs of
Living Things
Active Lecture Questions
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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
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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
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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.
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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.
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Review Question-3
The basic building blocks of all matter are
a. atoms.
b. molecules.
c. compounds.
d. matter.
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Review Question-3 Answer
The basic building blocks of all matter are
a. atoms.
b. molecules.
c. compounds.
d. matter.
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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.
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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.
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Review Question-5
Entropy is a measure of the degree of _____ in
a system.
a. order
b. disorder
c. light
d. oxygen
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Review Question-5 Answer
Entropy is a measure of the degree of _____ in
a system.
a. order
b. disorder
c. light
d. oxygen
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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.
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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.
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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
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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
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Thinking Environmentally-1
All of the following are examples of potential
energy except
a. batteries.
b. firewood.
c. gasoline.
d. light.
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Thinking Environmentally-1 Answer
All of the following are examples of potential
energy except
a. batteries.
b. firewood.
c. gasoline.
d. light.
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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.
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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.
© 2011 Pearson Education, Inc.