© 2011 pearson education, inc. chapter 3 basic needs of living things

© 2011 Pearson Education, Inc.

CHAPTER 3

Basic Needs of Living Things


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


The hierarchy of life


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


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


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


• 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.


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


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


Ecotones


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


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


Survival curve


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


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


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


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


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


Consumers


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.


Decomposers and Detrivores

• Decomposers: Recycle nutrients in ecosystems.• Detrivores: Insects or other scavengers that feed on

wastes or dead bodies.Figure 3-13Figure 3-13


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


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)


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


Food webs


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


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


A grassland food chain


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


Detritus food web


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


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


Energy pyramids on Wednesday, now… continue with population

dynamics


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.

• 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.

producersherbivorescarnivores


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


A biomass pyramid


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 producersbiomass of herbivoresbiomass of carnivores

(at one point in time)


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 level.

• J m-2 yr-1


Energy flow in :


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 producers# of herbivores# of carnivores


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:


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


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


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


A reverse pyramid in aquatic systems


CHAPTER 3

Basic Needs ofLiving Things

Active Lecture Questions


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.



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.



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.



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



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

© 2011 pearson education, inc. chapter 3 basic needs of living things

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