General Biology Review Sheet for End of Instruction

General Biology Review Sheet

for End of Instruction

THE CELLPASS Content Standard 1: The Cell

Cell Organelles

Nucleus• Function:

– Cell’s Control Center

– Eukaryotic Cells

– Plant and Animal Cells

– Not found in Prokaryotic Cells

– Location of DNA and RNA

Nucleolus

Cell Membrane or Plasma Membrane• Function

– Major part of controlling homeostasis

• Lets material in and out to maintain balance

• Located in prokaryotic and eukaryotic cells

• Consist of a phospholipid bilayer with embedded proteins.

Cell Membrane or Plasma Membrane• Homeostasis is the

maintaining of a constant internal environment

• Phospholipids are fatty molecules which consist of two layers.

• Proteins are used for ACTIVE and PASSIVE transport.

Cell Wall• Function

– Supports and protects the cell which contains cellulose

• Located in– Eukaryotic Cells and

some Prokaryotic Cells

– Plants ONLY in Eukaryotic Cells

– Bacterium have cell walls for protection

Cytoplasm• Function

– Provides internal structure for the cell

– Located in prokaryotic and eukaryotic cells

– Cytosol is the solution that fills the cytoplasm

• Function– Site where proteins are

produced

• Located– Both prokaryotic and

eukaryotic cells– Plant and animal cells

• Composed of 2 parts

AKA rRNA

Mitochondria

• Function– “Powerhouse of the cell”– Location of cellular

respiration that produces energy (ATP)

– Found in eukaryotic cells– Found in plants and

animals

Chloroplast

• Function– Produces food in the

form of glucose

– Site of photosynthesis

– Eukaryotic Cells

– Plant Cells ONLY

Type of Cell: ANIMAL & EUKARYOTIC#6 mitochondria #1 NUCLEUS

#2 Cell Membrane

#5 ribosomes

#4 Cytoplasm

Organization Levels

• Organism– Organ systems

• Organs– Tissue

» Cell» The basic unit of life –

• Cell (can be broken down further)– Organelles

• Molecules– Atoms

Organization Levels:smallest to largest level

A

M

O

C

T

O

S

O

ATOMS

MOLECULES

ORGANELLES

CELLS

TISSUES

ORGAN

ORGAN SYSTEMS

ORGANISMS

MATTER, ENERGY & ORGANIZATION INLIVING SYSTEMS

• COMPOSED OF:• A. ENERGY• B. MATTER• C. PHOTOSYNTHESIS• D. CELLULAR RESPIRATION• E. TRANSPORT• F. BIOGEOCHEMICAL CYCLES• G. FOOD WEBS

A. ENERGY: the ability to do work or cause change

1. Define: the ability to do work or cause change

2. Can energy be created? NO

State the Law which addresses this concept.

The Law of Conservation of Energy – energy cannot be created nor destroyed, only altered in form. AKA 1st Law of Thermodynamics.

A. ENERGY: the ability to do work or cause change

3. Where do plants get their energy?Through the process of photosynthesis introducing sunlight, water, and carbon dioxide.

4. Where do animals get their energy?Through the process of cellular respiration introducing oxygen and glucose.

5. Can an organism extract ALL of the available energy from their food or the sun? NO

B. Matter:Anything that has mass and takes up space

1. Define: Anything that has mass and takes up space.

2. What is an element?

Basic building block on matter that cannot be broken into smaller parts. Ex: carbon, hydrogen, oxygen

B. Matter:Anything that has mass and takes up space

3. List the most abundant elements found in living organisms.

Carbon, hydrogen, oxygen & nitrogen

4. What is a compound?A substance made up of 2 or more elements that chemically combined to form a new substance such as water and carbon dioxide.

B. Matter:Anything that has mass and takes up space

5. Give an example of compound common in organisms.

Carbon dioxide, water, glucose & oxygen.

6. If an organism takes 3 grams …….

3 grams. Law of conservation of Mass – matter cannot be created nor destroyed only altered in form.

C. Photosynthesis:Conversion of light energy into glucose

1. Define: Conversion of light energy, carbon dioxide, and water into organic compound called glucose.

2. Identify which organelle performs this process.Chloroplast

3. What is the energy source that “drives” (makes it happen) for this process?

Sun or sunlight is the energy source for this process.

C. Photosynthesis:Conversion of light energy into glucose

4. What colors of light are used by the plant for this process?

RED and BLUE

5. What are the two reactions of photosynthesis & where in the choroplast does each occur?

a. Light-dependent reaction occurs in the thylakoid membrane.

b. Light-independent reaction occurs in the solution filled area called the stroma which includes the Calvin cycle.

Chloroplast: organelle for photosynthesis

Light Dependent Reaction

Light Independent Reaction

Chemical Reactions:Composed to three parts

• 1. Reactants:• The ingredients that

make a reaction possible.

• 2. Yield arrow or sign

• always points AWAY from reactants.

• 3. Products:• The products are the

results of a reaction• 2. Yield arrow or

sign • always points

TOWARD products.

C. Photosynthesis:Conversion of light energy into glucose

6. What is required by the plant to perform photosyntheis?

The “ingredients” or reactants for photosynthesis are sunlight, water and carbon dioxide.

7. What is made by the plant from photosynthesis?

Glucose (or starch or technically, G3P)

Photosynthesis

Glucose + oxygen ← water + carbon dioxide + energy

Photosynthesis Facts

• Requires light (energy), water, carbon dioxide (ingredients)

• Produces oxygen and food (glucose) (results)

• Processed in the chloroplast in the components called the thylakoid and stroma.

Chloroplast

• Function– Produces food in the

form of glucose

– Site of photosynthesis

– Eukaryotic Cells

– Plant Cells ONLY

D. Cellular Respiration:Conversion of glucose into energy

1. Define: The making of ATP by breaking down organic compounds like glucose.

2. Identify which organelle performs this process.Mitochondria (but one step is accomplished in the cytosol of the cytoplasm.)

3. What is the energy source that “drives” (makes it happen) for this process?

Glucose. C6H12O6

D. Cellular Respiration:Conversion of glucose into energy

4. What are the three stages of cellular respiration and where in the cell does each occur?

a. Glycolysis – breaks six carbon chain to two three carbon chains in the cytosol of the cytoplasm

b. Kreb’s Cycle or Citric Cycle – occurs in the matrix of mitochondria which removes all of the six carbons to make electrons for the electron transport chain c. Electron Transport Chain – occurs in the inner mitochondrial membrane which converts electrons to ATP for use in the cell.

Chemical Reactions:Composed to three parts

• 1. Reactants:• The ingredients that

make a reaction possible.

• 2. Yield arrow or sign

• always points AWAY from reactants.

• 3. Products:• The products are the

results of a reaction• 2. Yield arrow or

sign • always points

TOWARD products.

The three stages of Cellular Respiration:

Mitochondria

Electron Transport Chain

Kreb’s Cycle

D. Cellular Respiration:Conversion of glucose into energy

5. What is required by the cell to perform cellular respiration?

Glucose (C6H12O6) and oxygen (O2).

What is released by the cell from cellular respiration?

Carbon dioxide (CO2), water (H2O) and energy in the form of ATP.

Cellular Respiration

Glucose + oxygen → water + carbon dioxide + energy

Cellular Respiration Facts

• Requires food and oxygen (ingredients)

• Produces carbon dioxide and water (results)

• Releases energy in the form of ATP (result)

• Reaction is completed in the mitochondria and cytoplasm of the cell

E. Transport:Movement of material across a barrier.

1. Define Passive TransportMovement of molecules from one place to another without the expense of energy.

a. Define “Diffusion”

Movement of particles from a high concentration to a low concentration without expense of energy.

Diffusion• Movement of particles across a membrane• Movement from high concentration to low concentration makes a

concentration gradient.• Osmosis – diffusion of water by way of the plasma membrane due to

a concentration gradient.

E. Transport:Movement of material across a barrier.

b. Define “Osmosis”:Diffusion of water through a semi-permeablemembrane .

(1.) What happens to a cell placed in a Hypotonic solution?(a) Plant cell: becomes turgid (stiff) because water goes

into cell (b) Animal cell: ruptures (lysis); burst open due to

movement of water into the cell.(2.) Give an example of a Hypotonic solution:

Pure or distilled water.

E. Transport:Movement of material across a barrier.

(3.) What happens to a cell placed in a Hypertonic solution?(a) Plant cell: plasmolysis; water leaves the cell, loses

turgid pressure, plant becomes limp(b) Animal cell: shrivels up; movement of water out of

the cell.(4.) What happens to a cell placed in an Isotonic solution?

(a) Plant cell: becomes flaccid; water leaves and enters the cell at the same rate, loses turgid pressure

(b) Animal cell: nothing

Osmotic Solutions

Solution Inside the Cell

Outside the Cell

Net Flow

Hypotonic Low WaterHigh

Molecules

High WaterLow

Molecules

INTO THE CELL

Hypertonic High WaterLow

Molecules

Low WaterHigh

Molecules

OUT OF THE CELL

Isotonic Equal Concentration of

water and molecules

Equal Concentration of

water and molecules

INTO AND OUT AT THE SAME RATE

SWELLINGNO CHANGESHRINKING

Active Transport

• Active Transport: movement of molecules or compounds across a barrier against the concentration gradient with the use of energy such as ATP

http://image.tutorvista.com/content/biomembranes/active-transport-stages.jpeg

Active Transport

F. Biochemical Cycles:Water, Carbon & Nitrogen

1. Water Cyclea. Draw the water cycle in the space provided.

b. Define:

(a) Ground water: water in the soil or in the underground formations of porous rock.

(b) Transpiration: the loss of water through the stomata (holes in the leaves) of plants.

Water Cycle

Water Cycle Processes• Evaporation

– Water entering into the atmosphere• Precipitation

– Water falling from the atmosphere• Condensation

– Change from water vapor to liquid which usually forms clouds or fog

• Transpiration– Change from liquid to water vapor usually in

plants for movement of water from roots to leaves.

F. Biochemical Cycles:Water, Carbon & Nitrogen

2. The Carbon Cyclea. Draw the water cycle in the space provided.

Carbon Cycle

Carbon Cycle Processes

• Photosynthesis– Takes in carbon as carbon dioxide– Releases carbon as glucose

• Cellular Respiration– Releases carbon as carbon dioxide

• Burning of Fossil Fuels– Releases carbon as carbon dioxide

• Decomposition– Releases carbon as carbon dioxide

F. Biochemical Cycles:Water, Carbon & Nitrogen

3. The Nitrogen Cyclea. Draw the water cycle in the space provided.b. Define:

(1.) Nitrogen fixation: The process of converting nitrogen gas (N2) to ammonia (NH3) What does this process? Bacteria(2.) Ammonification: the breakdown of corpses & wastes of organisms (by decomposers) to release the nitrogen in the form of ammonia.(3.) Nitrification: the uptake of ammonia in the soil by

bacteria which convert ammonia into nitrates (NO3) and nitrites (NO2).

(4.) Denitrification: return of nitrogen gas to the atmosphere by bacteria

Drawing of the Nitrogen Cycle

Nitrogen Cycle Processes• Ammonification – decomposers releasing

nitrogen to the soil• Nitrification – changing ammonia into nitrates• Denitrification – releasing nitrogen to the

atmosphere from nitrates in the soil• Nitrogen-fixation – plants taking nitrogen

directly from the atmosphere and making ammonia

• NOTE: Nitrogen is important in the protein synthesis because of the nitrogenous bases of the DNA and RNA.

G. Food Webs:

1. Draw a food chain in the space provided. Identify the producer(s) and specific types of consumers (herbivores, carnivores omnivores – if present)

Wheat grasshopper mouse hawkProducer to primary consumer to 2nd consumer to 3rd

Note: arrow points in the direction of the transfer of energy in a food chain.

Food Chain

Autotrophs vs Heterotrophs

• AUTOTROPHS• Two types:• 1. Photoautotrophs use

sunlight to convert energy into glucose

• 2.Chemoautotrophs use the compounds around them to survive.

• AKA producers and can be decomposers

• HETEROTROPHS• AKA consumers –

adjective is based position within trophic levels.

• Organisms that eat other consumers.

2. Draw a Food Web. Predict what would happen if the plants died out.

3. Define “Trophic Level” and give an example.

• Trophic Level is an organism’s position in the flow of energy such as producer, 1st order consumer, 2nd order consumer etc.

• Examples include producers (plants), 1st trophic level (energy directly from sun), Herbivores are considered 2nd trophic level, carnivores are 3rd trophic levels and above.

4. Draw an energy transfer diagram (an “Energy Pyramid”)

#4. Pyramid of Energy• Energy decreases at each level

– 90% of energy is lost at each level due to activity and heat• Rule of 10%

– 10% of energy transfers to the next level

Pyramid of Numbers

• Population decreases at each level

Pyramid of Biomass• Biomass – amount of living matter

III. The Molecular Basis of Heredity

A. The Cell Cycle

1. Draw and label the cell cycle in the space provided.

2. Identify what happens in phase of the cell listed below

Includes prophase, anaphase, metaphase, & telophase

Cell Cycle

replication

Mitosis• The division of the nucleus in nonsex cells• 1 diploid cell 2 diploid cells

– diploid – 2 sets of chromosomes

DNA• Double Helix• Complementary base

Pairs– A T– C G

• Found only in the nucleus

• Composed of phosphate, sugar, & nitrogenous base

B. DNA

1. DNA function?Determines the traits of individuals

2. One side of DNAA A T G G C T A TComplementary sideT T A C C G A T A

3. Mutated?The proteins may not function correctly.

4. DNA sideA A T G G C T A TRNA sideU U A C C G A U A

RNA• Single strand

• Found in nucleus and ribosomes

• Three types– mRNA– rRNA– tRNA

Heredity MaterialDNA RNA

Nucleic AcidName

Deoxyribonucleic Acid

Ribonucleic Acid

Base A, T, C, G A, U, C, G

Sugar Deoxyribose Ribose

Location Only in nucleus Made in nucleus, moves to ribosomes

Shape Double Helix Single Strand

Replication

• DNA DNA

– Base Pairings• A T• T A• C G• G C

– Making an exact copy or identical copy or the original strands

Transcription

• DNA RNA

– Base Pairings• A U• T A• C G• G C

– Type of RNA• mRNA

C. Genetics 1. Define the following:

a. Allele – Alternative forms of a gene for each variation of a trait such as tall or short

b. Dominate Trait – Observed trait of an organism that masks the recessive trait

c. Recessive Trait – Trait of an organism that masks by the dominant form of a trait; must have 2 copies to be seen physically.

Genetics

Alleles – different forms of the same gene

• B – Brown eyes• b – blue eyes

C. Genetics 1. Define the following:

d. Genotype – Letters to identify a trait Example: Ee, EE, or ee

e. Phenotype – what is seen in the organismExample: blue eyes, tall

f. Homozygous – The genes for a trait are the same; both dominant (TT) or both recessive (tt)

g. Heterozygous –the genes for a trait are different (Tt)

Traits• Dominant Trait

– Written as a capital letter to show that it is overpowering

• Recessive Trait– Written as a lowercase

letter to show that it can be covered up

• Genotype– The actual allele

combination– Example:

• AA, Aa, or aa

• Phenotype– The physical appearance

which expresses the genetic trait.

– Example: – brown eyes or blue eyes

• Homozygous

– When the two alleles are the same

– BB or bb

• Heterozygous– When the two alleles are

different– Bb

2. Solve the following monohybrid cross:

1.) Tt X ttHeterozygous X short

plant

2.) T , t t, t

3.)

4.) Genotype:Tt – 2/4 or ½tt - 2/4 or ½

2:25.) Phenotype:

Tall : 2/4 or ½Short : 2/4 or ½

2:2

T t

t Tt tt

t Tt tt

4. The following is a RECESSIVE Pedigree

What does a square represent?MALE

What does a circle represent?FEMALE

E is dominant for Brown eyese is recessive for Blue eyes

e e e e

E e E e

E e or E E

Meiosis

• Division of the nucleus in sex cells– Spermogeneis – making of sperm– Oogenesis – making of eggs

• 1 diploid cell 4 haploid cells (gametes)

Meiosis Phases

IV. Biological Diversity

IV. Biological Diversity: Diversity of species is developed through gradual processes

over many generations.A. Modification by Natural Selection

1. Define “Descent with Modification;”

The evolutionary change in an organism; changes that accumulate resulting in descendants being different from the ancestors.

2. List the four observations Darwin noted in his

development of the theory of Natural Selection

2. List the four observations Darwin noted in his development of the theory of Natural Selection

Organisms produce more offspring than can survive. i.e. birth rate exceeds death rate

Individuals with useful variations survive in their environment passing those variations to offspring.In a population,

individuals have variations. Variations are inherited.

B. Evidence of Evolution

1. Fossils 3.Biochemical analysis

2. Embryology studies 4. Artificial selection

5. Define Homologous Structures• Definition

– Structures that came from a common ancestor

• Example– Limbs in tetrapods

5. Define Analogous Structures

• Definition – structures that are similar, but do not have a common

ancestor• Example

– Wings in different species

Vestigial Structures

• Definition – a structure that is now no longer used as its original purpose– Hip bones in whale– Appendix

Cladograms• A model of evolutionary history of organisms

– Primitive traits evolve first– Derived traits are shown later in the cladogram

• Part of phylogeny

Dichotomous Key

• Tool used for identification of an organism by asking two questions at a time.

C. Adaptations

1. Define “Adaptation”• Adaptation – any behavior, structure that will allow a

species to survive better; any variation that aids an organism’s chances of survival in its environment.

C. Adaptations: continued

2. Adaptations results from?Natural selection

3. List the three categories of adaptation types and give an example:

a. Structural – large teeth & claws for defense or digging

b. Physiological – changes in an organism’s metabolism; snake venom; antibiotic resistance

c. Behavorial – breeding dances of birds

Variation with a species• Niche – a role a species plays in an area

– What type of food the organism eats, where it lives, how it interacts with other species.

Classification of Organisms

MONERANS has been broken into two kingdoms

6 Kingdoms• Archaebacteria• Eubacteria• Protist• Fungi• Plant • Animal

Archaebacteria

• Characteristics– Prokaryotic– Unicellular– Live in extreme

environments such as extreme salt water, in the hot pools at Yellowstone National Park, thermal vents located at bottom of oceans.

Eubacteria

• Characteristics– Prokaryotic– Unicellular– Most habitats– Consist on pili and

capsule for attachment and protection

Protists

• Characteristics– Eukaryotic– Unicellular and

multicellular– Can be autotrophic or

heterotrophic– Mostly located in aquatic

environments.

Fungi

• Characteristics– Eukaryote– Unicellular or

multicellular– Absorbs nutrients from

environment (chemoautotrophs)

Plants

• Characteristics– Eukaryotic– Autotrophic– Multicellular and

unicellular.– Contains chloroplast and

cell walls

Animals• Characteristics

– Eukaryotic– Multicellular– Heterotrophs – consumer other organisms to gain energy.

Classification Rankings• Kingdom

– Phylum• Class

– Order» Family » Genus» Species

• Kings–Play

• Chess–On

»Fiber»Glass»Stools

Genus and Species

• Genus is the first name of an organism. The genus is always capitalized such as

• Killer whale : Orca orca

• Species is the 2nd name of an organism. The species is always all lower case such as for human: Homo sapien

Organization LevelsFrom largest to smallest

• Organism– Organ systems

• Organs– Tissue

» Cell» The basic unit of life –

• Cell (can be broken down further)– Organelles

• Molecules– Atoms

Organization Levels:smallest to largest level

A

M

O

C

T

O

S

O

ATOMS

MOLECULES

ORGANELLES

CELLS

TISSUES

ORGAN

ORGAN SYSTEMS

ORGANISMS

Measurements and Graphs

Measurements

• Mass

• Volume

• Length

• Temperature

Mass: amount of matter in an object

• Units – grams (g)• Tool – Balance

• Tool -Digital BalanceTool -Triple Beam Balance

How to read a Triple Beam Balance• Add the numbers from each mass located on each

beam to find the total mass in grams.

Length: measurement of distance between two points

• Units – Meter (m)• Unit - Centimeter (cm)• Unit - Millimeter (mm)

• Tool – Ruler• Tool - Tape measure• Tool – Meter stick

Volume: amount of space an object occupies

• Unit – Liters (L)• Unit – Milliliters (mL)

– Used for liquids

• Unit – cubic centimeter– Used for solids with the

formula (L x W x H)

• Tools– Graduated Cylinder– Pipette (for small liquids)– Tool for solid object is based

type of solid

How to Read a Graduated Cylinder• Look at the bottom of the curve, called the meniscus,

on a flat surface to obtain a proper measurement.

Temperature: amount of kinetic energy of an object

• Units – degrees Celsius

– °C

• Tool – Thermometer

• Kinetic energy is energy in motion. As the temperature increase, the kinetic energy of an object increases.

Measurement Prefixes: words in place of numerical values

• Micro means 1/1,000,000 or 0.000001• Milli means 1/1,000 or 0.001• Centi means 1/100 or 0.01• Kilo means 1,000

Conversion of measurements

• Train track example:

Kilo Hecto Deka Base Deci Centi Milli

King Henry Died By Drinking Choc. Milk

Convert: 45 km to _____ cm 650 cL to ______ kL

Density: amount of matter in a given volume

• Density = mass/volume– g/mL or grams per milliliter– Very important measurement for identifing

different objects in the biosphere and beyond

• Population density = the number of organisms in an area– Pop. Density = # of organisms/ area of land

Steps to the Scientific Method

• State a Problem (in the form of a question)• State a hypothesis (an educated guess)• Set-up an experiment• Collect and analyze data• Conclusion (either null or accepted)• Re-work hypothesis, if null conclusion

Experiment Set-Up: Types of Experimental Data

• Qualitative data: data that does NOT require a numerical value such as color, yes/no, left/right, good/bad.

• Quantitative data: data does require a numerical value and an unit usually a measurement. Examples include the number of organisms, length of object, or temperature of the ecosystem.

Experiment Set-Up

• Independent Variable – what causes the change

• Dependent Variable – what changes or the results of the change if any

• Constant – factors that are kept the same in both groups.

• Control – part of the experiment that is not changed

Graphs

Making a graph

• 1. Write a title.• Independent v.

Dependent

• 2. Create X & Y axis

• 3. Label the axis

• 4. Determine the units for each axis

• 5. Graph the data

Graph Set-Up

• Independent Variable on the x-axis– Label (should include units)

• Dependent Variable on the y-axis– Label (should include units)

• Title– Y vs. X OR Independent vs. Dependent

• Key – optional to the presenter

What is the title?

What are the variables?

Main focus of graph?

SPEED

Line Graphs• Shows a relationship

between the two variables

• Positive Relationship:When one variable increases, as does the other

• Negative Relationship:When one variable increases, the other decreases

Line Graphs

• Single line graph shows change over time.

• Multiple line graphs can also show comparisons.

Bar Graph or Histograms• Shows comparisons.

Circle or Pie Chart

• Graph that shows the percentage of each variable

Ecology Terms

• Carrying Capacity– The maximum number

of species in an area

• Limiting Factors – The factor that restricts

the growth of an organism

• Ex: water, food, space

• Natality – Birth rate of organisms in an area

• Mortality – death rate of organisms in an area

• Immigration – movement of individuals into an area

• Emigration – movement of individuals out of an area

• Biotic Potential – the fastest rate on population increase for a species

• Colonization – the start of a population in a new area– Pioneer species

• Biomass – the amount of living matter in an area

• Population Density – the number of individuals in an area

Population Graphs

J-Shaped Curve

• Shows exponential growth

• Typical of smaller organisms– Insects– Flies

S-Shaped Curve

• Graphs shows carrying capacity

• Shows how limiting factors will affect a population

Density Dependent vs. Independent

• Density Dependent Factors

• 1. Illness & disease• 2. Competition • 3. Predators• 4. Parasites• 5. Food

• Density Independent Factors

1. Most are abiotic2. Temperature3. Weather4. Drought5. Chemical agents6. Major habitat

disruption

Succession: Changes over TimeSuccession: Changes over Time• Ecologists refer to the orderly, natural

changes and species replacements that take place in the communities of an ecosystem as succession.

• Succession occurs in stages. At each stage, different species of plants and animals may be present.

• The colonization of barren land by communities of organisms is called primary succession.

• Primary succession takes place on land where there are no living organisms.

Primary successionPrimary succession

Primary successionPrimary succession• The first species to take hold in an area like

this are called pioneer species.

• An example of pioneer species is a lichen, which is a combination of small organisms.

• Decaying lichens, along with bits of sediment in cracks and crevices of rock, make up the first stage of soil development.

• New soil makes it possible for small weedy plants, small ferns, fungi, and insects to become established.

Primary successionPrimary succession

• As these organisms die, more soil builds.

­

Exposed rock Primary succession

MossLichen

Pioneer species

Primary successionPrimary succession

• After some time, primary succession slows down and the community becomes fairly stable, or reaches equilibrium.

Primary successionPrimary succession

• A stable, mature community that undergoes little or no change in species is a climax community.

Secondary succession Climax community

Primary successionPrimary succession

Secondary successionSecondary succession• Secondary succession is the sequence of

changes that takes place after an existing community is severely disrupted in some way.

• Secondary succession, however, occurs in areas that previously contained life, and on land that still contains soil.