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Free PRAXIS II Life Sciences Study Guide

Updated on April 9, 2014

How to Pass the PRAXIS II Science Exam | Practice PRAXIS II Exam Questions | PRAXIS II Middle School Science Study Guide

This PRAXIS II study guide specifically covers the life sciences portion of the PRAXIS II Middle School Science (0439) and PRAXIS II General Science: Content Knowledge (0435) exams.

Here you'll find practice PRAXIS questions and detailed information about plant and animal biology, genetics, evolution, cell biology and ecology, which can also help you prepare for the PRAXIS II Biology: Content Knowledge (0235) exam.

Since the PRAXIS II science exams measure your knowledge of so many scientific topics, this free PRAXIS II study guide is split into four parts. Check out the links below to visit the basic principles of science, earth and space sciences, chemistry and physics portions of this free PRAXIS II study guide!

Image Credit: Umberto Salvagnin (Flickr)

100% Original Content

I created this study guide when preparing to take the PRAXIS II Middle School Science (0439) exam. I used a variety of sources to research these topics and rewrote what I learned in my own words. No part of this study guide has been copied from Wikipedia or any other source.

Official PRAXIS Study Guides - Study guides specifically written to help you pass the PRAXIS II exam

Praxis Middle School Science 0439 Teacher Certification Test Prep Study Guide
Praxis Middle School Science 0439 Teacher Certification Test Prep Study Guide

This PRAXIS II study guide covers all of the topics tested by the middle school science exam and includes a 90-question practice test. This book can be sold back to Amazon for up to 70% of the price you pay!

Praxis II Middle School: Science (0439) Exam Secrets Study Guide: Praxis II Test Review for the Praxis II: Subject Assessments
Praxis II Middle School: Science (0439) Exam Secrets Study Guide: Praxis II Test Review for the Praxis II: Subject Assessments

For those who fear the PRAXIS because they "just don't test well," this PRAXIS II study guide coaches aspiring science teachers to score higher using a variety of test-taking strategies.

Praxis II Middle School: Science (0439) Exam Flashcard Study System: Praxis II Test Practice Questions & Review for the Praxis II: Subject Assessments
Praxis II Middle School: Science (0439) Exam Flashcard Study System: Praxis II Test Practice Questions & Review for the Praxis II: Subject Assessments

Repetition is a proven recipe for test-taking success. These flash cards provide detailed-yet-digestible information about the PRAXIS II's fundamental topics and can be used as a classroom resource later on.

CliffsNotes Praxis II: Middle School Science (0439) (CliffsNotes (Paperback))
CliffsNotes Praxis II: Middle School Science (0439) (CliffsNotes (Paperback))

Looking for lots of practice PRAXIS II exam questions with detailed explanations? This CliffsNotes study guide offers up two full-length practice exams.



The Cell
The Cell

Image Credit: Jasper Nance (Flickr)

Plant Cell Diagram
Plant Cell Diagram

A. Demonstrate knowledge of the structure and function of organelles, including membranes

Organelles are specialized structures suspended in the cytoplasm of a cell that serve specific purposes.

  • CELL MEMBRANE: separates the chemical reactions occurring inside the cell from the chemicals found in the extracellular fluid; made of two layers of phospholipids; selectively permeable (diffusion: the movement of molecules from a high- to low-concentration area; osmosis: diffusion of water)
  • NUCLEUS: control center of the cell; contains genetic material (DNA made of chromatin), mRNA ("messenger" ribonucleic acid, which interprets DNA's genetic code and creates amino acids), tRNA ("transfer" RNA, which transports amino acids to the ribosomes) and a nucleolus (which produces ribosomes)
  • CHLOROPLASTS: found in plant cells; contain chlorophyll, a green pigment that absorbs sunlight; photosynthesis occurs here
  • VACUOLES: found in plant cells; liquid-filled storage containers
  • CELL WALL: found in plant cells; a rigid structure that surrounds the cell membrane for added stability; made of cellulose
  • RIBOSOMES: the cell's protein synthesizers
  • MITOCHONDRIA: the cell's power plant; converts glucose into ATP (adenosine triphosphate) through cellular respiration
  • LYSOSOMES: the cell's garbage men; produced by the Golgi apparatus; contain digestive enzymes
  • ENDOPLASMIC RETICULUM (ER): a series of canals that connects the nucleus to the cytoplasm (rough: dotted with ribosomes; smooth: contains transport vesicles); primary function = to synthesize and transport proteins (rough) and lipids (smooth)
  • GOLGI APPARATUS: packaging center of the cell; uses vesicles to transport enzymes in and out of the cell
Image Credit: Mariana Ruiz (Wikimedia Commons)

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Eukaryotes vs. Prokaryotes
Eukaryotes vs. Prokaryotes

B. Distinguish between prokaryotic and eukaryotic cells

Prokaryotes are simple, single-celled organisms; eukaryotes are complex.

PROKARYOTES: single-celled organisms that lack a true nucleus (example: bacteria, blue-green algae); contain a circular ring of DNA that floats in the cytoplasm

EUKARYOTES: complex organisms that contain a defined nucleus and organelles

Image Credit: National Center for Biotechnology Information (Wikimedia Commons)

Cell Cycle Diagram
Cell Cycle Diagram

C. Demonstrate understanding of the cell cycle and cytokinesis

The cell cycle is a three-part series of events that characterizes the life of every eukaryotic cell.

INTERPHASE: the cell grows in size, matures and replicates its DNA to prepare for mitosis

MITOSIS: division of a parent cell into two identical daughter cells; made up of the following four phases (PMAT):

  • (1) PROPHASE: chromosomes become visible; centrioles separate, dragging spindles across the cell; nuclear envelope dissolves;
  • (2) METAPHASE: chromosomes align at the center of the cell
  • (3) ANAPHASE: the cell elongates; chromosome pairs separate at their centromeres into individual chromosomes and move to opposite ends of the cell
  • (4) TELOPHASE: a nuclear envelope reforms around each group of chromosomes

CYTOKINESIS: literal division (cleavage) of the cell into two daughter cells; a new cell wall forms from a cell plate in plant cells

Image Credit: Kelvinsong (Wikimedia Commons)

Photosynthesis Diagram
Photosynthesis Diagram

D. Demonstrate understanding of chemical reactions in respiration and photosynthesis

During respiration and photosynthesis, cells create energy using a variety of chemical reactions.

CELLULAR RESPIRATION: the biochemical process by which cells obtain and release energy

  • AEROBIC RESPIRATION: requires oxygen; simplified = glucose and oxygen are combined to create carbon dioxide, water and ATP (C6H12O6 + 6O2 >> 6CO2 + 6H2O + ATP)
    • (1) GLYCOLYSIS: first stage of aerobic and anaerobic respiration; does not require oxygen; takes place in the cytoplasm; glucose is converted into 2 pyruvate molecules; produces 2 net ATP
    • (2) PYRUVATE OXIDATION: pyruvate molecules are oxidized into acetyl-CoA and CO2; produces NADH
    • (3) KREBS CYCLE: aka "citric acid cycle"; a series of reactions that takes place in the mitochondrial matrix; produces NADH; also creates 2 ATP for every glucose molecule sent through glycolysis
    • (4) OXIDATIVE PHOSPHORYLATION: occurs in the mitochondria's inner membrane; produces ATP with the addition of phosphate
  • ANAEROBIC RESPIRATION: does not require oxygen; produces energy through repeated glycolysis and fermentation

PHOTOSYNTHESIS: the process by which plants convert sunlight into fuel; simplified = carbon dioxide and water combine with sunlight to form oxygen and glucose (6CO2 + 6H2O + light >> C6H12O6 + 6O2)

Image Credit: Daniel Mayer (Wikimedia Commons)

Meiosis Diagram
Meiosis Diagram

E. Demonstrate understanding of mitosis and meiosis

Mitosis is the division of one cell into two identical daughter cells. Meiosis is the division of those daughter cells into gametes.

MITOSIS: see Section C above

MEIOSIS: the creation of haploid sex cells (gametes)

  • (1) PROPHASE I: chromosomes line up along the spindles in homologous pairs, which then intertwine during synapsis to form a tetrad; here, crossing-over (the swapping of alleles between chromatids) may occur
  • (2) METAPHASE I: the tetrads line up randomly at the center of the cell
  • (3) ANAPHASE I: the tetrads separate as pairs of chromatids to opposite ends of the cell
  • (4) TELOPHASE I: nuclear membranes reform; the cell physically divides into two hapoloid daughter cells containing 23 chromosomes
  • (5 - 8) MEIOSIS II: cells do not undergo DNA replication; stages similar to mitosis; results in the formation of four haploid cells
Image Credit: National Institutes of Health (Wikimedia Commons)



Image Credit: Neil Palmer / CIAT (Flickr)

DNA Replication Diagram
DNA Replication Diagram

A. Demonstrate understanding of DNA replication

DNA replication, or the creation of identical new DNA strands, must occur in order for cells to divide.

DNA REPLICATION: the process by which two identical daughter helices emerge from one parent helix of DNA (deoxyribonucleic acid)

  • STEP 1: The enzyme helicase unzips the DNA strand to create the replication fork; this separates the nucleotide "rungs" (Adenine + Thymine and Cytosine + Guanine; connected by hydrogen bonds) into two template strands (leading: 5'-3'; lagging: 3'-5')
  • STEP 2: RNA primers prep the strands (lead: continuously; lag: discontinuously)
  • STEP 3: DNA polymerase replaces the primer; DNA ligase connects the Okazaki fragments on the lagging strand
Image Credit: Mariana Ruiz (Wikimedia Commons)

Protein Synthesis Diagram
Protein Synthesis Diagram

B. Demonstrate understanding of the processes involved in protein synthesis

Transcription and translation are the two primary processes that occur during protein synthesis.

PROTEIN SYNTHESIS: the process by which cells build proteins

  • (1) TRANSCRIPTION: RNA polymerase unzips the DNA helix; one strand is utilized to create a complementary mRNA chain; DNA + RNA = Cytosine + Guanine, Guanine + Cytosine, Thymine + Adenine, Adenine + Uracil
  • (2) TRANSLATION: the mRNA chain is decoded to produce a polypeptide (protein strand)
    • mRNA chain attaches to a ribosome
    • tRNA (clover-shaped molecules that transport amino acids) enter the ribosome at the P site and A site
    • tRNA anticodons (i.e. UAG) attach to the complementary mRNA codons (i.e AUC)
    • peptide bonds form between the amino acids transported by the tRNA
    • the mRNA chain continues to slide until a stop codon enters the ribosome
    • the polypeptide is released into the cytoplasm
Image Credit: Kelvinsong (Wikimedia Commons)

C. Demonstrate understanding of the causes and results of mutation

Some mutations, or permanent DNA changes, are beneficial, others may be harmful or fatal.


  • FRAMESHIFT: occurs when a nucleotide is inserted or deleted from a codon; can result in cystic fibrosis, muscular dystrophy, physical deformities
    • INSERTION: occurs when an additional base pair is incorrectly inserted into a DNA sequence
    • DELETION: occurs when a piece of DNA is permanently removed from its sequence
  • SUBSTITUTION: occurs when a single nucleotide is replaced by a different nucleotide; can result in silent mutation, sickle-cell anemia

Punnett Square Illustrating Mendelian Inheritance
Punnett Square Illustrating Mendelian Inheritance

D. Demonstrate understanding of Mendelian inheritance

Gregor Mendel, a 19th century monk who studied pea plants, discovered the basic rules of chromosomal inheritance.

  • GENOTYPE: the genetic makeup of a certain trait
    • Homozygous: when both genes are dominant or recessive (RR, rr)
    • Heterozygous: when one gene is dominant and the other recessive (Rr)
  • PHENOTYPE: the physical expression of a gene
  • MONOHYBRID CROSS: examines one trait; results in a 1:2:1 genotypic and 3:1 phenotypic ratio
  • DIHYBRID CROSS: examines two traits
  • LAW OF DOMINANCE: hereditary information for two different forms of a single trait can coexist in an individual; one will be dominant, the other recessive
  • LAW OF SEGREGATION: hereditary information comes in paired units (one from each parent) that separate randomly during the formation of sex cells
  • LAW OF INDEPENDENT ASSORTMENT: the inheritance of one trait is unrelated to the inheritance of another; the units from one pair segregate into the gametes independently of the units from another pair
Image Credit: Pbroks13 (Wikimedia Commons)

Codominant Inheritance Diagram
Codominant Inheritance Diagram

E. Demonstrate understanding of some aspects of non-Mendelian inheritance

Non-Mendelian inheritance explains how traits can be passed down in ways other than chromosomal inheritance.

  • MULTIPLE ALLELES: when a population (i.e. blood type) has more than two alleles in it
    • ALLELES: DNA codes that account for various traits; each is located on a specific locus on a chromosome
  • INCOMPLETE DOMINANCE: when a heterozygous individual exhibits a phenotype halfway between the dominant and recessive phenotypes (i.e. the color of snapdragon flowers)
  • CODOMINANCE: both dominant and recessive traits appear (i.e. blood type)
  • POLYGENIC INHERITANCE: when more than one gene affects the phenotype (i.e. skin color)
  • PHENOTYPIC PLASTICITY: when the phenotype is affected by the environment (i.e. IQ)
  • X-LINKED INHERITANCE: affects genes found on the X chromosome
Image Credit: Apers0n (Wikimedia Commons)

F. Demonstrate knowledge of how recombinant DNA is constructed and identify its uses

Artificially constructed DNA has many valuable applications in medicine and agriculture.

RECOMBINANT DNA: artificial DNA that is created through the insertion of a specific code into an existing DNA strand, such as the plasmids of bacteria

  • USES: the production of vaccines, genetically enhanced crops and peptide hormone medications such as insulin

Karyotype Illustrating Trisomy of the 21st Chromosome
Karyotype Illustrating Trisomy of the 21st Chromosome

G. Identify chromosomal and gene aberrations that lead to common human genetic disorders

Mutations such albinism and Down Syndrome occur as the result of gene abnormalities.

AUTOSOMAL MUTATIONS: caused by an abnormality in a single gene; inherited in a Mendelian fashion; occur on autosomal chromosomes, which determine physical characteristics

  • RECESSIVE: a mutation that results in an allele that produces a nonfunctional protein; the phenotype will appear only if both copies of the allele are present (homozygous carrier); can be passed on if one copy is present (heterozygous carrier); includes albinism, sickle-cell anemia
  • DOMINANT: a mutation that results in the production of a protein with an abnormal and harmful action; all heterozygous carriers will show the phenotype; includes Huntington's Disease
CHROMOSOMAL DISORDERS: result from the gain or loss of an entire chromosome (nondisjunction: when a pair of homologous chromosomes fails to separate during meiosis I)
  • TRISOMY: three copies of a chromosome; fatal (exception: #21, which causes Down Syndrome)
  • MONOSOMY: one copy of a chromosome; fatal (exception: X chromosome, which causes Turner Syndrome)
  • POLYPLOIDY: an entire set of extra chromosomes; fatal (exception: fish, plants)
SEX-LINKED DISORDERS: caused by the mutation of a sex cell
  • X-CHROMOSOME RECESSIVE: women possess two copies of the X chromosome; an x-linked recessive disorder (i.e. color blindness, hemophilia) can thus be overridden in a female but not in a male
Image Credit: National Human Genome Research Institute (Wikimedia Commons)

The Cartoon Guide to Genetics - The perfect textbook for people who can't stand textbooks.

The Cartoon Guide to Genetics (Updated Edition)
The Cartoon Guide to Genetics (Updated Edition)

If your eyes glaze over at the mere sight of a traditional textbook (whose don't, really?), this is the study guide for you. Illustrated by nonfiction cartoonist Larry Gonick, the Cartoon Guide to ___ series -- which covers everything from calculus to chemistry -- is a phenomenal resource for students and aspiring teachers alike. I used this genetics guide while studying for the PRAXIS II Middle School Science exam and scored higher on that portion of the test than any other.




Image Credit: Michael Ransburg (Flickr)

Diagram of Homologous Structures
Diagram of Homologous Structures

A. Identify evidence that supports the theory of evolution

The theory of evolution states that all life on Earth evolved from a common ancestor through the process of natural selection.

ROCK & FOSSIL FORMATION: fossils are the only direct evidence of evolution; rock formation helps date fossils

COMPARATIVE ANATOMY: different animals possess similar anatomical structures

  • HOMOLOGOUS STRUCTURES: anatomical features in different species that point to a common ancestor (i.e. human arm and whale flipper)
  • ANALOGOUS STRUCTURES: features that have superficial similarities due to their similar functions but which do not result from a common ancestor (i.e. bat wing and insect wing)
  • VESTIGIAL STRUCTURES: features that serve no apparent modern function; help determine how an organism evolved (i.e. appendix)
COMPARATIVE EMBRYOLOGY: some homologous structures which do not appear in maturity are visible in vitro (i.e. human tail)

MOLECULAR EVOLUTION: molecular clocks (genes and proteins that change at a constant rate over time) help determine when ancient species split from their common ancestor

Image Credit: Thomas Hunt Morgan (Wikimedia Commons)

Diagram Illustrating Genetic Mutations and Natural Selection
Diagram Illustrating Genetic Mutations and Natural Selection

B. Demonstrate understanding of the mechanisms of evolution

Evolution is made possible by changes in DNA, which, if favorable, become more common in a species.

GENETIC MUTATIONS: favorable mutations become more common while harmful mutations decline

GENE FLOW: the transfer of alleles from one population to another; aka "migration"

GENETIC DRIFT: a change in the relative frequency of an allele that occurs due to random sampling/chance; a gene pool can change in the absence of environmental or other external influences

NATURAL SELECTION: the process by which beneficial traits outlast others

  • STABILIZING: eliminates extremes
  • DIRECTIONAL: eliminates one extreme
  • DISRUPTIVE: eliminates intermediates
Image Credit: Elembis (Wikimedia Commons)

Speciation Diagram
Speciation Diagram

C. Demonstrate knowledge of isolating mechanisms and speciation

Isolating mechanisms allow for the creation of new species.

ISOLATING MECHANISM: any property of two species that stops them from interbreeding

  • PREZYGOTIC MECHANISMS: ecological, seasonal, sexual, mechanical, pollinator, gametic
  • ZYGOTIC MECHANISMS: hybrid inviability, hybrid sterility, hybrid breakdown
SPECIATION: the creation of new species; occurs when two species become reproductively isolated
  • ALLOPATRIC: occurs when species become geographically isolated
  • ADAPTIVE RADIATION: the creation of several species from a single parent species; occurs over relatively short periods of time when a species faces competition and environmental pressures; fueled by natural selection
Image Credit: Ilmari Karonen (Wikimedia Commons)

D. Demonstrate understanding of the scientific hypotheses for the origin of life on Earth

ORIGIN OF LIFE: life began 3.5 billion years ago; the atmosphere of Earth was composed mostly of hydrogen, water, ammonia and methane; electric discharges from lightning, radioactivity and ultraviolet light caused the formation of basic molecules such as nucleotides and simple proteins; over time, the molecules became more complex heterotrophs; their anaerobic processes released CO2 into the atmosphere; photosynthetic autotrophs evolved and released oxygen; heterotrophs then developed aerobic respiration;



Image Credit: Umberto Salvagnin (Flickr)

Cell Diagram
Cell Diagram

A. Demonstrate understanding of the levels of organization and characteristics of life

There are 11 widely recognized levels of organization and seven characteristics that define a living thing.


  • (1) atoms
  • (2) molecules: a group of at least two atoms held together in a definite arrangement by a chemical bond
  • (3) organelles: a specialized unit within a cell
  • (4) cells: the basic structural and functional unit of all life
  • (5) tissues: a group of cells that perform the same function
  • (6) organs: a group of tissues that perform the same function
  • (7) organ systems: a group of organs that perform the same function
  • (8) multi-cellular organisms
  • (9) populations: a group of interbreeding organisms living within a defined area
  • (10) communities: a group of interacting populations living within a defined area
  • (11) ecosystems: the combined chemical and biological elements of an environment
  • (1) cellular organization
  • (2) metabolism (energy use)
  • (3) homeostasis
  • (4) growth and development
  • (5) environmental adaptation (response to stimuli)
  • (6) reproduction/heredity
  • (7) evolution
Image Credit: Holly Fischer (Wikimedia Commons)

B. Identify the elements of the hierarchical classification scheme

All living things are classified into groups based on their physical and genetic similarities.

Kingdom > Phylum > Class > Order > Family > Genus > Species

"King Philip Came Over For Great Steak"


  • Bacteria: bacteria, cyanobacteria, actinobacteria
  • Archaea: halophiles, thermophiles, methanogens, psychrophiles
  • Protista: amoebae, green and brown algae, diatoms, slime molds, euglena
  • Fungi: mushrooms, yeast, mold
  • Plantae: mosses, angiosperms, gymnosperms, liverworts, ferns
  • Animalia: mammals, amphibians, insects, worms, sponges
* These are the six kingdoms most commonly taught in the United States. However, this system of classification varies and may include anywhere from five to eight kingdoms.

Virus Diagram
Virus Diagram

C. Demonstrate knowledge of the characteristics of viruses, bacteria, protists, fungi, plants, and animals

  • VIRUSES: tiny infectious agents that invade all types of cells; parasitic
  • BACTERIA: prokaryotic; reproduce asexually via binary fission; includes bacteria and blue-green algae
  • PROTISTS: eukaryotic; mostly unicellular; includes amoebas, sporozoa, algae and slime molds
  • FUNGI: eukaryotic; heterotrophic; includes yeast, mushrooms and molds
  • PLANTS: eukaryotic; photosynthetic; includes mosses, ferns, trees and flowers
  • ANIMALS: eukaryotic; heterotrophic; includes coral, worms, insects, fish, reptiles, birds and mammals
Image Credit: Anderson Brito (Wikimedia Commons)



Image Credit: Neil Palmer / CIAT (Flickr)

A. Demonstrate understanding of the characteristics of vascular and nonvascular plants

Vascular plants take in water via specialized tissues while nonvascular plants absorb water through osmosis or diffusion.

VASCULAR: plants with specialized tissues (xylem and phloem) that transport water and nutrients

  • Examples: flowering plants, ferns, trees
NONVASCULAR: plants lacking a vascular system; absorb and transport water through osmosis or diffusion
  • Examples: mosses, liverworts, hornworts, algae

Leaf Diagram
Leaf Diagram

B. Demonstrate understanding of the structure and function of roots, stems and leaves

Roots, stems and leaves are the three primary structures that make up a plant.

  • ROOTS: organs that absorb water and nutrients; stabilize plants by anchoring them to the ground
    • TAPROOT: a single large root (i.e. carrots)
    • FIBROUS ROOTS: several primary roots with smaller branches
    • AERIAL ROOTS: grow above ground
    • AERATING ROOTS: grow above water
  • STEMS: support structures that (1) keep a plant's fruits, flowers and/or leaves close to its light source, (2) store nutrients, (3) produce new tissue and (4) transport fluids
  • LEAVES: specialized structures that (1) perform photosynthesis, (2) allow for gas exchange and (3) store nutrients during germination
Image Credit: Zephyris (Wikimedia Commons)

Diagram Illustrating the Life Cycle of a Flowering Plant
Diagram Illustrating the Life Cycle of a Flowering Plant

C. Demonstrate understanding of control mechanisms

Hormones, photoperiods and tropisms are mechanisms that affect the metabolism of plants.


  • HORMONES: Chemicals that regulate plant growth as well as the formation of new flowers, stems and leaves, the shedding of leaves and the development and ripening of fruit. Unlike animals, plants do not rely on glands to produce hormones. All plant cells are capable of producing hormones.
  • PHOTOPERIODS: The amount of time during which a plant is exposed to light
  • TROPISMS: A plant's ability to alter its growth in the direction of more favorable conditions (i.e. phototropism - plants grow toward the nearest light source even when they sprout in a shaded area)
Image Credit: Mariana Ruiz (Wikimedia Commons)

D. Demonstrate understanding of water and nutrient uptake and transport systems

Xylem and phloem are specialized tissues that transport water and nutrients in vascular plants.

  • XYLEM: transports water and nutrients from a plant's roots to its stems and leaves
  • PHLOEM: transports sugar-rich sap down through the plant's leaves to its roots
  • ROOTS AND STEMS: absorb and transport water and nutrients
  • TRANSPIRATION: a process similar to evaporation whereby water leaves the plant

Plant Reproduction Diagram
Plant Reproduction Diagram

E. Demonstrate understanding of sexual and asexual reproduction in plants

Plants produce either unique offspring through sexual reproduction or offspring that are genetic clones of the parent through asexual reproduction.

SEXUAL REPRODUCTION: involves the male (stamen) and female (pistil) parts of a plant. The stamen produces pollen which, when transported to the pistil, fertilizes it to create seeds.

ASEXUAL REPRODUCTION: only requires one plant and does not involve meiosis. Occurs when a plant is fragmented and re-planted (vegetative reproduction) or through the creation and dispersal of seeds (apoximis).

Image Credit: Noah Elhardt (Wikimedia Commons)



Image Credit: Paul Williams (Flickr)

Human Digestive System Diagram
Human Digestive System Diagram

A. Demonstrate understanding of the anatomy and physiology of structures associated with life functions of animals

Ten specialized systems control all of the bodily processes that allow organisms in the animal kingdom to live.

  • DIGESTIVE SYSTEM: digestion is the process by which food is broken down into parts, both mechanically and chemically, that are able to be absorbed and utilized by the body; structures involved include the salivary glands, teeth, tongue, throat, stomach, pancreas, liver, gallbladder and small and large intestines
  • CIRCULATORY SYSTEM: circulation is the process by which materials such as blood and nutrients are transported, or circulated, through the body; structures involved include the heart, veins and arteries
  • RESPIRATORY SYSTEM: respiration is the process by which oxygen is brought into the body's cells and exchanged for carbon dioxide, which is then transported back out of the body; structures involved include the nose, mouth, trachea and lungs
  • EXCRETORY SYSTEM: excretion is the process by which waste products are removed from the body; structures involved include the kidneys, urinary tract and rectum
  • NERVOUS SYSTEM: the body system that receives and responds to external and internal stimuli; structures involved include the brain, nerves and spinal cord
  • MUSCULO-SKELETAL SYSTEM: the body system responsible for support, growth and movement; structures involved include bones, joints, muscles and tendons
  • IMMUNE & LYMPHATIC SYSTEMS: immunity is the body's ability to defend itself against invading pathogens and disease; structures involved include white blood cells and red bone marrow
  • ENDOCRINE SYSTEM: the body system responsible for the production of hormones; structures involved include the hypothalamus, pituitary glands, adrenal glands and pancreas
  • REPRODUCTIVE SYSTEM: reproduction is the body's ability to pass on its genetic material to a new organism; structures involved include the ovaries, uterus and testes
  • INTEGUMENTARY SYSTEM: the system responsible for protecting the body's internal processes from external factors; structures involved include skin, hair and nails
Image Credit: Mariana Ruiz (Wikimedia Commons)

B. Demonstrate knowledge of homeostasis and how it is maintained

Maintaining homeostasis, or a stable internal environment, is an essential component of animal survival.

HOMEOSTASIS: the body's ability to regulate its internal environment despite external changes; all human body systems are involved in homeostasis

HOW HOMEOSTASIS IS MAINTAINED: the nervous and endocrine systems respond to feedback mechanisms from other body systems in order to maintain homeostasis

  • POSITIVE FEEDBACK EXAMPLE: oxytocin is released by the endocrine system to increase contractions during childbirth
  • NEGATIVE FEEDBACK EXAMPLE: increased glucose spurred by the consumption of sugar-packed foods causes the body to release insulin, which stimulates the pancreas to help normalize blood sugar levels

C. Demonstrate knowledge of how animals respond to stimuli

Involuntary responses to stimuli are automatic while voluntary responses are consciously chosen.

INVOLUNTARY RESPONSE: a response determined by the automatic nervous system, such as blood clotting or pulling away from a hot object

VOLUNTARY RESPONSE: a response determined by learned behaviors or beliefs, such as choosing which route to take when driving to the mall



Image Credit: Loco Steve (Flickr)

A. Demonstrate understanding of population dynamics

Scientists study population dynamics in order to measure ecological changes in different groups of individuals.

POPULATION DYNAMICS: the ecological study of short- and long-term changes in different populations (groups of individuals that interbreed and share the same gene pool) and the processes that influence those changes; factors like growth rate and the availability of resources affect populations

Example of a Threat Display
Example of a Threat Display

B. Demonstrate knowledge of social behaviors

Social behaviors determine how an animal acts when confronted by others of either the same or a different species.

  • TERRITORIALITY: a type of interspecific competition that results from the exclusion of others from a specific space; exhibited through songs, calls, intimidation behavior, attacks and scent-marking;
  • DOMINANCE: when some animals within a population exert influence over the others (i.e. gorillas, wolves); dominance may be rewarded with access to resources, mates and territory;
  • ALTRUISM: when an animal sacrifices its own well-being for the benefit of another; most common in kin relationships; may appear in wider social groups due to reciprocity;
  • THREAT DISPLAY: a type of behavior aimed at intimidating a potential enemy (i.e. cats, porcupines)
Image Credit: Chris Huh (Wikimedia Commons)

C. Demonstrate understanding of intraspecific competition

Intraspecific competition impacts available resources and controls population levels.

INTRASPECIFIC COMPETITION: when members of the same species compete for the same resource in an ecosystem; impacts the environment's carrying capacity (maximum population level)

D. Demonstrate understanding of interspecific relationships

Interspecific relationships are defined by which organism benefits and which, if any, does not.

INTERSPECIFIC RELATIONSHIPS: interaction between different species; can be both beneficial and detrimental

  • COMMENSALISM: a relationship in which one species benefits and the other is unaffected (i.e. sharks/remoras)
  • MUTUALISM: a relationship in which both species benefit (i.e. bees/flowers)
  • PARASITISM: a relationship in which one species benefits and the other is harmed (i.e. caterpillars/plants)

Diagram Illustrating Secondary Succession
Diagram Illustrating Secondary Succession

E. Demonstrate understanding of succession

Succession refers to the predictable changes that impact an ecological community over time.

SUCCESSION: predictable changes in the structure or composition of an ecosystem

  • PRIMARY: the establishment of plants on land that has not been previously vegetated; begins with the colonization of pioneer species;
  • SECONDARY: the invasion by plants of land that was previously vegetated; may occur after logging, cultivation or a natural disaster;
  • ALLOGENIC: caused by a change in environmental conditions
  • AUTOGENIC: caused by the activities of plants over time; both the plant community and environment change;
  • PROGRESSIVE: when the community becomes more complex and contains more species and biomass
  • RETROGRESSIVE: when the community becomes more simplistic and contains fewer species and less biomass
Image Credit: Katelyn Murphy (Wikimedia Commons)

Diagram of Biomes in North and South America
Diagram of Biomes in North and South America

F. Identify the types and characteristics of biomes

Biomes are areas of the earth characterized by similar climates, geography, vegetation and animal populations.


  • MARINE: include oceans, coral reefs and estuaries; typically divided into the intertidal/littoral zone (beach), the neritic zone (continental shelf) and the pelagic zone (open ocean); the pelagic zone consists of a photic zone (600 feet below sea level; home to photosynthetic plankton and bony fish) and aphotic zone (a dark, extremely cold and high pressure environment);
  • FRESHWATER: includes rivers, lakes and marshes; life is affected by temperature, salt concentration, light penetration, depth and availability of dissolved CO2 and O2; smaller and less stable than marine biomes;
  • TUNDRA: a biome in which tree growth is inhibited by low temperatures and short growing seasons; vegetation includes dwarf shrubs, grasses, mosses and lichens; subsoil is often permafrost (permanently frozen); includes arctic tundra, antarctic tundra (fewer mammal species) and alpine tundra (lacks permafrost);
  • TAIGA: largest terrestrial biome; characterized by boreal coniferous (evergreen) forests with little understory vegetation; bears, moose and deer are common; soil is often slow to decompose, acidic and mineral deficient; found in Russia and Canada;
  • TEMPERATURE DECIDUOUS FOREST: characterized by a moderate climate, leaf-shedding trees and well-developed understory vegetation; home to many different herbivores/carnivores and some amphibians/ reptiles; soil is characterized by rapid decomposition; severely impacted by humans; found primarily in the Eastern United States, Europe and Eastern Asia;
  • DESERTS: characterized by very little rainfall (less than 10 inches per year); limited vegetation includes shrubs and cacti; soil tends to be mostly sandy or rocky with little organic matter; home to specialized reptiles, birds and insects; radical temperature changes between day and night; found in Asia, Africa, Australia and North America;
  • TEMPERATE GRASSLANDS: vegetation includes shrubs and grasses; fertile, nutrient-rich soil; home to many burrowing/grazing animals; found in the American mid-West;
  • TROPICAL SAVANNAS: grasslands with scattered, drought-resistant trees that do not form a closed canopy; typically border rainforests; characterized by distinct wet and dry seasons; richest diversity of grazing animals; nutrient-rich soil; found primarily in Africa;
  • TROPICAL RAINFOREST: characterized by extensive precipitation (up to 180 inches per year) and the greatest diversity of plant and animal life; hot and humid throughout the year; soil is quick to decompose, acidic and nutrient-deficient; found in Central America, the Amazon, Central Africa and Southeast Asia;
Image Credit: Sten Porse (Wikimedia Commons)

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    • wildsimplicity profile imageAUTHOR


      5 years ago from Atlanta, GA

      @JennyReis: Thanks, JennyReis! :)

    • wildsimplicity profile imageAUTHOR


      5 years ago from Atlanta, GA

      @anonymous: Hey Shota. I was really familiar with certain concepts in the list of topics that the middle school science exam covers so some things didn't make it onto my study guide. :)

    • wildsimplicity profile imageAUTHOR


      5 years ago from Atlanta, GA

      @anonymous: Awesome! I'm happy I could help. :) There were no free online study resources when I was preparing for the exam and it was so stressful.

    • profile image


      5 years ago

      This is by far the best study guide that i have found! Thank you so much!

    • profile image


      5 years ago

      This has been SUPER helpful, but i noticed that there are some items missing for Ecology. "demonstrate understanding of the concepts of stability and ecosystems and the effects of disturbances", "demonstrate understanding of energy flow (for example, trophic levels and food webs)", and "Demonstrate understanding of bio-geochemical cycles (for example, nitrogen, carbon, and water)" were missing.

    • JennyReis profile image


      6 years ago

      A truly engaging lens! Well done!

    • profile image


      6 years ago

      What an awesome lens! Very well put together and interesting, just got done going through all this in BIO I and the content is certainly accurate. Well done.

    • profile image


      6 years ago

      Thanks a lot for putting this together. I found this to help me tremendously.


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