TEAS 6 SCIENCE
Endocrine System
ANATOMY AND PHYSIOLOGY
Gland/Organ Hormone Secreted Function
Hypothalamus Releasing/Inhibiting
... [Show More] hormones Stimulate Pituitary
Anterior Pituitary (base of brain; controls growth and development Adrenocorticotropic Hormone (ACTH) Stimulate adrenal cortex to secrete glucocorticoids
Thyroid Stimulating Hormone (TSH) Stimulate the Thyroid gland
Follicle Stimulating Hormone (FSH) Stimulates production of ova (females) and sperm (males)
Luteinizing Hormone (LH) Stimulates Ovaries (females) and Testes
(males)
Prolactin Stimulates milk production
Growth Hormone (GH) Stimulates growth (bones) and metabolic functions
Posterior Pituitary (back of anterior pituitary) Antidiuretic Hormone (ADH) Promotes retention of water by the kidneys
Oxytocin Stimulates contraction of uterus and mammary gland cells
Pineal Gland (center of
brain) Melatonin Sleep cycles; biorhythms
Thyroid (neck; hormones regulate growth,
development, and metabolism) Triiodothyronine (T3) Metabolism
Thyroxine (T4) Metabolism and temperature
Calcitonin Inhibits release of Calcium from bones
Parathyroid (4 glands on Thyroid) Parathyroid Hormone (PTH) Stimulates release of calcium from bones, back into blood.
Thymus (lymphoid organ
that produces T-Cells) Thymosin Stimulates T-Cell Development
Adrenal Glands (Above Kidneys; regulate HR, BP, and other functions) See below See below
Adrenal Cortex (stimulates fight or flight response) Cortisol/Glucocorticoids Stress response; Increase blood glucose, Decrease immune response; metabolism
Aldosterone Regulates Na content in blood
Adrenal Medulla (stimulates fight or flight response) Epinephrine Fight
Norepinephrine Flight
Ovaries (female gonads) Estrogen Stimulates egg maturation, controls 2ndary sex
characteristics
Progesterone Prepares uterus to receive fertilized egg
Testes (male gonads) Testosterone Regulates sperm production and 2ndary sex characteristics
Kidneys Erythropoietin Response to cellular hypoxia
Renin Promotes production of Angiotensin
Liver Angiotensin II Vasoconstriction, Increase BP
Pancreas Glucagon (Alpha Cells) Increase blood glucose
Insulin (Beta Cells) Decrease blood glucose
Stomach Gastrin Response to food; stimulates production of gastric juices
Intestine Secretin Response to acidity in small intestine; stimulates secretion by liver and pancreas
Cholecystokinin Production of Bile Salts
Heart Atrial Natriuretic Peptide (ANP) Increase renal Na excretion, decrease ECF
Gastrointestinal System
Enzyme Production site Release site
Carbs Salivary Amylase Salivary Glands Mouth
Pancreatic Amylase Pancreas Small Intestine
Maltase Small Intestine Small Intestine
Protein Pepsin Chief Cells (gastric gland) Stomach
Trypsin Pancreas Small Intestine
Peptidases Small Intestine Small Intestine
Nucleic Acids Nuclease Pancreas Small Intestine
Nucleosidase Pancreas Small Intestine
Lipids Lipase Pancreas Small Intestine
Bile Salt LiverGallbladder Small Intestine
*Bile is technically not an enzyme, but a salt that emulsifies lipid into fatty droplets. Chief Cells: Covert pepsinogen to pepsin
Goblet Cells: Mucus secretions Parietal Cells: HCl production
Peyer's Patches: Lymphatic Tissue found in Ileum to protect GI tract from pathogens
Integumentary System
Epidermis: Most superficial layer of skin; entirely epithelial cells
• Does NOT contain blood vessels
• 5 layers
o Stratum Corneum: "Top Layer"- Dead keratinocytes
o Stratum Lucidum: "Clear Layer"- Colorless protein eleidin
o Stratum Granulosum: "Thin Layer"- granular layer
o Stratum Spinosum: "Spiny Layer"- Thickest layer, keratinocytes, immune dendritic cells, sensory cells
o Stratum Basale: "Basal Layer"- Bottom layer; contains melanocytes.
Dermis: Directly below epidermis; mostly connective tissue
• Contains blood vessels
• Sensory receptors
• Hair follicles
• Sebaceous glands
• Sweat glands
• Elastin and Collagen fibers
Hypodermis/SubQ: Connective tissue
• Binds the skin to underlying muscle
• Fat deposits cushion and insulate the body Glands
Exocrine: Secrete substances into ducts
• Holocrine: secretory products; whole cells; connected to hair follicle
o Sebaceous Glands: secrete sebum: an oily mixture of lipids and proteins; waterproofs skin, protects from pathogens
• Eccrine: Not connected to hair follicle, activated by high body temperature, located throughout the body. A type of sweat gland (sudoriferous gland) in thermoregulation.
o Secrete a salty solution of electrolytes and water
NaCl
KHCO3
Glucose
Antimicrobial Peptides
• Apocrine: Secrete an oily solution (fatty acids, triglycerides, and proteins)
o Located in:
Armpits
Groin
Palms
Soles of feet
o Secrete (sweat) during anxiety or stress
o Body Odor forms from bacteria feeding on apocrine sweat
Urinary System
Kidney (2): Regulates fluid balance and filters waste from blood
• Receive blood from renal artery (extension of aorta)
• Filter blood
• Reabsorb need materials
• Excrete waste and water via urine
• Renal Cortex: Outer Layer
o Contains ~1 million Nephrons (filters)
o Glomerulus: Capillary in nephron
o Bowman's Capsule: encapsulates the glomerulus
• Renal Medulla: Middle Layer
o Proximal Convoluted Tubule: Water, glucose, ions, and other organic molecules are reabsorbed back into the blood stream.
o Distal Convoluted Tubule: Urea and drugs are removed from blood. pH in blood is adjusted with H+ ions.
• Renal Pelvis: Inner Layer
o Materials arrive as urine from distal convoluted tubule.
Reproductive System
MALES
• Produce, maintain, and transfer sperm and semen into the female reproductive tract.
• Produce and secrete male hormones.
External Organs: Penis, Scrotum, Testes
• Scrotum: Protects testes; keeps optimal temperature for spermatogenesis.
• Testes: Male gonads; produce sperm and testosterone.
Internal Organs: Epididymis, Vas Deferens, Ejaculatory Ducts, Urethra, Seminal Vesicles, and Bulbourethral glands
• Epididymis: Stores sperm as it matures
• Vas Deferens: Mature sperm move from epididymis to Vas Deferens to the ejaculatory duct
• Seminal Vesicles: Secrete alkaline fluids with protein and mucus into ejaculatory duct
• Prostate Gland: Secretes a milky white fluid with proteins and enzymes as part of semen
• Bulbourethral (Cowper's) Gland: Secrete a fluid to neutralize the acidity in the urethra
Hormones
• FSH: Stimulates spermatogenesis
• LH: Stimulates testosterone production
• Testosterone: Male sex characteristics
FEMALES
• Produce ova (oocytes/egg cells)
• Transfer ova to fallopian tubes for fertilization
• Receive sperm from male
• Provide a protective, nourishing environment for developing embryo
External Organs: Labia Majora, Labia Minora, Bartholin's Glands, Clitoris
• Labia (both): Close and protect vagina
• Bartholin's Gland: Secrete lubricating fluid
• Clitoris: Contains erectile tissue and nerve endings for sensual pleasure
Internal Organs: Ovaries, Fallopian Tubes, Uterus, Vagina
• Ovaries: Female gonads; produce ova, and secrete estrogen and progesterone
• Fallopian Tubes: Carry mature egg toward uterus; site of fertilization
• Uterus: Fertilized egg implants on uterine wall; protects and nourishes developing embryo until birth
• Vagina: Muscular tube from cervix to outside of body; receives semen, is site of intercourse, and birth canal
Hormones
• Estrogen: Stimulates egg maturation; female sex characteristics
• Progesterone: Prepares uterus to receive fertilized egg
• FSH: Stimulates oogenesis
• LH: Stimulates estrogen production
• Oxytocin: Stimulates contraction of uterus and mammary gland cells
• Prolactin: Stimulates milk production
Immune System
Function: Protects the body against invading pathogens including bacteria, viruses, fungi, and protists.
Lymphatic System: Lymph, lymph capillaries, lymph vessels, lymph nodes.
• Skeletal muscle contractions move the lymph one way through the lymphatic system to lymphatic ducts
o Dump back into venous supply via lymph nodes
• Red marrow- produces blood cells
• Leukocytes- WBC
Lymph Nodes: located in neck, armpit, and groin
• Small swellings in the lymphatic system where lymph is filtered and lymphocytes are formed
Lymph Tissue: Tonsils, adenoids, thymus, spleen, peyer's patches
• Tonsils: Located in pharynx
o Protect against pathogens entering via mouth or throat
• Thymus: Maturation chamber for immune T Cells formed in bone marrow
• Spleen: Cleans blood of dead cells and pathogens
• Peyer's Patches: Located in ileum of Sm. Intestine.
o Protects GI tract from pathogens
General Immune Defenses
• Skin: Primary barrier (intact)
• Ciliated Mucous Membranes: Cilia protect respiratory system
• Glandular Secretions: Exocrine- destroy bacteria
• Gastric Secretions: Gastric Acid destroys pathogens
• Normal Bacterial Populations: Compete with pathogens in gut and vagina
3 Types of WBC
• Macrophage: Phagocytes that alert T-Cells to the presence of foreign substances
o Largest, longest living phagocyte
o Engulf and destroy pathogens
o Found in lymph
• T Lymphocytes: Directly attack cells infected by viruses and bacteria
o Helper T, Killer T, Memory T, Suppressor T
• B Lymphocytes: Target specific bacteria for destruction
o Plasma Cells: Antibody production.
Other Immune Cells
• Helper T-Cells: Activate B-Cells to make Antibodies and other chemicals
• Suppressor T-Cells: Stop other T-Cells when the battle is over
• Memory T-Cells: Remain in blood on alert incase invader attacks again
• Killer/Cytotoxic T-Cells: Destroy Cells infected with a pathogen, virus, or tumor
Leukocytes: WBC- Produced in Red Marrow
• Monocyte
o Macrophage
o Dendritic Cell: Present antigens to T Cell
• Granulocyte
o Neutrophil: Short living phagocyte; responds quick to invaders
o Basophil: Alerts body of invasion
o Eosinophil: Large, long living phagocyte; Defend against multicellular invaders
• T Lymphocyte
• B Lymphocyte
• Natural Killer Cell
Antibody Mediated Response: Response is to an antigen
Cellular Mediated Response: Response is to an already infected cell
Antigen: Foreign particle that stimulates the immune system
• Typically a protein on the surface of bacteria, virus, or fungi Antibody: A blood protein that counteracts a specific antigen
Steps of Immune System
1. Macrophage engulfs antigen and presents fragments of antigen on its surface
2. A Helper T Cell joins the Macrophage
3. Killer/Cytotoxic T Cells and B Cells are activated
4. Killer/Cytotoxic T Cells search and destroy cells presenting the same antigen
5. B Cells differentiate into Plasma Cells and Memory Cells
Innate Immune System
• Born with it
• Non Specific response
• EX) Skin, hair, mucus, earwax, secretions, normal flora, antimicrobials, inflammation, interferons, complement, NK Lymphocytes, phagocytes
Adaptive Immune System
• Responds to specific antigens
• Vaccinations or previous encounters
o Reaction: Cytotoxic T Cells kill pathogen
o Prevention: B Cells produce Antibodies
• Activated by Antigen and Helper T Cells
• Helper T Cells activated by Antigen Presenting Cells (APC)
Naturally Acquired Active Immunity: Exposure to pathogen without immunization
Naturally Acquired Passive Immunity: Occurs during pregnancy and during breast feeding
• Antibodies are passed from mother to child
• Provides protection from infancy to childhood
Artificially Acquired Active Immunity: Build immunity via Vaccination
Artificially Acquired Passive Immunity: Immunization given during an outbreak or emergency
• Quick, short lived protection
• Antibodies come from another person or animal
Skeletal System
Function: Movement, Protection, and Metabolism
Bone: Hard calcified material that makes up the skeletal system
• Constantly being reorganized
• Synthesize blood and immune cells
• Stores calcium, phosphate, and lipids
• 4 Types:
o Long Bones: long compact hollow shafts containing marrow
Ends are spongy with air pockets
EX) Humerus, Ulna, Radius, Tibia, Fibula
o Short Bones: Wider than they are long
EX) Metatarsals, Clavicle
o Flat Bones: Not hollow, but contain marrow
EX) Scapula, Ribs, Sternum
o Irregular Bones: Nonsymmetrical shape
EX) Skull, Knee, Elbow, Vertebra Ligament: Articulates BONE to BONE
Tendon: Articulates MUSCLE to BONE
Hyaline Cartilage: Covers articulating surface of bones
• Prevents bone on bone grinding Synovial Joint: Contain lubricating synovial fluid
• Pivot Joint: Neck
• Ball and Socket Joint: Hip
• Hinge Joint: Knee Osteocytes: Bone Cells
• Osteoclast: Multinucleate
o Removes/absorbs bone tissue during growth and healing
• Osteoblast: Mononucleate
o Cells that build bone
Periosteum: Fibrous sheath that covers bone and contains nerve and blood vessels
Osteon: Cylindrical structure that comprise, synthesize, and compact bone
• Composed of Calcium and phosphate rich Hydroxyapatite embedded in collagen matrix
Collagen: Primary structural protein of connective tissue
Canaliculi: Small channel or duct in ossified bone
Cartilage: Tough, elastic connective tissue found in parts of the body (Ear)
Haversian Canal: Channels in bone that contain BV and Nerves
Lamellae: Layers of the bone, tissues, or cell walls
Lining Cells: Flattened bone cells that come from osteoblasts
Volkmann Canal: Channels in bone that transmit BV and communicate with Haversian Canals
Bone Disease
• Osteoporosis: causes brittle, fragile bones
• Brittle Bone Disease: Group of Diseases that
affect the collagen (defect in the matrix) and results in fragile bones
• Osteoarthritis: Degenerative joint disease
• Rheumatoid Arthritis: Progressive disease the causes joint inflammation and pain
Cardiovascular/Circulatory System
Function: Movement of blood and lymph around the body, which permits nutrient distribution, waste removal, communication, and protection
• Closed Double loop system
o Pulmonary Loop: Deoxygenated blood from Rt. Ventricle to lungs and returns Oxygenated blood to Lt. Atrium
o Systemic Loop: Oxygenated blood from Lt. Ventricle to body, returning Deoxygenated blood to Rt. Atrium
• Systole: Contraction of ventricles (heart expels blood)
• Diastole: Relaxation of ventricles (heart refills with blood)
• SA Node: "Pacemaker" controls contractions via electrical signals
• Blood Pressure: Fluid pressure generated by cardiac cycle (sys/dias)
Artery: Blood vessel that carries blood AWAY from heart
• Aorta: large artery branching off heart to the rest of the body
o Coronary Artery
o Carotid Artery
o Subclavian Artery
o Common Iliac Artery
o Renal Artery
Vein: Blood vessel that carries blood TO the heart
• Vena Cava- All veins empty here prior to entering the heart
o Jugular Vein
o Subclavian Vein
o Hepatic Portal Vein
o Common Iliac Vein
o Renal Vein Arteriole: Small artery Venule: Small vein
Capillary: Small blood vessel that connects arterioles to venules
Heart: Muscle that pumps blood throughout the body
Blood: The red liquid that circulates in the arteries and veins
• Carries oxygen to and carbon dioxide from the tissues of the body.
• 4 Main Components:
o RBC: Disc shaped cells that carry Hemoglobin and O2
o WBC: Immune defense
o Platelets: Clotting cells
o Plasma: Liquid portion of blood (mostly water)
Disease:
Myocardial Infarction: Heart attack; Death of the heart muscle due to inadequate blood supply
Stroke: "Brain Attack." Damage to the brain due to inadequate blood supply
Aneurysm: Localized abnormal, weak spot on a blood vessel wall that causes an outward bulging, likened to a bubble or balloon. Hemorrhage occurs when it bursts.
Atherosclerosis: Narrowing of arteries due to plaque buildup on artery walls
Anemia: Not enough healthy RBC
Arrhythmia: Abnormal heart rhythm
• Tachycardia: Too fast
• Bradycardia: Too slow
Hypertension: High blood pressure. Systole is over 140 mmHg; Diastole is over 90 mmHg
Respiratory System
Function: transporting O2 from the atmosphere into the body's cells and moving CO2 in the other direction.
Lungs: 5 Lobes (2 left, 3 right). Main structure of respiratory system. Alveoli: Tiny air sacs; site of O2 and CO2 exchange.
• Occurs by diffusion (passive transport)
Bronchi: The main passageways directly attached to the lungs
Bronchiole: Small passages that connect bronchi to alveoli
Trachea: Windpipe, connects Larynx to lungs Larynx: Voice box
Pharynx: Located behind mouth, also part of GI system
Diaphragm: Dome-shaped sheet of muscle and tendon that serves as the main muscle of respiration and plays a vital role in the breathing process
Pleura: Membrane around lungs, inside chest cavity
Perfusion: Passage of fluid to an organ or tissue
Surfactant: A fluid secreted by alveoli; reduces surface tension- Prevent lung collapse
Tidal Volume: The amount of air breathed in a normal inhalation or exhalation
Ventilation: Movement of air in and out of body via inhalation and exhalation
• Inhalation: Diaphragm contracts downward, ribs push out, lungs fill with air
• Exhalation: Diaphragm relaxes upward, ribs relax, air pushes out
• Hyperventilation: More CO2 than the body can produce (breathing out more than in)
• Hypoventilation: Breathing at an abnormally slow rate, resulting in an increased amount of carbon dioxide in the blood
Neuromuscular System
Function: Controls voluntary and involuntary movement.
Nerve: Long bundles of axons that transmit signals from the CNS
• Electrical impulse from dendrite to axon terminal
o Transmitted from cell to cell via neurotransmitters secreted into the synapse from the axon terminal
Synapse: The structure that allows neurons to pass signals to other neurons, muscles, or glands
Neurotransmitter: A chemical substance that is released from the AXON TERMINAL by the arrival of a nerve impulse
• Diffuses across the SYNAPSE,
• causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure at the DENDRITE of the other cell
o Acetylcholine: NT; causes muscle to contract
o Dopamine: NT; precursor to epinephrine Central NS: Brain and Spinal Cord
Peripheral NS:
• Sensory NS: AFFERENT; send messages TO CNS
• Motor NS: EFFERENT; send messages TO MUSCLES
o Somatic NS: Carries information to CNS from senses, and from CNS to skeletal muscles
o Autonomic NS: Involuntary; controls actions involving cardiac and smooth muscle
Sympathetic NS: Arouses body; FIGHT or FLIGHT
Parasympathetic NS: Calms body; Rest and Digest
Brain: Control center
• 4 Lobes
o Frontal Lobe: thinking, organizing, emotions, behavior, personality
o Parietal Lobe: perception, making sense, arithmetic, spelling
o Temporal: memory, understanding, language
o Occipital: vision
Brain Anatomy
Cerebellum: Balance and coordination
Cerebrum: Anterior brain
Pons: Brainstem that links medulla and thalamus
Medulla Oblongata: Control center for heart and lungs
Brainstem: Contains the Pons, Medulla Oblongata, Midbrain
Midbrain: Develops from the middle of the embryonic brain
Thalamus: Relays sensory information; pain perception
Hippocampus: Emotion, memory, ANS Amygdala: Emotions
MUSCLES
Myosin: THICK FILAMENT; fibrous protein; forms the contractile filaments of muscle cells
Actin: THIN FILAMENT; protein involved in motion; works with myosin
Sarcomere: Myofibril containing myosin and actin Smooth Muscle: Involuntary muscle, not striated
• Stomach, lung, intestine…
Striated Muscle: Voluntary muscle; striated
• Biceps, triceps,
gluteus maximus…
Cardiac Muscle: Involuntary muscle; striated
• Heart
BIOLOGY
Macromolecules: Carbohydrate, Lipid, Nucleic Acid, Protein, Enzyme Carbohydrate: Sugars and starches which body breaks down to glucose
• Structural function: cellulose and chitin
• Energy storage: amylose, amylopectin, glycogen
• Recognition molecules: glycoproteins and glycolipids Lipids: Fatty acids and their derivatives that are soluble in water
• H and C and main components
• Fats
• Hydrophobic- thus help separate aqueous compartments
• Store energy (fats, oils, adipose)
Protein: Molecules composed of amino acids joined by peptide bonds
• Monomer: amino acids (amino group + carboxylic acid)(20 types)
• Keratin and Collagen (hydrophobic)- not soluble in water, found in structural protein
• Globular proteins are hydrophilic (hemoglobin, antibodies, enzymes)
• Function as transport carries or signal transfer
Nucleic Acids: Long molecules made of nucleotides; DNA and RNA
• DNA stores genetic material
• Chromosomes
• RNA is a messenger (mRNA) also rRNA and tRNA Enzymes: Class of protein that catalyze biochemical reactions
• Not consumed in reaction
• Speed up reaction by lowering activation energy
• Exergonic: release energy
• Endergonic: require energy
• Energy is supplied and released as ATP
• Lock and Key (substrate must fit into enzymes active site)
DNA and RNA
DNA: macromolecule that contains coded instructions for the body to produce proteins
• Nucleotide: the building block of DNA and RNA
• Nitrogenous Base: Adenine, Thymine, Guanine, and Cytosine
• Purines: Adenine and Guanine
• Pyrimidines: Thymine and Cytosine
• Codon: A group of 3 nitrogenous bases used to synthesize amino acids (Synthesized from RNA during TRANSLATION)
• Hydrogen Bonds: Connect a Purine to a Pyrimidine (A-T) and (C-G). Non-covalent, weak.
o RNA: Uracil replaces Thymine
• Double Helix structure
• Coded or read 5'3'
• Sugar(pentose)-Phosphate backbone (deoxyribose and phosphate group- bound to 4 oxygen atoms)
DNA Replication
DNA Helicase: Unzips and Unwinds DNA strand
DNA Primase: Generates RNA Primer. Act as a template for starting point of DNA Replication
DNA Polymerase: Synthesize new DNA molecules by adding nucleotides to leading and lagging DNA strands in 5'3' direction
Topoisomerase: Prevents supercoiling
DNA Ligase: Joins DNA fragments together by forming phosphodiester bonds between nucleotides
Okazaki Fragment: Short, newly synthesized DNA fragments that are formed on the lagging strand
Single Strand Binding Protein: Stabilize structure during replication
Leading Strand: Replicated continuously in the 3' to 5' direction
Lagging Strand: Replicated discontinuously in short sections
Cellular Organelles and Structure
Mitosis
Meiosis
CHEMISTRY
States of Matter
Solid: rock, wood, paper…
• Molecules are packed together in a tight, orderly pattern
• Vibrational motion, not translational motion
• Retains shape
• Retains density Liquid: water, juice, soda…
• Molecules are less ordered than solids, less tightly packed
• Vibrational and translational motion
• Shape is indefinite- takes shape of container
• Retains volume
Gas: Oxygen, Methane, Carbon Dioxide…
• Molecules are rapidly moving and spread far apart
• Highly compressible- expands to fill container
• No definite shape
• No definite volume
Change in Matter
• Condensation: Gas Liquid
• Deposition: Gas Solid
• Evaporation: LiquidGas
• Freezing: Liquid Solid
• Melting: SolidLiquid
• Sublimation: SolidGas
Boiling: The transition of liquid to gas when a substance has acquired enough thermal energy.
Critical Point: The temperature at which LIQUID and GAS phases have same density.
Phase Diagram: A graph of physical states of a substance under varying temperature and pressure.
Triple Point: The temperature and pressure at which all 3 phases of a pure substance coexists.
Chemical Bonds and Structures
Covalent Bond: A chemical bond where electrons are SHARED between atoms (2 NON metals)
Ionic Bond: Between 2 metals or a metal and a nonmetal. Complete TRANSFER of electrons
Proton: positively charged atomic particle (determines atomic number)
Electron: Negatively charged atomic particle- very small and irrelevant to mass of atom.
Neutron: Determines isotope. Added to number protons to get atomic mass. No electric charge.
Anion: Negatively charged ion
Cation: Positively charged ion
Atom: The most basic complete unit of an element
SCIENTIFIC INQUIRY
Scientific Method:
I. Identify the problem
II. Ask Questions (by conducting research)
III. Develop Hypothesis (IF/THEN statement)
IV. Conduct Experiment
V. Analyze Results
VI. Form a Conclusion Independent variable
• The thing you are testing
• "If" statement of the hypothesis
• Cause Dependent Variable
• The thing you are measuring
• "Then" statement of the hypothesis
• Effect Control Variable
• Scientific Constant
• Remains unchanged throughout the experiment
*Must be able to replicate data for a successful experiment and must have a large sample [Show Less]