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Homeostasis Study Guide (Chapter 5, Cengage Biology Honors)
| ALL REVIEW Q’S HOMEOSTASIS GIZMOS |
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Feedback Loops
| CLASS PRESENTATIONS |
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Positive vs. Negative Feedback Loops
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| Positive | Negative |
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| Results in amplification | Results in stabilization |
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Graphic by Tanisha Kurani
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Feedback Loop Examples
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| Example | Information |
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| Blood Clotting | Group of blood cells, platelets, and protein clumped together over a wound to stop bleedingNegative loopBleeding (input) is stopped by clot (output), reverses direction of blood |
| Ice-Albedo | Albedo - Amount of sunlight or radiation reflected by a surface  Positive loopIce is highly reflective, it reflects some sunlight back to space, heating the ocean up and melting more and more ice. |
| Body Temperature | Receptors are stimulated by a discrepancy from the normal 98.6 degrees F and send a signal to control centerControl center decides whether to vasodilate (cool down) or vasoconstrict (heat up) and sends a signal to effectors w/ decisionEffectors execute the decision w/ sweat glands or muscle contractionNegative loopThe body loses or retains heat to stabilize yourself to a particular temperature |
| Labor/Giving Birth | More pressure on cervix stimulates receptor cells that releases oxytocinOxytocin goes back to cervix and simulates contractionsPositive loop - Contractions go back to more pressure on the cervix until baby is born |
| Fruit Ripening | Acidic levels rise and amount of simple sugars increase, activating fruit ripening enzymesEnzymes cause the ripened fruit to ripen more fruit |
| Guard Cells/Stomata | Guard cells = 2 epidermal cells that open and close stomatal poresStomata = Tiny substance essential to photosynthesis, made up of guard cellsTakes in CO2, releases O2  Stomata must open to release water, but when it opens, leads to water going in and needing to refillNegative loop |
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Transport
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| BIGELOW SLIDES PARAMECIUM GIZMOS OSMOSIS PRACTICE PROBLEMSSTUDY BOOKLET (HANDED OUT IN CLASS) OSMOSIS GIZMOS PRACTICAL APPLICATION PRACTICAL APPS WORKSHEET |
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Factors that influence diffusion:
Concentration
Temperature
Size
Charge
Pressure
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Concentration
Concentration gradient - adjacent regions with different concentrations
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When a cell goes through passive transport or diffusion, it tries to travel from a high concentration gradient to a low concentration gradient.
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KEY VOCAB:
Solute: The thing being dissolved
Solvent: The thing dissolving the solute
Solution: The product once it’s dissolved
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Passive Transport
Diffusion - The movement of atoms/molecules from an area of high concentration to low concentration
Osmosis - Diffusion relating to water
Facilitated diffusion - Diffusion where molecules pass through protein channel
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| Hypertonic - Outside > InsideIf the solvent is hypertonic, the solute is hypotonicEnds in shriveling up | Isotonic - Outside=InsideIf the solvent is isotonic, the solute is tooThe end goal of all diffusion | Hypotonic - Inside > OutsideIf a solvent is hypotonic, the solute is hypertonicEnds in swelling and ruptures |
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Turgor Pressure - Plants fill themselves with water to preserve structure
- If it loses that water, it stops pushing and becomes soft
Osmotic Pressure - The amount of turgor needed to stop osmosis
Plasmolysis - Cell membrane pulling away from cell wall (opposite of turgor)
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Active Transport
Active transport moves against the concentration gradient (low to high) and requires energy.
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Protein pump - A pump that moves molecules across the membrane
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| Endocytosis | Exocytosis |
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Into the cell - uses cell membrane to engulf materials  \n Phagocytosis - The cell eats the particles and uses them for stuffPinocytosis - The cell drinks up the particles and uses it for stuffReceptor-Mediated - The cell uses receptors to target specific molecules | Fuses with cell  |
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Examples
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Bioenergetics
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| BIGELOW SLIDES |
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Energy - The ability to do work
Entropy - Unusable dispersed energy
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Laws of Thermodynamics
First Law of Thermodynamics: Energy cannot be created or destroyed
Second Law of Thermodynamics: Energy tends to disperse spontaneously, always increasing entropy in a system
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Potential vs. Kinetic Energy, Endergonic Exergonic
Potential energy - Energy that is stored in a fixed position or motion
- Chemical energy - form of potential energy due to arrangement of atoms within the molecules
Kinetic energy - Energy of motion
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| Endergonic | Exergonic |
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| Reactions that store energy into the moleculeCondensation, photosynthesis | Reactions that have a release of free energyCellular respiration |
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Metabolic Control + Enzymes
Most enzymes not only have an active site, but also an Allosteric Regulation
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Allosteric Regulation - Cofactors/Coenzymes bind to atom and change active site of enzymes
Allosteric Activation - Changes shape of active site so enzyme is turned on and works
Allosteric Inhibition - Changes shape of active site so the enzyme is turned off and doesn’t work
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Coenzyme - Allows redox reactions to proceed
Ex: ATP - provides activation energy to start reactions whenever needed
- Breaks bonds between 2nd and 3rd phosphate groups, giving off the potential energy, can spend and refill
- Stores (Endergonic) and releases (Exergonic)
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Feedback Inhibition - Final product of a process decreases/stops the process once the product is made
Negative loop
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Electron Transfer Chains and Redox Reactions
Metabolic reactions may be Redox reactions, Redox reactions transfer electrons between atoms.
REMEMBER: The electron that has a charge is being reduced
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Electron Transfer Chains - Can be formed with many Redox reactions over and over, releases energy in small amounts (slow) and fuels many reactions in a cell