BROOKS BIOLOGICAL PRINCIPLES EXAM 2 | QUESTIONS & ANSWERS (VERIFIED) | LATEST UPDATE | GRADED A+

1 BROOKS BIOLOGICAL PRINCIPLES EXAM 2 | QUESTIONS & ANSWERS (VERIFIED) | LATEST UPDATE | GRADED A+ Cytology Correct Answer: the study of cells Cell Theory Correct Answer: all living things are composed of cells and come from living cells Robert Hooke Correct Answer: one of the first to use microscope, observing a piece of cork from the stem of plants, where he found chambers arising in the idea of a cell. Light Microscope Correct Answer: takes pictures of large atoms. nucleus, not electrons Scanning Electron Microscope Correct Answer: electrons are reflected off of a specimen and are analyzed by a computer to create a 3D image 2 Transmission Electron Microscope Correct Answer: Microtome: a tool used to cut extremely *thin* slices of material for observation under a TEM. Microtomes are often made of diamonds Can you see electrons using the electron microscopes? Correct Answer: No, can only see neutrons & protons Why are most cells small? Correct Answer: To maximize the ratio of surface area to volume for regulating the internal cell environment Smaller cells have bigger membranes Does cell need a bigger surface area or volume? Correct Answer: surface area Plasma Membrane Correct Answer: aka "Fluid Mosaic Model" composed of fluidlike phospholipid bilayer, proteins, cholesterol (*helps maintain proper fluid viscosity*), and glycoproteins (antigens: "name tags" for immune system) "self" antigen: produced by the body "not self" antigen: not produced by the body so antigens will attack this Get sick more when younger because body is still learning these "name tags" 3 Arthritis: autoimmune disease where the body attacks itself Pollen grain: not self, antigens will attack = phagocytosis involved in *ATP production* and the electron transport system Cell Wall Correct Answer: outside of the cell membrane in some organisms (plants); composed of carbohydrates or carbohydrate derivatives (peptidoglycan for bacteria) Cytoplasm Correct Answer: material outside the nucleus • site for metabolic activity • cytosol: solution with dissolved substances such as glucose, CO2, & O2, etc • organelles: membrane-bound subunits of cells with specialized functions Cytoskeleton Correct Answer: supportive and metabolic structure composed of microtubules (*biggest, tubular dimers*), microfilaments (*smallest, actin*), and intermediate filaments Microtubules Correct Answer: form cilia (*numerous & short*) , flagella ( *long, usually 1 or 2*) , & centrioles Prokaryotes 4 Correct Answer: have a simple cellular organization with no nucleus or other membranebound organelles • nucleoid w/ DNA in continuous loop • 360 flagella rotation • ribosomes present • plasma membrane produces ATP • cell wall Ex: Bacteria & Archaea Eukaryotes Correct Answer: have a complex cellular organization; membrane-bound organelles, located inside the cell membrane Nucleus Correct Answer: contains the dna in form of chromosomes; control cellular activities via gene Nucleolus Correct Answer: located in the nucleus, the site for ribosome synthesis Rough ER Correct Answer: has ribosomes, necessary for protein synthesis 5 Smooth ER Correct Answer: no ribosomes, involve in lipids synthesis Golgi Apparatus Correct Answer: packaging center for molecules; synthesizes carbohydrates Lysosome Correct Answer: contains hydrolytic enzymes for intracellular digestion Peroxisome Correct Answer: involved in hydrogen peroxide synthesis and degradation Chloroplast Correct Answer: site of photosynthesis Chromoplast Correct Answer: contains nongreen pigments Leukoplast Correct Answer: stores starch Mitochondria Correct Answer: produces ATP, aerobic 6 mitochondria have their *own* DNA and mitochondrial DNA *doesn't change* as much, showing a clearer view of *phylogeny* DNA is more similar to *bacteria,* than DNA found in our nucleus (due to the endosymbiotic hypothesis, that life arose from prokaryotes) all of our mitochondria comes from our *mothers* Vacuole Correct Answer: storage and space-filling structure Absolute 0 Correct Answer: a theory that when there is no molecular motion at 0 K. contradicts "everything must have energy" Passive Transport Correct Answer: relies on the *thermal energy* of matter; the cells *do not* do the work 3 Types of Passive Transport Correct Answer: 1. Simple Diffusion 2. Facilitated Diffusion 3. Osmosis Diffusion Correct Answer: Passive Transport 7 movement from an area of high concentration to one of low concentration generally lipids and small charged particles lipids cross the membrane easily between the phospholipids without needing a protein to help them cross End result of simple diffusion is random dispersement, reaching an equilibrium Facilitated Diffusion Correct Answer: Passive Transport a permease, or *membrane* enzyme, carries a substance • Channel proteins: proteins that create a hydrophilic core through which ions diffuse • Carrier proteins: change shape in response to a solute entering the protein, allowing the solute to be released on the other side of the membrane Ex: aquaporin- facilitates the diffusion of *water* Osmosis Correct Answer: Passive Transport •facilitated diffusion across a *semi-permeable* membrane •movement of water from a hypotonic environment to a hypertonic environment (however the amount of water *molecules* on each side is the *same*) •Solute does not cross the membrane Osmotic Pressure Correct Answer: The pressure of water wanting to move to the other side 8 Causes the height of the water in the compartment containing the sugar to rise, due to the movement of pure water from the compartment without sugar to the compartment containing sugar water This process will stop once the pressure of the water and sugar water are equated Cell sap: attracts water Turgor Pressure Correct Answer: Pushes the plasma membrane against the cell wall of the plant Caused by osmotic flow of water from area of low solute concentration (hypotonic) outside of the cell into the cell's vacuole, which has a higher solute concentration (hypertonic) Healthy plant cells are turgid and plants rely on turgidity to maintain rigidness Ex: Wilting: becomes limp through heat, loss of water or disease; to droop & Plasmolysis: the process in which plants lose water in a hypertonic solution (aka crenation) Turgid Correct Answer: When a plant cell is in a hypotonic solution, the vacuole swells The presence of a cell wall prevents the membrane from bursting Bulk Flow Correct Answer: a mass movement of fluid affected by pressure and solutes, Ex: Trees 9 When it rains, what happens to the vacuoles of plant cells? Correct Answer: the water goes towards the solutes in the vacuole and fill up the cell wall Tonicity Correct Answer: Comparison of *solute* concentrations of *2 or more* solutions A measure of *osmotic pressure* gradient of two solutions separated by a semipermeable membrane Influenced only by solutes that *cannot cross* the membrane, as only these exert an osmotic pressure 3 Classifications of Tonicity Correct Answer: 1. Hypotonic 2. Hypertonic 3. Isotonic Hypotonic Correct Answer: A solution with a lower concentration of solute in *its surroundings*, so in an attempt to balance concentrations, water will rush *into* the cell causing *swelling* Pure water is most likely to be *hypotonic* Hypertonic 10 Correct Answer: A solution with a higher concentration of solute on the *outside of the cell* When a cell is immersed into a hypertonic solution, the tendency is for the water to *flow out* of the cell in order to balance the concentration of the solute Isotonic Correct Answer: A solution with the same solute concentration; Water molecules diffuse through the plasma membrane in *both directions*, and as the rate of water diffusion is the same in each direction, cells will *neither gain nor lose water* The best way to describe a solution with 50% solute and 50% solvent is Correct Answer: a 50% solution What would happen if you were in a swimming pool for eight hours? Correct Answer: you will gain weight because the water is hypotonic Salt water fish Correct Answer: more water will enter the fish to reach equilibrium than fresh water fishes with a 1% tonicity How do salt water birds excrete salt from their bodies? Correct Answer: through their eyes, forming a crust 11 Blood cells in DI water will Correct Answer: explode cause water is hypotonic Crenation Correct Answer: aka *Plasmolysis* the process in which cells *lose water* in a *hypertonic* solution so they *shrivel* up Causes plants to wilt Cytolysis Correct Answer: aka *Hemolysis* occurs when a cell *bursts* due to *excess water* in a *hypotonic* solution Flaccid Correct Answer: When a plant cell is in an isotonic solution Active Transport Correct Answer: Moving solute against the concentration gradient utilizing energy in the form of ATP Against the concentration gradient, from low to high concentration 3 Types of Active Transport Correct Answer: 1. Membrane Pump 2. Endocytosis 12 3. Exocytosis Membrane Pump Correct Answer: A protein embedded in the plasma membrane that allows materials (usually ions) to go in and out of the cell, against its gradient does not rely on thermal energy, requires ATP all living cells have a charge difference (battery) Na/K Exchange Pump Na/K Exchange Pump Correct Answer: Sodium and potassium ions are pumped in opposite directions across the membrane building up a chemical and electrical gradient for each Forces Na outside of the cell and K inside For every 3 Na's moved out of the cell, there are 2 K's that are moved in This requires ATP Binding of the cytoplasmic Na+ to the protein stimulates phosphorylation by ATP Ex: *nerve impulses* Phosphorylation Correct Answer: The metabolic process of introducing a phosphate group into an organic molecule Endocytosis 13 Correct Answer: materials brought into the cell via: *Phagocytosis* (cell eating): solids *Pinocytosis* (cell drinking): liquids Exocytosis Correct Answer: materials expelled from the cell involves excretion (of a waste product) and secretion (of necessary product) Plasmodesmata Correct Answer: cell to cell communication in plants 3 Types of Animal Cell Connections Correct Answer: Tight Junctions Gap Junctions Desmosomes Tight Junction Correct Answer: 2 cells membranes join together to form a virtually impermeable barrier to fluid Present only in vertebrates The junction that operates in the *urinary bladder* Gap Junction 14 Correct Answer: make holes through the plasma membrane to *communicate*, used for exchanging hormones like plasmodesmata in plants found in *liver* present in *synapse* Desmosomes Correct Answer: enables cells to expand without breaking allows for elasticity that changes diameter but recoils present in *small intestine, stomach, & esophagus* Potential Energy Correct Answer: aka *free energy* stored energy for subsequent use in order to do work exists whenever an object which has mass has a position within a force field energy that *could be* doing work Ex: earth's gravitational field Kinetic Energy Correct Answer: is an action or is actively doing some kind of work as a result of motion/velocity energy that *is* doing work 15 Specific Energy Forms Correct Answer: nuclear, magnetic, electrical, radiant, chemical, and thermal Laws of natural physics dictate that when conversions between any specific kinds of energy occur, thermal energy will be involved, even if unintended Radiant Energy Correct Answer: from the sun supplies energy for organisms to battle entropy and remain organized photosynthetic organsims (producers) convert radiant energy directly into organic molecules (chemical energy) which are eaten by herbivores (primary consumers) which are eaten by carnivores (secondary consumers) powers all life on earth Which energy type is the most important of all the energy types? Correct Answer: Heat, however it's least useful First Law of Thermodynamics Correct Answer: "Conservation of Energy" States that the total energy of any closed system remains constant; energy can be transformed from one *form* to another, but cannot be created or destroyed Closed System vs. Open System Closed System 16 Correct Answer: total energy remains *constant* It can merely change form, but the total energy always stays the same therefore the universe has the same amount of energy its always had due to the 1st law of thermo Ex: the universe Open System Correct Answer: can receive and release energy Ex: Earth; energy can leave earth and go into outer space Second Law of Thermodynamics Correct Answer: The free (potential) energy in any system *decreases*, but entropy (disorder) *increases* No transfer of energy is totally efficient because heat will always be part of the energy transfer responsible for roller coasters getting slower towards the end of the ride Change in Free Energy Equation Correct Answer: ΔG = Gfinal state - Ginitial state What is heat? Correct Answer: Entropy (disorder), wasteful kind of energy disorder in burning fossil fuels and breaking macromolecules 17 Exergonic Correct Answer: Energy is released Catabolic Exothermic More *natural* type of reaction since it is easier to make happen than an endergonic reaction Delta G is negative Less free energy in the products than there was in the reactants Ex: eating Endergonic Correct Answer: Energy is consumed/required Anabolic Endothermic Delta G is positive More free energy in products than reactants *Most likely to go in reverse* Which side of this equation has the greatest free energy? 2H2 + O2 --> 2H2O + Energy Correct Answer: left side 18 Activation Energy Correct Answer: aka heat of activation the minimum energy required to get a reaction to occur in endergonic reactions Catalysts Correct Answer: lowers the activation energy by speeding up reactions biological catalysts are enzymes Enzymes Correct Answer: initiate reactions with *minimal* heat requirement heat would *denature* the enzyme, since enzymes are *proteins* require a specific 3D shape active site: region that binds the substrate; where the reaction takes place; all enzymes are proteins, not all proteins are enzymes Enzyme-Substrate Complex Correct Answer: E + S <==> ES Complex <==> E + P Enzyme + Substrate <==> Enzyme Substrate Complex <==> Enzyme + Product The reaction can go in both directions, but usually doesn't because most reactions are exothermic and there might not be enough free energy to reverse the reaction it will return to its original shape at the end The substrate becomes the product and is different than what it was in its original form 19 Enzymes after a reaction Correct Answer: stay the same, don't get used up Cofactors Correct Answer: *non*protein organic molecules or metallic ions that are part of the active site, making the enzyme-substrate complex possible to form 2 Types of Cofactors Correct Answer: Prosthetic Groups Coenzymes Prosthetic Groups Correct Answer: are *permanently attached* to the enzyme Ex: Zn, Cu, Fe Coenzymes Correct Answer: are *temporarily attached* to the enzyme *not an enzyme/protein, but a nucleic acid instead* Ex: Vitamins, NAD, NADP, FAD Competitive Inhibition Correct Answer: mimics the substrate and competes for the active site 20 Noncompetitive Inhibition Correct Answer: inhibitor binds to the enzyme at a location away from the active site (allosteric site), but alters the conformation of the enzyme so that the active site is no longer fully functional *more natural way* known as on/off switch Poisons Correct Answer: Act as enzyme inhibitors Ex: Cyanide, heavy metals, nerve gases, and antibiotics Enzymes are controlled by Correct Answer: cell condition Summary of Enzyme Kinetics Correct Answer: 1. Enzymes form complexes with a substrate (the Enzyme-Substrate Complex) 2. Enzymes increase *local* substrate concentration 3. Enzymes orient the substrate for maximum efficiency so they can fit like a puzzle piece 4. Enzymes change the substrate shape to facilitate the reaction 5. Enzyme can temporarily change its own shape, but it will return to its original shape after the reaction. They do not change/get altered 21 Rate of Reaction Correct Answer: As the substrate's concentration increases, the rate of reaction increases As heat increases, the rate of reaction increases However, if the heat increases too much, the enzyme can denature pH has an effect on the rate of reaction, because in order for an enzyme to be in optimal conditions, it must usually have a pH of 7 *the exception is pepsin which has a pH of 2 & tripsin is basic, having a pH of 9* What organ has a ph of 8-10? Correct Answer: the duodenum (tripsin); since the stomach produces so much acid, the duadenum needs to be very basic to neutralize the acids As the temperature increases by 10 degrees, what happens to the reaction rate? Correct Answer: The reaction rate doubles Enzyme Teams Correct Answer: More than 1 enzyme working together It's a process where a product of one reaction becomes the substrate for the subsequent reaction in coupled reactions T/F some enzymes work better at different temperatures Correct Answer: True. 22 the face, ears, tail and feet are the coldest parts of the body melanin is said to work better in these areas for those reasons, which is why some cats and dogs have different colored hair in these areas What does cemo therapy do? Correct Answer: it stops cells from replicating very fast, which is what we need in our stomach for stomach replacement and hair growth this is why we get nasea and loss of hair when going through treatment ATP Correct Answer: Adenosine Triphosphate Cellular energy currency High energy molecule Made up of adenine (a nitrogen base found also in DNA and RNA), ribose sugar, and 3 phosphate groups ALL organisms use ATP ATP is *very unstable* Amount of ATP in humans Correct Answer: cannot be measured because ATP is so small, therefore we must be recycling ATP rapidly Does ATP hydrolysis produce a negative delta G or a positive delta G? 23 Correct Answer: negative, exergonic Does ATP synthase produce a negative delta G or a positive delta G? Correct Answer: positive, endergonic Cellular Work: 3 Types Correct Answer: 1. Transport 2. Mechanical 3. Chemical Transport Cellular Work Correct Answer: Pumping of molecules and ions across a plasma membrane against their concentration gradient Mechanical Cellular Work Correct Answer: Beating of cilia, muscle contractions, etc. Chemical Cellular Work Correct Answer: Pushing endergonic reactions that would not occur spontaneously ATP Usage 24 Correct Answer: The *average* adult uses on average *100 lbs* of adenosine triphosphate every day, therefore ATP must be synthesized very *rapidly* so that we can use this much ATP ATP Energy Storage: Short or Long Term? Correct Answer: short term storage Glucose Energy Storage: Short or Long Term? Correct Answer: long-term storage (lipids are even better) Bonds of ATP Correct Answer: has strong *covalent bonds*, creating *a lot* of energy What is the main problem of ATP? Correct Answer: it is *used up very quickly* by the metabolic needs of a cell Glucose Correct Answer: 6 carbon molecule is used to *synthesize (make) ATP* a source of *highly energized electrons* These energized electrons are derived from the *sun* 25 This is why we eat plants, because they consume their sunlight energy which is stored in the form of energized electrons. Electrons get "energized" from the *sun* (in photosystem 1), and lower energized electrons come from *water* Why do we eat? Correct Answer: to consume molecules that contain *highly electrolyzed electrons*, such as glucose, to keep electrons charged, creating a positive, negative dipole membrane Why do we breathe? Correct Answer: To bring in oxygen to remove low energy electrons from the end of the ETS to make ATP NAD Correct Answer: Nicotinamide Adenine Dinucleotide Coenzyme of cellular respiration NAD+ = Oxidized (losses electron), picks up an electron , in doing so it becomes reduced NADH = Reduced (gains an electron), release the electron in the ETS The reduction of NAD is highly endergonic, and within the cell, the electrons do not remain with NADH. Oxygen is highly electronegative and readily accepts electrons from the reduced NADH molecule. 26 NADP Correct Answer: Nicotinamide Adenine Dinucleotide Phosphate Coenzyme of cellular respiration & photosynthesis Produces 3 ATP for every 1 glucose NADP+ = Oxidized NADPH = Reduced FAD Correct Answer: Flavin Adenine Dinucleotide Coenzyme of cellular respiration Produces 2 ATP for every 1 glucose FAD+ = Oxidized FADH = Reduced Dehydrogenase Correct Answer: Coenzymes work with enzymes called dehydrogenase It is an enzyme that oxidizes a substrate by a reduction reaction that transfers one or more hydrides (removes a hydrogen) Enzyme that oxidizes/reduces NAD+ to NADH and vice versa; *facilitate the removal of electrons and protons* Proton Pump 27 Correct Answer: form of facilitated diffusion, or modified osmosis that creates a proton gradient across a membrane. Electrons initiate the process T/F Most organisms require ATP Correct Answer: T, but not *all* because not all organisms go through the ETS T/F No energy is required to decay upon death Correct Answer: T, muscles in a fixed state of contraction, not producing anymore ATP T/F Battery can be used to do work Correct Answer: T T/F Entropy is always occurring Correct Answer: T T/F Everything will eventually turn into hydrogen Correct Answer: T, its the simplest molecule and matter tends to go to the lowest and simplest energy level T/F Sunlight provides the energy for Life Correct Answer: T, life is constantly being interrupted by entropy 28 What is cellular respiration? Correct Answer: turning food into energy 3 steps of cellular respiration Correct Answer: 1. Glycolysis 2. Krebs (Citric Acid) Cycle 3. Chemiosmotic Phosphorylation (ETS) Glycolysis Correct Answer: Purely *anaerobic* reaction (does not require oxygen) it can be performed in the *presence* of an aerobic process Occurs in the *cytoplasm/cytosol* 1. Start with glucose 2. Break it up into *two pyruvates* (3-carbon molecule) = *2 ATP* 3. *The reduction of NAD to NADH* = *2 NADH* •Oxygen is *not present* -> *fermentation* will occur where the pyruvate is converted to, in yeast, *ethanol (alcohol)* &*carbon dioxide*, in humans, *lactic acid* This is very *inefficient,* only yields 2 ATP, whereas in the presence of oxygen, yields 36 ATP •Oxygen is *present* -> pyruvate turns into *Acetyl CoA*, where its ready to enter the Kreb Cycle Substrate-Level Phosphorylation 29 T/F Muscles can run out of oxygen Correct Answer: T Limiting factor of Glycolysis Correct Answer: is NAD+ (oxidized), when unavailable, glycolysis *stops*. NADH takes electrons *back to pyruvate* to engage in *fermentation* reactions. Cannot go to the ETS because no oxygen is available at the end of the system to accept electrons. Main role of Glycolysis Correct Answer: to produce *NADH* Main role of Fermentation Correct Answer: is to supply *NAD+* so that glycolysis can continue to produce its limited amount of ATP when oxygen is also limited Kreb/Citric Acid Cycle Correct Answer: *Aerobic* process that *oxidizes* Acetyl CoA (2 carbon molecule) to *carbon dioxide* Occurs in the mitochondria (matrix) of eukaryotes & cytosol of prokaryotes Produce *2 ATP,* add electrons to NAD & FADH (reduce) -> *NADH & FADH2* *Lipids and proteins* enter the Krebs cycle at other points and are subsequently oxidized. 30 Substrate-Level Phosphorylation Main role of the Kreb/Citric Acid Cycle Correct Answer: to produce NADH & FADH2 Substrate-Level Phosphorylation Correct Answer: The formation of high-energy phosphate bonds by phosphorylation of ADP to ATP in coupled reactions. Occurs when no oxygen is present Alternate way of making ATP Chemiosmotic Phosphorylation (ETS) Correct Answer: The formation of high-energy phosphate bonds by phosphorylation of *ADP to ATP* coupled to the transfer of electrons from reduced coenzymes to molecular oxygen (byproduct) via the *electron transport chain*; occurs in the *mitochondria* with F1 particles (which synthesize ATP - ATP Synthase) Aka *oxidative phosphorylation* or *chemiosmosis* produces 32 ATP 1. Electrons carried via NADH & FADH2 enter the ETS where they move through cytochromes (protein complex's) and the energy generated from the cytochromes is used to pump protons (H+) to the outside of the inner membrane. The electrons are then carried to other protons and 1/2 oxygen ( 2 electrons per oxygen is picked up, 4 electrons total, to fulfill the Octet rule), making the byproduct of water. 31 So the oxygen that we breathe in is going to be an *electron acceptor* & the protons pumped by cytochromes will flow through ATP Synthase combining with electrons and oxygen to release water. On average, *36* (2+2+32) ATP is produced. Cytochromes Correct Answer: agents of Redox reactions embedded in the membrane; transfers electrons inside the cristae membranes and pumps protons to the outer membrane space (intermembrane) Cristae Membrane Correct Answer: The internal compartments formed by the inner membrane of a mitochondrion Studded with proteins, including ATP Synthase and a variety of cytochromes Inner membrane is positive ATP Synthase Correct Answer: The enzyme that makes ATP by chemiosmosis It allows protons to pass through the membrane and uses the kinetic energy to phosphorylate ADP, *making ATP* The generation of ATP by chemiosmosis occurs in chloroplasts and mitochondria They resynthesize ATP by generating an H+ ion concentration to phosphorylate ATP as it goes back toward the water 32 H+ flow from an area of high concentration to an area of low concentration, producing ATP What is oxygen's primary role? Correct Answer: to take/accept low energy electrons 3 Key Parts of Cell Respiration Correct Answer: 1. Glycolysis 2. Krebs (Citric Acid) Cycle 3. Chemiosmotic Phosphorylation (ETS) Cellular Respiration Equation Correct Answer: C6H12O6 (glucose) + 6O2--> 6CO2 + 6H2O + ATP What is photosynthesis? Correct Answer: make food from simple molecules sunlight or radiant energy captured by chlorophyll and carotenoid photopigments (found in cytoplasm in prokaryotes and chloroplasts in eukaryotes) in two main steps 3 Parts of Chloroplasts Correct Answer: 1. Stroma 2. Thylakoid 3. Grana 33 Stroma Correct Answer: The solution inside chloroplasts where the the Light Independent (Dark Reactions) aka Calvin Cycle take place Thylakoid Correct Answer: 1 Single disk in grana Captures Light Light Dependent (Light Reactions) Light-harvesting Antennae Photosystems I & II ETS CF1 particles Grana Correct Answer: The name for the stacks of thylakoids Light-harvesting Antennae Correct Answer: absorb photons using Chlorophylls *A & B + Carotenes* Reaction Center in Photosynthesis Correct Answer: Composed of: Chlorophyll A 34 *Various* Proteins Photosystem I Photosystem II *The reaction center converts the absorbed light energy into chemical energy* Chlorophyll A Correct Answer: Absorbs Violet/Red Most important pigment Chlorophyll B Correct Answer: Absorbs Blue/Light Red Carotene Correct Answer: Absorbs Blue/Green It is orange in color Black Correct Answer: Black is an absence of color Therefore black is not reflecting back Cones in the Eye Correct Answer: Help you see *color* 35 Rods in the Eye Correct Answer: Help you see at *night*, but they operate on a much more *basic* level than cones If the light is off, there is *no* color. Rather, it is "electromagnetic energy" Why are most plants green? Correct Answer: Green is not absorbed by plants, but rather it is reflected T/F All photosynthetic organisms have Chlorophyll A Correct Answer: T Electromagnetic Spectrum Correct Answer: Wavelength (nm) measured in *billions of a meter* •Short wavelengths = higher energy, however damaging DNA and cells •Long wavelengths = less energy; poor cell signal due to longer wavelengths •X-rays penetrate *every tissue* •UV light activates cells to produce more *melanin,* therefore us getting darker/tanner is the body's way of absorbing *radiation* so DNA doesn't •Some animals can *see* UV radiation, *we cannot* •IR = heat •Microwave: heats up water molecules; used as communication •Visible Light: how retina sends signals to brain to interpret color, ROYGBIV red= long wavelength 36 violet = short wavelength T/F Plants can see visible light Correct Answer: T, just like us = evolution Wavelength in Photo System I Correct Answer: P700 Wavelength in Photo System II Correct Answer: P680 Light-Dependent Reactions Correct Answer: aka "Light Reaction" or "Cyclic Photophosphorylation" ADP is phosphorylated Occurs in Photosystem I *only* in the thylakoid membrane electrons energized and eventually returned to chlorophyll A *No NADPH formed* This cycle is *less efficient* compared to light-independent reactions Cyclic- No NADPH, just ATP Noncyclic- *ATP & NADPH formed* energized electrons are not recycled, but rather stored temporarily with NADPH to be used later in the light-independent reactions with ATP 37 Light-Independent Reactions Correct Answer: aka "Dark Reactions," "Calvin Cycle" or "Calvin Benson Cycle" Occur in Stroma Carbon Fixation- converting inorganic carbon to organic, usable carbon Water supplies electrons & protons *Oxygen is byproduct* Photosystem I Correct Answer: absorbs light energy at 700 nm and passes an excited electron to NADP+, reducing it to NADPH Photosystem II Correct Answer: absorbs light energy at 680 nm, oxidizes water molecules, and initiates the ETS that produces ATP Cyclic Electron Transport Correct Answer: This pathway uses only Photosystem I and produces ATP, but not NADPH; its cyclic because the electrons flow from the reaction center of photosystem I, through the ETS, and then back to photosystem I Most important enzyme on Earth Correct Answer: Rubisco: allows carbon dioxide to enter Calvin Cycle 38 Photorespiration Correct Answer: The process by which in the presence of light, plant consumes oxygen and releases carbon dioxide (instead of fixing carbon dioxide) during photosynthesis, resulting in a decrease in photosynthetic output since no ATP is produced and carbon (as well as nitrogen in the form of ammonia) is lost inevitably. Its a plants response to *heat* Unfortunately, many plants *have no innate protection* against this phenomena How is the proton gradient achieved in Photosynthesis? Correct Answer: 1. splitting water by sunlight (photolysis) 2. ETS T/F Photosynthesis in oceans outnumbers the photosynthesis in forests Correct Answer: T C3 plants Correct Answer: under photorespiration C4 & CAM Correct Answer: protection against photorespiration C4 39 Correct Answer: has a 3 carbon molecules that stores CO2, so that when CO2 levels are low, it wont engage in photorespiration Ex: sugarcane, corn CAM Correct Answer: it lowers its pH to not engage in photorespiration Ex: cactus