Biology- Unit 4- ATP & Photosynthesis

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What is energy?
The ability to do work
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Examples of different forms of energy ?
gravitational-potential energy, geothermal energy, elastic-potential energy, kinetic energy.
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What can it not be? How is it measured?
Created or destroyed, only changed from one form to another. Joules (J).
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Why do organisms need energy? (6 examples)
Metabolism, movement, active transport, maintenance repair and division, production of substances, maintenance of body temperature in endothermic animals.
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What do we mean by movement? what is active transport?
Within the body (blood circulation) or locomotion itsself. Movement of substances against the concentration gradient.
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What is the flow of energy through living systems?
Light energy in the sun converted into chemical energy during photosynthesis. chemical energy then converted into ATP via respiration, ATP used by cells to produce useful work.
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How does ATP store energy?
Adenosine triphosphate has three phosphate groups. These bonds are very unstable and so have a low activation energy, As a result they are easily broken. When the bond breaks, they released a considerable amount of energy,
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Which group is usually removed? Equation? What is the reaction?
The last phosphate group is removed to produce ADP. ATP + H20 ---> ADP + Pi (inorganic phosphate) + E (energy) Hydrolysis reaction- breaking bond with addition of water.
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Describe the conversion of ATP to ADP?
Its a reversible reaction and therefore energy csn br udrf yo add a Pi to ADP to re-form ATP. The reverse is therefore a condensation reaction.
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Enzyme?
ATPase
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Name the 3 ways that the synthesis of ATP from ADP can occur?
photophosphorylation, oxidative phosphorylation, substrate-level phosphorylation
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photophosphorylation?
Takes place in the chlorophyll- containing plant cells during photosynthesis.
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oxidative phosphorylation?
occurs in the mitochondria of plant and animal cells during the process of electron transport.
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substrate-level phosphorylation?
Phosphate groups are transferred from donor molecules to ADP to form ATP. (example: formation of pyruvate at the end of glycolysis).
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Whats special about the first two cases?
its synthesized using energy released during the transfer of electrons along a chain of electron carrier molecules.
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Why is ATP not a good long term storage molecule for energy? What is used instead? What is ATP therefore?
because it has unstable phosphate bonds. fats and carbohydrates (eg: glycogen). an immediate energy source
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Why is ATP better suited to its role as an immediate energy source then glucose?
Each ATP molecule releases less energy then a glucose molecule. Its therefore released in smaller more manageable quantities. The hyodrolysis reaction for ADP is a single reaction while breakdown of glucose is a long series of reactions so takes +.
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What is ATP a source of energy for?
metabolic processes (building macro-molecules), movement (muscle contraction), active transport (changing shape of carrier proteins), secretion, activation of molecules.
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PHOTOSYNTHESIS
you love plants. You know you do. Yes you do. Oh yes. Much love. Plants. Yes. God. Yes. Plants. Joys. Medicine here we come with our knowledge of plants. Yes mate. #lad.
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Equation for photosynthesis?
6Co2 + 6H20 ---> (light) C6H12O6 + 6O2
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What are leaves adapted to do?
Bring together the 3 raw materials for photosynthesis and remove the products.
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Name these adaptions?
large surface area (as much light as possible absorbed), arrangement of leaves so they minimize overlapping (not shadowing- more sun), thin to decrease diffusion pathway, transparent cuticle to allow light to pass through
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conc
long narrow mesophyll cells with lots of chloroplast. Stomata that opens and closes in response to light, many air spaces in the mesophyll layer to allow for gas exchange. Xylem for water and phloem for taking sugars away.
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What are the 3 main structures in the chloroplasts you need to know?
Grana, stroma, thylaknoids.
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What is the grana? Stroma?
Grana are stacks of up to 100 disc like structures called thylakoids. The stroma is a fluid filled matrix where the light independent stage takes place. Within these we have starch grains.
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thylakoids?
Where the light-dependant stage takes place. Within these we have the photosythetic pigment chlorophyll.
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What is light energy used for?
To add an inorganic phosphate group to ADP thus forming ATP. To split water into H+ and OH- ions in a process called photolysis.
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What is oxidation?
When a substance loses electrons, loses hydrogen or gains oxygen.
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Reduction?
Gains electrons, gains hydrogen or loses oxygen.
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What happens when a chlorophyll molecule absorbs light energy?
The energy of a pair of electrons gets boosted. This causes them to be raised into a higher energy level and therefore be in the excited state. Because they are so energetic, they leave the chlorophyll molecule.
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What takes up these electrons? What has happened to the chlorophyll and the thing thats taken the electrons up?
Electron carriers. The chlorophyll molecule has been oxidised while the electron carrier has been reduced.
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What happens to the electrons next?
They get passed along a number of electron carriers in a series of oxidation-reduction reactions. Each new carrier is at a slightly lower energy level then the previous so the electrons lose energy at each stage.
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Where does this transfer chain occur?
in the membranes of the thylakoids.
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What is this energy used for?
Combine Pi with ADP to form ATP.
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Why must photolysis of water occur? What occurs in photolysis of water?
It must occur because the chlorophyll loses electrons when light strikes it. In order to keep absorbing light, these electrons must be replaced. The replacement is provided from water molecules being split using light energy.
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Equation?
2H20 ---> 4H+ + 4e- + O2
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What are the H+ ions used for?
they get taken up by electron carriers called NADP. Upon taking these they become reduced, NADPH. The reduced ones then energy the light-independant reaction along with the electrons from the chlorophyll molecules.
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Why is NADPH important?
Further potential source of chemical energy to the plant.
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Where does the LDR take place? How are chloroplasts adapted?
Thyakoids of chloroplasts. The membrane has a large surface area for the attachment of chlorophyll, electron carriers and enzymes. Proteins hold the chlorophyll in very specific place, max absorption of light.
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