Energy for Biological Processes

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  • Created by: LBCW0502
  • Created on: 22-10-16 13:05
Give examples of metabolic activities in organisms
Active transport, anabolic reactions, movement due to cilia/flagella etc.
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What is the law of conservation?
Energy cannot be created or destroyed
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What is photosynthesis?
Light energy is trapped by chlorophyll molecules and is converted into chemical energy (produces organic molecules from inorganic molecules)
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What is respiration?
The process by which organic molecules (e.g. glucose), are broken down into smaller inorganic molecules (e.g. carbon dioxide and water). This is linked to the synthesis of ATP
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What determines whether a reaction in exothermic or endothermic?
Depends on the total number and strength of bond that are broken or formed during th
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Organic molecules contain large numbers of which two elements?
Carbon and hydrogen
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How are photosynthesis and respiration linked?
Respiration is the reverse of photosynthesis
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What is ATP?
Adenosine triphosphate - a nucleotide composed or a nitrogenous base (adenine), a pentose sugar and three phosphate groups. The universal energy currency of cells
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Why is ATP vital and a crucial step in both respiration and photosynthesis?
Energy provided from photosynthesis is used to form chemical bonds in ATP (then used to released energy to make bonds as glucose is formed). In respiration, energy is released and used to synthesis ATP (used to break bonds in metabolic reactions)
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What is chemiosmosis?
The synthesis of ATP driven by a flow of protons across a membrane
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How are electrons excited (raised to higher energy levels)?
Electrons present in pigment molecules are excited by absorbing light energy form the Sun or high energy electrons are released when chemical bonds are broken in respiratory substrate molecules
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What are electron carriers?
Proteins that accept and release electrons
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How can protons move back through the membrane down their concentration gradient?
Through hydrophilic membrane channels linked to the enzyme ATP synthase. Flow of protons through these channels provide energy used to synthesis ATP from ADP and Pi
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What is the definition of autotrophic?
Organisms that can photosynthesis (convert inorganic molecules into organic molecules using light energy)
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What is the definition of heterotrophic?
Organisms obtain complex organic molecules by eating other (heterotrophic/autotrophic) organisms
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In which organelle does photosynthesis take place?
Chloroplast
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What is a thylakoid?
A series of membranous compartments in a chloroplast that contain chlorophyll and molecules needed for the light-dependent reaction
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What is a granum?
Membranes forming flattened sacs (thylakoids) which are stacked (plural - grana)
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What are lamellae?
Membranous channels which join grana together
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What is stroma?
Fluid enclosed in the chloroplast. This is the site of many chemical reactions (formation of organic molecules) and contains enzymes, sugars and organic acids
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What are pigments?
Molecules that absorb specific wavelengths of light
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What is the primary pigment in photosynthesis?
Chlorophyll (a)
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Why do plants appear green?
Chlorophyll mainly absorbs red and blue light but reflects green light
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Name the accessory pigments
Chlorophyll b, xanthophylls and carotenoids
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What is the reason for the different shades and colours of leaves?
Different combinations of pigments
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What does the light harvesting system (an antennae complex) consist of?
Accessory pigments embedded in the thylakoid membrane of the chloroplast and other proteins and pigments
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What is the role of the light harvesting system?
To absorb or harvest light energy of different wavelengths and transfer this energy quickly and efficiently to the reaction centre
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Which pigment is present in the reaction centre
Chlorophyll a
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What is the light harvesting system and reaction centre collectively known as?
A photosystem - protein complexes involved in the absorption of light and electron transfers in photosynthesis
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Which experiment is used to separate different pigments in a plant extract?
Chromatography
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How do you calculate Rf values?
Distance moved by spot / distance moved by solvent
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What are the two stages of photosynthesis?
The light-dependent stage and the light-independent stage
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What is phosphorylation?
The addition of phosphate group to a molecule
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Which photosystems are involved in non-cyclic photophosphorylation?
PSII (680nm), PSI (700nm)
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Outline the process of non-cyclic photophosphorylation
Electrons from PSII passed to ECC, ATP produced, electrons move to PSI, ATP produced, electrons move down ECC, electron react with NADP and H+ to produce NADPH
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What is photolysis?
A process involving the use of light energy to break down a water molecule into 1/2 O2, 2 electrons and 2 hydrogen ions (electrons produced replace electrons lost from photosystems)
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Outline the process of cyclic photophosphorylation
Electrons move from PSI, ECC then return to PSI, ATP produced (no NADPH produced)
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What are the three stages of the Calvin cycle?
Fixation, reduction and regeneration
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Describe the process of fixation
Three molecules of CO2 combine with three molecules of RuBP (with RuBisCO) to produce three molecules of a 6-carbon unstable intermediate
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Describe the process of reduction
Three molecules of the unstable intermediate break down to form 6 GP molecules. This is reduced to 6 molecules of TP (6ATP - 6ADP and 6NADPH - 6NADP)
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Describe the process of regeneration
One TP molecule is put aside for the synthesis of organic molecules. 5 TP molecules regenerate into 3 RuBP molecules (3ATP - 3ADP)
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Give examples of the organic molecules produced from TP
Glucose, amino acids and lipids
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What does RuBP stand for?
Ribulose bisphosphate
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What does RuBisCO stand for?
Ribulose bisphophate carboxylase
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What does GP stand for?
Glycerate-3-phosphate
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What does TP stand for
Triose phosphate
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What is a limiting factor?
Factor which limits the rate of a process
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Name the factors which affect the rate of photosynthesis
Light intensity, carbon dioxide concentration, temperature and light wavelength
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What does the law of limiting factors state?
The rate of a physiological process will be limited by the factor which in the shortest supply
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Which chemical can be used to monitor the rate of photosynthesis?
DCPIP - turns from blue colourless when reduced
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How does a reduced light intensity affect the light-dependent stage?
Less ATP and NADPH will be produced
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How does a reduced light intensity affect the light-independent stage?
Less ATP and NADPH provided, high levels of GP and low levels of RuBP and TP
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How does a decrease in carbon dioxide concentration affect the Calvin cycle?
Low levels of GP and TP but high levels of RuBP
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How does a high temperature affect the stages in photosynthesis?
Increases rate of reaction but eventually proteins will denature, when the temperature is too high, leading to photosynthesis not being carried out efficiently
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How does a low temperature affect the stages in photosynthesis?
Slow rate of reaction for the stages in photosynthesis due to having less kinetic energy
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Other cards in this set

Card 2

Front

What is the law of conservation?

Back

Energy cannot be created or destroyed

Card 3

Front

What is photosynthesis?

Back

Preview of the front of card 3

Card 4

Front

What is respiration?

Back

Preview of the front of card 4

Card 5

Front

What determines whether a reaction in exothermic or endothermic?

Back

Preview of the front of card 5
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