Plant Physiology 25-35
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_____ can be defined as the energy transformations that occur in living organisms, and the flow of that energy through these organisms.
Biological energy transductions (transfers) are based on the _____.
First two laws of thermodynamics
_____ is the energy of the universe is constant. This law refers to energy conservation. Energy does not change form.
First Law of Thermodynamics
_____ says in any physical or chemical process, the amount of entropy tends to increase. This law states that no energy transformation process is 100% efficient. There is always some quantity of energy that is converted to a form that is no longer useful (lost as heat).
Second Law of Thermodynamics
_____ can be defined as the extent of randomness or disorder in a system.
Natural systems are always moving towards a state of increasing entropy (theoretically, finally terminating in _____), and energy must be put into the system in order to stop the trend towards increased entropy.
The ability of a reaction to accomplish work is based on the principle of _____.
_____ can be defined as the mean molecular kinetic energy of matter.
Temperature cannot be held constant when this thermal energy is given up, thus the lost thermal energy is considered _____-goes toward entropy increase.
Reactions with a negative ΔG are known as _____ reactions, or energy yielding reactions.
Reactions with a positive ΔG are known as _____ reactions, or energy consuming/requiring reactions.
At equilibrium, there will be _____ in the concentrations of reactants and products.
No net change
The net free energy in coupling reactions must always be _____.
Oxidation of a carbon atom in a carbon compound is synonymous with ______ (loss of hydrogen atoms bonded to carbon).
In cells, electrons can be transferred from one molecule to another in four different ways:
- 1. directly as electrons
- 2. as a hydrogen atom (1 electron & 1 proton)
- 3. as a hydride ion (2 electrons & 1 proton)
- 4. as a direct combination of an organic reductant with oxygen, producing a molecular product in which oxygen is covalently bonded
Photosynthesis and respiration are primarily a sequence of electrochemical reactions, mostly consisting of a series of _____ and _____ reactions, or _____ reactions.
Oxidation and reduction
Each redox reaction can be conveniently dissected into 2 half reactions involving the _____ and _____ of one or more electrons.
Donation and acceptance
The electron donor becomes _____.
The electron acceptor becomes ______.
A reduced/oxidized pair is known as a _____.
The ability of a molecular species to accept electrons from, or donate electrons to another molecule, is known as its _____.
When a redox couple is 50% reduced, this is known as the _____.
There are 4 primary reasons why ATP will spontaneously hydrolize into ADP and Pi:
- 1. electron repulsion amongst the four negative charges is somewhat relieved by charge separation after hydrolysis
- 2. inorganic phosphate (Pi) released by hydrolysis is stabilized by resonance hybride which does not allow H+ to bond to the oxygen atoms of Pi
- 3. ADP is also immediately ionized and releases a H+ ion into a high pH (7.0) solution
- 4. ADP and Pi have a higher degree of solvation (hydration) in water than does ATP; this further stabilizes products over reactants.
Under conditions that define standard free energy change, the mass-action ration for ATP hydrolysis is _____ than equilibrium.
Five orders of magnitude less
The maintenance of a steady-state system is known as _____.
ATP links _____ (breakdown of biomolecules into smaller precursors) and _____ (building of biomolecules in the cell.
ATP is used primarily for the following processes:
- 1. synthesis of metabolic intermediates and macromolecules from smaller precursors (anabolism).
- 2. transport of substances across membranes against concentration gradients (active transport)
- 3. phosphorylation of biomolecules and group transfer reactions
- 4. energy storage
- 5. mechanical motion
The exergonic reaction of ATP hydrolysis actually occurs as a _____ step process.
Phosphorylated compounds can have a high or low _____, depending of how effectively they can be used to phosphorylate other compounds.
Phosphate group transfer potential
A group of enzymes known as _____ catalyze the phosphorylation of certain molecules by ATP.
The size and complexity of ATP allows it to form many more favorable _____ between itself and the substrate, over what would be possible with pyrophosphate (PPi).
Many noncovalent interactions that are formed increased the _____ (energy derived from the formation of noncovalent interactions) and dramatically increase the rate of reaction.
_____ is a electrostatic attraction between oppositely charged regions of water molecules, or between two molecules with polar covalent bonds.
_____ is an electrostatic interaction between charged groups.
_____ is attractive interactions between non-polar groups.
_____ are attractive forces between large, closely positioned molecules.
Van der walls forces
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