30 Questions
What is plant physiology a study of?
How plants grow, develop, and function in their environments
What is essential for photosynthesis in plants?
Water
What is the role of water in plants?
To prevent leaf desiccation
What do plants need to prevent dehydration?
Less water loss
What is essential for plant survival?
All of the above
What is the relationship between structure and function in plants?
They represent different frames of reference of a biological unity
What is the primary mechanism of transport in cells at a small scale?
Diffusion
What is the term for the diffusion of water across a selectively permeable barrier?
Osmosis
What is the driving force behind the movement of molecules during diffusion?
Random thermal agitation
What is the result of the random movements of molecules during diffusion?
Net movement from high to low concentration
What determines the number of molecules crossing an imaginary plane during diffusion?
The number of molecules on either side
What is the tallest height that trees can transport water, due to cohesion and adhesion?
100 m
What is the stored free energy in the form of the H+ gradient?
Electrochemical potential for H+
What is the physical property that predicts the direction in which water will flow?
Water potential
What is the unit of pressure used to measure water potential?
Megapascal (MPa)
What is the water potential of pure water in a container open to the atmosphere under standard conditions?
0 MPa
What occurs when a substance is more concentrated on one side of a membrane than the other?
The substance diffuses across the membrane down its concentration gradient.
What is the purpose of the proton motive force generated by electrogenic H+ transport?
To drive the transport of other substances against their gradient of electrochemical potentials
What is the term for the absorption or loss of water by a cell?
Osmosis
What is required for active transport to occur?
Energy from the cell
What is the function of transport proteins in biological membranes?
To facilitate the passage of selected ions and polar molecules
What determines the transport specificity of channels?
The size of the pore and the density of surface charges on its interior lining
What is the function of gates in channel proteins?
To open and close the pore in response to external signals
What type of transport occurs through channels?
Passive transport
What is the optimal temperature condition for enzyme catalysis?
A moderate temperature to allow the greatest number of molecular collisions
Why are enzymes sensitive to pH?
Because the catalytic groups are usually ionizable
What happens to the enzyme's active site at pH values below 7?
The active site becomes disrupted due to conformational change
What is the purpose of allosteric activators or inhibitors?
To modulate enzymatic activity
What are cofactors in enzyme catalysis?
Nonprotein helpers that are required for catalytic activity
What is the function of cofactors in enzyme catalysis?
To activate enzymatic activity
A quiz on plant physiology, covering the study of plant processes, growth, development, and interaction with the environment.
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