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61 Cards in this Set

  • Front
  • Back
first law of thermodynamics
the total amount of energy in the universe remains constant
energy cannot be created or destroyed; it can only be converted from one form to another
What are the four types of energy?
potential, kinetic, chemical, and heat/thermal energy
For what three kinds of work do cells use energy?
chemical work - to stockpile, build, rearrange, and break apart substances
mechanical work - to move flagella and other cell structures and (in multi-celled species) the whole body or portions of it
electrochemical work - to move charged substances into or out of the cytoplasm or an organelle compartment
a measure of the degree of a system's disorder
-everything will eventually crumble and die
second law of thermodynamics
a law of nature stating that the spontaneous direction of energy flow is from organized (usable) forms to less organized (unusable) forms; with each conversion, some energy is randomly dispersed in a form (usually heat) not as useful for doing work

Overall, energy flows in one direction.
Energy changes in living cells tend to proceed spontaneously in the direction that results in a _______ in usable energy.

increase or decrease?
endergonic reaction
e.g. in photosynthetic cells, energy inputs from the sun drive reactions that make glucose, the result being a net increase in usable energy
we say the reaction sequence is endergonic (meaning energy in)
exergonic reaction
reaction from "top of the energy hill" to the "base"
energetically, the downhill run is favored; it will proceed on its own and end w/ a net loss in energy
we say the reaction sequence is exergonic (meaning energy out)
structure of ATP (adenosine triphosphate)
nucleotide: covalent bonds join the five-carbon sugar ribose, the nucleotide base adenine, and three phosphate groups
What is phosphorylation?
hundreds of diff. enzymes can split off the outer phosphate group and join it to another molecule, which thus becomes primed to enter a reaction
=phosphate group transfer
Phosphorylation (getting rid of a phosphate group) produces what?
ADP (adenosine diphosphate) and a free inorganic phosphate atom (Pi)
After phosphorylation, ADP can be converted back to ATP when an enzyme attaches inorganic phosphate (or a phosphate group derived from some other molecule) to it
-regenerating ATP this way is important aspect of __________
This circle of events is called: _________
ATP/ADP cycle
Oxidation is:
when a molecule loses one or more electrons
Reduction is:
when a molecule gains one or more electrons
Oxidation and reduction are central to the formation of _____ during photsynthesis and aerobic respiration.
substances that enter a reaction
substances that form during a reaction (or a sequence of reactions)
substances left at the end of a reaction
energy carriers
activate enzymes and other molecules by phosphate-group transfers

mainly ATP
assist enzymes by picking up electrons, atoms, or functional groups from a reaction site and giving them up at diff. sites
What are four features of enzymes?
1. speed up reactions
2. can be reused
3. can recognize both reactants and products in order to catalyze a reaction in both directions
4. very selective about the substances to which they will bind and thereby bring about change
What 3 events occur in light-dependent reactions?
1. pigments absorb sunlight energy and give up excited electrons
2. electron and hydrogen transfers lead to ATP and NADPH formation
3. the pigments that gave up the electrons in the first place get electron replacements
What happens in the cyclic pathway of ATP formation?
excited electrons leave the P700 reaction center, pass through an electron transport system, and then return to the original photosystem I
-electron flow drives ATP formation
-no NADPH is formed
What happens in the noncyclic pathway of ATP formation?
-transfers electrons through two photosystems and two electron transport systems in the thylakoid membranes
-begins when the chlorophyll P680 in photosystem II absorbs energy
1)boosted electron moves through a transport system that releases energy for ADP + Pi ==== ATP
2) electron fills "hole" left by electron boost in P700 of photosystem I
3) electron from photolysis (splitting) of water fills "electron hole" left in P680 and produces oxygen byproduct
-pathway continues when chlorophyll P700 in photosystem I absorbs energy
1)energy hole is filled by electron from P680
2)boosted electron P700 passes to acceptor, then ETS; it finally joins NADP to form NADPH (which along w/ ATP can be used in synthesis of organic compounds)
Explain the chemiosmotic model of ATP formation.
1) hydrogen ions from photolysis of water accumulate inside the thylakoid compartment of chloroplasts to set up concentration and electric gradients
2) oxygen atoms from photolysis combine to form O2 which is released into the atmosphere
3) as the hydrogen ions flow out through channels into the stroma, enzyme action links Pi to ADP to form ATP
Which of the following would NOT be true of CAM plants?
a. fix carbon only once
b. live in desert environments
c. fix carbon mostly during the day
d. open stomata only at night
e. grow slowly
c. fix carbon mostly during the day
If one continues to increase the temperature in an enzyme-catalyzed reaction, the rate of the reaction:
a. does not change
b. increases and then levels off.
c. decreases and then levels off.
d. increases and then decreases rapidly.
e. decreases and then increases rapidly.
d. increases and then decreases rapidly
During chemiosmosis, ________ are transferred from NADH and FADH2 to electron acceptor molecules; and the energy released is used to create a(n) ____________ gradient across the inner mitochondrial membrane.
electrons; proton
In C4 plants, reactions that fix CO2 into four-carbon compounds occur in:
mesophyll cells
Select the process that are matched with the INCORRECT amount of ATP produced by that process per glucose molecule.
a.glycolysis-2 ATP(net)
b.citric acid cycle-4 ATP
c.electron transport chain-34(max)ATP
d.alcohol fermentation-2 ATP(net)
e.lactate fermentation-2 ATP(net)
b.citric acid cycle-4 ATP
In photosynthesis, ATP and NADPH are produced during:
the light-dependent phase
Considering only glycolysis and the conversion of pyruvate molecules to acetyl CoA molecules, how many NADH molecules will be produced from one glucose molecule?
The electrons lost by the P680 reactive center are replaced by electrons from:
a water molecule
The most important photosynthetic pigment is:
chlorophyll a
Parts of the enzyme molecule that interact with a substrate are called:
active sites
How many electrons are needed to reduce one molecule of NADP+ to NADPH?
The production of alcohol or lactate from pyruvate during __________ occurs as a means of regenerating ___________ from __________.
fermentation; NAD+; NADH
What are the reactants of the Calvin-Benson cycle?
Which process does not match the products shown?
a.electron transport and chemiosmosis-ATP, H2O, NAD+
b.citric acid cycle-CO2, NADH, FADH2, ATP
c.formation of acetyl CoA-Acetyl CoA, CO2, NADH
d.glycolysis-pyruvate, ATP, NADH
e.All of the processes match the products.
e. All of the processes match the products.
According the chemiosmotic theory, concentration and electric gradients drive the formation of ____.
Because of its location in the electron transfer chain, delivery of electrons to each FAD results in how many ATPs?
Name this process.

This leads to the formation of glucose-6-phosphate (sugar phosphate) from 2 molecules of phosphoglyceraldehyde.
Calvin-Benson cycle
Name this process.

In this process carbon dioxide is incorporated first into an unstable intermediate compound and then into phosphoglycerate.
carbon dioxide fixation
Name this process.

This yields NADPH as well as ATP.
light-dependent reactions
Name this process.

This is a carbon-fixing system that precedes the Calvin-Benson cycle in some plants.
C4 pathway
Name this process.

PGAL molecules are formed from the reaction of PGA molecules with ATP and NADPH in this pathway.
Calvin-Benson cycle
Name this process.

produces NADH and CO2; changes pyruvate
acetyl-CoA formation
Name this process.

produces ATP, NADH, and CO2
the Krebs cycle
Name this process.

splits glucose into 2 pyruvate molecules
Name this process.

regenerates NAD+ as pyruvate; is converted to ethanol or lactate
What process precedes (comes before) the Krebs cycle?
The generation of concentration gradients across mitochondrial membranes is called ____________.
b.ATP synthesis
c.electron transport chain
d.aerobic respiration
Which components, structures, or processes of photosynthesis is associated with light-independent reactions (dark reactions)?
B.Photosystem I and II
C.The Calvin-Benson cycle
E.Breakdown of glucose to two molecules of pyruvate
C.The Calvin-Benson cycle
What happens during the TCA (Krebs) cycle?
I. Pyruvate is eventually oxidized to CO2.
II. Electrons and protons (H+ ions) are transferred to NAD+ and FAD+.
III. Oxygen serves as the final electron acceptor.
A.I only
B.II only
C.III only
D.I and II only
E.I, II, and III
D.I and II only
Which statement(s) about glycolysis is(are) correct?
I. A steady supply of NAD+ is needed.
II. An ATP molecule is needed to begin the pathway.
III. PGAL is converted to pyruvate through a reduction reaction.
A.I only
B.II only
C.III only
D.I and II only
E.I, II, and III
D.I and II only
How do inhibitors of enzyme-catalyzed reactions work?
A.They bind to the enzyme active site.
B.They tie up the molecule of ATP to prevent a coupled reaction.
C.They use up all of the reactants.
A.They bind to the enzyme active site.
In plant cells undergoing photosynthesis, what kind of chemical reaction produces ATP from ADP and inorganic phosphate?
A.Coenzyme activation
Which statement(s) about endergonic reactions is(are) true?
I. They have a negative G.
II. They are nonspontaneous.
III. The products of the reaction have more free energy than the reactants.
A.I only
B.II only
C.III only
D.II and III only
E.I, II, and III
D.II and III only
__________ plays no role in glycolysis.
Which of the following processes occurs in both respiration and photosynthesis?
a. chemiosmosis
b. calvin cycle
c. citric acid cycle
d. krebs cycle
e. glycolysis
a. chemiosmosis
Which of the following statements is INcorrect?
a.glycolysis can occur w/ or w/o oxygen
b.glycolysis occurs in the mitochondria
c.glycolysis is the first step in both anaerobic and aerobic respiration
d.glycolysis leads to production of 2ATP, 2NADH, and 2 pyruvate
b. glycolysis occurs in mitochondria
*glycolysis occurs in CYTOPLASM