According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?
A) They can move laterally along the plane of the membrane.
B) They frequently flip-flop from one side of the membrane to the other.
C) They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane.
D) They have hydrophilic tails in the interior of the membrane.
A
Which of the following statements is correct about diffusion?
A) It is very rapid over long distances.
B) It requires an expenditure of energy by the cell.
C) It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.
D) It requires integral proteins in the cell membrane.
C
For living organisms, which of the following is an important consequence of the first law of thermodynamics?
A) The energy content of an organism is constant.
B) The organism ultimately must obtain all of the necessary energy for life from its environment.
C) The entropy of an organism decreases with time as the organism grows in complexity.
D) Organisms grow by converting energy into organic matter.
E) Life does not obey the first law of thermodynamics.
B
Which of the following is true of osmosis?
A) In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.
B) Osmisis only takes place in red blood cells.
C) Osmosis is an energy -demanding or "active" process.
D) In osmosis, solutes move across a membrane from areas of lower water concentration to areas of higher water concentration.
A
Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ________ is to ________.
A) exergonic; spontaneous
B) exergonic; endergonic
C) free energy; entropy
D) work; energy
E) entropy; enthalpy
B
When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?
A) It is used to power yet more cellular work.
B) It is used to store energy as more ATP.
C) It is used to generate ADP from nucleotide precursors.
D) It is lost to the environment.
E) It is transported to specific organs such as the brain.
D
Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's ____.
A) entropy.
B) activation energy.
C) endothermic level.
D) equilibrium point.
E) free-energy content.
B
When a molecule of NAD+ gains a Hydrogen atom(not a proton), the molecule becomes _____.
A) dehydrogenated.
B) oxidized.
C) redoxed.
D) reduced.
D
In the presence of oxygen, the 3-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO2, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. The three listed steps result in a formation of ____.
A) acetyl CoA, NADH, and CO2.
B) acetyl CoA, FADH2, and CO2.
C) acetyl CoA, NAD+, ATP, and CO2.
D) acetyl CoA, O2, and ATP.
A
Halobacterium has a photosynthetic membrane that is colored purple. Its photosynthetic action spectrum is exactly complementary (opposite to) the action spectrum for green plants. What wavelengths of light do the Halobacterium photosynthetic pigments absorb?
A) red and yellow
B) blue, green, and red
C) green and yellow
D) red and green
E) blue and red
C
What event accompanies energy absorption by chlorophyll (or other pigment molecules of the antenna complex)?
A) ATP is synthesized from the energy absorbed.
B) A carboxylation reaction of the Calvin cycle occurs.
C) An electron is excited.
D) Electrons are stripped from NADPH
D
In the process of carbon fixation, RuBP attaches a CO2 to produce a six-carbon molecule, which is then split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces glyceraldehyde 3-phosphate(G3P), what more needs to happen to complete the Calvin cycle?
A) regeneration of ATP from ADP.
B) regeneration of NADP+.
C) addition of a pair of electrons from NADPH.
D) regeneration of RuBP
D
Substrate-level phosphorylation accounts for approximately what percent of the ATP formed in glycolysis?
A) 100%
B) 38%
C) 2%
D) 0%
A
In a plant cell, where are the ATP synthase complexes located?
A) thylakoid membrane only
B) plasma membrane only
C) inner mitochondrial membrane only
D) thylakoid membrane and inner mitochondrial membrane
E) thylakoid membrane and plasma membrane
D