Both channels and transporters discriminate between solutes mainly on the basis of size and electric charge.

Channels will allow the passage of any solute as long as it is smaller than the diameter of the channel pore; transporters bind their solutes with great specificity.

Channels discriminate between solutes mainly on the basis of size and electric charge; transporters bind their solutes with great specificity in the same manner an enzyme binds its substrate.

Transporters discriminate between solutes mainly on the basis of size and electric charge; channels bind their solutes with great specificity.

Channels allow the passage of solutes that are electrically charged; transporters facilitate the passage of molecules that are uncharged.

The breakdown of polysaccharides into simple sugars occur __________. Glycolysis occurs in the __________. The citric acid cycle and oxidative phosphorylation occurs in the __________.
extracellularly; mitochondria; cytosol
intracellularly; cytosol; Golgi apparatus
intracellularly; Golgi apparatus; mitochondria
extracellularly; cytosol; mitochondria

Which of the following generates the largest amount of ATP?
Group of answer choices
Fermentation
Glycolysis
The citric acid cycle
Gluconeogenesis
Oxidative phosphorylation

The apicoplast that defines the phylum Apicomplexa is a membrane-bound organelle. Which of the following is true of membrane-bound organelles?
I. They are only present in eukaryotes.
II. They are bound by a single phospholipid layer.
III. They do not have membrane-associated proteins attached.
Group of answer choices
I and III
I, II, and III
II only
II and III
I only

Voltage-gated channels contain charged protein domains, which are sensitive to changes in membrane potential. By responding to a threshold in the membrane potential, these voltage sensors trigger the opening of the channels. Which of the following best describes the behavior of a population of channels exposed to such a threshold?
Group of answer choices
Some channels remain closed. Many open fully.
All channels open fully.
Some channels open partially, while others open fully. None remain closed.
Some channels remain closed, some open partially, and some open fully.

Fermentation is an _____________________ process that converts _____________ into carbon dioxide and _____________________.
Group of answer choices
aerobic, pyruvate, ethanol
anaerobic, lactate, ethanol
aerobic, lactate, ethanol
anaerobic, pyruvate, ethanol

Monomeric G proteins:
Group of answer choices
turn themselves on by phosphorylating GDP to form GTP.
are active only in their trimeric forms.
turn themselves on by hydrolyzing GTP to form GDP.
are active when GTP is bound.
are active when GDP is bound.

The organelles that produce ATP in eukaryotic animal cells:
Group of answer choices
contain eukaryotic-like biosynthetic machinery for making RNA.
evolved from bacteria engulfed by ancestral cells billions of years ago.
reproduce sexually.
have a separate set of DNA that contains many of the same genes found in the nucleus.

Which membrane-enclosed organelles most likely evolved in a similar manner?
Group of answer choices
Chloroplasts and the nucleus
Mitochondria and the ER
Chloroplasts and the ER
The nucleus and the ER

When the basilar membrane in the organ of Corti vibrates, stereocilia on the hair cells _________, which results in the opening of __________-gated ion channels.
Group of answer choices
raise the roof; volume
also vibrate; mechanically
also vibrate; voltage
tilt; mechanically

The __________ pH inside endosomes causes many internalized receptors to __________ their cargo.
Group of answer choices
neutral; release
low; bind
high; bind
low; release
high; release

Fatty acids can easily be used to generate energy for the cell. Which of the following fatty acids will yield the most energy?
Group of answer choices
CH3-CH2-CH2-CH2-CH2-CH2-CH2-COOH
CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-COOH
CH3-CH2-CH2-CH2-CH2-COOH
CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-COOH

If pinocytosis were not balanced by _________, cells would constantly be shrinking in size.
Group of answer choices
endocytosis
autophagy
exocytosis
phagocytosis
metamorphosis

Which one of the following cell types would you predict to have the highest density of cristae?
Group of answer choices
Liver
Skin
Salivary gland
Muscle

Which of the following is a post-translational process?
Group of answer choices
chloroplast import
All the other answers are post-translational processes.
nuclear export
mitochondrial import

When Na+ channels are opened in an animal cell, what happens to the membrane potential?
Group of answer choices
It becomes less negative inside the cell.
It rapidly reaches the resting membrane potential.
It stays the same.
It disappears and the membrane potential stabilizes at 0 mV.mm

Which of the following is NOT true?
Group of answer choices
The citric acid cycle, in addition to the conversion of pyruvate to Acetyl CoA, produces the CO2 that we exhale.
Inhibition of oxidative phosphorylation will not affect the citric acid cycle.
Each turn of the citric acid cycle generates 3 NADHs.
Oxaloacetate is regenerated at the end of each turn of the citric acid cycle.
Each turn of the citric acid cycle generates 1 GTP and 1 FADH2.

Using genetic engineering techniques, you have created a protein that contains both a signal for import into mitochondria and a signal for retention in the ER. Into which organelle will this protein be imported?
Group of answer choices
the ER
a mitochondrion
the Golgi apparatus
the nucleus

Uncoupling is defined as a condition in which the rate of electron transport can no longer be regulated by an intact chemiosmotic gradient. Which of the following acts as an uncoupling agent by directly disrupting the chemiosmotic gradient?
Group of answer choices
Cyanide, which binds cytochrome c oxidase and inhibits electron transport
An outer mitochondrial membrane protein that allows protons to flow into the intermembrane space without passing through ATP synthase
An inner mitochondrial membrane protein that allows protons to flow into the mitochondrial matrix without passing through ATP synthase
Malonate, which binds succinate dehydrogenase and inhibits the citric acid cycle

Iron (Fe) is an essential trace metal that is needed by all cells. It is required, for example, for synthesis of the heme groups and iron-sulfur centers that are part of the active site of many proteins involved in electron-transfer reactions; it is also required in hemoglobin, the main protein in red blood cells. Iron is taken up by cells by receptor-mediated endocytosis. The iron-uptake system has two components: a soluble protein called transferrin, which circulates in the bloodstream; and a transferrin receptor—a transmembrane protein that, like the LDL receptor, is continually endocytosed and recycled to the plasma membrane. Fe ions bind to transferrin at neutral pH but not at acidic pH. Transferrin binds to the transferrin receptor at neutral pH only when it has an Fe ion bound, but it binds to the receptor at acidic pH even in the absence of bound iron. Which of the following is likely true of this system?
Group of answer choices
All of the other answers are true.
Once iron is bound, the iron–transferrin complex can bind to the transferrin receptor on the surface of a cell and be endocytosed.
Under the acidic conditions of the endosome, the transferrin releases its iron, but the transferrin remains bound to the transferrin receptor, which is recycled back to the cell surface, where it encounters the neutral pH environment of the blood.
Transferrin without Fe bound does not interact with its receptor and circulates in the bloodstream until it catches an Fe ion.
The neutral pH of the blood causes the receptor to release the transferrin into the circulation, where it can pick up another Fe ion to repeat the cycle.

Which of the following is NOT part of the process known as oxidative phosphorylation?
Group of answer choices
Molecular oxygen serves as a final electron acceptor.
ATP molecules are produced in the cytosol as glucose is converted into pyruvate.
The electron carriers in the electron-transport chain toggle between reduced and oxidized states as electrons are passed along.
FADH2 and NADH become oxidized as they transfer a pair of electrons to the electron-transport chain.
Electrons lose energy as they pass through the electron transport chain.

Which of the following statements is NOT true of mitochondrial proteins that are synthesized in the cytosol?
Group of answer choices
The proteins are unfolded as they are transported into the mitochondria.
The proteins cross both the inner and outer mitochondrial membranes as they are imported.
The proteins must be transported across the mitochondrial membranes while being synthesized.
The proteins usually have a signal sequence at their N-terminus.

Which of the following is true?
Group of answer choices
The ATP made in the mitochondrial matrix is only used in the matrix.
The import of Pi into the mitochondrial matrix directly requires ATP.
The pyruvate used by the citric acid cycle passively diffuses across the inner mitochondrial membrane.
None of the other answers is true.

Mitochondria and peroxisomes do NOT have what in common?
Group of answer choices
Their membranes contain a protein translocator.
Proteins need to unfold to enter them.
They are present in eukaryotic cells.
They must import proteins to function.

Both channels and transporters discriminate between solutes mainly...