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| 1 | |
Which one of the following biological macromolecules is least likely to be a component of a biomembrane? |
| | A) | Lipids |
| | B) | Carbohydrates |
| | C) | Proteins |
| | D) | Nucleic acids |
| | E) | All of the choices are common components of biomembranes. |
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| 2 | |
A solute crossing a biomembrane from a region of low concentration to a region of high concentration with the aid of a transport protein and energy is most accurately referred to as |
| | A) | selective permeability. |
| | B) | active transport. |
| | C) | passive diffusion. |
| | D) | facilitated diffusion. |
| | E) | fluidity. |
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| 3 | |
Which of the following is not a type of transport protein? |
| | A) | Transporters |
| | B) | Channels |
| | C) | Antiporters |
| | D) | Symporters |
| | E) | All of the choices are forms of membrane transport proteins. |
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| 4 | |
Which of the following is not an integral membrane protein? |
| | A) | Transmembrane protein |
| | B) | Lipid-anchored protein |
| | C) | Transmembrane segment |
| | D) | Extrinsic proteins |
| | E) | All of the choices are integral membrane proteins. |
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| 5 | |
Under what conditions would a biomembrane be the most fluid at 37°C? |
| | A) | Long unsaturated fatty acyl tails plus cholesterol |
| | B) | Short unsaturated fatty acyl tails and no cholesterol |
| | C) | Short saturated fatty acyl tails and no cholesterol |
| | D) | Short unsaturated fatty acyl tails plus cholesterol |
| | E) | Long saturated fatty acyl tails plus cholesterol |
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| 6 | |
If the Frye and Edidin experiment was repeated using an incubation temperature of 30°C instead of 37°C, mouse H-2 protein would still be distributed evenly on both sides of the hybrid cell, but would take longer for the distribution to complete. |
| | A) | True |
| | B) | False |
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| 7 | |
Which of the following statements does not represent a reason why integral membrane proteins might be restricted in their movements? |
| | A) | It is energetically unfavorable for the hydrophilic region of a membrane protein to cross the hydrophobic interior of the membrane. |
| | B) | The cytosolic face of an integral membrane protein can be linked to the cell's cytoskeleton. |
| | C) | Proteins are larger molecules than lipids and therefore move more slowly than lipids through a lipid bilayer. |
| | D) | Integral membrane proteins can be attached to molecules in the extracellular space. |
| | E) | All of the choices describe possible reasons for the restricted movement of integral membrane proteins. |
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| 8 | |
The technique most commonly used to study the interior of a biomembrane is known as |
| | A) | transmission electron microscopy. |
| | B) | fluorescence microscopy. |
| | C) | freeze-fracture electron microscopy. |
| | D) | scanning electron microscopy. |
| | E) | fluorescence recovery after photo bleaching. |
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| 9 | |
Arrange the following molecules in order from most likely to least likely to pass through a biomembrane.
- glucose
- carbon dioxide
- Water
- K+ (Potassium ion)
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| | A) | iv > i > iii > ii |
| | B) | iii > ii > i > iv |
| | C) | ii > iii > iv > i |
| | D) | iv > iii > i > ii |
| | E) | ii > iii > i > iv |
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| 10 | |
True or False: The movement of water across a semipermeable membrane to balance solute concentrations is called osmosis and requires energy input. |
| | A) | True |
| | B) | False |
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| 11 | |
A beaker of water is divided into two compartments, A and B, by an artificial lipid bilayer. The concentration of Na+ in compartment A is 1.0 M, while the concentration of Na+ in compartment B is 1.5 M. With regards to Na+ concentration, compartment A would be referred to as __________, while compartment B would be referred to as __________. |
| | A) | isotonic; hypertonic |
| | B) | hypertonic; hypotonic |
| | C) | hypotonic; isotonic |
| | D) | hypotonic; hypertonic |
| | E) | hypertonic; isotonic |
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| 12 | |
How does a freshwater organism like a paramecium maintain proper osmotic balance? |
| | A) | Paramecium have a rigid cell wall which prevents water loss. |
| | B) | The cell membranes of paramecium contain special water pumps to move water into the cytoplasm. |
| | C) | The cell membranes of paramecium contain special water pumps to move water out of the cytoplasm. |
| | D) | Paramecium have contractile vacuoles which accumulate water, fuse with the plasma membrane, and discharge the water into the extracellular environment. |
| | E) | No special mechanism is necessary because the cytoplasm is isotonic with the extracellular environment. |
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| 13 | |
A transmembrane channel that opens and closes in response to the direct binding of a molecule to the channel protein itself is referred to as a(n) |
| | A) | mechanosensitive channel. |
| | B) | aquaporin. |
| | C) | voltage-gated channel. |
| | D) | ligand-gated channel. |
| | E) | phosphorosensitive channel. |
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| 14 | |
Carriers that bind two or more molecules or ions and transport them in opposite directions are called __________, while carriers that bind two or more molecules or ions and transport them in the same direction are called __________. |
| | A) | symporters; cotransporters |
| | B) | uniporters; symporters |
| | C) | symporters; antiporters |
| | D) | antiporters; uniporters |
| | E) | antiporters; symporters |
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| 15 | |
True or False: Existing proton (H+) gradients frequently provide the energy required to move nutrients against their concentration gradients. |
| | A) | True |
| | B) | False |
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| 16 | |
Which one of the following statements about Na+/K+-ATPase pumps is incorrect? |
| | A) | Na+/K+-ATPase pumps are an example of an electrogenic pump. |
| | B) | A typical animal cell utilizes thousands of Na+/K+-ATPase pumps to maintain ATPase gradients across the cell membranes. |
| | C) | The Na+/K+-ATPase pump results in 2 K+ being released into the cytosol and 3 Na+ being released into the extracellular space. |
| | D) | A Na+/K+-ATPase pumps alternates between two different conformations known as E1 and E2. |
| | E) | Some animal cell types, like neurons, utilize a majority of their ATP to operate pumps like the Na+/K+-ATPase pump. |
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| 17 | |
Which of the following is not a function of an electrochemical gradient? |
| | A) | Export of waste products. |
| | B) | Contraction of muscle fibers. |
| | C) | Synthesis of ATP. |
| | D) | Transmission of nerve impulses. |
| | E) | Glycosylation. |
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| 18 | |
Vesicles destined for exocytosis are typically derived from |
| | A) | mitochondria. |
| | B) | smooth endoplasmic reticulum. |
| | C) | lysosomes. |
| | D) | the Golgi apparatus. |
| | E) | vacuoles. |
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| 19 | |
Which one of the following statements about endocytosis is incorrect? |
| | A) | Endocytic vesicles can be formed when a receptor molecule binds a specific cargo molecule. |
| | B) | All cell types are capable of phagocytosis, a form of endocytosis. |
| | C) | Internalization of extracellular fluid is a form of endocytosis. |
| | D) | Endocytosis is an invagination of the plasma membrane. |
| | E) | All of these statements about endocytosis are correct. |
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| 20 | |
True or False: Bacteria invading a mammalian host are often removed when the host's immune system cells engulf the bacteria and fuse with lysosomes, which provide the energy for destruction of the bacteria. |
| | A) | True |
| | B) | False |
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