 |
1 | |
Phospholipids form effective barriers between the aqueous cytosol of cells and the aqueous extracellular fluid because they are |
| | A) | polar. |
| | B) | nonpolar. |
| | C) | lipids. |
| | D) | rigid. |
| | E) | amphipathic. |
|
|
2 | |
Tight junctions |
| | A) | hold cells tightly together so that they cannot readily be pulled apart. |
| | B) | form barriers that regulate the passage of materials across epithelial membranes. |
| | C) | are commonly found in smooth muscle. |
| | D) | A and B. |
| | E) | B and C. |
|
|
3 | |
Which of the following is not true regarding cell membrane junctions? |
| | A) | Tight junctions anchor cells to basement membranes in tissues that are subjected to stretch. |
| | B) | Desmosomes anchor adjacent cells together. |
| | C) | Gap junctions seal spaces between cells and control permeability across epithelial membranes. |
| | D) | A and B. |
| | E) | A and C. |
|
|
4 | |
Functions of smooth (also called agranular) endoplasmic reticulum include |
| | A) | synthesis of proteins for use in the cell. |
| | B) | synthesis of steroids. |
| | C) | storage of intracellular calcium ion. |
| | D) | A and C. |
| | E) | B and C. |
|
|
5 | |
The organelles that digest engulfed bacteria and cell debris are the |
| | A) | peroxisomes. |
| | B) | endosomes. |
| | C) | lysosomes. |
| | D) | ribosomes. |
| | E) | mitochondria |
|
|
6 | |
The major lipids in cellular membranes are phospholipids. |
| | A) | True |
| | B) | False |
|
|
7 | |
The special functions of plasma and organelle membranes depend primarily on the specific composition of the phospholipids of those membranes. |
| | A) | True |
| | B) | False |
|
|
8 | |
One function of integral membrane proteins in the plasma membrane of cells is to form channels to allow passage of nonpolar solutes into the cell. |
| | A) | True |
| | B) | False |
|
|
9 | |
Peripheral membrane proteins are involved in regulating cell shape and motility. |
| | A) | True |
| | B) | False |
|
|
10 | |
Desmosomes are structures that permit direct communication between cells by allowing the cells to exchange small molecules in their cytoplasms. |
| | A) | True |
| | B) | False |
|
|
11 | |
Chromosomes are condensed forms of chromatin. |
| | A) | True |
| | B) | False |
|
|
12 | |
Free ribosomes differ from membrane-bound ribosomes in that free ribosomes specialize in synthesizing proteins for export (secretion) from the cell. |
| | A) | True |
| | B) | False |
|
|
13 | |
Transcription can be described as |
| | A) | when the 3-base anti-codon in an amino acid tRNA complex pairs with its corresponding codon in the region of the mRNA and then bonds to the ribosome |
| | B) | is the process of transferring genetic information from DNA to RNA |
| | C) | occurs in the nucleus |
| | D) | A and C |
| | E) | B and C |
|
|
14 | |
Messenger RNA codes for the amino acid sequence of proteins |
| | A) | True |
| | B) | False |
|
|
15 | |
Two ligands, A and B, bind to a site on protein X. Their binding curves are shown below. When ligand A binds, it produces a biological effect. Ligand B produces no effect when it binds. Therefore:
 <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif:: ::/sites/dl/free/0072437936/65657/chap04.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (1.0K)</a>]]> |
| | A) | Increasing the concentration of A will always result in an increase of the biological effect. |
| | B) | The binding site on X has a higher affinity for A than for B. |
| | C) | Increasing the concentration of B in the presence of A will decrease the biological effect. |
| | D) | A and B |
| | E) | B and C |
|
|
16 | |
Allosteric proteins |
| | A) | contain more than one kind of binding site. |
| | B) | undergo a change of shape when a ligand binds to the regulatory binding site. |
| | C) | are always activated when a modulator molecule binds to the regulatory site. |
| | D) | A and B. |
| | E) | A, B and C. |
|
|
17 | |
The term "allosteric modulation" refers to |
| | A) | regulation of physiological functions by the sympathetic division of the autonomic nervous system. |
| | B) | modification of the functional state of a protein by temperature or pH. |
| | C) | the change in the shape and functional state of a protein that occurs when a ligand binds to a receptor site. |
| | D) | A and B. |
| | E) | B and C. |
|
|
18 | |
When a chemical binds noncovalently to a protein at a distance from its functional site and causes a conformational change in the site that prevents the natural ligand from binding, this is an example of |
| | A) | allosteric modulation. |
| | B) | noncompetitive antagonism. |
| | C) | competitive modulation. |
| | D) | A and B. |
| | E) | none of the above. |
|
|
19 | |
Proteins are broken down to amino acids by enzymes called trans-aminases. |
| | A) | True |
| | B) | False |
|
|
20 | |
Removal of the amino group from an amino acid is necessary before the amino acid can be metabolized for energy. |
| | A) | True |
| | B) | False |
|
|
21 | |
Human beings can synthesize all twenty amino acids the body must have. |
| | A) | True |
| | B) | False |
|
|
22 | |
An essential nutrient is one necessary for optimal health that may or may not be synthesized by the body. |
| | A) | True |
| | B) | False |
|
|
23 | |
Glucose is not considered an essential nutrient because it is not essential for good health. |
| | A) | True |
| | B) | False |
|
|
24 | |
Fat-soluble vitamins are required for health because they act as coenzymes. |
| | A) | True |
| | B) | False |
|
|
25 | |
Glycolysis can be described by all of the following except |
| | A) | occurs aerobically |
| | B) | consists of 10 enzymatic reactions, the end product of which can be pyruvate |
| | C) | takes place in the cytosol |
| | D) | glucose is the primary carbohydrate metabolized |
| | E) | a net synthesis of two molecules of ATP occurs |
| | F) | A and C |
|
|
26 | |
Following glycolysis, pyruvate can enter the Krebs Cycle and be broken down into carbon dioxide if oxygen is present. |
| | A) | True |
| | B) | False |
|
|
27 | |
Glycogen |
| | A) | is the storage form of fats |
| | B) | is the storage form of glucose |
| | C) | is found primarily in the kidney and brain |
| | D) | the enzymes for glycogen synthesis and breakdown are located in the mitocondria |
| | E) | B and C |
|
|
28 | |
Transfer RNA |
| | A) | functions to transport mRNA out of the nucleus. |
| | B) | binds specifically to mRNA and nonspecifically to amino acids. |
| | C) | binds specifically to amino acids and nonspecifically to mRNA. |
| | D) | binds specifically to mRNA and to amino acids. |
| | E) | none of the above |
|
|
29 | |
How does the synthesis of proteins that are destined to be secreted differ from that of proteins with functions inside the cell? |
| | A) | Proteins destined to be secreted have a signal sequence. |
| | B) | Proteins destined to be secreted are synthesized on free ribosomes. |
| | C) | Proteins destined to be secreted are packaged into secretory vesicles in the rough endoplasmic reticulum. |
| | D) | A and B. |
| | E) | A and C. |
|
|
30 | |
Functions of the Golgi apparatus include |
| | A) | sorting of proteins destined for various destinations in the cell. |
| | B) | modifying proteins destined for secretion. |
| | C) | packaging enzymes destined for lysosomes. |
| | D) | A and B. |
| | E) | A, B and C. |
|