MCQOPTIONS
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MCQOPTIONS
This section includes 657 Mcqs, each offering curated multiple-choice questions to sharpen your Testing Subject knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
In DNA, guanine pairs with? |
| A. | Adenine |
| B. | Cytosine |
| C. | Thymine |
| D. | Uracil |
| Answer» C. Thymine | |
| 2. |
DNA gyrase in E. coli....... |
| A. | adds positive supercoils to chromosomal DNA |
| B. | can be inhibited with antibiotics |
| C. | is required only at the oriC site |
| D. | performs the same function as helicase in eukaryotes Answer u0026 Explanation |
| Answer» C. is required only at the oriC site | |
| 3. |
In DNA, there are? |
| A. | five bases known as adenine, guanine, thymine, tryptophan andcytosine |
| B. | four bases known as adenine, guanine, thymine and cytosine |
| C. | three bases known as adenine, guanine and cytosine |
| D. | only two bases known as adenine and cytosine |
| Answer» C. three bases known as adenine, guanine and cytosine | |
| 4. |
Messelsen and Stahl model of replication was called? |
| A. | conservative replication |
| B. | semi-conservative replication |
| C. | dispersive replication |
| D. | Cri du Chat |
| Answer» C. dispersive replication | |
| 5. |
The most common liquid volumes in molecular biology are measured in? |
| A. | ml |
| B. | μl |
| C. | nl |
| D. | 1 |
| Answer» C. nl | |
| 6. |
The 5' and 3' numbers are related to the____ |
| A. | length of the DNA strand |
| B. | length of the DNA strand |
| C. | the number of phosphates |
| D. | the base pair rule |
| Answer» C. the number of phosphates | |
| 7. |
The chromosomal DNA complexes with___ |
| A. | three types of histone as H1, H2A and H4 |
| B. | five types of histone as H1, H2A, H2B, H3 and H4 |
| C. | four types of histone as H1, H2A, H3 and H4 |
| D. | two types of histone as H1 and H4 |
| Answer» C. four types of histone as H1, H2A, H3 and H4 | |
| 8. |
Taylor, Woods and Hughes labeled Vicia DNA by allowing new DNA synthesis in the presence of radioactive thymine. After DNA replication (S phase of the cell cycle), it was observed that______ |
| A. | only one chromatid of a chromosome was labeled |
| B. | both chromatids of a chromosome were labeled |
| C. | both (a) and (b) |
| D. | neither chromatid was labeled |
| Answer» C. both (a) and (b) | |
| 9. |
The accepted hypothesis for DNA replication is? |
| A. | conservative theory |
| B. | dispersive theory |
| C. | semi-conservative theory |
| D. | evolutionary theory |
| Answer» D. evolutionary theory | |
| 10. |
Buried hydrophobic side chains in a globular protein fit into a hole formed by the side chains of? |
| A. | 1-3 other amino acids |
| B. | 5-7 other amino acids |
| C. | 9-12 other amino acids |
| D. | 13-15 other amino acids |
| Answer» C. 9-12 other amino acids | |
| 11. |
Attractive Vaan der Waals forces occur between____ |
| A. | apolar molecules in the liquid state |
| B. | any pair of nearby atoms |
| C. | polar molecules in the solid state |
| D. | only if other forces are less favorable |
| Answer» C. polar molecules in the solid state | |
| 12. |
For the unfolding reaction of Protein G, ΔH° =210.6 kJ/mol, this means that..... |
| A. | unfolding is favored enthalpically |
| B. | folding is favored enthalpically |
| C. | the entropy is positive at all temperatures |
| D. | the entropy is negative at all temperatures |
| Answer» C. the entropy is positive at all temperatures | |
| 13. |
Coomassie Blue stains when the proteins by reacting with..... |
| A. | arginine residues |
| B. | free c-termini |
| C. | peptide bonds |
| D. | aromatic ring |
| Answer» B. free c-termini | |
| 14. |
Unpaired H-bond donors and acceptors are found in the hydrophobic core of a protein____ |
| A. | only at the ends of a-helices |
| B. | only at the turns connecting p-strands |
| C. | only on Pro residues |
| D. | rarely |
| Answer» E. | |
| 15. |
Stereo chemical configuration of all a-amino acids derived from proteins is........ |
| A. | L |
| B. | D |
| C. | L and D |
| D. | None of these |
| Answer» B. D | |
| 16. |
Serine and threonine are polar amino acids due to_______ |
| A. | reactive hydroxyl group in the side chain |
| B. | reactive alcoholic group in the side chain |
| C. | reactive keto group in the side chain |
| D. | reactive aldehyde group in the side chain |
| Answer» B. reactive alcoholic group in the side chain | |
| 17. |
The sulphur containing side chain of cysteine is..... |
| A. | ampiphillic, highly reactive and capable of reacting with anothercysteine |
| B. | hydrophillc, highly reactive and capable of reacting with anothercysteine |
| C. | hydrophobic, highly reactive and capable of reacting with anothercysteine |
| D. | none of the above |
| Answer» D. none of the above | |
| 18. |
The sequence of letters 'WYQN' will represent_____ |
| A. | Tryptophan, tyrosine, glutamic acid, asparagine |
| B. | Tryptophan, tyrosine, glutamine, asparagine |
| C. | Tryptophan, glutamine, tryptophan, asparagine |
| D. | Glutamine, tyrosine, tryptophan, aspartic acid |
| Answer» C. Tryptophan, glutamine, tryptophan, asparagine | |
| 19. |
Amino acids required in the human diet and not synthesized by the body are called...... |
| A. | Specialized |
| B. | Trace |
| C. | Essential |
| D. | Accessory |
| Answer» D. Accessory | |
| 20. |
Proteins and macromolecular structures take on their higher order structures________ |
| A. | by self-assembly |
| B. | with the help of molecular chaperons |
| C. | with the help of precursor sequences that are removed from the finalstructures |
| D. | all of the above |
| Answer» E. | |
| 21. |
D-Alanine and L-Alanine are technically known as? |
| A. | anomers |
| B. | enantiomers |
| C. | epimers |
| D. | polymer |
| Answer» C. epimers | |
| 22. |
In a polypeptide average mass of an amino acid residue is..... |
| A. | 110 daltons |
| B. | 118 daltons |
| C. | 80 daltons |
| D. | 150 daltons |
| Answer» B. 118 daltons | |
| 23. |
An essential amino acid is one that_____ |
| A. | is essentially easy to synthesize |
| B. | is essential to flagella motion |
| C. | the body cannot synthesize |
| D. | the body can synthesize under essential conditions |
| Answer» D. the body can synthesize under essential conditions | |
| 24. |
The isoelectric point of an amino acid is defined as the pH____ |
| A. | where the molecule carries no electric charge |
| B. | where the carboxyl group is uncharged |
| C. | where the amino group is uncharged |
| D. | of maximum electrolytic mobility |
| Answer» B. where the carboxyl group is uncharged | |
| 25. |
Molecules that bear charged groups of opposite polarity are known as.... |
| A. | zwitterions |
| B. | ambions |
| C. | ion conversion |
| D. | amphions |
| Answer» B. ambions | |
| 26. |
When the amino acid alanine (R-group is CH3) is added to a solution with a pH of 7.3, alanine become___ |
| A. | a cation |
| B. | nonpolar |
| C. | a zwitterions |
| D. | an isotope |
| Answer» D. an isotope | |
| 27. |
The elements oxygen, nitrogen, and carbon________ |
| A. | can all form covalent bonds with other elements |
| B. | contain protons and neutrons in their atomic nuclei |
| C. | are common elements in the molecules that make up living organisms |
| D. | All of the above |
| Answer» E. | |
| 28. |
The main difference between an acid and a base is that_____ |
| A. | bases are polar molecules and acids are not |
| B. | acids are polar molecules and bases are not |
| C. | bases donate hydrogen ions in water while acids accept hydrogen ions |
| D. | acids donate hydrogen ions in water while bases accept hydrogen ion |
| Answer» E. | |
| 29. |
The reason that fats contain more energy than simple sugars, is fats have many more..... |
| A. | carbon atoms |
| B. | hydrogen atoms |
| C. | covalent bonds |
| D. | hydrogen bonds |
| Answer» D. hydrogen bonds | |
| 30. |
Weak acids generally have pKa_____ |
| A. | values less than 1 |
| B. | pKa values greater than 2 |
| C. | been seldom found in living systems |
| D. | that cannot be used to buffer |
| Answer» C. been seldom found in living systems | |
| 31. |
The dissociation constant of H2O at 25° C is? |
| A. | 10-14 M |
| B. | 1014 M |
| C. | 10-7 M |
| D. | 107 M |
| Answer» B. 1014 M | |
| 32. |
The lone pair electrons on oxygen in a H20 molecule______ |
| A. | carry a partial positive charge |
| B. | are not important for the properties of water |
| C. | carry a partial negative charge |
| D. | form covalent bonds in ice |
| Answer» D. form covalent bonds in ice | |
| 33. |
The strength of an acid depends on_______ |
| A. | number of neutrons gain |
| B. | electronegativity |
| C. | number of double bonds |
| D. | number of protons released |
| Answer» C. number of double bonds | |
| 34. |
Which of the following statements about covalently bonded molecules is false? |
| A. | Electrons are shared between the atoms that make up the molecule |
| B. | Noncovalent bonds may also be present, especially if the molecule islarge |
| C. | Such molecules often result from the interaction of ionized atoms |
| D. | The chemical bonds that hold the molecule together are relativelystrong |
| Answer» D. The chemical bonds that hold the molecule together are relativelystrong | |
| 35. |
H2O and CH4 are both examples of? |
| A. | molecules |
| B. | ions |
| C. | acids |
| D. | none of these |
| Answer» B. ions | |
| 36. |
Hydrogen bonds and hydrophilic interactions are types of......... |
| A. | weak chemical bonds that hold together the atoms within a molecule |
| B. | strong chemical bonds that hold together the atoms within a molecule |
| C. | weak chemical bonds that link together separate molecules |
| D. | strong chemical bonds that link together separate molecules |
| Answer» D. strong chemical bonds that link together separate molecules | |
| 37. |
If protein is made exclusively from nonpolar amino acids, and this protein interact with water, then_______ |
| A. | it will be repelled by water |
| B. | It will be attracted to water |
| C. | It will form a membrane in water |
| D. | It will act as a buffer and stabilize the pH |
| Answer» B. It will be attracted to water | |
| 38. |
The effectiveness or capacity of a buffer solution can be affected by..... |
| A. | molar concentration of the buffer components |
| B. | concentration of the conjugate base to the weak acid |
| C. | both (a) and (b) |
| D. | temperature of buffer components |
| Answer» D. temperature of buffer components | |
| 39. |
A biological polymer contains alanine, tyrosine, and lysine. Which of the following will be true about this molecule? |
| A. | DNA |
| B. | Strong base |
| C. | Phospholipid |
| D. | Protein |
| Answer» E. | |
| 40. |
A compound that is capable of forming hydrogen bonds with water____- |
| A. | is probably held together by noncovalent bonds |
| B. | contains at least some polar covalent bonds |
| C. | should act as a good buffer for acids and bases |
| D. | does not dissolve well in water |
| Answer» C. should act as a good buffer for acids and bases | |
| 41. |
Which of the following acid/base pairs act as natural buffers in living systems? |
| A. | H2CO3/HCO3- |
| B. | H2PO4-/HPO42- |
| C. | Histidine+/histidine |
| D. | All of these |
| Answer» E. | |
| 42. |
What is the concentration, in moles/liter, of the hydrogen ion, if pH of a solution is 7? |
| A. | 7 |
| B. | 7 x 10-7 |
| C. | 5 x 10-7 |
| D. | 1 x 10-7 |
| Answer» E. | |
| 43. |
Most of the important functional groups in biological molecules contain__________ |
| A. | oxygen and/or nitrogen and are acidic |
| B. | oxygen and a phosphate |
| C. | nitrogen and a phosphate |
| D. | oxygen and/or nitrogen and are polar |
| Answer» E. | |
| 44. |
Salt dissolves well in water as water molecules______- |
| A. | form hydrogen bonds with the positively and negatively charged ions |
| B. | make nonpolar covalent bonds with the positively charged ions only |
| C. | surround the ions because of their charge but do not form hydrogenbonds |
| D. | share electrons with the ions to make polar covalent bonds |
| Answer» D. share electrons with the ions to make polar covalent bonds | |
| 45. |
Buffer solutions____ |
| A. | will always have a pH of 7 |
| B. | are rarely found in living systems |
| C. | cause a decrease in pH when acids are added to them. |
| D. | tend to maintain a relatively constant pH. |
| Answer» E. | |
| 46. |
Polyprotic acids such as H3PO4, can act as acid-base buffers______ |
| A. | only in combination with polyprotic bases |
| B. | if their concentration is kept low |
| C. | at pH values around neutrality |
| D. | at pH values around any of their pKa's |
| Answer» E. | |
| 47. |
The pH of a solution is determined by? |
| A. | Concentration of salt |
| B. | Relative concentration of acids and bases |
| C. | Dielectric constant of the medium |
| D. | Environmental effect |
| Answer» C. Dielectric constant of the medium | |
| 48. |
The reactions of molecules_____ |
| A. | are the reactions of the functional groups |
| B. | are independent of the functional groups |
| C. | require an enzyme in all cases |
| D. | all of the above |
| Answer» B. are independent of the functional groups | |
| 49. |
Pollen grains in plants are produced in..... |
| A. | roots |
| B. | leaves |
| C. | flower |
| D. | stem |
| Answer» D. stem | |
| 50. |
Mycobacterium leprae causes leprosy, Corynebacterium diphtheria causes diphtheria and Vibrio comma causes______ |
| A. | tetanus |
| B. | influenza |
| C. | cholera |
| D. | typhoid |
| Answer» D. typhoid | |