o 201 e6 Flashcards
(95 cards)
1
Q
1. Which stage of mitosis is also a cell cycle checkpoint? A. Prophase B. Metaphase C. Anaphase D. Telophase
A
C. Anaphase
2
Q
2. Which of the following will NOT allow a dividing cell to transition from G1 to S phase? A. Sensitivity to growth factors B. Sensitivity to TGF B C. Synthesis of cyclin E D. Presence of sufficient nutrition
A
B. Sensitivity to TGF B
3
Q
3. Which of the following cyclins phases of the cell cycle usually takes the longest time? A. G1 phase B. S phase C. G2 phase D. M phase
https://docs.google.com/document/d/1xPGEvvii92XcfBpTed3OTl5oCZT26gSXFbJc2BBCUjc/edit?usp=sharing
A
A. G1 phase
4
Q
4. Which of the following cyclins is completely absent during the M phase of the cell cycle? A. Cyclin D B. Cyclin E C. Cyclin A D. Cyclin B
https://docs.google.com/document/d/1xPGEvvii92XcfBpTed3OTl5oCZT26gSXFbJc2BBCUjc/edit?usp=sharing
A
B. Cyclin E
5
Q
5. How many chromatids are there in normal human differentiated cells? A. 0 B. 23 C. 46 D. 92
A
A. 0
6
Q
- Which of the following cell checkpoint is associated with the least DNA amount?
A. G1 checkpoint
B. G2 checkpoint
C. S checkpoin
A
A. G1 checkpoint
7
Q
7. Which of the following phases of the cell cycle is almost nonexistent in the initial series of cellular divisions of a single-celled embryo? A. G1 phase B. S phase C. G2 phase D. M phase
A
A. G1 phase
8
Q
8. Which of the following ploidy in human cells is able to undergo normal nuclear division? A. 1N B. 2N C. Multiploidy D. All of the above
A
D. All of the above
9
Q
9. Which of the following stages in mitosis us the chromosome most condensed? A. Prophase B. Metaphase C. Anaphase D. Telophase
A
B. Metaphase
10
Q
10. Which of the following will allow normal halting of the cell cycle progression to allow checkpoint mechanism to take place? A. Proto-oncogene B. Oncogene C. One-hit mutation on suppressor gene D. Two-hit mutation on suppressor gene
A
C. One-hit mutation on suppressor gene
11
Q
11. Which of the following cycle inhibitors disassembles the cycle and the CDK complex? A. P16 B. P21 C. P27 D. P57
A
A. P16
12
Q
- Which of the following is NOT a means of regulating the action of CDKs?
A. RNA polymerase II activity on cyclin genes
B. Kinase activity on CDKs
C. Ubiquitinase activity on CDKs
D. Proteasome activity on CDK inhibitors
A
D. Proteasome activity on CDK inhibitors
13
Q
13. Which of the following is NOT associated with apotosis? A. Inflammation B. Phagocytosis C. Chromatin condensation D. Chromatin fragmentation
A
A. Inflammation
14
Q
14. Which of the following is NOT associated with necrosis? A. Cell membrane rupture B. Mitochondrial swelling C. Cell shrinkage D. All of the above
A
C. Cell shrinkage
15
Q
15. Which of the following death mechanism does not cause inflammation? A. Pyroptosis B. Autophagy C. Oncosis D. A and C
A
B. Autophagy
16
Q
- Which of the following statements about intrinsic apoptosis is FALSE?
A. Mitochondria is always involved
B. Bcl-2 can either promote or inhibit apoptosis
C. Cytochrome C is a part of the apoptosome
D. Apoptosome activates caspase 8
A
D. Apoptosome activates caspase 8
17
Q
17. Which of the following cell death mechanisms is associated with pathogen dissemination? A. Pyroptosis B. Apoptosis C. Oncosis D. Autophagy
A
C. Oncosis
18
Q
18. Which of the following is the initial common caspase shared by both intrinsic and extrinsic pathways of apoptosis? A. Caspase 8 B. Caspase 7 C. Caspase 6 D. Caspase 3
A
18. Which of the following is the initial common caspase shared by both intrinsic and extrinsic pathways of apoptosis? A. Caspase 8 B. Caspase 7 C. Caspase 6 D. Caspase 3
19
Q
19. In addition to apoptosis, which of the following cell death mechanisms involves caspase? A. Pyroptosis B. Autophagy C. Oncosis D. Necrosis
A
A. Pyroptosis
20
Q
- Which step can the extrinsic apoptotic pathway recruit the intrinsic apoptotic pathway?
A. Activation of caspase 8
B. Binding of liganfs to the death receptor
C. Release of cytochrome C from the inner mitochondrial membrance
D. Cleavage of bid to t-bid
A
D. Cleavage of bid to t-bid
21
Q
- The following is a requirement for osmosis:
A. The presence of aquaporins
B. A concentration gradient for the solutes across the membrane
C. A positive hydrostatic pressure on one side of the membrace
D. The presence of a non-permeable proteins on one side of the membrane
A
B. A concentration gradient for the solutes across the membrane
22
Q
- Osmotic balance between the extracellular and intracellular fluid compartment is established because of the:
A. Permeability of the cell membrane to water
B. Impermeability of the cell membrane to sodium, the major extracellular cation
C. Ability of water to drag along solutes when it moves into the cell
D. Ability if the cell to generate osmotically active particles
A
A. Permeability of the cell membrane to water
23
Q
- Whish of the following is an example of a positive feedback mechanism?
A. When thyroid hormone level is low, thyroid stimulating hormone level is high
B. In the dehydrated state, angiotensin 2 production is increased which leads to increased sodium reabsorption
C. During childbirth, uterine contraction becomes more frequent and more powerful
D. Normally, we sleep at night and are awake during daytime
A
C. During childbirth, uterine contraction becomes more frequent and more powerful
24
Q
24. In the baroreceptor mechanisms, which of the following is the receptor? A. The carotid body B. Nucleus ambiguous C. Rostral ventrolateral medulla D. Sympathetic preganglionic neurons
A
A. The carotid body
25
25. When blood pressure increases from normal the flowing happens:
A. Inhibitory fibers are sent to the vagal parasympathetic system
B. Stretching of the receptors at the right atrium causes inhibition of the vasoconstrictor center at the nucleases tractus solitaries
C. Heart rate decreases
D. The caudal ventrolateral medulla is inhibited
C. Heart rate decreases
26
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26. During a marathon, a runner experiences dehydration. What type of fluid is lost during the marathon?
A. Pure water
B. Hypotonic
C. Isotonic
D. Hypertonic
```
B. Hypotonic
27
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27. Of the following regulators of our body function, which has the slowest response time?
A. Chemical
B. Neural
C. Autoregulation
D. Both chemical and neural regulation
```
A. Chemical
28
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28. Of the following regulators of our body function, which arts only a short time?
A. Chemical
B. Neural
C. Autoregulation
D. Both chemical and neural regulation
```
B. Neural
29
29. Which is the effector component of this feedback system?
A. There is an increase in the blood sugar after meal
B. The high blood sugar level is detected by the insulin secreting cells of the pancreas
C. Insulin is released into the blood
D. The muscle cells take up glucose
D. The muscle cells take up glucose
30
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30. During sleep, renal sodium excretion is kept constant through
A. Afferent arteriolar vasoconstriction
B. Afferent arteriolar vasodilation
C. Efferent arteriolar vasoconstriction
D. Efferent arteriolar vasodilation
```
B. Afferent arteriolar vasodilation
31
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31. What is the extracellular fluid volume of a 25 year old male who weighs 60kg?
A. 36L
B. 24L
C. 12L
D. 9L
```
C. 12L
32
32. Stimulation of the low pressure stretch receptors will
A. Stimulate ADH secretion
B. Increase the release of the atrial natriuretic peptide
C. Increase the sympathetic stimulation to the kidneys
D. Increase rennin secretion by the kidneys
B. Increase the release of the atrial natriuretic peptide
33
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33. Low pressure baroreceptors are found in the:
A. Aortic arch
B. Carotid sinus
C. Cardiac atria
D. Renal artery
```
C. Cardiac atria
34
34. An order for ultrasound of the urinary bladder was given to a patient. The radiology technician told a patient to drink more than one liter of water so that the urinary bladder will be fully distended. Which of the following results of osmolarity studies is appropriate for the patient?
A. Serum osmolarity: 285 mmosm/L, urine osmolarity: 100 mosm/L
B. Serum osmolarity: 300 mmosm/L, urine osmolarity: 300 mosm/L
C. Serum osmolarity: 250 mmosm/L, urine osmolarity: 100 mosm/L
D. Serum osmolarity: 285 mmosm/L, urine osmolarity: 600 mosm/L
A. Serum osmolarity: 285 mmosm/L, urine osmolarity: 100 mosm/L
35
35. What will be the results of an osmolarity study on this 20 year old male who just donated 500 ml of blood?
A. Serum osmolarity: 285 mmosm/L, urine osmolarity: 100 mosm/L
B. Serum osmolarity: 300 mmosm/L, urine osmolarity: 300 mosm/L
C. Serum osmolarity: 250 mmosm/L, urine osmolarity: 100 mosm/L
D. Serum osmolarity: 285 mmosm/L, urine osmolarity: 600 mosm/L
D. Serum osmolarity: 285 mmosm/L, urine osmolarity: 600 mosm/L
36
36. Which one describes the change that happens in the body fluid osmolarity or volume after a massive hemorrhage:
A. There is no change in the body fluid osmolarity
B. There is a decrease in the volume of the intracellular fluid compartment
C. There is a decrease in the osmolarity of the intravascular fluid
D. There is a decrease in the osmolarity of the intracellular fluid
A. There is no change in the body fluid osmolarity
37
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37. Regulation of extracellular fluid volume is dependent on the regulation of:
A. Water
B. Potassium
C. Protein
D. Sodium
```
D. Sodium
38
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38. Whish of the following provides stimulus for the earliest release of ADH?
A. Increase in plasma osmolarity
B. Thirst
C. Low blood pressure
D. Low plasma sodium
```
A. Increase in plasma osmolarity
39
39. A man trapped for 3 days in the rubbles of his home after a major earthquake was rescued. He said he survived only because he drank his urine. Is there physiologic basis for this?
A. No. No one can ever drink his own urine.
B. No. He will immediately die from the toxic waste matters that the kidneys excrete.
C. Yes. There is an increase in the effective circulating volume.
D. Yes. The fluid ingested will be distributed equally in all the compartments.
C. Yes. There is an increase in the effective circulating volume
40
```
40. In this patient rescued after being adrift in the ocean, the treatment priority is to correct the
A. Intracellular volume
B. Intracellular osmolarity
C. Intravascular volume
D. Intravascular osmolarity
```
C. Intravascular volume
41
```
41. The threshold for thirst is a plasma osmolarity of
A. 280 mosmol/L
B. 285mosmol/L
C. 290 mosmol/L
D. 295 mosmol/L
```
D. 295 mosmol/L
42
```
42. The steady state volume of the cell is determined by the concentration of
A. Intracellular impereant solutes
B. Extracellular impermeant solutes
C. Intracellular pereant solutes
D. Extracellular permeant solutes
```
B. Extracellular impermeant solutes
43
43. The brain safeguards itself from rapid increase in plasma osmolarity by
A. Closing the aquaporins thus making the cell impermeable to water
B. Gain of electrolytes
C. Production of intracellular osmolytes
D. Entry of organic osmolytes
B. Gain of electrolytes
44
44. In which of the following scenario is the secretion of antidiuretic hormone inappropriate?
A. Hypotension from massive blood loss secondary to a bleeding gastric ulcer
B. After participating in a 5k run
C. When renin release is stimulated leading to angiotensin 2 production
D. When one goes on a beer drinking spree
D. When one goes on a beer drinking spree
45
45. When effective circulating volume falls, the effector organs will work to
A. Increase blood flow to the vital organs
B. Prevent antidiuretic hormone secretion
C. Increase rate of water absorption
D. Increase rate of sodium retention
D. Increase rate of sodium retention
46
identify the type of regulation of the following body functions. Choose from the letters below:
A. Chemical regulation
B. Neural regulation
C. Autoregulation
46. Postponing micturition until a socially acceptable time and place become available
B. Neural regulation
47
identify the type of regulation of the following body functions. Choose from the letters below:
A. Chemical regulation
B. Neural regulation
C. Autoregulation
47. When blood pressure increase, the arteriole vasoconstricts
C. Autoregulation
48
identify the type of regulation of the following body functions. Choose from the letters below:
A. Chemical regulation
B. Neural regulation
C. Autoregulation
48. When blood pressure increases, the heart rate decreases
B. Neural regulation
49
identify the type of regulation of the following body functions. Choose from the letters below:
A. Chemical regulation
B. Neural regulation
C. Autoregulation
49. When it is time to micturate, the external sphincter muscle relaxes
B. Neural regulation
50
identify the type of regulation of the following body functions. Choose from the letters below:
A. Chemical regulation
B. Neural regulation
C. Autoregulation
50. Insulin level is high after eating
A. Chemical regulation
51
identify the type of regulation of the following body functions. Choose from the letters below:
A. Chemical regulation
B. Neural regulation
C. Autoregulation
51. Sodium excretion remains constant despite fluctuations in renal perfusion
C. Autoregulation
52
identify the type of regulation of the following body functions. Choose from the letters below:
A. Chemical regulation
B. Neural regulation
C. Autoregulation
52. Increase in parathyroid hormone secretion when serum calcium level is low
A. Chemical regulation
53
identify the type of regulation of the following body functions. Choose from the letters below:
A. Chemical regulation
B. Neural regulation
C. Autoregulation
53. Blood pressure remains constant in our usual day to day activities
B. Neural regulation
54
identify the type of regulation of the following body functions. Choose from the letters below:
A. Chemical regulation
B. Neural regulation
C. Autoregulation
54. Rennin is release when blood pressure decreases
A. Chemical regulation
55
identify the type of regulation of the following body functions. Choose from the letters below:
A. Chemical regulation
B. Neural regulation
C. Autoregulation
55. Angiotensin stimulates thirst when dehydrated
A. Chemical regulation
56
```
56. Refers to the state the cell actively maintains to be able to maintain a normal structure and function.
A. Cellular adaptation
B. Homeostasis
C. Cell injury
D. Cell physiology
```
B. Homeostasis
57
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57. The process which occurs wherein the cell undergoes changes to achieve a new steady state, that would be compatible with viability in the new environment
A. Cellular adaptation
B. Homeostasis
C. Cell injury
D. Cell physiology
```
A. Cellular adaptation
58
```
58. Occurs when the limits of adaptive response of the cell is exceeded
A. Cellular adaptation
B. Homeostasis
C. Cell injury
D. Cell physiology
```
C. Cell injury
59
```
59. The occurrence of cellular injury depends on the following factors EXCEPT:
A. Type of stress
B. Intensity of the stress
C. The cell types
D. None of the above
```
D. None of the above
60
```
60. The first manifestations of cell death is
A. Loss or impairment of function
B. Biochemical chenages
C. Ultrastructural changes
D. Gross morphologic changes
```
A. Loss or impairment of function
61
61. True statements regarding the effect of hypoxia on energy metabolism and the cell
A. Interferes with O2 utilization and ability to generate ATP
B. Does not affect utilization of nutrients needed for protein synthesis
C. Causes shift to aerobic glycolysis
D. All of the above
A. Interferes with O2 utilization and ability to generate ATP
62
62. Cell injury results from damage to cell membrane integrity through the following
A. Damage to plasma membrane increases cell permeability to sodium and water causing cell lysis
B. Leakage of potassium affect abilitu to maintain resting membrane potential
C. Lysosomal injury release hydrolytic enzymes esulting in autodigestion of cellular proteins
D. All of the above
D. All of the above
63
63. Loss of calcium homeostasis will result in entry of calcium intracellularly activating kinases which can cause the following damaging changes
A. Decrease ATP due to activating of ATPases
B. Nuclear chromatin damge
C. Disruption of cytoskeletal protein
D. All of the above
D. All of the above
64
64. The main sites of damage for free radicals include the following EXCEPT
A. Lipid peroxidation of membranes
B. Increased degradation of loss of activity of cellular proteins
C. Damage to DNA
D. Impairment of ATP production
D. Impairment of ATP production
65
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65. Refers to loss of blood supply from impeded arterial flow compromising supply of oxygen and other metabolic substrate
A. Hypoxia
B. Ischemia
C. Anoxia
D. infarction
```
B. Ischemia
66
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66. The mechanism of cell damage in cyanide poisoning
A. Loss of oxygen carrying capacity
B. Blockage of cell enzyme
C. Inadequate blood flow to tissue
D. Depressed oxygenation
```
B. Blockage of cell enzyme
67
```
67. Which of the following tissue can endure several hours of hypoxia without irreversible cell injury?
A. Skeletal muscle
B. Hepatocytes
C. Myocardium
D. Neurons
```
A. Skeletal muscle
68
68. Ischemia causes cell damage through various mechanisms including all of the following:
A. Diminished supply of ATP resulting in decrease in cytosolic calcium
B. Accumulation of phospholipids
C. Activation of proteins causing cytoskeletal damage
D. All of the above
C. Activation of proteins causing cytoskeletal damage
69
69. The following statements correctly refers to reperfusion injury, EXCEPT:
A. Paradoxicacal accelerated injury of cells following restoration of blood flow
B. Restoration of flow may compromised flow to high concentrations of sodium
C. Reperfusion can result in increased free radicals
D. Clinically seen post reperfusion in myocardial infarction
B. Restoration of flow may compromised flow to high concentrations of sodium
70
70. Major mechanism of electricity induced injury:
A. Alteration of cell membrane resting potential eliciting muscle tetany
B. Disruption of cell membrane
C. Coagulation necrosis
D. All of the above
D. All of the above
71
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71. This chemical agent binds to sulfhydryl groups of cell membrane causing increase membrane permeability and inhibition of ATP-ase dependent transport
A. Mercury
B. Cyanide
C. Carbon tetrachloride
D. Acetaminophen
```
A. Mercury
72
```
72. Swelling of smooth endoplasmic reticulum and dissociation of ribosomes from rough ER
A. Mercury
B. Cyanide
C. Carbon tetrachloride
D. Acetaminophen
```
C. Carbon tetrachloride
73
```
73. Barret’s esophagus is an example of what kind of cellular adaptation
A. Hypertrophy
B. Hyperplasia
C. Metaplasia
D. Aplasia
```
C. Metaplasia
74
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74. Which is an example of physiologic atrophy?
A. Uterine atrophy in menopause
B. Cerebral atrophy
C. Atrophy of ischemia
D. Denervation atrophy
```
A. Uterine atrophy in menopause
75
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75. Abnormal cell growth of disproportionate cell type
A. Hypertrophy
B. Hyperplasia
C. Metaplasia
D. Dysplasia
```
D. Dysplasia
76
76. Which of the following statements is/are correct?
A. Factor X catalyzes the conversion of prothrombin to thrombin
B. Thrombin catalyzes the conversion of fibrinogen to fibrin
C. Factor XI catalyzes the cross-linking of fibrin
D. Both A and B
B. Thrombin catalyzes the conversion of fibrinogen to fibrin
77
77. Which of the following statements is/are correct?
A. Tissue thromboplastin activates the extrinsic pathway of coagulation
B. Tissue thromboplastin is a transmembrane receptor for factor VIII
C. Contact with collagen activates the intrinsic pathway of coagulation
D. Both A and C
D. Both A and C
78
78. Which of the following statements is/are correct?
A. Factors II, VII, IX and Xi are all vitamin K-independent coagulation factors
B. All functional vitamin K dependent coagulation factors contain gamma-carboxyglutamate
C. Vitamin K immediately reverses the coagulation deficit resulting from warfarin toxicity
D. Both B and C
B. All functional vitamin K dependent coagulation factors contain gamma-carboxyglutamate
79
79. Which of the following statement is/are correct?
A. A thrombin is formed in the intravascular space after death
B. Vitamin K deficiency predisposes to thrombus formation
C. Antithrombin deficiency predisposes to thrombus formation
D. Both A and B
C. Antithrombin deficiency predisposes to thrombus formation
80
80. Which of the following statement is/are correct?
A. Heparin is used clinically as a parentally administered anticoagulant agent
B. Heparin interferes with blood coagulation mainly for chelating calcium ions
C. Cross-linking of fibrin renders thrombi more susceptible to thrombolysis
D. Both A and C
A. Heparin is used clinically as a parentally administered anticoagulant agent
81
81. Which of the following statements is/are correct:
A. Tissue plasminogen activator is more effective against ild versus newly formed thrombi
B. Tissue plasminogen activator proteolytically cleaves plasminogen to form plasmin
C. Tissue plasminogen activator selectively acts on fibrin-associated plasminogen
D. Both B and C
D. Both B and C
82
82. Which of the following statements is/are correct?
A. Stasis, endothelial damage, hypercoaguability of blood predisposes thrombus formation.
B. Hypercoaguability predisposes polycythemia, which predisposes hyperviscosity, and in turn, stasis
C. Excess thrombomodulin, Protein c and /or Protein S predisposes hypercoaguability
D. Both A and B
A. Stasis, endothelial damage, hypercoaguability of blood predisposes thrombus formation.
83
83. Which of the following statements is/are correct?
A. Typical innate immune responses feature prominent immunological memory
B. Antibody class switching typically results in production of IgM
C. T helper cells typically recognize antigen presented with class II MHC molecules
D. Both A and C
C. T helper cells typically recognize antigen presented with class II MHC molecules
84
84. Which of the following statements is/are correct?
A. IgG typically crosses the placental barrier
B. IgM typically constitutes the majority of circulating antibodies in the plasma
C. IgE typically constitutes the majority of antibodies on mucosal surfaces
D. Both A and C
D. Both A and C
85
85. Which of the following statements is/are correct?
A. Class I MHC molecules are normally expressed on mature human erythrocytes
B. Class I MHC molecules present fragments of endogenous antigens in most cell types
C. Class II MHC molecules typically enable recognition of antigens by T-cytotoxic cells
D. Both B and C
B. Class I MHC molecules present fragments of endogenous antigens in most cell types
86
86. Which of the following statements is/are correct?
A. T cytotoxic cells typically destroy targets by necrosis
B. T helper cells typically express CD8 coreceptor for antigen recognition
C. T helper cells typically secrete cytokines that activate other immune cells
D. Both A and B
C. T helper cells typically secrete cytokines that activate other immune cells
87
87. Which of the following statements is/are correct?
A. Active immunization entails actual exposure to antigen
B. Passive immunization is exemplified by classical vaccination
C. Passive immunization is exemplified by maternal antibody transfer
D. Both A and C
D. Both A and C
88
88. Which of the following statements is/are correct?
A. Blood group antigens include MHC antigens
B. Histocompatibility antigens include blood-group antigens
C. T helper cells typically secrete cytokines that activate other immune cells
D. Both A and B
D. Both A and B
89
89. Which of the following statements is/are correct?
A. Th1 stimulates antibody production of B cells
B. Th2 stimulates cell mediated actions by T cytotoxic cells and macrophages
C. Th17 primarily elicits immune responses against extracellular pathogens
D. Both A and B
C. Th17 primarily elicits immune responses against extracellular pathogens
90
90. Which of the following statements is/are correct?
A. Cross-presentation enables T helper cell activation against tumors.
B. Dendritic cells employ mainly class I MHC for cross-presentation.
C. Endogenous antigens are recognized primarily via cross-presentation.
D. Both B and C
B. Dendritic cells employ mainly class I MHC for cross-presentation
91
91. Which of the following is/are correct?
A. ABO blood groups are dependent on peptide epitopes on plasma membranes.
B. Antibodies for A and B are present in people with blood type O during normal development.
C. Maternal blood type of AB is a known risk factor for fetal haemolytic anemia for a fetus with blood type O.
D. Both A and B
B. Antibodies for A and B are present in people with blood type O during normal development.
92
92. Which of the following is incorrect?
A. Degranulation is induced by cross-linking of receptor-bound IgA on mast cells
B. Histamine is released during degranulation (exocytosis) of mast cells
C. Anaphylaxis is an acute local response featuring mast cell degranulation
D. Both A and C
B. Histamine is released during degranulation (exocytosis) of mast cells
93
93. Which of the following statements is/ are CORRECT?
A. Phagocytes include neutrophils, macrophages and lymphocytes.
B. Activation of compliment pathways contributes to opsonization.
C. Decreased vascular permeability is a hallmark of inflammation.
D. Both A and B.
B. Activation of compliment pathways contributes to opsonization.
94
94. Which of the following statement/s is/are CORRECT?
A. Lysozymes serve to catalyze hydrolysis of fungal cell walls
B. Cytokines and chemokines are mainly specialized antibody molecules
C. Endotoxin from gram negative bacteria is lipopolysaccharide (LPS)
D. Both B and C
C. Endotoxin from gram negative bacteria is lipopolysaccharide (LPS)
95
95. Which of the following statement/s is/are CORRECT?
A. Most antibodies are normally coded for by modified germline DNA sequences.
B. Both heavy and light chains contribute to antigen binding by antibodies
C. Both heavy and light chains determine antibody class
D. Both A and B
D. Both A and B
