POM summative prep QS

Question 1

How is the rate of glycolysis controlled?
A) Phosphoglucose isomerase is an allosteric enzyme
B) Glucose-6-phosphate inhibits hexokinase
C) Pyruvate saturation within the cytoplasm
D) Phosphofructokinase activityis controlled by ATP, ATP is an inhibitor

Answer 1

Answer: D

A:Phosphoglucose isomerase is not an
allosteric enzyme, however
phosphofructokinase is
B: This is partly true; however not the best
answer since glucose-6-phosphate
concentrations are reliant on
phosphofructokinase activity
C: Pyruvate saturation does not inhibit
glycolysis (anaerobic respiration, conversion
to lactate or enter into mitochondria)
D: Phosphofructokinase is an allosteric
enzyme, therefore ATP concentrations that are
elevated express an inhibitory effect on the
enzyme → Reduction in activity.

Question 2

Which enzyme can be used as a diagnostic tool for a myocardial infarction?
A) Hexokinase-IV
B) Pyruvate dehydrogenase
C) Lactate dehydrogenase
D) Creatine phosphatase
Explain Why?

Answer 2

Answer: C

Lactate dehydrogenase is present predominantly in heart, liver, kidneys, skeletal muscles, blood and lungs. Cell necrosis → LDH released into circulation, influencing LDH serum levels.

Question 3

What are the 7 molecules that arise from degradation of all 20 AAs?

Answer 3

Pyruvate, Acetyl CoA, Acetoacetyl CoA, Oxaloacetate, alpha-ketoglutarate, Succinyl CoA, fumarate

Question 4

What is incorrect regarding the glycerol-phosphate shuttle?
A) Dihydroxyacetone phosphate→ Glycerol-3-phosphate
B) Reduced FAD transfers electrons to coenzyme Q
C) Inner mitochondrial membrane is impermeable to NADH & NAD+
D) Mitochondrial glycerol dehydrogenase uses FAD

Answer 4

Answer: B

A: Dihydroxyacetone phosphate (DHAP) is
reduced to form glycerol-3-phosphate by
reduced cytosolic NADH
B: Reduced FAD directly transfers electron to
complex II within the ETC → Coenzyme Q
C: True
D: Mithoncrial glycerol dehydrogenase is a
transmembrane protein that used FAD as an
electron carrier; to shuttle electrons into the
electron transport chain.

Question 5

What type of inhibitor does orlistat behave?

Answer 5

Potent inhibitor of gastric and pancreatic lipases, behaving as competitive inhibitor

Question 6

Why can’t acetyl CoA be used as a substrate for gluconeogenesis?

Answer 6

This is because it cannot be recovered back into pyruvate effectively

Question 7

Why is hexokinase IV effective?

Answer 7

Hexokinase IV found in the liver is less sensitive to blood glucose concentrations, therefore less susceptible to the inhibitory effect of glucose-6-phosphate

Question 8

Which substrate is most suitable for
the brain during prolonged fasting?
A) Glucose
B) Ketone bodies
C) Fatty acids
D) Amino acids

Answer 8

Answer: A

Question 9

Which does not increase erythropoiesis?
A) Chronic bronchitis
B) Increased serum iron inhereditary haemochromatosis
C) Renal cell carcinoma
D) Polycystic ovarian syndrome

Answer 9

Answer: B
A: Chronic bronchitis is associated with
anoxia due to reduced oxygenation of the
blood, this results in hypoxic conditions →
Increased hypoxia inducible factor
B: Hereditary haemochromatosis causes a
reduction in hepcidin therefore increased iron
enterocyte absorption through ferroportin into
circulation → This causes increased iron
levels; ion overload and damage kidneys
reducing epo synthesis
C: Increases epo synthesis and secretion
influencing the rate of erythropoiesis
D: Increased testosterone stimulates the
release of erythropoietin, PCOS is associated
with elevated testosterone levels.

Question 10

How are excess iron levels regulated?

Answer 10

Increased ferritin iron sequestration

Increased iron levels suppress ferroportin integration into enterocyte basolateral membrane, therefore increasing sequestration of iron as storage as ferritin → shed across
epithelium into lumen

Question 11

Why does inflammation cause anaemia?

Answer 11

Inflammation causes hepcidin production this led to a decreased ferroportin expression in enterocytes and thus decreases iron entry into plasma.

Question 12

Which molecules’ internal shape is
independent of the external
environment?
A) Glucose
B) NaCl
C) Insulin ligand receptor
D) Phosphoglucose isomerase

Answer 12

Answer:A
Glucose consists of covalent bonding,
therefore its configuration does not dissociate
into ions.
B: Sodium chloride is an ionic compound
dissociating into ions when in solution
C: Insulin receptor ligand gated hence changes
domain of tyrosine kinases and undergoes
conformational change
D: Enzyme undergoes conformational change
upon substrate binding at active site; also can
be denatured depending on temperature & pH
of external environments
Receptors and enzymes are proteins →
Denatured

Question 13

Which is the correct function of
FOXP3?
A) Exclusively found in Treg
cells
B) Promotes cellular division
C) Exerts local suppressor
effects during immune
response
D) Synthesized only in the
thymus
E) Found in Th3, Tr1, Treg cells

Answer 13

Answer: E

Question 14

Which is not a cause of pernicious
anaemia?
A) Achlorhydria
B) Veganism
C) Autoimmune disorder on
gastric chief cells
D) Atrophic gastritis

Answer 14

Answer: C
Pernicious anaemia concerns a B12
deficiency
A: Achlorhydria refers to insufficient
secretion of hydrochloric acid from parietal
cells → Inability to liberate B12, to bind onto
intrinsic factor.
B:Vegan leads to an inadequate intake of
sources containing the compound
C: Gastric cells do not secrete intrinsic factor
of HCl, parietal cells do
D: Atrophy of parietal cells causes a reduction
in intrinsic factor secretion, reduced B12-IF
complex formation reduces serum
transportation to enterocyte.

Question 15

How are erythrocytes recycled?

Answer 15

Splenic reticuloendothelial macrophages hydrolyse erythrocytes within the spleen

Question 16

Which one provides a more reliable count: polychromasia or reticulocyte count?

Answer 16

Reticulocyte count is less subjective and more reliable

Question 17

What is used to stain reticulocyte and why are they a suitable choice?

Answer 17

Methylene blue
Reticulocytes in general young cells have a higher RNA content so hence it binds to methylene blue causing a blue tinge on the cytoplasm

Question 18

Target cells, elliptocytes and spherocytes are examples of what?
A) Anisocytosis
B) Poikilocytosis
C) Spherocytosis
D) Microcytosis

Answer 18

Answer: B
Poikilocytosis: Erythrocytes illustrate more variation in shape than is normal. Poikilocytes can exist as spherocytes, irregularly contracted cells, sickle cells, target
cells, elliptocytes, and as fragments.

Question 19

Why do white cells stain blue?
A) Application of H&E stain
B) Application of Giemsa stain
C) Application of Ziehl-Neelson
stain
D) Application of Leischman’s
stain

Answer 19

Answer: D
A: Used to stain basophilic structures with
purplish blue colour
B: Giemsa stains binds to chromosomes and is
responsible for lighter and darker regions
C: Binds to acid fast bacteria (TB)
D: Red cells look red, white cells look blue

Question 20

What are the four main fluid compartments are there in your body? (In order from highest to lowest and include the percentages).

Answer 20

Intracellular fluid (55%)
Interstitial fluid (36%)
Blood plasma (7% )
Transmembrane fluid (2%)

Question 21

Where does lipogenesis and beta-oxidation occur respectively?

Answer 21

Lipogenesis - Cytoplasm
Beta-Oxidation - Mitochondrial matrix

Question 22

How does increased iron in hereditary haemochromatosis led to a reduce in erythropoiesis?

Answer 22

Hereditary haemochromatosis causes a reduction in hepcidin therefore increased iron enterocyte absorption through ferroportin into circulation → This causes increased iron levels; ion overload and damage kidneys reducing erythropoietin synthesis

Question 23

What is the definition in terms of tumour of:
a) differentiation
b) growth pattern

Answer 23

a) Differentiation refers to how much of the cells of the tumour resemble of the cells of the tissue it derived from.

b) Growth pattern refers to how much the architecture of the tumour resemble the architecture of the tissues it derived from

Question 24

Where do erythropoietin synthesis occur?

Answer 24

Kidney

Question 25

How does symptoms of scurvy develop due to vitamin C deficiency?

Answer 25

Vitamin C is a co-factor for the enzymes Prolyl hydroxylase and Lysyl Hydroxylase. These enzymes hydroxylate the proline and lysine residues of collagens for cross-linking which is needed for stability. Thus deficiency of Vitamin C would eventually led to an impaired hydroxylation between collagens thus leading to symptoms of scurvy

Question 26

A patient is suspected to be experiencing a Hypersensitivity reaction. If the reaction is Type III, which of the following would NOT be seen? A. Elevated IgG antibodies B. Inflammation of joints C. Lowered Haptoglobin levels D. Neutrophilia

Answer 26

Answer: C Type III Hypersensitivity is characterized by failure to clear immune complexes made of IgG and/or IgM antibodies. This failure to clear can cause deposition of the immune complexes in various tissues such as the joints, which leads to inflammation via complement activation. Neutrophils are therefore rapidly recruited to the area of inflammation via chemotaxis. Haptoglobin is an alpha-2 globulin found in plasma. It forms complexes with haemoglobin which can be used to diagnose a haemeolytic anaemia, a probable result of a type II hypersensitivity reaction where RBCs are destroyed faster than they are produced.

Question 27

What is the therapeutic use of haptoglobin in plasma?

Answer 27

Haptoglobin is an alpha-2 globulin found in plasma. It forms complexes with haemoglobin which can be used to diagnose a haemeolytic anaemia

Question 28

What is the difference between type II and type III hypersensitivity in terms of the location of tissue damage in relation of the location of immune complexes?

Answer 28

Type II hypersensitivity - Damage where immune complexes are formed (tissue specific) Type III hypersensitivity - Damage where immune complexes are deposited (not tissue specific)

Question 29

What is the mechanism of wafarin?

Answer 29

mechanism of warfarin → interferes with the carboxylation of glutamic acid residues and thereby interrupting the function of factors II, VII, IX, and X

Question 30

What is the name of the ligand present in the endothelial surface that is involved in tight adhesion step of neutrophil extravasation?

Answer 30

ICAM1

Question 31

What molecule mediates cytoskeletal arrangement and extension of pseudopodia in the transmigration step on neutrophil extravasation?

Answer 31

PECAM

Question 32

Which of these immune evasionmechanism proteins is involved in preventing C3 and C5 convertase formation? A= SpA B= SKIN C= SCIN D= CHIPs

Answer 32

C

Question 33

How does SpA help S. Aureus to evade immune response?

Answer 33

SpA binds to Fab region of antibody therfore preventing normal opsonisation

Question 34

Which of these isn’t a soluble effector mechanism in humoral immunity? A= Iron chelation to prevent replication B= Antibiotic-like peptides C= Lectin-binding to neutralise cell attachment D= Digestion with phagosomes

Answer 34

Answer: D D is a cellular effector mechanism in humoral immunity NOT a soluble effector

Question 35

How is natural anti-coagulation performed? A) Thrombin binds to thrombomodulin, activating protein S B) Thrombin and factor IXa are inactivated by antithrombin C) t-PA binds to glycine residues D) Plasmin stimulates further plasmin generation

Answer 35

Answer: D A: Thrombin binds to thrombomodulin activating Protein C, in the presence of cofactor protein S B: Thrombin and factor Xa are inactivated by antithrombin C: Tissue plasminogen activator binds to lysine residues D:Correct, plasmin further stimulates plasmin generation by producing more active forms of both tissue plasminogen activator and urokinase

Question 36

Does plasmin stimulates further plasmin generation? Explain your choice

Answer 36

Plasmin further stimulates plasmin generation by producing more active forms of both tissue plasminogen activator and urokinase

Question 37

Which drug is a synthetic derivative of lysine? A) Tranexamic acid B) Urokinase C) Recombinant t-PA D) DOACs

Answer 37

A

Question 38

How is tranexamic acid able to cease fibrinolysis?

Answer 38

Tranexamic acid is a synthetic derivative of lysine, works by binding to plasminogen thereby behaves as a competitive inhibitor by preventing plasmingeon from binding to lysine residues of fibrin → Fibrinolysis is ceased

Question 39

How does lovastatin treat familial hypercholesterolaemia?

Answer 39

Inhibition of de novo cholesterol synthesis by the liver. Lovastatin works by being a competitive inhibitor of HMG-CoA-reductase.

Question 40

What are adherens junctions composed of? What is their main role?

Answer 40

Composed of cadherins Cell to cell junction

Question 41

How is HPV infection a mechanism of epithelial proliferation?

Answer 41

HPV infections controls cellular machinery of stratified squamous epithelia and inducing increased cell proliferation.

Question 42

Which collagen molecule is non-fibrillar? A) Type I B) Type II C) Type III D) Type IV

Answer 42

Answer: D Types 1-3 are fibrillar Type 4 is non-fibrillar and forms the basement membrane

Question 43

What is a formation of corns an example of?

Answer 43

Corns (or calluses) is an example of hyperproliferation, cells accumulate into thick hard layers due to frequent abrasion and pressure

Question 44

Which of the following is not a multi-adhesive glycoprotein? A) Decorin B) Fibronectin C) Laminin D) Fibrogen

Answer 44

A - Decorin is a proteoglycan

Question 45

What kind of proteoglycans are decorin, syndecans 1-4, aggrecan and perlecan?

Answer 45

Decorin = Small leucine-rich proteoglycans Syndecans 1-4 = Cell surface proteoglycans Aggrecan = aggregating proteoglycans (interact w/hyaluronan) Perlecan = BM proteoglycans

Question 46

Which of the following plasma proteins is most positively charged? A) Gamma globulins B) Albumin C) Alpha-1 globulins D) Alpha-2 globulins

Answer 46

A - Gamma globulins Order of plasma proteins from the least positively charged to the most positively charged : Albumin, Alpha1, Alpha2, Beta,. Gamma globulins

Question 47

Which cell regulates immediate-type hypersensitivity reactions? A) Th2 cells B) Th1 cells C) Neutrophils D) Eosinophils

Answer 47

D - eosinophils

Question 48

Which cell is associated with killing tumour cells and virus-infected cells? A) CD8 cytotoxic T killer cells B) CD4+ Cells C) NK cells D) Neutrophils

Answer 48

Answer: C A: Cytotoxic CD8 T cells are mainly for the specific immune system, secrete perforins and granzymes to form pores within cell surface membrane, however they are not the main cell to target virus infected cells. B: CD4+ cells are not capable to exhibit cytotoxic effects effectively C: NK cells are similar to CD8 cells, secreted perforins and granzymes, and play a more significant role in virus-infected cells ; secreting IFN-Y which activates macrophages. D: False

Question 49

What condition is asssociates with hypersegmentation of neutrophils and what other condition causes non-segmented (left shift) neutrophils?

Answer 49

Neutrophillia - Hypersegmented neutrophils Neutropenia - Non-segmented neutrophils

Question 50

What type of condition is Epstein-Barr infection?

Answer 50

Infectious mononucleosis which is a type of lymphocytosis.

Question 51

What are the three features you can see in blood film of those infected with Epstein-Barr virus (infectious mononucleosis)?

Answer 51

Intensely basophilic cytoplasm (purplish patina) Scalloped margins and hugging of nearby RBCs Large irregular nuclei

Question 52

What are the two things that increases hepcidin production?

Answer 52

Increased iron intake Pro-inflammatory cytokines

Question 53

Why does increased iron intake will result in increased hepcidin production?

Answer 53

In order to down-regulate the translation and expression of ferroportin within enterocytes -> reducing iron uptake

Question 54

Patient V liked to Wear his favourite shirt everyday, he found out he is allergic to Cotton and has redness on his chest. What are plausible effect/causes A Type 4 Hypersensitivity B Wheal and flare Reaction D He was scratching his chest D The shirt was rubbing against his chest a lot

Answer 54

Answer:A Contact dermatitis of the shirt on his chest. Whilst scratching excessively may lead to redness around his chest this is unlikely the sole cause. The shirt rubbing against a chest will lead to more contact rather than the action of friction causing the redness. Wheal and Flare reactions are type 1 and are the reason for this example.. This is a type 4 reaction on skin.

Question 55

Which cardiac MI after 7 days is the best?

Answer 55

LDH

Question 56

Which category of Acyl CoA dehydrogenases does not exist? A) Very Short Chain B) Short Chain C) Long Chain D) Very Long Chain

Answer 56

A

Question 57

What are the four causes of target cells production?

Answer 57

Obstructive jaundice Liver disease Heamoglobinopathies e.g. sickle cell and thalessaemia Hyposplenism - Spleen removed/doesn't work

Question 58

What are the 5 things that affect different cells to divide at different rates?

Answer 58

- Embryonic vs adult - necessity for renewal - complexity of system - state of differentiation - tumour

Question 59

Cellular adaptation observed due to compensatory mechanism in one kidney upon donation of the other. A) Hyperplasia B) Hypertrophy C) Metaplasia D) Dysplasia

Answer 59

A

Question 60

Example of injury that leads to scar formation as part of repair A) Superficial skin wound B) Myocardial Infarction C) Partial hepatectomy D) Cancer

Answer 60

Answer: B It is not A because the epidermis comprises several layers of cells, which are naturally very good at regenerating. As such, superficial injuries such as scrapes tend not to scar. Underneath the epidermis is the dermis, or the deeper layer of the skin.

Question 61

Which statement is correct regarding centrosomes? A) Centrioles are made from a globular protein, actin B) Centrioles occur in triplets at right angles to each other C) Microtubules elongate from mother centriole within centrosome D) Centrosome forms microtubule packaging centre

Answer 61

Answer: C A: Centrioles are made from tubulin B: Occurs in pairs (mother and daughter) at right angles C: Correct D: Microtubule organising centre is formed

Question 62

Which statement is false regarding the quiescent phase? A) Cells enter phase during an absence of stimulus B) Cells are dormant and non- dividing C) Most differentiated cells are in this phase D) Exist from G0 requires growth factors and intracellular signalling cascades

Answer 62

Answer: B Cells are not dormant, but are non-dividing

Question 63

A 19 year old fresher comes in after sports night to the hepatology ward; a biopsy of hepatocytes were sampled. Which result is most likely? A) Alcoholic fatty change due to increased beta oxidation B) Hepatic steatosis C) Ballooning degeneration, hepatocytes decrease in size D) Irreversible fatty change

Answer 63

Answer: B A: Beta-oxidation is inhibited, there is an accumulation of fat within the liver. Induction of lipogenesis due to ethanol activation of sterol regulatory element binding protein I. B: Fatty liver begins as hepatic steatosis C: Ballooning degeneration is associated with increasing hepatocyte size D: Fatty change is reversible

Question 64

What does an increase in gamma globulin fraction indicates?

Answer 64

Increase in Gamma globulin fraction indicates infection and inflammation

Question 65

Which sugar is encoded by the B- gene? A) Fucose stem (H-antigen) B) N-acetyl galactosamine C) Galactose D) H-antigen only

Answer 65

Answer: C A: The fucose stem is the common glycoprotein for both the A & B genes B: This is encoded by the A gene C: This is encoded by the B gene

Question 66

Which chemokine is a neutrophil attractant? A) CXCL7 B) CXCL8 C) IL-1 D) ICAM-1

Answer 66

Answer: B B: CXCL8 (IL-8) is secreted by macrophages, are a chemotactic attractant for neutrophils; stimulates neutrophil migration to the site of infection; associated with G-coupled 7- transmembrane proteins (CXCR1/2) C: IL-1 form a chemotactic signal, released by macrophages, activates T-cells. D: ICAM-1 is a ligand on the endothelial surface aiding with neutrophil migration

Question 67

A 21-year old female was bitten a second time by a venomous snake, a week soon after; she notices increased swelling, inflammation, fever and a rash. What mechanism is happening? A) IgM/IgG mediated cytotoxic response against snake venom B) Antibody-snake venom immune complexes forming C) Delayed type T cell mediated hypersensitivity D) Antibodies reacting against anti-venom antibodies

Answer 67

Answer: D This is an example of serum sickness, a type III hypersensitivity. A: Type I response, incorrect B: Partially correct however , the symptoms best associate with serum sickness C: This is a type IV response, therefore incorrect D: Correct; the patient was given anti-serum for the initial venomous bite (Antibodies specific to snake venom proteins). Foreign proteins neutralise venom, however the body will react against them to produce antibodies that recognise the antivenom antibodies. Onset takes several weeks. Re-exposure to snake venom and anti-serum will result in rapid synthesis and activation of antibodies, resulting in inflammation

Question 68

4) For use in the TaqMan method of quantitative Real Time PCR (qPCR) which desirable properties should probes and primers have? A) The gene-specific probe and reverse primer should be able to bind to each other B) The gene-specific probe and reverse primer should be at least 50 nucleotides in length C) The gene-specific probe and reverse primer should bind to the same template strand of DNA D) The gene-specific probe and reverse primer should have a complementary sequence to each other E) The gene-specific probe should be labelled with a fluorophore and quencher.

Answer 68

E