November Formative Questions

Question 1

The most common of all histological stains is hematoxylin and eosin (H&E). If a tissue is stained using H&E, the cell nucleus would appear dark blue/purple because:

1) The nucleus is am acidophilic organelle which reacts strongly with eosin
2) The nucleus is an acidophilic organelle which reacts strongly with hematoxylin
3) The nucleus is a basophilic organelle which reacts strongly with hematoxylin
4) The nucleus is a basophilic organelle which reacts strongly with eosin
5) The nucleus reacts strongly with both hematoxlyin and eosin

Answer 1

3

The nucleus is slightly acidic due to nucleic acids and hence reacts strongly with hematoxylin, which is a basic dye reacting strongly with acids.

Eosin is an acidic dye and e.g. reacts well with collagen as collagen is acidophilic

Question 2

The fluidity of the cytoplasmic membrane must be maintained for proper cell functioning. Fluidity of the phospholipid bilayer is increased by which of the following?

1) Short chain fatty acids
2) Reduced hydrocarbon chain interaction
3) Increased amount of unsaturated fatty acids
4) Low cholesterol content
5) All of the above

Answer 2

5

Membrane fluidity refers to the viscosity of the lipid bilayer of this cell membrane. The membrane phospholipids incorporate fatty acids of varying length and saturation.

Lipids with shorter chains are less stiff and less viscous because they are more susceptible to changes in kinetic energy due to having a smaller molecular size and less surface area to undergo
stabilising forces with neighbouring hydrophobic chains.
Lipid chains with carbon-carbon double bonds are more fluid than lipids that are saturated with hydrogens and thus have single bonds. On a molecular level, unsaturated double bonds make it harder for the lipids to pack together as they out kinks into the otherwise straightened hydrophobic chain.
At low temperatures, cholesterol intercalates between the phospholipids and prevents them fro clustering and stiffening.

Question 3

Which of the following apply to the cytoskeleton?

1) It does not occupy the general nucleoplasm
2) It is found in the cytosol
3) It consists, in part, of bundles/networks of fibrous proteins
4) Its protein components have been highly conserved throughout evolution
5) All of the above

Answer 3

5
The eukaryotic cytoplasm occurs in all cell types and therefore has been highly conserved during evolution.
It does not occur in the general nucleoplasm, although elements of it can be found in the nuclear lamina that lines the nuclear membrane.
The cytoskeleton is typically composed of three types of fibrous protein (microfilaments, intermediate fibres and microtubules) that form bundles or networks throughout the cytosol

Question 4

Saliva has a buffer capacity that neutralises acids in the mouth. A buffer is a solution consisting of:

1) A strong acid and weak base
2) A weak acid and its conjugate base
3) A weak base and its conjugate acid
4) A weak acid and a weak base
5) Both 2 and 3

Answer 4

5
A buffer is an aqueous solution of either a weak acid and its conjugate base or a weak back and its conjugate acid. Buffers are used to maintain a stable pH in a solution, as they can neutralise small quantities of additional acid or base.
For a given buffer solution, there is a working pH range and a set amount of acid/base that can be neutralised before the pH will change. This amount is called the buffer capacity.

Question 5

When [S] = 0.7 x Km, the velocity of an enzyme-catalysed reaction is:

1) 0.1 x Vmax
2) 0.7 x Vmax
3) 0.9 x Vmax
4) 0.4 x Vmax
5) 0.5 x Vmax

Answer 5

4

Use Michealis-Menton equation.

V = Vmax x 0.7Km / Km
+ 0.7Km

V = Vmax x 0.7Km / 1.7Km

V = 0.41Vmax

Question 6

Which of the following best describes what the Nernst equation shows at physiological concentrations?

1) Ek = 60mV and Ena = -90mV
2) Ek = -60mV and Ena = -90mV
3) Ek = 90mV and Ena = -60mV
4) Ek = -90mV and Ena = 60mv
5) Ek = -90mV and Ena = -60mV

Answer 6

4
The intracellular fluid and extracellular dluie are both strictly regulated and their ionic composition is well known. Using known values for concentrations of the common ions, we can use Nernst equation to predict that, for most cells in the body, Ek (equilibrium potential for potassium ions) = -90mV, Ena = 60Mv and Eca = +120mv

Question 7

The beta - pleated sheet is a common motif of regular secondary structure in proteins. Which one of the following best describes the B-pleated sheet in proteins?

1) Is stabilised by covalent bonds
2) Is stabilised by hydrogen bonds between amino and carboxyl groups
3) Is stabilised by hydrogen bonds between N-H and C=O groups of the peptide bond
4) Is stabilised by ionic interactions of basic groups
5) Is stabilised by van der Waal interactions between hydrophobic side groups

Answer 7

3

Question 8

What type of cell signalling is characterised by a cell releasing a signal molecule into the environment, followed by a number of cells in the immediate vicinity responding?

1) Hormonal signalling
2) Autocrine signalling
3) Paracrine signalling
4) Endocrine signalling
5) Synaptic signalling

Answer 8

3

Paracrine signalling is a form of cell signalling in which a cell produces a signal to induce changes in nearby cells by altering the behaviour of those cells.

Autocrine signalling: a cell secretes a signal which has an effect in the same cell
Hormonal and endocrine signalling: a signal/hormone is released by a cell in the blood stream and travels around the body leading to changes in distant cells.
Synaptic signalling: specialised type of paracrine signalling whee it occurs between cells via a synapse e.g. a neuromuscular junction

Question 9

Which one of the following best completes the statement?
Because steroids generally act by —-, their effects are typically —- than the effects of peptide hormones
1) activating second messengers, slower
2) inactivating second messengers, slower
3) opening ion channels, faster
4) regulating transcription, slower
5) regulating transcription, faster

Answer 9

4

Steroids hormones are hydrophobic hormones, whicih means that they will not diffuse through the plasma of the blood. They have to be carried by carrier proteins to their target cell.
Once they reach the target cell, they will be able to diffuse through the plasma membrane of the cell and bind to receptors in the cytoplasm.
The hormone is then taken to the nucleus where is regulates transcription. This is why their effects are exerted more slowly and can take days.

As for protein hormones (peptides), they are hydrophilic hormones. They will be able to diffuse through the plasma of the blood but not the plasma membrane of cells. They must attach to receptors on the cell surface and activate secondary messengers. The secondary messengers then modify the activity of enzymes in the cytoplasm. It does not regulate transcription, therefore the effects are immediate.

Question 10

Pharmacokinetics is the effect of the — and pharmacodynamics is the effect of the —

1) Body on the drug, drug on the body
2) Body on the drug, drug on a drug
3) Drug on the body, body on the drug
4) Drug on a drug, body on a drug
5) Drug on a drug, drug on a drug

Answer 10

1

Pharmacokinetics: it is important to understand how a drug is absorbed and the fate of the drug once in contact with the body i.e. how it is distributed, metabolised and eliminated as these factors will determine the speed of onset, intensity and duration of the drug to be used chronically, the dosing regimen.

Pharamacodynamics is about the qualitative and quantitative study of the biochemical and physiological effects of drugs on the body.
Qualitative studies investigate the mechanisms of the action of drugs and endogenous molecules, whereas quantitative studies allow comparison of the relationship between the drug concentration and effect.

Question 11

In multiple sclerosis patients, nerves in the central nervous system are demyelinated. Which cells myelinate axons in the central nervous system and what is the effect of demyelination?

1) Schwann cells: A decrease in velocity of action potential conduction
2) Oligodendrocytes: A decrease in velocity of action potential conduction
3) Schwann cells: An increase in the velocity of action potential conduction
4) Oligodendrocytes: An increase in the velocity of action potential conduction
5) Both Schwann cells and oligodendrocytes: An increase in the velocity of action potential conduction

Answer 11

2

Both Schwann cells and oligodendrocytes myelinate axons but they do so in different locations and have different embryonic origins.

Oligodendrocytes arise within the developing brain and myelinate axons within the central nervous system. Schwann cells arise from the neural crest cell population during embryonic development and myelinate axons of the peripheral nervous system.

Question 12

In response to a sudden blood loss, the sympathetic nervous system is activated. What is the effect of the sympathetic nervous system activation on heart rate and skin vasculature?

1) Decrease in heart rate and vasodilation in skin
2) Increase in heart rate and vasodilation in skin
3) Decrease in heart rate and vasoconstriction in skin
4) Increase in heart rate and vasoconstriction in skin
5) Increase in heart rate, no change in skin vasculature

Answer 12

4

In response to a sudden blood loss, arterial baroreceptors sense a reduction in blood pressure and trigger the sympathetic nervous system to increase heart rate and contractility to maintain cardiac output.

Sympathetic stimulation also constricts venous capacitance vessels in skin and splanchnic arterial beds (blood supply to the gastrointestinal tract, liver, spleen and pancreas) to maintain blood pressure.

Question 13

Botulinum toxin (botox) is a neurotoxin which can be used to reduce saliva secretion in patients during hyper-salivation. Botox acts on which branch of the autonomic nervous system and by which mechanism?

1) Activates parasympathetic system by blocking the release of acetylcholine.
2) Activates parasympathetic system by stimulating the release of acetylcholine
3) Inhibits parasympathetic system by blocking acetylcholine release
4) Inhibits sympathetic system by blocking the release of noradrenaline

Answer 13

3

Botox is a neurotoxic protein produced by bacteria. Infection with the bacterium causes the disease botulism. The toxin binds specifically to a parasympathetic nerves, which use the neurotransmitter acetylcholine. Once bound to the nerve terminal, the neuron takes up the toxin.
Once inside the cytoplasm of the neuron, the toxin cleaves SNARE proteins, which mediate vesicle fusion, meaning that the acetylcholine vesicles cannot bind to the intracellular cell membrane, preventing the cell from releasing vesicles or neurotransmitter. This stops nerve signalling.

Question 14

Where and how does the breakdown of glycogen to form glucose occur?

1) In the liver, by phosphorolysis
2) In the muscles, by phosphorolysis
3) In the liver, by hydrolysis
4) In the muscles, by hydrolysis
5) Both 1 and 2 are correct

Answer 14

5

Hexokinase in the skeletal muscle converting it from glycogen to glucose-1-phosphate .
Glucakinase in the liver converting from glycogen to glucose.

Question 15

Which one of the following best describes the tissue in the two images below?

• single cell layer with cells flattened
  1) Simple columnar epithelium
  2) Pseudostratisfied epithelium
  3) Simple squamous epithelium
  4) Stratified squamous epithelium
  5) Simple cuboidal epithelium

Answer 15

3

Simple squamous epithelia are tissues formed from one layer of squamous cells that line surfaces. Squamous cells are large, thin and flat and contain a rounded nucleus.

Question 16

The teeth ang gums seperate the oral cavity proper from which of the following?

1) Nasal cavity
2) Oral vestibule
3) Oropharynx
4) Paralingual space
5) Submandibular space

Answer 16

2

The oral vestibule is the area between the teeth, lips and cheeks.

Question 17

Which of the following best describes the concept or homeostasis?

1) Includes the concept of an error signal
2) Refers to maintaining physiological functions in a stable condition
3) Refers to only the regulation of body temperature
4) Both 1 and 2 are correct
5) 2 and 3 are correct

Answer 17

4

Homeostasis refers to keeping the cell/tissue/body in a steady-state and an ability to respond to internal and external environmental changes. The error signal refers to the difference between the physiological ideal and the actual values measured by sensors.

Question 18

Plasma osmolarity can be increased in pathological situations such as diabetic ketoacidosis. What is the normal osmolarity of physiological fluids?

1) 300 mOsmolL^-1
2) 30 mOmolL^-1
3) 0.3 mOmolL^-1
4) 300 OmolL^-1
5) 30 OsmolL^-1

Answer 18

1

Osmolarity matters because cells cannot survive if the osmolarity of their surroundings is much different from their own.
Water moves across a membrane from lower osmolarity to higher osmolarity.
In other words, it moved from the dilute side to the concentrated side.
The dilute side loses water and becomes more concentrated. The concentrated side gains water to become more dilute. Cell survival depends on balancing water uptake and loss. Cell can burst if they take on too much water, or collapse if they lose too much.

Question 19

Which of the following types of joints are fibrous?

1) Gomphoses
2) Synchondroses
3) Suture
4) Symphyses
5) 1 and 3

Answer 19

5

A fibrous joint is where the bones are bound by tough, fibrous tissue. These are typically joints which require strength.
Fibrous joints can be sub - classified into sutures, gomphoses and syndesmoses.
Synchondroses and symphyses and cartilaginous joints.

Question 20

While compact bone appears at first glance to be solid and uninteruppted, closer inspection reveals the presence of spaces including lacunae. The lacunae of bone contain what?

1) Blood vessels
2) Osteons
3) Chondrocytes
4) Bone marrow
5) Osteocytes

Answer 20

5

The osseous tissue of compact bone is arranged in cylindrical osteons. Each osteon is a compact cylinder of concentric lamellae. The only cells in an osteon are the osteocytes that are found on the edges of each lamella.
Osteocytes compose 90-95% of all bone cells in adult bone. Osteocytes are found in lacunae, which are cell-shaped empty spaces. Cytoplasmic extensions branch out from each osteocyte and are houses in the canaliculi.
At the centre of each osteon is a central canal (known as the Haversian canal) through which travel blood vessels/ lymph vessels and nerves. Bone marrow is found in spongey bone and chondroblasts are found in cartilage.

Question 21

Cartilage is found on the mandibular condyle. What is the major type of collagen found in cartilage matrix?

1) Type I collagen
2) Type II collagen
3) Type VI collagen
4) Type IX collagen
5) Type XII collagen

Answer 21

2

Type II collagen is the basis for articular and hyaline cartilage. It makes up 50% of all protein found in cartilage and 85-90% of collagen of articular cartilage. Type II collagen does form fibrils.
The fibrillar network of collagen allows cartilage to entrap the proteoglycan aggreagate as well as provide tensile strength to the tissue.

Question 22

Given these zones within the epiphyseal plate:
1. Zone of calcification 
2. Zone of hypertrophy 
3. Zone of proliferation
4. Zone of resting cartilage
Arrange them in order running from the epiphysis to the diaphysis 
1) 1,2,3,4
2) 1,3,4,2
3) 2,4,1,3
4) 3,2,1,4
5) 4,3,2,1

Answer 22

5

Question 23

A sarcomere is the unit of striated muscle tissue. Which one of the following best describes the sarcomeric bands shown in label E of the electron micrograph of cardiac muscle?

1) E labels H band of myosin filaments
2) E labels H bands of actin filaments
3) E labels A band of myosin and actin filaments
4) E labels I band of myosin filaments
5) E labels I band of actin filaments

Answer 23

5

The I bands are two regions that exclusively contain thin filaments (mostly actin) and are less dense in electron micrographs.

Question 24

Identify the structures labelled A, B and C

1) A=arteriole, B=lymphatic vessel, C=venule
2) A=venule, B=arteriole, C=lymphatic vessel
3) A=arteriole, B=venule, C=lymphatic vessel
4) A=venule, B=lymphatic vessel, C=arteriole
5) A=lymphatic vessel, B=arteriole, C=venule

Answer 24

B

Arterioles: thin tunica intima, may include a thin internal elastic lamina, <6 layers of smooth muscle cells in tunica media, insignificant tunica adventitia.

Lymphatic vessels: extremely flattened endothelial cells, a rudimentary basal lamina and do not contain red blood cells.

Venule walls have three layers: an inner endothelium compose of squamous endothelial cells that act as a membrane, a middle layer of muscle and elastic tissue and an outer layer of fibrous connective tissue. The middle layer is poorly developed so the venules have thinner walls than arterioles.

Question 25

Which of the following correctly identifies the skin layer labelled 3?

1) The hypodermis, a layer of loose connective tissue and adipose tissue containing eccrine sweat glands
2) The living cell layer of the epidermis
3) The papillary layer of the dermis
4) The reticular layer of the dermis
5) The stratum corneum (dead cell layer) of the epidermis

Answer 25

3

1 = statum corneum
2 = the living cell layer of dermis
3 = papillary layer of dermis
4 = reticular layer of dermis
5 = hypodermis

The epidermis can be distinguished due to its higher cell density, hence a darker staining.

Question 26

Antibodies, also known as immunogolbulins, are used by the immune system to neutralise pathogenic bacteria and viruses. Which one of these blood cells produces antibodies?

1) T lymphocytes
2) B lymphocytes
3) Monocytes
4) Granulocytes
5) Platelets

Answer 26

2

B lymphocytes, are a white blood cells of the lymphocyte subtype. They have surface immunoglobin (receptor for antigen) and respond to antigen by proliferating and maturing into plasma cells (activated B lymphocytes), which then secrete the same immunoglobin (antibody).

Question 27

If a needle was inserted into the heart, in which order would it travel through the layers of the heart and covering, beginning on the outside?

1) endocardium, myocardium, fibrous pericardium, parietal pericardium, visceral pericardium
2) fibrous pericardium, parietal pericardium, visceral pericardium, myocardium, endocardium
3) parietal pericardium, fibrous pericardium, visceral pericardium, myocardium, endocardium
4) visceral pericardium, parietal pericardium, fibrous pericardium, endocardium, myocardium
5) visceral pericardium, parietal pericardium, fibrous pericardium, myocardium, endocardium

Answer 27

2

Question 28

The Frank-Starling law of the heart says that a higher end diastolic volume is related to which one fo the following?

1) decreased sympathetic activity
2) decreased blood pressure
3) decreased cardiac output
4) increased end systolic volume
5) increased stroke volume

Answer 28

5

The greater the ventricular diastolic volume, the more the myocardial fibres are stretched during diastole.
Within a normal physiological range, the more the myocardial fibres are stretched, the greater the tension in the muscle fibres and the greater the force of contraction when stimulated. The Frank-Starling relationship is the observation that ventricular output increases as preload (end-diastolic pressure) increased.

Question 29

Which one of the following best desribes the teeth shown in the images below?

1) Lower right lateral incisor A and lowe right canine B
2) Lower left central incisor A and upre rigjt inscior B
3) Upper left central incisor A and lower left lateral incisor B
4) Lower left central incisor A and lower left lateral incisor B
5) Upper right central incisor A and upper right canine B

Answer 29

1

Question 30

Which one of the following descriptions best describes the morphological features of human canines?

1) The mesial ridge is shorter than the distal ridge and the apical part of the root is curved slightly distally
2) The distal ridge is shorter than the mesial ridge and the apical part of the root is slightly curved distally in most of the cases
3) The distal ridge is shorter then the mesial ridge and the apical part of the root is slightly curved mesially is most of the cases
4) The mesial ridge is shorter than the distal ridge and the apical part of the root is curved slightly mesially in post cases
5) The mesial ridge and the distal ridge have same length separated by a cusp and the apical part of the root slightly distally curved in most of the cases.

Answer 30

1