hllj/quesmed huggingface dataset:
Which of the following is formed from cells which disperse from the neural plate during neurulation?

Options:
explanation: The adrenal medulla is formed from neural crest cells which are released from the neural plate's crest as it fuses into the neural tube during neurulation.
name: Adrenal medulla
label: a
answer: yes
explanation: Intercostal muscles are formed from paraxial mesoderm alongside the ribs and vertebra, each consisting of components from the 2 adjacent somites. They are encoded for by HOX genes which correspond to their appropriate spinal level.

<br>
name: Intercostal muscles
label: e
answer: no
explanation: The telencephalon is a paired structure formed from the neural tube's cranial aspect during the 5 vesicle stage. Together with the diencephalon, it forms the forebrain, making up the cerebral cortices, thalamus and hypothalamus.
name: Telencephalon
label: d
answer: no
explanation: Intervertebral discs are formed from the remnants of the notochord after it has induced neurulation in the ectoderm through the release of factors such as BMP-4.
name: Intervertebral discs
label: b
answer: no
explanation: Glomeruli are formed from the intermediate layer mesoderm which forms the urogenital ridges from which the pronephros, mesonephros and metanephros arise. The glomeruli of the adult kidney are formed embryonically when the ureteric bud (endoderm-derived) and mesenchyme interact. The mesenchyme of the metanephric ridge expresses WT1, and undergoes mesenchymal to epithelial transition to form nephric vesicles which join to the tubular structures of the branching ureteric bud, making up the glomeruli of the nephrons.
name: Glomeruli
label: c
answer: no

Correct answer: a
Which structure is formed from the left horn of the embryonic sinus venosus?

Options:
explanation: The coronary sinus is formed from the left horn of the sinus venosus. It drains the great, middle, small and oblique coronary veins directly into the right atrium.
name: The coronary sinus
label: a
answer: yes
explanation: The aortic arch is formed from the bridging of the 4th left aortic arch between the ventral and left dorsal aorta. Up to 6 paired aortic arches initially form between the ventral aorta and paired dorsal aorta. Most of these atrophy but those remaining form the great vessels and their branches.
name: The adult aortic arch
label: d
answer: no
explanation: The smooth right atrium is the adult structure formed from the right horn of the sinus venosus. It is separated from the right atrial appendage by the sulcus terminalis externally and crista terminalis internally and does not contain pectinate muscles.
name: The smooth right atrium
label: b
answer: no
explanation: The right atrial appendage is the remnant of the primitive atrium on the cranial side of the sinus venosus. It is separated from the smooth right atrium by the sulcus terminalis externally and crista terminalis internally and contains pectinate muscles.

<br>
name: The right atrial appendage
label: e
answer: no
explanation: The aorticopulmonary (spiral) septum is formed from the septation of the truncus arteriosus by endocardial cushions and is aided by the infiltration of neural crest cells. Defects in this process can cause tetralogy of Fallot, a cyanotic congenital heart disease characterised by pulmonary stenosis, an over-riding aorta, a ventricular septal defect and right ventricular hypertrophy.
name: The aorticopulmonary septum
label: c
answer: no

Correct answer: a
During limb development, excessive Sonic Hedgehog (SHH) release can lead to which condition?

Options:
explanation: SHH is produced in the zone of polarising activity in the caudal aspect of the distal limb bud. This results in the differential development of the digits into the digitus minimus to pollux morphologies.

Injection of SHH or transplantation of the zone of polarising activity to another part of the limb bud in chicken embryos is sufficient to alter the development of the autopod into a different orientation.

Enhanced SHH expression in vivo leads to polydactyly in which extra digits are produced.
name: Polydactyly
label: a
answer: yes
explanation: Chondrodysplasia Grebe type is a micromelia (small, deformed limb) congenital malformation of the limbs. It results from autosomal recessive mutations in GDF5, a growth and differentiation factor which enhances the condensation of the mesenchyme to promote bone thickening.
name: Grebe-type chondrodysplasia
label: b
answer: no
explanation: Phocomelia describes the lack of formation of the stylopod (forms the adult humerus) and sometimes zeugopod (forms the adult radius and ulna - lost in type 1 phocomelia, retained in type 2) whilst the development of the autopod (forms the most distal features including the carpals, metacarpals and phalanges) is retained.

In development, the more distal features of the embryonic limb bud are induced to become the autopod and zeugopod based on the concentration of FGF received from the apical ectodermal ridge.

Phocomelia was a common thalidomide-induced birth defect as the drug impaired the proliferation of cells in the progress zone of the developing limb bud while not affecting FGF secretion.
name: Phocomelia
label: d
answer: no
explanation: Split hand-foot malformation (SHFM) occurs due to multi-factorial genetic and environmental factors causing the failure of the apical ectodermal ridge, resulting in aplasia and hypoplasia of some phalanges and metacarpals/metatarsals. SHH can be implicated in SHFM but due to deficiency, not excess.

<br>
name: Split hand-foot malformation
label: e
answer: no
explanation: Pituitary dwarfism occurs when the growth of an individual is restricted uniformly across the entire body due to a deficiency in growth hormone. This can occur due to factors at birth (genetic disease, congenital pituitary agenesis) or acquired factors in early life (severe brain injury, pituitary adenoma compressing the somatotropic anterior pituitary cells).
name: Pituitary dwarfism
label: c
answer: no

Correct answer: a
Which of these statements best describes the windlass mechanism?

Options:
explanation: To prevent scapular winging, the serratus anterior (under the control of the long thoracic nerve) contracts, pulling the scapula anteriorly. Disruption of this nerve, for example by misplaced chest drain insertion, can cause scapular winging which can be corrected using a scapular brace.
name: When pushing the extended arm against a wall, a muscle contracts to keep the scapula in place
label: c
answer: no
explanation: This is the locking of the knee. Upon full extension of the knee, the femur rotates inwards on the tibial plateau, causing the tightening of the anterior and posterior cruciate ligaments. This allows the leg to remain extended with less muscular activity to conserve energy while standing. This locking can then be unlocked by the popliteus muscle externally rotating the femur on the tibia.
name: Extension of the knee causes the leg to lock
label: b
answer: no
explanation: When abducting the shoulder in the glenohumeral joint, the first 15 degrees of movement are mediated by the suprascapularis, and the next rotation up to 90 degrees is mediated by the deltoid. Further rotation from this point onwards is mediated by the rotation of the scapula at the acromioclavicular joint by the trapezius (as the glenohumeral joint is already at its full abduction).

<br>
name: The rotation of the scapula during arm abduction
label: e
answer: no
explanation: This is the windlass mechanism. Weight-bearing on the first metatarsophalangeal joint causes its extension, tightening the plantar aponeurosis into a tight band, raising the height of the medial longitudinal arch, externally rotating the leg, and inverting the calcaneus.
name: Pressure on the hallux causes tightening of the arch of the foot through the plantar fascia
label: a
answer: yes
explanation: The pelvis is formed of arches which produce strong structures for weight bearing. One arch is formed between the ischial tuberosities, pubis and pubic symphysis to support the body when sitting. Another is formed between the acetabulums, ilium and sacrum to support the body when standing.
name: When sitting, a bony arch supports the weight of the body
label: d
answer: no

Correct answer: a
Which of these statements best describes Wallerian degeneration?

Options:
explanation: This describes the development of GnRH-releasing neurons. This process is disrupted in Kallmann syndrome resulting in an impaired sense of smell and delayed puberty.
name: Migration of GnRH-releasing neurons from the nasal placode to the hypothalamus
label: c
answer: no
explanation: This is the process of Wallerian degeneration which occurs after axonotmesis or neurotmesis as the distal aspect of the axon is detached from its cell body.
name: Schwann cells dissociate from the axon and macrophages remove axon debris
label: a
answer: yes
explanation: This process is known as neural pruning which peaks between ages 2 and 16 to remove unused neurons, improving the strength of connections between more frequently utilised neurons.

<br>
name: The degeneration of central neurons due to insufficient signalling through them during development
label: e
answer: no
explanation: This is the process by which neuron axons link to their target structures in embryonic stages and during peripheral nerve regeneration after Wallerian degeneration (it is only likely to be successful after axonotmesis as the growth cone can be guided by the endoneurium, whilst after neurotmesis, the growth cone may not meet the epineurium).
name: Axon growth cones follow the concentration gradient of neurotrophic factors to the target tissue
label: b
answer: no
explanation: This process is known as disuse atrophy, which occurs, for example, to the muscles of the thenar eminence in median nerve palsies.
name: Degeneration of muscular tissue upon denervation
label: d
answer: no

Correct answer: a
Which of these statements about beta-oxidation is true?

Options:
explanation: To enter the mitochondria, fatty acyl-CoA is conjugated to carnitine (which takes the place of coenzyme A) by carnitine acyltransferase 1. It can then be bound by translocase in the inner mitochondrial membrane. Once in the mitochondrial matrix, it can be de-conjugated by carnitine acyltransferase 2, becoming fatty acyl-CoA again.
name: To enter the mitochondria, fatty acyl-CoA must be bound to translocase in the cytoplasm. Once bound, it can then freely diffuse across the lipid bilayer of the inner mitochondrial membrane
label: c
answer: no
explanation: ACP is a co-factor which is added to 3-carbon malonyl-groups by switching places with the co-enzyme A on malonyl-CoA. This generates malonyl-ACP.
name: Acyl carrier proteins (ACP) cofactors must first be added to fatty acids to facilitate beta-oxidation
label: b
answer: no
explanation: Beta-oxidation releases an acetyl-CoA molecule, an FADH2 molecule and an NADH molecule for each 2-carbon unit of fatty acid. Oxidative glycolysis produces a net gain of 2 acetyl-CoA molecules, 2 NADH molecules and 2 ATP molecules per 6-carbon glucose molecule. Through the citric acid cycle and oxidative phosphorylation, these products are converted to a total of 17.7 ATP per 2 carbon unit of fatty acid (Mr=28) and 34.2 ATP per 6 carbon unit of glucose (Mr=180). Therefore per gram of molecular weight, beta-oxidation with oxidative phosphorylation generates 0.63 moles of ATP whilst oxidative glycolysis with oxidative phosphorylation generates 0.19 moles of ATP.
name: The process of beta-oxidation and subsequent oxidative phosphorylation releases less energy per gram than oxidative glycolysis and subsequent oxidative phosphorylation
label: d
answer: no
explanation: This is the final stage of beta-oxidation. Prior to this stage, fatty acyl-CoA is oxidised by acyl-CoA dehydrogenase, and the resulting trans-delta-squared enoyl-CoA is hydrated by enoyl-CoA hydratase. Hydroxyacyl-CoA is then oxidised by hydroxy acyl-CoA dehydrogenase to ketoacyl-CoA.
name: Beta-oxidation involves the thiolysis of ketoacyl-CoA into the shorter fatty acids acyl-CoA and acetyl CoA
label: a
answer: yes
explanation: Acyl-CoA dehydrogenases use FAD cofactors and are divided into 4 types: very long-chain acyl-CoA dehydrogenase, long-chain acyl-CoA dehydrogenase, medium-chain acyl-CoA dehydrogenase and short-chain acyl-CoA dehydrogenase. Each dehydrogenase processes fatty acyl-CoA molecules of different lengths during beta-oxidation. Reduction in the activity of the acyl-CoA dehydrogenases by a compound in unripe ackee fruit inhibits beta-oxidation causing the depletion of glycogen reserves, resulting in Jamaican vomiting sickness.

<br>
name: Acyl-CoA dehydrogenases are NAD+ dependent
label: e
answer: no

Correct answer: a
Regarding oxidative phosphorylation, which of the following statements is true?

Options:
explanation: The electron transport chain drives protons out of the mitochondrial matrix across the inner mitochondrial membrane to create an electrochemical gradient into the matrix through the F0 component of ATP synthase.
name: The electron transport chain drives protons into the mitochondrial matrix
label: b
answer: no
explanation: FADH2 is converted to FAD by complex 2 (succinate dehydrogenase, also involved in the citric acid cycle). Complex 2 does not pump protons itself but transfers electrons to ubiquinone, which are subsequently accepted by complex 3 (which pumps 4 protons). These electrons are then transferred to cytochrome C which transfers the electrons to complex 4 which pumps 2 protons (total protons pumped = 6). The electrons are finally transferred to oxygen, the terminal acceptor, which generates water.
name: FADH2 is converted to FAD by complex 1, resulting in the pumping of 10 protons across the inner mitochondrial membrane
label: d
answer: no
explanation: ATP synthase is formed of the F0 proton pore and the F1 rotating component which binds and combines ADP and phosphate molecules. This occurs in 3 stages: binding, combination and release. A full turn of F1 requires 3 individual 120-degree rotations of F1 (each of which produces 1 ATP molecule). All 3 stages (binding, combination and release) occur simultaneously, meaning they occur 3 times during each 360-degree rotation, generating 3 ATP molecules.

8 protons have to pass through the F0 pore to facilitate a full rotation of F1. Since the ATP synthesis reaction occurs in one out of the three stages of ATP synthase rotation (combination stage), we can deduce that only 1/3 of the energy from the movement of the 8 protons is used to drive the ATP synthesis reaction, whilst the rest is used to bind the ADP and phosphate (binding stage) and release the newly formed ATP (release stage).

<br>
name: The ATP synthesis reaction demands most of the energy that the proton gradient confers onto ATP synthase
label: e
answer: no
explanation: The greatest changes in redox potential in the electron transport chain are from NADH to iron-sulfur complexes, from cytochrome b562 to cytochrome b566, and from cytochrome a to cytochrome a3, all of which occur in complexes 1, 3 and 4. This corresponds with the complexes in which protons are pumped across the inner mitochondrial membrane as there is sufficient energy to drive this movement.
name: The reactions with the largest changes in redox potential in the electron transport chain occur within complexes 1, 3 and 4
label: a
answer: yes
explanation: 2,4-dinitrophenol is a molecule which uncouples the electron transport chain from ATP synthase by inserting itself into the inner mitochondrial membrane and facilitating proton transport back into the matrix. This dissipates the electrochemical gradient and leads to an increased rate of oxidative phosphorylation without ATP generation.
name: 2,4-dinitrophenol increases the rate of oxidative phosphorylation, boosting ATP production
label: c
answer: no

Correct answer: a
Which of the following enzymes is directly utilised in the conversion of pyruvate to glucose during gluconeogenesis?

Options:
explanation: Hexokinase hydrolyses ATP to release a phosphate molecule which is used to generate glucose-6-phosphate from glucose. Hexokinase will not, however, catalyse the opposite reaction, instead requiring glucose-6-phosphatase to hydrolyse phosphate from glucose-6-phosphate during gluconeogenesis.
name: Hexokinase
label: b
answer: no
explanation: Fructose-2,6-bisphosphatase catalyses the removal of phosphate from the '2' group of fructose-2,6-bisphosphate. Fructose-2,6-bisphosphate is the most potent known activator of phosphofructokinase-1, stimulating increased glycolysis. Fructose-2,6-bisphosphatase, therefore, down-regulates glycolysis and could be used to indirectly up-regulate gluconeogenesis. However, fructose-2,6-bisphosphatase is not involved in the core processes in the way enzymes like fructose-1,6-bisphosphatase are.

<br>
name: Fructose-2,6-bisphosphatase
label: e
answer: no
explanation: Phosphofructokinase-1 catalyses the addition of an extra phosphate group to the '1' position of fructose-6-phosphate to generate fructose-1,6-bisphosphate. Phosphofructokinase-1 will not, however, catalyse the opposite reaction, instead requiring fructose-1,6-bisphosphatase to hydrolyse phosphate from fructose-1,6-bisphosphate during gluconeogenesis.
name: Phosphofructokinase-1
label: c
answer: no
explanation: Pyruvate carboxylase hydrolyses ATP to release energy so that it can add a bicarbonate group to pyruvate, generating oxaloacetate. Phosphoenolpyruvate carboxykinase can then use the energy from GTP hydrolysis to remove CO2 from oxaloacetate and generate phosphoenolpyruvate. This overcomes the non-reversible reaction by pyruvate kinase during glycolysis and facilitates gluconeogenesis.
name: Pyruvate carboxylase
label: a
answer: yes
explanation: Pyruvate kinase catalyses the transfer of a phosphate group from phosphoenolpyruvate to ADP during glycolysis, generating ATP and pyruvate. This reaction, however, has a large Gibbs free energy change and the hydrolysis of a single ATP molecule is insufficient to reverse it. This makes the reaction effectively irreversible. To overcome this during gluconeogenesis, an intermediate step is performed in which an ATP molecule is hydrolysed to produce oxaloacetate. A GTP molecule is then hydrolysed to convert the oxaloacetate into phosphoenolpyruvate oxaloacetate.
name: Pyruvate kinase
label: d
answer: no

Correct answer: a
The unique structure of which amino acid allows tight twists in the structure of collagen molecules?

Options:
explanation: Although it may be found in small proportions in collagen molecules, methionine does not contribute to the tight twists of collagen molecules. Methionine's R-group consists of a 2-carbon alkyl chain linked to a sulphur molecule which is itself linked to a methyl group.
name: Methionine
label: d
answer: no
explanation: Although it may be found in small proportions in collagen molecules, isoleucine does not contribute to the tight twists of collagen molecules. Isoleucine's R-group consists of a 3-carbon alkyl chain with a methyl group branching off the 1st carbon of the chain.
name: Isoleucine
label: b
answer: no
explanation: Collagen is formed mainly of repeats of glycine, proline and hydroxyproline. Proline's variable R-group consists of a 3-carbon acyl chain, the terminal carbon of which is linked to the nitrogen atom in the amine group. This causes a tight bend in amino acid chains in which proline is present.
name: Proline
label: a
answer: yes
explanation: Although it may be found in small proportions in collagen molecules, phenylalanine does not contribute to the tight twists of collagen molecules. Phenylalanine's R-group consists of a single carbon alkyl group linked to a benzene ring.

<br>
name: Phenylalanine
label: e
answer: no
explanation: Although it may be found in small proportions in collagen molecules, lysine does not contribute to the tight twists of collagen molecules. Lysine's R-group consists of a 4-carbon alkyl chain with an amine group linked to the 4th carbon of the chain.
name: Lysine
label: c
answer: no

Correct answer: a
Upon activation, the Ga-q subunit of a G-protein does what?

Options:
explanation: This is one of the functions of the Ga-13 subunits which bind to the guanine nucleotide exchange factors for Rho GTPases. This activates their modulatory action on the actin cytoskeleton to alter cell conformation.
name: Modulates the cytoskeleton
label: d
answer: no
explanation: This is one of the functions of the beta-gamma subunit: they promote the opening of inward-rectifying potassium channels, thus hyper-polarising cells. These subunits can also modulate the activity of calcium channels and the Ras-Raf mitogenic signalling pathway.

<br>
name: Opens potassium channels
label: e
answer: no
explanation: This is the function of Ga-s which increases the generation of cAMP. This activates PKA which phosphorylates intracellular targets to modulate cell activity.
name: Activates adenylyl cyclase
label: b
answer: no
explanation: This is the function of Ga-q which increases the generation of diacylglycerol. This activates PKC which phosphorylates intracellular targets to modulate cell activity and inositol trisphosphate, which binds to IP3 receptors. This allows for calcium efflux from the endoplasmic reticulum into the cytoplasm to modulate cell activity.
name: Activates phospholipase C
label: a
answer: yes
explanation: This is the function of Ga-i/o subunits. This reduces the generation of cAMP which reduces the activity of PKA and subsequently reduces the phosphorylation of intracellular targets to modulate cell activity.
name: Inactivates adenylyl cyclase
label: c
answer: no

Correct answer: a
Which reaction does PI3K catalyse (upon activation) downstream of the insulin receptor?

Options:
explanation: Serine phosphorylation of Akt is performed by PDK-1 and mTORC2, activating its anabolic functions only when insulin is bound to the receptor and the cell is in an ATP-rich state.

<br>
name: Serine phosphorylation of Akt
label: e
answer: no
explanation: Phospholipase C catalyses the hydrolysis of PIP3 to diacylglycerol (DAG). This activates PKC which phosphorylates intracellular targets to modulate cell activity, as well as inositol trisphosphate (IP3) which binds to IP3 receptors and allows for calcium efflux from the endoplasmic reticulum into the cytoplasm to modulate cell activity.
name: Hydrolysis of PIP3 to IP3 and DAG
label: b
answer: no
explanation: This is the description of a guanine nucleotide exchange factor such as a G-protein coupled receptor. An example of a G-protein coupled receptor is the a1 adrenoceptor which accelerates GDP release from Ga-q type G-proteins to allow GTP entry and the activation of G-protein function.
name: Exchange of GDP for GTP in G-proteins
label: d
answer: no
explanation: Phosphoinositide-3-kinase (PI3K) phosphorylates PIP2 to PIP3 on the inner side of the plasma membrane. This acts as a scaffold for the pleckstrin homology domain of Akt which phosphorylates targets including FOXO1, mTOR, glycogen synthase kinase and components of the GLUT4 exocytosis pathway. Together, this promotes protein synthesis, inhibits gluconeogenesis, promotes glycogenesis and promotes glucose uptake into cells.
name: Phosphorylation of PIP2 to PIP3
label: a
answer: yes
explanation: Upon binding of insulin to the external domains of the constitutively hetero-tetrameric insulin receptor, the tyrosine-rich cytoplasmic domains change conformation, allowing for the trans-phosphorylation of the tyrosine residues on each domain. This creates a scaffold for the SH3 domains of substrates to bind to and initiate downstream signalling.
name: Tyrosine phosphorylation of the insulin receptor
label: c
answer: no

Correct answer: a