General Revision Q's

Question 1

Concerning fertilisation of the human ovum:

(i) spermatozoan penetration of the corona radiata causes cortical granules to release their contents within the ovum to prevent further entry from additional spermatozoa.

(ii) fertilisation is complete once the male and female pronuclei have fused.

(iii) the ovum contains 21 chromosomes in total.

(iv) the cytoplasm of the spermatozoan does not contribute to the formation of the embryo proper or supporting tissues

KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct

Answer 1

B

Question 2

Concerning implantation of the embryo:

(i) the blastocyst ‘hatches’ from the zona pellucida on day 3-4

(ii) embryoblast cells penetrate the endometrium of the uterus and initiate proliferation of blood vessels and glands.

(iii) Luteinising hormone promotes continued production of progesterone from the corpus luteum to maintain endometrial thickness following implantation.

(iv) ectopic pregnancies are defined by implantation occurring in any location other than the body of the uterus.

KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct

Answer 2

D

Question 3

Concerning the formation of the primitive streak:

(i) it forms as a thickening of the hypoblast.

(ii) it elongates towards the prechordal plate of the embryo.

(iii) epiblast cells migrate through the primitive groove to displace hypoblast cells and form the definitive ectoderm.

(iv) the invagination of cells through the primitive pit forms the notochordal process.

KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct

Answer 3

B

Question 4

Concerning the process of ossification:

(i) formation of bone tissue directly from a condensed mesenchyme is called endochondral ossification.

(ii) irregular-shaped bones such as the vertebra and os coxa form from a single primary ossification centre.

(iii) all secondary ossification centres form after birth.

(iv) the epiphyseal plate is the site of endochondral ossification during longitudinal bone growth.

KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct

Answer 4

D

Question 5

Concerning the development of the musculoskeletal system:

(i) the sclerotome contributes to the formation of the vertebrae and ribs.

(ii) the hypomere forms the skeletal muscles of the thoracic and abdominal walls, and limbs.

(iii) sacralisation is characterised when L5 vertebra fuses with S1 to contribute to the formation of the sacrum.

(iv) in the case where only one chondrification centre develops in the body of the vertebra, a hemivertebra may form resulting in congenital scoliosis.

KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct

Answer 5

E

Question 6

Concerning spina bifida:

(i) spina bifida occulta is more common in neonates than adults, suggesting that it may represent delayed fusion of the vertebral arch rather than failed fusion in some patients.

(ii) spina bifida may result from a failure of the neural tube to close.

(iii) in spina bifida cystica, if the cyst contains only meninges and cerebrospinal fluid it is classified as a meningocele.

(iv) spina bifida myeloschisis is fatal.

KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct

Answer 6

E

Question 7

Concerning cell fate, organisers and gene signalling:

(i) the right/left axis is established by Nodal secreted by the primitive node being pushed to the left side of the embryo by the directional beating of cilia.

(ii) the severity of upper limb defects in infants was higher in women taking Thalidomide earlier in their pregnancy.

(iii) expression of Runx2 is required for mesenchyme or cartilaginous tissue to differentiate into bone tissue.

(iv) the anterior/posterior axis is established by a thickening of the epiblast cells called the prechordal plate

KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct

Answer 7

C

Question 8

Concerning bone tissues:

(i) bones are unable to use interstitial growth to expand due to the hardness of the tissue bestowed by its inorganic/mineral phase.

(ii) osteoblasts are multinucleated cells that resorb bone tissue.

(iii) the periosteum is a source of blood vessels and mesenchymal stem cells for tissue growth and repair.

(iv) osteons are formed from multiple concentric lamellae surrounding a perforating canal in trabecular bone tissue.

KEY: A = only statements (i) and (iii) are correct
B = only statements (ii) and (iv) are correct
C = only statements (i), (ii) and (iii) are correct
D = statement (iv) ONLY is correct
E = ALL statements are correct

Answer 8

A

Question 9

Explain the purpose of the periosteal callus during fracture healing and describe the event that signals consolidation of the callus

Question 10

Concerning the foetal circulation:

(i) The fossa ovalis directs blood flow from the right atrium to the left atrium

(ii) Avoids the pulmonary system

(iii) The closure of the fossa ovalis is made from the septum secundum and septum primum

(iv) The ductus arteriosus directs blood flow from the aorta to the pulmonary artery

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 11

Concerning the foetal circulation:

(i) the ductus arteriosus carries blood to the inferior vena cava.

(ii) the oxygenated blood is carried from the placenta of the embryo/foetus to the umbilical vein.

(iii) the umbilical vein regresses to form the medial umbilical ligaments.

(iv) the ductus arteriosus allows the blood to bypass the pulmonary circuit in the foetus

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 12

Concerning the effect of oestrogen deficiency on bone remodeling:

(i) osteoclastic resorption is relatively rapid, osteoblastic replacement of bone may take up to 3 months in adult humans, creating a temporary bone deficit called the remodelling space.

(ii) oestrogen deficiency also stimulates osteoclast apoptosis.

(iii) both osteoblast and osteoclast numbers increase with oestrogen deficiency.

(iv) the average lifespan of an osteoblast is 12 days, while the osteoclast lifespan varies from a few days to 100 days.

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 13

Concerning ageing of the muscular system:

(i) an increased sedentary lifestyle with age results in a decrease in muscle mass, known as sarcopenia.

(ii) with reduced diameters, the muscle fibres have a decreased ability to produce ATP and therefore have reduced ability to produce force and fatigue quickly.

(iii) the rate of sarcopenic muscle loss can be controlled by the level of activity and exercise of the individual.

(iv) motoneuron number and calcium ion release from the sarcoplasmic reticulum increases with age resulting in less fine control of movements and diminished muscle force production

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 14

Concerning the development of the axial skeleton:

(i) cells of the sclerotome migrate to surround the neural tube and form the spinal chord.

(ii) the epimere differentiates into the myotome and hypomere.

(iii) the notochord persists in the intervertebral disks as the nucleus pulposus, but degenerates in the bodies of the vertebrae.

(iv) the epimere forms the superficial muscles of the back

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 15

Concerning spina bifida:

(i) myeloschisis is classified as a neural tube defect

(ii) occulta is the most severe form of Spina Bifida

(iii) meningocele contains nervous tissue, cerebrospinal fluid and meninges

(iv) it is a result from failed fusion of the chondrification centres of the right and left hemiarches of vertebral column

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 16

Concerning the mechanistic steps that lead to changes in osteological activity:

(i) mechanochemical transduction of signal: mechanical detection results in mechanochemical transduction in osteocytes.

(ii) cell-to-cell signalling: signal transferred through osteocyte network via canalicular network through intracellular transport of signalling molecules such as prostaglandins, RANKL and sclerostin.

(iii) effector cell response: signal received by effector cell (osteoblasts and bone lining cells) leading to production of osteoregulatory factors that affect bone remodelling/bone function.

(iv) effector cell down-regulation: increase in follicle stimulating hormone following the production of osteoregulatory factors causes the downregulation of osteoblasts to inhibit any opportunity for overproliferation.

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 17

Concerning bone adaptation:

(i) Wolff’s law states that bone resorption precedes bone formation.

(ii) It is easier to lose bone mass than it is to gain it.

(iii) Bone adapts only when loads are increased above the minimum effective strain.

(iv) In the mechanostat theory the physiological range in the level of loading that the bones are accustomed to, where no change in bone mass will occur.

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 18

Concerning the Zona pellucida:

(i) it is a protective layer of the spermatozoa.

(ii) hatching is when the blastocyst ovulates.

(iii) it secrets degradative enzymes.

(iv) it prevents premature implantation and polyspermy.

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 19

Concerning fertilisation:

(i) it typically occurs in the isthmus.

(ii) it can occur outside the female reproductive tract.

(iii) it involves the fusion of a spermatozoa with an ovum.

(iv) it occurs before ovulation

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 20

Concerning implantation of the embryo in the uterus:

(i) it occurs shortly after fertilisation.

(ii) the embryo embeds itself into the uterine lining during implantation.

(iii) implantation typically takes place in the fallopian tube.

(iv) successful implantation is necessary for pregnancy to continue.

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 21

Concerning bone tissue:

(i) osteoblasts are multinucleated.

(ii) formation of bone tissue directly from a condensed mesenchyme is called intramembranous ossification.

(iii) osteocytes are cells that detect mechanical stimuli.

(iv) during endochondral ossification, ossification cannot commence until blood vessels have invaded the cartilage model

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 22

Concerning cartilaginous tissues:

(i) in most cases, they are surrounded by a dense irregular connective tissue membrane called the “perichondrium”.

(ii) they grow by appositional growth mechanisms only.

(iii) there are three subtypes of cartilaginous tissues.

(iv) Chondrocytes are housed in lasoons

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 23

Concerning the articular cartilage’s ability to resist compressive loads:

(i) inter- and intramolecular forces of proteoglycans have shock absorption capacities.

(ii) the Negative charges of glycosaminoglycans repel each other helping to absorb shock.

(iii) the positively charged cations of water molecules are attracted to the negatively charged glycosaminoglycans causing water influx which adds to shock absorbance.

(iv) loading of the joint causes a bounce-back reaction that provides shock absorption

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 24

Concerning the muscle co-operation, an antagonist is defined as:

(i) a muscle that performs the desired action.

(ii) a muscle that antagonises the unwanted action of an agonist that has two or more actions.

(iii) a muscle that opposes the desired action.

(iv) a muscle that antagonises the unwanted action of an agonist that has two or more actions & enhances desired action

KEY: (a) only statements (i) and (iii) are correct
(b) only statements (ii) and (iv) are correct.
(c) only statements (i), (ii) and (iii) are correct
(d) statement (iv) ONLY is correct
(e) ALL statements are correct

Question 25

Concerning ectopic pregnancies: (i) the most common sites for implantation in ectopic pregnancy occurs in the uterine tube and uterine body. (ii) ectopic pregnancies typically occur due to delayed transport of the embryoblast to the uterine body. (iii) the main types of ectopic pregnancies are cervical, abdominal and rectal. (iv) the most common site of implantation within the uterine tube occurs in the ampulla KEY: (a) only statements (i) and (iii) are correct (b) only statements (ii) and (iv) are correct. (c) only statements (i), (ii) and (iii) are correct (d) statement (iv) ONLY is correct (e) ALL statements are correct

Question 26

Concerning the implantation of the embryo: (i) human placental lactogen (hPL) promotes continued production of progesterone from the corpus luteum to maintain endometrial thickness. (ii) the embryoblast is also known as the outer cell mass. (iii) the most optimal location for implantation is the perimetrium of the uterine body. (iv) pre-existing vasculature in the periosteum may be sufficient in some cases for ectopic pregnancies to survive. KEY: (a) only statements (i) and (iii) are correct (b) only statements (ii) and (iv) are correct. (c) only statements (i), (ii) and (iii) are correct (d) statement (iv) ONLY is correct (e) ALL statements are correct

Question 27

Concerning the primitive streak and gastrulation: (i) the primitive streak forms within the epiblast. (ii) the primitive pit and groove allow epiblast cells to form the ectoderm. (iii) gastrulation is the process responsible for converting the bilaminar disc into the trilaminar disc. (iv) the primitive node acts as an organizer in establishing body axes KEY: (a) only statements (i) and (iii) are correct (b) only statements (ii) and (iv) are correct. (c) only statements (i), (ii) and (iii) are correct (d) statement (iv) ONLY is correct (e) ALL statements are correct

Question 28

Concerning cell fate determination and critical periods in embryonic development: (i) it is influenced by signalling molecules secreted by organisers such as the notochord. (ii) the orientation of cells is established through polarisation, defining the cranial and caudal ends. (iii) Situs inversus totalis results from Nodal expression on the left side of the embryo. (iv) changes in the pattern of cardiac looping can lead to dextrocardia KEY: (a) only statements (i) and (iii) are correct (b) only statements (ii) and (iv) are correct. (c) only statements (i), (ii) and (iii) are correct (d) statement (iv) ONLY is correct (e) ALL statements are correct

Question 29

Concerning morphogenesis and embryonic development: (i) the primitive streak is responsible for elongating the epiblast and forms the ectoderm. (ii) gastrulation is a critical process that results in the conversion of the bilaminar disc into the trilaminar disc. (iii) the mesoderm arises from the invagination of epiblast cells through the primitive streak. (iv) the endoderm originates from the epiblast cells that do not migrate through the primitive streak KEY: (a) only statements (i) and (iii) are correct (b) only statements (ii) and (iv) are correct. (c) only statements (i), (ii) and (iii) are correct (d) statement (iv) ONLY is correct (e) ALL statements are correct

Question 30

Concerning the concept of cell fate determination and critical periods in embryological development: (i) cell fate is determined by the polarisation of cells, establishing cranial and caudal orientation. (ii) specific organisers like the notochord secrete signalling molecules that influence morphogenesis. (iii) Situs inversus totalis results from Nodal being expressed on the right side of the embryo. (iv) Dextrocardia is a condition where the heart has a right-sided orientation due to changes in cardiac looping KEY: (a) only statements (i) and (iii) are correct (b) only statements (ii) and (iv) are correct. (c) only statements (i), (ii) and (iii) are correct (d) statement (iv) ONLY is correct (e) ALL statements are correct

Question 31

Concerning the significance of the primitive streak and germ layers: (i) the primitive streak forms within the hypoblast and marks the cranial end of the embryo. (ii) gastrulation is the process by which the embryo transforms from a trilaminar disc to a bilaminar disc. (iii) the endoderm results from epiblast cells that migrate through the primitive pit and groove. (iv) the establishment of body axes is influenced by the primitive node, which acts as an organiser KEY: (a) only statements (i) and (iii) are correct (b) only statements (ii) and (iv) are correct. (c) only statements (i), (ii) and (iii) are correct (d) statement (iv) ONLY is correct (e) ALL statements are correct

Question 32

Concerning Lefty2 INEXPRESSION: (i) Lefty1 would not be expressed. (ii) nodal expression would be contained to the left side of the primitive node. (iii) the neural tube would not form. (iv) nodal expression would cross the midline KEY: (a) only statements (i) and (iii) are correct (b) only statements (ii) and (iv) are correct. (c) only statements (i), (ii) and (iii) are correct (d) statement (iv) ONLY is correct (e) ALL statements are correct

Question 33

Concerning the formation of the primitive streak: (i) it establishes the orientation of the embryo, defining the craniocaudal and longitudinal axes. (ii) it consists of a primitive node, pit, and groove. (iii) it marks the commencement of gastrulation. (iv) it occurs on the surface of the hypoblasts KEY: (a) only statements (i) and (iii) are correct (b) only statements (ii) and (iv) are correct. (c) only statements (i), (ii) and (iii) are correct (d) statement (iv) ONLY is correct (e) ALL statements are correct

Question 34

Concerning the stages in fracture healing: (i) there is soft callous formation (ii) endochondral ossification occurs. (iii) haematoma formation occurs. (iv) there is glycosaminoglycans movement KEY: (a) only statements (i) and (iii) are correct (b) only statements (ii) and (iv) are correct. (c) only statements (i), (ii) and (iii) are correct (d) statement (iv) ONLY is correct (e) ALL statements are correct

Question 35

Concerning the tissue types resulting from high interfragmentary strain: (i) there is formation of hard cartilagenous tissue. (ii) there is no tissue (non-union) formation. (iii) there is formation of lamellar bone tissue. (iv) there is soft fibrous tissue formation KEY: (a) only statements (i) and (iii) are correct (b) only statements (ii) and (iv) are correct. (c) only statements (i), (ii) and (iii) are correct (d) statement (iv) ONLY is correct (e) ALL statements are correct

Question 36

Concerning the functions of an ‘organiser’ in embryological development: (i) they assist in orienting cells through polarisation. (ii) they act on a region of the embryo to induce cell differentiation and cell fate (iii) it directs structure and morphogenesis in surrounding cells to steer the development into specific organs and tissues. (iv) they aid in the formation of the vertebral discs KEY: (a) only statements (i) and (iii) are correct (b) only statements (ii) and (iv) are correct. (c) only statements (i), (ii) and (iii) are correct (d) statement (iv) ONLY is correct (e) ALL statements are correct

Question 37

Concerning the 3rd week of morphogenesis: (i) the Urinary system begins to form. (ii) the Cardiovascular System begins to form. (iii) the Central Nervous System begins to form. (iv) the Reproductive System begins to form KEY: (a) only statements (i) and (iii) are correct (b) only statements (ii) and (iv) are correct. (c) only statements (i), (ii) and (iii) are correct (d) statement (iv) ONLY is correct (e) ALL statements are correct