Bone replaces cartilage by which of the following processes?

# Bone replaces cartilage by which of the following processes? 

a. Interstitial growth

b. Endochondral development

c. Intramembranous bone formation

d. Membranous bone formation

The correct answer is: B. Endochondral development.

Interstitial growth is growth within the cartilage matrix by each cartilage cell enlarging

and forming matrix around each cell.

Bone replaces cartilage by a process termed endochondral bone development.

Intramembranous bone is formed when collagen fibers of connective tissue organize into closely knit meshwork, and this matrix gradually calcifies into bone.

Intramembranous bone formation is also known as membranous bone formation.

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The cerebral hemispheres develop from which of the following vesicles:

 # The cerebral hemispheres develop from which of the following vesicles? 

a. Forebrain

b. Midbrain

c. Hindbrain

d. Primary brain

The correct answer is a. Forebrain.

 The cerebral hemispheres develop from the forebrain vesicles.

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The first step of mitosis is:

 # The first step of mitosis is which of the following? 

a. Telophase

b. Metaphase

c. Prophase

d. Anaphase 

The correct answer is: C. Prophase.

Prophase is the first step of mitosis in which four structural changes occur.

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Melanoblastoma are derived from:

 # Melanoblastoma are derived from:

A. Basal epidermal cells

B. Neural crest cells

C. Prickle cells of epidermis

D. Somato pleuric mesoderm

The correct answer is B. Neural crest cells.

Melanoblastoma are derived from Neural crest cells.

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Notochord develops in:

 # Notochord develops in:

A. 3rd week

B. 3rd month

C. 6th month

D. 10th month

The correct answer is A. 3rd week.

The notochord arises from axial mesoderm at about 16 days and is completely formed by the beginning of the fourth week. It defines the longitudinal axis of the embryo, determines the orientation of the vertebral column, and persists as the nucleus pulposus of the intervertebral discs.

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Implantation occurs at the stage of:

 # Implantation occurs at the stage of:

A. Zygote

B. Morula

C. Blastocyst

D. Primary villi

The correct answer is C. Blastocyst.

The blastocyst is a structure formed in the early development of mammals. It possesses an inner cell mass (ICM) which subsequently forms the embryo. The outer layer of the blastocyst consists of cells collectively called the trophoblast. This layer surrounds the inner cell mass and a fluid-filled cavity known as the blastocoel. The trophoblast gives rise to the chorion and amnion that surround the embryo.

In humans, blastocyst formation begins about 5 days after fertilization when a fluid-filled cavity opens up in the morula, the early embryonic stage of a ball of 16 cells. The blastocyst has a diameter of about 0.1–0.2 mm and comprises 200–300 cells following rapid cleavage (cell division). About seven days after fertilization, the blastocyst undergoes implantation, embedding into the endometrium of the uterine wall. There it will undergo further developmental processes, including gastrulation. Embedding of the blastocyst into the endometrium requires that it hatches from the zona pellucida, which prevents adherence to the fallopian tube as the pre-embryo makes its way to the uterus.

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AIIMS MDS ENTRANCE PAST QUESTIONS NOV 2010

# An 8 year old child has increased horizontal anterior bone loss with premature loss of deciduous teeth. There is defective cementum and shows excretion of phosphoethanolamine in the urine. The child is suffering from:
A. Hypophosphatasia
B. Vit D resistant rickets
C. Juvenile periodontitis
D. Osteomalacia

# A 9 year old female patient with severe oraL ulceration is suffering with salivation, fever, headache and malaise. The peeling of skin of hand and sole is noted. There is increased tendency for sweating. She is also giving one month history of using a new teething gel available in the market. The most probable diagnosis is:
A. Erosive lichen planus
B. Epidermolysis bullosa
C. Acrodynia
D. Stevens Johnsons syndrome

# A constant feature associated with radicular cyst is:
A. Vital tooth
B. Non vital tooth
C. Both
D. None

# Ehler Danlos syndrome is:
A. Autosomal dominant
B. Autosomal recessive
C. X linked dominant
D. X linked recessive

# Increased monocytic count is seen in typhus and which of the following conditions?
A. SABE
B. Herpes labialis
C. HIV
D. Characteristic parasitic infections

# Monocytes are seen in tuberculosis, monocytic leukemia, typhoid, and:
A. Pernicious anemia
B. Hodgkins lymphoma
C. Parasitic infection
D. Sub acute bacterial endocarditis

# Moth eaten appearance is seen in all EXCEPT:
A. Osteomyelitis
B. Haemorrhagic cyst
C. OKC
D. Osteosarcoma

# Moth eaten appearance is seen in:
A. Chronic osteomyelitis
B. Fibrous dysplasia
C. Multiple myeloma
D. Osteopetrosis

# Radiographs of 40 year old female revealed radiolucent areas around several of her mandibular teeth, all teeth which tested vital on the electric pulp tester. These areas represent:
A. Multiple granulomas
B. Periapical osteofibrosis
C. Chronic Periapical abscess
D. Bone hypoplasias associated with opalescent teeth