Modern Assisting14thEdition
Editors :
**
Jeffrey R. Smith & Debbie S. Robinson
** ** ** ** ** **
,Chapter 1. Oral Embryology and Histology
** ** ** ** **
1. Which of the following is the process by which the cells of the fertilized egg divide and
** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** **
form a ball of cells during embryonic development?
** ** ** ** ** ** **
A. Cleavage
B. Differentiation
C. Organogenesis
D. Implantation
Answer: A. Cleavage ** **
Rationale: Cleavage is the series of rapid mitotic divisions that occur after fertilization, le
** ** ** ** ** ** ** ** ** ** ** ** **
ading to the formation of a ball of cells known as the morula.
** ** ** ** ** ** ** ** ** ** ** **
DIF: Easy **
TOP: Embryonic development** ** **
MSC: Multiple Choice ** **
2. During the first week of embryonic development, the fertilized egg becomes a structure
** ** ** ** ** ** ** ** ** ** ** ** **
called a: **
A. Zygote
B. Blastocyst
C. Morula
D. Embryo
Answer: B. Blastocyst ** **
Rationale: After fertilization and cleavage, the ball of cells (morula) forms into a blastocy
** ** ** ** ** ** ** ** ** ** ** ** **
st, which implants into the uterine wall.
** ** ** ** ** **
DIF: Easy **
TOP: Embryonic development** ** **
MSC: Multiple Choice ** **
3. The oral cavity begins to develop during which of the following stages of embryonic
** ** ** ** ** ** ** ** ** ** ** ** ** **
development?
A. Zygote
B. Fetal
C. Pre-implantation
D. Embryonic
Answer: D. Embryonic ** **
Rationale: The development of the oral cavity starts during the embryonic stage, around t
** ** ** ** ** ** ** ** ** ** ** ** **
he third week of pregnancy, as the facial structures begin to form.
** ** ** ** ** ** ** ** ** ** **
DIF: Moderate **
TOP: Oral cavity development
** ** ** **
MSC: Multiple Choice ** **
4. The process by which the neural tube forms and begins to develop into the brain and
** ** ** ** ** ** ** ** ** ** ** ** ** ** ** **
spinal cord is known as: ** ** ** **
A. Gastrulation
B. Neurulation
C. Cleavage
D. Organogenesis
, Answer: B. Neurulation ** **
Rationale: Neurulation is the process where the neural tube forms, which later gives rise t
** ** ** ** ** ** ** ** ** ** ** ** ** **
o the central nervous system (brain and spinal cord).
** ** ** ** ** ** ** **
DIF: Moderate **
TOP: Neural development MS** ** **
C: Multiple Choice
** **
5. Which of the following is the primary function of the mesoderm layer in embryonic
** ** ** ** ** ** ** ** ** ** ** ** ** **
development?
A. Formation of the nervous system ** ** ** **
B. Development of the skin and hair ** ** ** ** **
C. Formation of muscles, bones, and circulatory systems ** ** ** ** ** **
D. Formation of the digestive system ** ** ** **
Answer: C. Formation of muscles, bones, and circulatory systems
** ** ** ** ** ** ** **
Rationale: The mesoderm layer gives rise to structures such as muscles, bones, and the circulat
** ** ** ** ** ** ** ** ** ** ** ** ** **
ory system during embryonic development.
** ** ** **
DIF: Moderate TO ** **
P: Germ layers
** **
MSC: Multiple Choice ** **
6. The term "histology" refers to the study of:
** ** ** ** ** ** **
A. The structure and function of tissues
** ** ** ** **
B. The development of organs ** ** **
C. The structure of cells ** ** **
D. The development of embryos ** ** **
Answer: A. The structure and function of tissues** ** ** ** ** ** **
Rationale: Histology is the study of tissues, including their structure and function, and the
** ** ** ** ** ** ** ** ** ** ** ** **
ir role in the body.
** ** ** **
DIF: Easy TO ** * *
P: Histology
**
MSC: Multiple Choice ** **
7. The enamel of the tooth is derived from which embryonic tissue?
** ** ** ** ** ** ** ** ** **
A. Ectoderm
B. Mesoderm
C. Endoderm
D. Neural crest **
Answer: A. Ectoderm ** **
Rationale: Enamel, the hard outer surface of the tooth, develops from the ectodermal laye
** ** ** ** ** ** ** ** ** ** ** ** **
r of the embryo.
** ** **
DIF: Moderate **
TOP: Tooth development MSC** ** **
: Multiple Choice
** **
8. The development of the face and oral cavity during embryonic development involves
** ** ** ** ** ** ** ** ** ** ** **
fusion of which structures? ** ** **
A. Palatal shelves **
B. Maxillary and mandibular processes ** ** **
C. Frontal nasal process ** **
D. Both B and C ** ** **
, Answer: D. Both B and C ** ** ** ** **
Rationale: The development of the face and oral cavity involves the fusion of the maxilla
** ** ** ** ** ** ** ** ** ** ** ** ** **
ry and mandibular processes, as well as the frontal nasal process.
** ** ** ** ** ** ** ** ** **
DIF: Moderate **
TOP: Facial development MSC ** ** **
: Multiple Choice
** **
9. Which structure is responsible for the formation of the teeth during embryonic
** ** ** ** ** ** ** ** ** ** ** **
development?
A. Neural crest **
B. Ectoderm
C. Mesoderm
D. Endoderm
Answer: A. Neural crest ** ** **
Rationale: The neural crest cells play a crucial role in the formation of the teeth during embryo
** ** ** ** ** ** ** ** ** ** ** ** ** ** ** **
nic development.
**
DIF: Moderate **
TOP: Tooth formation ** ** *
*MSC: Multiple Choic ** **
e
10. The first indication of tooth development occurs during which week of embryonic
** ** ** ** ** ** ** ** ** ** ** **
development?
A. 2nd week **
B. 5th week **
C. 6th week **
D. 7th week **
Answer: C. 6th week ** ** **
Rationale: The first indication of tooth development appears during the 6th week of embr
** ** ** ** ** ** ** ** ** ** ** ** **
yonic development, when the dental lamina forms.
** ** ** ** ** **
DIF: Moderate **
TOP: Tooth development MSC ** ** **
: Multiple Choice
** **
11. The process of ossification refers to:
** ** ** ** **
A. The formation of blood cells ** ** ** **
B. The formation of bone ** ** **
C. The development of the skin ** ** ** **
D. The development of the digestive system
** ** ** ** **
Answer: B. The formation of bone ** ** ** ** **
Rationale: Ossification is the process by which bone tissue is formed from cartilage or ot
** ** ** ** ** ** ** ** ** ** ** ** ** **
her connective tissue.
** **
DIF: Moderate **
TOP: Bone development ** ** **
MSC: Multiple Choice ** **
12. Which of the following is a key feature of the histological structure of enamel?
** ** ** ** ** ** ** ** ** ** ** ** **
A. It is composed of collagen fibers
** ** ** ** **
B. It is avascular and has no living cells
** ** ** ** ** ** **
C. It contains many blood vessels
** ** ** **
D. It has a high content of water
** ** ** ** ** **