Developmental Biology Exam Questions
And Correct Answers (Verified Answers)
Plus Rationales 2025/2026 Q&A
1. Which process converts a fertilized egg into a multicellular
embryo?
A. Gastrulation
B. Cleavage
C. Organogenesis
D. Neurulation
Answer: B. Cleavage
Cleavage is the series of rapid mitotic divisions that transform the
zygote into a multicellular embryo.
2. The fertilized egg is known as a:
A. Blastula
B. Morula
C. Zygote
D. Gastrula
Answer: C. Zygote
The zygote is the single diploid cell formed after fusion of sperm and
egg.
3. The morula stage is characterized by:
A. Formation of germ layers
B. Hollow cavity formation
C. Solid ball of cells
D. Neural tube formation
,Answer: C. Solid ball of cells
The morula is a compact mass of blastomeres formed after several
cleavage divisions.
4. The blastocoel is:
A. The yolk sac
B. Fluid-filled cavity in blastula
C. Neural groove
D. Amniotic cavity
Answer: B. Fluid-filled cavity in blastula
The blastocoel forms during blastulation and creates internal space
for cell migration.
5. Gastrulation results in formation of:
A. Neural tube
B. Three germ layers
C. Limb buds
D. Placenta
Answer: B. Three germ layers
Gastrulation forms ectoderm, mesoderm, and endoderm.
6. Which germ layer forms the nervous system?
A. Endoderm
B. Mesoderm
C. Ectoderm
D. Yolk sac
Answer: C. Ectoderm
The ectoderm gives rise to skin and the nervous system.
,7. The mesoderm gives rise to:
A. Liver
B. Skin
C. Muscle
D. Intestine
Answer: C. Muscle
Mesoderm forms muscle, bone, blood, and connective tissue.
8. The endoderm forms which structure?
A. Brain
B. Heart
C. Lung epithelium
D. Skeleton
Answer: C. Lung epithelium
Endoderm forms epithelial lining of digestive and respiratory systems.
9. Neurulation results in formation of the:
A. Blastula
B. Neural tube
C. Somites
D. Placenta
Answer: B. Neural tube
Neurulation creates the neural tube, precursor to the central nervous
system.
10. Failure of neural tube closure leads to:
, A. Cleft palate
B. Spina bifida
C. Polydactyly
D. Hydrocephalus
Answer: B. Spina bifida
Incomplete closure of the neural tube causes neural tube defects such
as spina bifida.
11. The primitive streak appears during:
A. Cleavage
B. Gastrulation
C. Organogenesis
D. Neurulation
Answer: B. Gastrulation
The primitive streak marks the start of gastrulation and germ layer
formation.
12. Somites give rise to:
A. Brain
B. Skin epidermis
C. Vertebrae
D. Intestine
Answer: C. Vertebrae
Somites differentiate into vertebrae, skeletal muscle, and dermis.
13. The notochord primarily functions to:
A. Form placenta
B. Induce neural tube formation
And Correct Answers (Verified Answers)
Plus Rationales 2025/2026 Q&A
1. Which process converts a fertilized egg into a multicellular
embryo?
A. Gastrulation
B. Cleavage
C. Organogenesis
D. Neurulation
Answer: B. Cleavage
Cleavage is the series of rapid mitotic divisions that transform the
zygote into a multicellular embryo.
2. The fertilized egg is known as a:
A. Blastula
B. Morula
C. Zygote
D. Gastrula
Answer: C. Zygote
The zygote is the single diploid cell formed after fusion of sperm and
egg.
3. The morula stage is characterized by:
A. Formation of germ layers
B. Hollow cavity formation
C. Solid ball of cells
D. Neural tube formation
,Answer: C. Solid ball of cells
The morula is a compact mass of blastomeres formed after several
cleavage divisions.
4. The blastocoel is:
A. The yolk sac
B. Fluid-filled cavity in blastula
C. Neural groove
D. Amniotic cavity
Answer: B. Fluid-filled cavity in blastula
The blastocoel forms during blastulation and creates internal space
for cell migration.
5. Gastrulation results in formation of:
A. Neural tube
B. Three germ layers
C. Limb buds
D. Placenta
Answer: B. Three germ layers
Gastrulation forms ectoderm, mesoderm, and endoderm.
6. Which germ layer forms the nervous system?
A. Endoderm
B. Mesoderm
C. Ectoderm
D. Yolk sac
Answer: C. Ectoderm
The ectoderm gives rise to skin and the nervous system.
,7. The mesoderm gives rise to:
A. Liver
B. Skin
C. Muscle
D. Intestine
Answer: C. Muscle
Mesoderm forms muscle, bone, blood, and connective tissue.
8. The endoderm forms which structure?
A. Brain
B. Heart
C. Lung epithelium
D. Skeleton
Answer: C. Lung epithelium
Endoderm forms epithelial lining of digestive and respiratory systems.
9. Neurulation results in formation of the:
A. Blastula
B. Neural tube
C. Somites
D. Placenta
Answer: B. Neural tube
Neurulation creates the neural tube, precursor to the central nervous
system.
10. Failure of neural tube closure leads to:
, A. Cleft palate
B. Spina bifida
C. Polydactyly
D. Hydrocephalus
Answer: B. Spina bifida
Incomplete closure of the neural tube causes neural tube defects such
as spina bifida.
11. The primitive streak appears during:
A. Cleavage
B. Gastrulation
C. Organogenesis
D. Neurulation
Answer: B. Gastrulation
The primitive streak marks the start of gastrulation and germ layer
formation.
12. Somites give rise to:
A. Brain
B. Skin epidermis
C. Vertebrae
D. Intestine
Answer: C. Vertebrae
Somites differentiate into vertebrae, skeletal muscle, and dermis.
13. The notochord primarily functions to:
A. Form placenta
B. Induce neural tube formation
