Q.1 Which stage of embryonic development involves the formation of three germ layers?
Zygote
Blastula
Gastrula
Morula
Explanation - During gastrulation, the single-layered blastula reorganizes into a three-layered structure called the gastrula, forming ectoderm, mesoderm, and endoderm.
Correct answer is: Gastrula
Q.2 Which hormone primarily regulates human growth during childhood?
Thyroxine
Insulin
Growth Hormone
Adrenaline
Explanation - Growth Hormone (GH), secreted by the anterior pituitary, stimulates growth of bones and tissues during childhood and adolescence.
Correct answer is: Growth Hormone
Q.3 The cleavage in embryonic development is best described as:
Cell growth
Rapid cell division without growth
Cell differentiation
Organ formation
Explanation - Cleavage involves rapid mitotic divisions of the zygote without an increase in overall size, producing smaller cells called blastomeres.
Correct answer is: Rapid cell division without growth
Q.4 Which structure gives rise to the vertebral column in vertebrates?
Neural tube
Notochord
Somites
Endoderm
Explanation - The notochord, derived from mesoderm, serves as a primitive axial skeleton and induces development of the vertebral column.
Correct answer is: Notochord
Q.5 Which of the following is the primary site of fertilization in humans?
Uterus
Ovary
Fallopian tube
Cervix
Explanation - Fertilization of the ovum by sperm typically occurs in the ampullary region of the fallopian tube.
Correct answer is: Fallopian tube
Q.6 Organogenesis begins during which period of embryonic development?
Cleavage
Gastrulation
Blastulation
Fetal stage
Explanation - Organogenesis starts after gastrulation when the three germ layers differentiate into various tissues and organs.
Correct answer is: Gastrulation
Q.7 Which type of stem cell can give rise to all cell types of the body?
Multipotent
Totipotent
Pluripotent
Unipotent
Explanation - Pluripotent stem cells can differentiate into nearly all cell types of the body but not extraembryonic tissues, unlike totipotent cells.
Correct answer is: Pluripotent
Q.8 Which of the following is a key feature of apoptosis?
Cell division
Programmed cell death
Cell enlargement
Cell migration
Explanation - Apoptosis is a controlled process by which cells die to maintain tissue homeostasis or remove damaged cells.
Correct answer is: Programmed cell death
Q.9 Which part of the embryo develops into the central nervous system?
Endoderm
Ectoderm
Mesoderm
Trophoblast
Explanation - The ectoderm differentiates into the central and peripheral nervous systems as well as the epidermis and sensory organs.
Correct answer is: Ectoderm
Q.10 Which extraembryonic membrane forms the placenta in humans?
Yolk sac
Amnion
Chorion
Allantois
Explanation - The chorion, in association with maternal tissues, contributes to placenta formation, allowing nutrient and gas exchange.
Correct answer is: Chorion
Q.11 Which factor primarily influences metamorphosis in amphibians?
Insulin
Thyroxine
Cortisol
Growth Hormone
Explanation - Thyroxine, secreted by the thyroid gland, regulates the process of metamorphosis, such as the transformation of tadpoles into adult frogs.
Correct answer is: Thyroxine
Q.12 Which phase of the cell cycle is most critical for DNA replication?
G1 phase
S phase
G2 phase
M phase
Explanation - During the S (synthesis) phase, DNA is replicated to ensure that each daughter cell receives an identical set of chromosomes.
Correct answer is: S phase
Q.13 What is the primary function of somites in vertebrate embryos?
Forming the gut
Forming muscles and vertebrae
Neural tube development
Placenta formation
Explanation - Somites are segmented blocks of mesoderm that differentiate into vertebrae, skeletal muscles, and dermis.
Correct answer is: Forming muscles and vertebrae
Q.14 Which type of cell division produces gametes in humans?
Mitosis
Meiosis
Binary fission
Budding
Explanation - Meiosis reduces the chromosome number by half, producing haploid gametes essential for sexual reproduction.
Correct answer is: Meiosis
Q.15 Which growth curve is characteristic of human population growth under ideal conditions?
Exponential
Logistic
Linear
Random
Explanation - Under ideal conditions without limiting factors, populations grow exponentially, as described by the J-shaped curve.
Correct answer is: Exponential
Q.16 The amniotic fluid primarily functions to:
Provide nutrients
Protect the embryo from mechanical shock
Form blood cells
Stimulate cell division
Explanation - Amniotic fluid cushions the developing embryo, allowing free movement and protecting it from physical shocks.
Correct answer is: Protect the embryo from mechanical shock
Q.17 Which process increases cell number during development without increasing individual cell size?
Hypertrophy
Hyperplasia
Differentiation
Apoptosis
Explanation - Hyperplasia is the increase in the number of cells, whereas hypertrophy refers to an increase in cell size.
Correct answer is: Hyperplasia
Q.18 Which structure connects the developing embryo to the maternal blood supply?
Yolk sac
Placenta
Amnion
Allantois
Explanation - The placenta facilitates nutrient, gas, and waste exchange between maternal and fetal blood.
Correct answer is: Placenta
Q.19 Which factor regulates limb development along the anterior-posterior axis?
FGF
SHH
BMP
Wnt
Explanation - Sonic Hedgehog (SHH) protein plays a crucial role in specifying the anterior-posterior patterning of limbs during embryogenesis.
Correct answer is: SHH
Q.20 Which germ layer gives rise to the lining of the digestive tract?
Ectoderm
Endoderm
Mesoderm
Trophoblast
Explanation - The endoderm forms the epithelial lining of the digestive and respiratory tracts, as well as associated glands.
Correct answer is: Endoderm
Q.21 Which is the earliest stage at which organ primordia are visible in the human embryo?
Zygote
Blastocyst
Gastrula
Neurula
Explanation - During the neurula stage, neural tube formation occurs and organ primordia begin to appear.
Correct answer is: Neurula
Q.22 Which growth factor is critical for angiogenesis during development?
VEGF
EGF
FGF
IGF
Explanation - Vascular Endothelial Growth Factor (VEGF) stimulates the formation of new blood vessels during embryonic development and tissue growth.
Correct answer is: VEGF
Q.23 Which type of placentation is characteristic of humans?
Diffuse
Cotyledonary
Discoid
Zonary
Explanation - Humans exhibit discoid placentation where a single disc-shaped area of the chorion interacts with maternal tissues.
Correct answer is: Discoid
Q.24 Which structure is the first to form in vertebrate embryos, serving as a primitive brain and spinal cord?
Neural tube
Notochord
Somite
Blastopore
Explanation - The neural tube, derived from ectoderm, is the precursor of the central nervous system.
Correct answer is: Neural tube
Q.25 Which hormone triggers the onset of labor in humans?
Progesterone
Oxytocin
Prolactin
Estrogen
Explanation - Oxytocin, secreted by the posterior pituitary, stimulates uterine contractions to initiate labor.
Correct answer is: Oxytocin