Free Growth and Development MCQs with Answers

141. In hen, process of development requires the fertilized eggs to be kept at:

• A. 20°C
• B. 28°C
• C. 32°C
• D. 34°C
• E. 37°C

Explanation: In hen, process of development requires the fertilized eggs to be kept at 37°C.

142. The embryonic stage which contains a fluid-filled "segmentation cavity" is:

• A. Cleavage
• B. Morula
• C. Blastula
• D. Gastrula
• E. Zygote

Explanation: The embryonic stage which contains a fluid-filled "segmentation cavity" is blastula. A blastula is an early stage of embryonic development in animals, following the morula stage. It is characterized by the formation of a fluid-filled cavity called the blastocoel. The blastula represents the next stage of development after the morula, and it is a precursor to the formation of more complex structures, such as the gastrula and, eventually, the embryo.The blastula is a critical developmental stage in the early embryonic development of animals. In some species, the blastula will undergo further changes and invaginate to form a structure called the gastrula, which is the next step in embryonic development and leads to the formation of the three primary germ layers: ectoderm, endoderm, and mesoderm. These germ layers give rise to all the tissues and organs of the developing organism. The specific details of blastula formation can vary among different animal species.

143. The marginal cells of blastoderm lie unseparated from the yolk and form the zone of junction with central region:

• A. Area - opaca
• B. Area pellucida
• C. Area - phellogen
• D. Both A and B
• E. None of these

Explanation: Peripheral part of the blastoderm where the cells lie unseparated from the yolk is termed as area opaca.

144. Rearrangement of cells of the "area pellucida" of blastoderm gives rise to:

• A. Endoderm
• B. Mesoderm
• C. Ectoderm
• D. Both A and B
• E. None of these

Explanation: Rearrangement of cells of the "area pellucida" of blastoderm gives rise to endoderm. The endoderm is one of the three primary germ layers that form during early embryonic development in animals. It is one of the fundamental tissue layers from which various organs and tissues in the body originate. The other two primary germ layers are the ectoderm and the mesoderm.During gastrulation, a process that follows the blastula stage in embryonic development, some cells in the developing embryo migrate inward through the primitive streak and give rise to the endoderm. These cells form an inner layer within the developing embryo.The endoderm plays a crucial role in the formation and development of several vital organs and systems.

145. Number of cells of epiblast pass through the primitive streak, move laterally into the blastocoel to form a new layer of cells, called:

• A. Endoderm
• B. Mesoderm
• C. Ectoderm
• D. Both A and B
• E. None of these

Explanation: Number of cells of epiblast pass through the primitive streak, move laterally into the blastocoel to form a new layer of cells, called mesoderm. The mesoderm is one of the three primary germ layers that form during early embryonic development in animals. The other two primary germ layers are the ectoderm and the endoderm. These three germ layers give rise to the various tissues, organs, and systems of the body.During gastrulation, which follows the blastula stage in embryonic development, some cells in the developing embryo migrate to the middle layer. This middle layer becomes the mesoderm. The mesoderm is situated between the outer ectoderm and the inner endoderm.The mesoderm plays a central role in the development of the body's musculoskeletal system and is crucial for the formation of organs and structures responsible for support, movement, and transport, such as the circulatory system. It also gives rise to connective tissues that support and connect various organs and structures within the body.The mesoderm, in conjunction with the ectoderm and endoderm, is essential for the development of a wide range of tissues and organs during embryogenesis. It is responsible for creating the structural framework of the body and the various systems that allow for movement, circulation, and other essential physiological functions.

146. Ectoderm is formed by the cells of:

• A. Mesoblast
• B. Periblast
• C. Epiblast
• D. Monoblast
• E. None of these

Explanation: Ectoderm is formed by the cells of epiblast. The epiblast is a crucial component of the early embryo, specifically in amniotes, which are a group of vertebrates that includes reptiles, birds, and mammals. The term "epiblast" refers to a specific layer of cells in the developing embryo, and its fate and contributions to the developing organism vary among different species. The epiblast is an upper layer of cells in the developing embryo, situated above another layer called the hypoblast or primitive endoderm.During early embryonic development, the epiblast is primarily responsible for giving rise to the three primary germ layers, which are the ectoderm, mesoderm, and endoderm. These germ layers, in turn, develop into various tissues and organs of the body.The contribution and role of the epiblast can differ among species. For example, in mammals, the epiblast forms the embryo proper and plays a central role in the development of the fetus. In birds and reptiles, the epiblast contributes to the formation of the embryo and extraembryonic structures, such as the amnion and the chorion.

147. The process of formation of neural tube is known as:

• A. Gastrulation
• B. Neurogenesis
• C. Neurulation
• D. Both A and B
• E. None of these

Explanation: The process of formation of neural tube is known as neurulation. Neurulation is a critical early stage in the embryonic development of vertebrates, including humans, where the neural tube is formed. The neural tube is the precursor to the central nervous system, which includes the brain and spinal cord. Neurulation is a complex and highly coordinated process that occurs during the early stages of embryonic development.Neurulation begins after the process of gastrulation, where the three primary germ layers (ectoderm, mesoderm, and endoderm) are formed. In neurulation, the ectoderm gives rise to the neural plate, a flat sheet of cells.Neurulation is a pivotal event in embryonic development because it sets the stage for the formation of the entire central nervous system. Any defects or abnormalities in the process can lead to serious congenital disorders, including neural tube defects (NTDs) such as spina bifida and anencephaly.

148. The process of selection of activation of some genes by a cell, which are not activated by other cells of the embryo is:

• A. Cell Development
• B. Cell Growth
• C. Cell Division
• D. Cell Differentiation
• E. Cell Induction

Explanation: The process of selection of activation of some genes by a cell, which are not activated by other cells of the embryo is cell differentiation. Cell differentiation is the process by which unspecialized or undifferentiated cells undergo changes in gene expression and morphology to become specialized, or "differentiated," cells with specific functions and characteristics. This process is a fundamental aspect of development in multicellular organisms, allowing cells to take on distinct roles within tissues and organs.Cell differentiation plays a central role in the development of complex organisms. During embryonic development, the process of cell differentiation leads to the formation of diverse cell types, tissues, and organs.Differentiated cells form tissues with specific functions. For example, in the nervous system, neurons (nerve cells) differentiate to transmit electrical signals, while in the skin, keratinocytes differentiate to form the protective outer layer.Cell differentiation is closely tied to gene expression. Differentiated cells express specific sets of genes while repressing others. This gene expression pattern determines the cell's structure and function.Cell differentiation is a fundamental concept in biology and is essential for the functioning of complex multicellular organisms. It is a highly regulated and intricate process that has been the focus of extensive research in fields such as developmental biology and regenerative medicine.

149. The grey crescent area is present:

• A. Just below to the point of entrance of sperm nucleus in the ovum
• B. Just above to the point of entrance of sperm nucleus in the ovum
• C. Just opposite to the point of entrance of sperm nucleus in the ovum
• D. Just adjacent to the point of entrance of sperm nucleus in the ovum
• E. All statements are incorrect

Explanation: The grey crescent is a characteristic feature that appears in the fertilized egg of amphibians during a process called cortical rotation. After sperm entry, the cortex of the egg rotates relative to the inner contents of the egg, creating a distinctive crescent-shaped region with a different appearance, often appearing "grey" or lighter in color.The formation of the grey crescent is significant in amphibian development. It marks the establishment of the dorsal-ventral (back-belly) axis, which is crucial for the subsequent development of the embryo. It plays a role in organizing and patterning the embryonic tissues.The grey crescent is essential for the process of gastrulation, during which the single-layered blastula is transformed into a multi-layered structure known as the gastrula. This transformation is a key step in embryonic development and results in the formation of the three primary germ layers: ectoderm, mesoderm, and endoderm.

150. As a result of first cleavage, the zygote divides:

• A. Vertically into two daughter cells
• B. Horizontally into two daughter cells
• C. Obliquely Into two daughter cells
• D. Vertically into four daughter cells
• E. Horizontally into four daughter cells

Explanation: As result of first cleavage, the zygote divides vertically into two daughter cells. In the process of cleavage, which follows fertilization, the zygote undergoes a series of rapid cell divisions. During the first cleavage, the zygote typically divides into two daughter cells. These early cleavages are characterized by rapid, successive rounds of cell division, and the resulting cells are called blastomeres.The first cleavage can be described as a vertical or longitudinal division, resulting in two blastomeres. These blastomeres are initially undifferentiated and have the same genetic material as the original zygote. Over subsequent cleavage divisions, the blastomeres continue to divide and give rise to a multicellular structure called a morula, which eventually develops into a blastocyst in mammals.The blastocyst is a more advanced stage of embryonic development that consists of an outer layer of cells (the trophoblast) and an inner cell mass. The inner cell mass eventually gives rise to the embryo proper, while the trophoblast is involved in the formation of the placenta.