Answer : (a)

Answer : (b)

Answer : (b)

The movement of cells in the early embryo that change the shape or form of differentiating cells and tissues. Answer : (b)

Amnion of mammalian embryo is derived from ectoderm and mesoderm. It is one of the extraembryonic membranes which is formed by the amniogenic cells of ectodermal origin on the inner side and somatopleuric extraembryonic mesoderm on outer side. Answer : (c)

Haemoendothelial Placenta: In this type of placenta the chorionic villi looses their epithelium and mesenchymal layers to such a degree that the endothelial wall of the foetal blood vessels remain in contact with the maternal blood. The haemoendothelial placenta is observed in mouse, rat, rabbit, guinea-pig etc. Answer : (d)

Gametogenesis, in embryology, the process by which gametes, or germ cells, are produced in an organism. We call gametogenesis in the male spermatogenesis and it produces spermatozoa. In the female, we call it oogenesis. It results in the formation of ova. Answer : (c)

Heroblastic cleavage: Cleavage furrows extend completely through the entire length of the egg and biesct into equal or almost equal sized blastomeres. Example: Amphioxus, marsupials and placental mammals. Answer : (d)

The membranous labyrinth or endolymphatic labyrinth is the part of the inner ear housed in the osseous labyrinth. It develops from ectoderm. The inner part of the adrenal gland (a small organ on top of each kidney). It also develops from ectoderm. Answer : (a)

Macrolecithal or megalecithal are the eggs of egg laying animals. The eggs contain a very large amount of yolk, e.g., reptiles and birds. Oligolecithal eggs are those eggs in which very small amount of evenly distributed yolk is present, e.g., in many invertebrates. Mesolecithal eggs have comparatively more yolk than the microlecithal eggs. The distribution of yolk is distinctly unequal. The eggs of sharks, ganoid fishes, dipnoi and many amphibians are of this type. Alecithal Egg: When the egg contains no yolk, it is called alecithal egg. Eg. The eggs of eutherian mammals. Answer : (a)

Middle piece of a sperm is a long cylindrical part which lies between the neck and the tail. Axoneme or axial filament of microtubules runs through it. The same is covered by mitochondrial spiral (Nebenkern) of 10-14 turns. Mitochondrial activity helps in providing energy. Answer : (b)

Notochord, heart, blood, muscles and bone are derived from mesoderm. Liver is derived from endoderm. Answer : (b)

any considerable amount of yolk will retard the division, or prevent the complete division, of the fertilized ovum. The amount and distribution of the yolk will therefore determine the type of segmentation. The cleavage can be holoblastic (total or entire cleavage) or meroblastic (partial cleavage). Answer : (a)

The prostate's primary function is to produce the fluid that nourishes and transports sperm (seminal fluid). Answer : (b)

Meroblastic cleavage is called as partial or incomplete cleavage is shown in telolecithal eggs in which yolk is concentrated to one end of the egg. Answer : (c)

Ganglia, sensory cells and neural system is derived from neural crest. Answer : (d)

After the fertilization, the zygote is formed. It undergoes rapid mitotic divisions and the process is known as cleavage. During cleavage the zygote divide from one cell to two cell to four and so on. After the cleavage is completed an 8-16 cell structure is formed that is known as the morula. Morula is a ball like structure that later develops into blastula and so on. Answer : (b)

During gastrulation, the blastomeres move from one place to. another. These cell movements transform the blastula into gastrula. As these movements lead to the formation of a new shape to the. embryo, these movements are called morphogenetic movements. Answer : (c)

During gastrulation, the blastomeres move from one place to. another. These cell movements transform the blastula into gastrula. As these movements lead to the formation of a new shape to the. embryo, these movements are called morphogenetic movements. Answer : (a)

The egg of the frog is mesolecithal as moderate amount of yolk is present. As the yolk is concentrated in the lower part of the egg and the cytoplasm in the upper part, these eggs are moderately telolecithal. Answer : (c)

The eye lens is derived from the ectoderm. Answer : (a)

Vitellogenesis (also known as yolk deposition) is the process of yolk formation via nutrients being deposited in the oocyte, or female germ cell involved in reproduction of lecithotrophic organisms. It takes place in the primary oocyte of the Graafian follicle. This process is regulated by the Vit gene and the major protein is vitellogenin. Answer : (b)

The blastocoel progressively shrinks and eventually disappears, which marks the end of gastrulation. Answer : (a)

In mammals, the blastula is referred to as a blastocyst. The blastocyst contains an embryoblast (or inner cell mass) that will eventually give rise to the definitive structures of the fetus, and a trophoblast which goes on to form the extra-embryonic tissues. Answer : (b)

A placenta in which the chorion is next to the lining of the uterus but does not invade or erode the lining. Epitheliocohorial type of mammalian placenta is observed in cattle, pigs etc. Answer : (d)

Notogenesis is the development of the notochord by epiblasts that form the floor of the amnion cavity. The notochord is a flexible rod and primitive beginning to the backbone. It's development start from third week of gestation period. Answer : (b)

Eggs with abundant yolk concentrated in one hemisphere of the egg are termed telolecithal. This occurs in many invertebrates and in all vertebrates lower than marsupial mammals. Answer : (b)

The blastocoel progressively shrinks and eventually disappears, which marks the end of gastrulation. Answer : (a)

Meroblastic cleavage is the type of cleavage in which the cell divides partially. Meroblastic cleavage takes place in those eggs where the amount of yolk is high, which leads to the partial or incomplete cleavage. It can be discoidal or superficial. It is usually found in monotremes, birds including pigeons, reptiles and certain fishes and arthropods. Answer : (a)

Epidermis of skin and brain is derived from ectoderm. Liver is derived from endoderm. Skeleton is derived from mesoderm. Answer : (a)