On the basis of presence or absence of shell, eggs are differentiated into (a)Cleidoic eggs are the type of egg which reptiles and birds lay. It's characteristic is that it is surrounded by water proof shell. (b) Noncleiodic eggs in which shell is absent. Answer : (d)

Meroblastic superficial: Cleavage furrows divide zygote nucleus repeatedly without the division of egg cytoplasm. Example: insects. Answer : (c)

Centrolecithal: Yolk is concentrated in the centre in the centre and the cytoplasm is peripheral. It is seen in insect eggs. Eggs of insects undergo meroblastic superficial cleavage. Meroblastic superficial: Cleavage furrows divide zygote nucleus repeatedly without the division of egg cytoplasm. Answer : (d)

The cleidoic egg is the type of egg which reptiles and birds lay. These eggs have a protective shell, and are laid out of water. Because the eggs are laid on land, internal fertilisation is needed. The young one develops inside the egg. So the development is outside the body of these animals and is called as external development. Answer : (d)

Epiboly: Overgrowth of ectoderm around the endoderm forming region. It occurs in frog where micromeres divide rapidly in the animal half and over the megameres over spread the vegetal half. Other options are example of emboly. Emboly is migration of prospective endodermal and mesodermal cells from the surface into the interior of the embryo. Answer : (a)

Gastrulation: Transformation of the blastocyst into gastrula with primary germ layers by rearrangemnt of the cells is called gastrulation. The primary gut that forms during gastrulation in the developing zygote is known as the archenteron, the gastrocoel or the primitive digestive tube. It develops into the endoderm and mesoderm of an animal. All the option excluding option(b) is correct. Answer : (b)

Braxton Hicks contractions are a tightening in your abdomen that comes and goes. They are contractions of your uterus in preparation for giving birth. They tone the muscles in your uterus and may also help prepare the cervix for birth. Answer : (c)

Holoblastic cleavage(Equal): Cleavage furrows extend completely through the entire length of the egg and bisect it into equal or almost equal sized blastomeres. It is seen in marsupial and placental mammals. Assertion is true. Centrolecithal eggs are seen in insects. Reason is false. Answer : (c)

Amniotes are a clade of tetrapod vertebrates that comprise sauropsids (including reptiles and birds) and synapsids (including mammals). They are distinguished by a membrane (amnion) protecting the embryo and a lack of a larval stage. Answer : (c)

During gastrulation, cells from one region of embryo move to another to take up their future fateful position. In frog, at the onset of gastrulation a great mass migration started to occupy their definite position in the developing embryo. Gastrulation begins with the appearance of a small cleft-like invagination at one side and just above the grey crescent. Epiboly is also seen, and Invagination is a part of emboly. Thus, all the options are correct. Answer : (d)

Answer : (d)

The main difference between morula and blastula is that morula is a spherical mass of blastomeres, which are formed following the splitting of a zygote whereas blastula is an early developmental stage of the embryo, consisting of a spherical layer of cells filled with fluid. Morula is solid cell mass whereas blastula has a hollow structure. Answer : (d)

Early blastocyst consists of inner cell mass and trophoblast. While in late blastocyst, inner cell mass becomes differentiated into epiblast and hypoblast with an amniotic cavity. Both the hypoblast and epiblast form a disc called the embryonic disc. Answer : (b)

Trophoblast secretes a fluid into the interior. It creates a cavity called blastocoel. The primary gut that forms during gastrulation in the developing zygote is known as the archenteron, the gastrocoel or the primitive digestive tube. The gastrulation is followed by neurulation, during which the primordium of nervous system, the neural plate is laid down. Neurulation is a process in which the neural plate bends up and later fuses to form the hollow tube that will eventually differentiate into the brain and the spinal cord of the central nervous system. Answer : (d)

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

The cumulus oophorus, (discus proligerus), is a cluster of cells that surround the oocyte both in the ovarian follicle and after ovulation. In the antral follicle, it may be regarded as an extension of the membrana granulosa. The innermost layer of these cells is the corona radiata. Answer : (c)

The vascular system, also called the circulatory system, is made up of the vessels that carry blood and lymph through the body. Blood circulatory system is erived from mesoderm. Answer : (d)

The egg cell is the largest human cell. It measures from 0.15 to 0.2 mm and is just visible to the naked eye (largest). Morula is a 32-celled structure with size dimensions of 60-85 micrometers (smallest). The blastula has a diameter of about 0.1-0.2 mm and has 200-300 cells which follow rapid cell division i.e. cleavage. The gastrula is an embryo at the stage following the blastula, when it is a hollow cup-shaped structure having three layers of cells. Answer : (c)

Middle ear is derived from endoderm. Answer : (b)

In anatomy, the Eustachian tube, also known as the auditory tube or pharyngotympanic tube, is a tube that links the nasopharynx to the middle ear, of which it is also a part. Middle ear is derived from endoderm. Answer : (c)

Biradial cleavage: When the first three divisions do not cut straight the axis of egg. It is seen ctenophorans. Cnidaria and Ctenophora are two types of phyla composed of coelenterates. Answer : (c)

Brain, spinal cors, cranial and spinal motor nerves constitute nervous sysytem. Nervous system is ectodermal in origin. Answer : (b)

Answer : (b)

Coeloblastula: Blastoderm is formed of a single layer of cells. Blastocoel is present, which is filled with mucopolysacc harides. Example frog, Amphioxus, Echinoderms. Answer : (b)

Brain, spinal cord is derived from ectoderm. Heart and notochord is derived from mesoderm. Answer : (a)

Answer : (b)

The middle part of the sperm is rich in mitochondria and has a very less amount of the cytoplasm that surrounds the mitochondria and known as microplasm. Answer : (b)

The primary gut that forms during gastrulation in the developing zygote is known as the archenteron, the gastrocoel or the primitive digestive tube. It develops into the endoderm and mesoderm of an animal. Internal lining of alimentary canal is lined with endoderm. Answer : (c)

Somatic cell is diploid (2n) in nature. It is given that the number of somatic chromosomes is 40. Seminiferous tubules contain haploid (n) spermatozoa. These spermatozoa are haploid in nature. Answer : (b)

Holoblastic unequal clavage is seen in amphibians. Frog is an example of amphibians. Answer : (b)