Secondary spermatocytes are haploid (N) cells that contain half the number of chromosomes. Answer : (c)

In the case of monozygotic twins (derived from one zygote), a zygote divides into two separate cells (embryos) at the first cleavage division. Monozygotic twins can also develop from two inner cell masses. A rare occurrence is the division of a single inner cells mass giving rise to twins. Answer : (c)

Ovum acquires polarity as two poles become distinct. Since nucleus is present at animal pole, this is where sperm penetrates ovum and sperm's nucleus fuses with the nucleus of the ovum to form a zygote. Animal pole the active, formative part of an ovum. It contains the nucleus and the bulk of the cytoplasm and is the site where the polar bodies form. In mammals, the animal pole is also the site where the inner cell mass develops and gives rise to germ layers. Also called germinal pole. the correct answer is 'Animal pole'. Answer : (a)

The trophoblast will give rise to extra-embryonic structures, notably the chorion, which is the fetal part of the placenta. The inner cell mass will give rise to the embryo. Answer : (b)

Human embryogenesis is the process of cell division and cellular differentiation of the embryo that occurs during the early stages of development and does not affect the size of fertilized egg. Answer : (b)

A Sertoli cell is a "nurse" cell of the testicles that is part of a seminiferous tubule and helps in the process of spermatogenesis; that is, the production of sperm. Its main function is to nourish the developing sperm cells through the stages of spermatogenesis Answer : (b)

The oocyte that arises from the oogonium via the process of oocytogenesis, and gives rise to secondary oocyte and polar body after first meiotic division (meiosis I). Answer : (b)

polar bodies don't last too long, and the second polar body which forms as the result of meiosis II, extrude only after fertilisation. The secondary oocyte is arrested in metaphase II until it becomes fertilised, so meiosis II can only by completed after ovulation and fertilisation (see e.g. UNSW Embryology: Meiosis at https://embryology.med.unsw.edu.au). Expanation is provided by kanishka Answer : (b)

Germinal epithelium is also known as the wall of the seminiferous tubule within the testes. The seminiferous tubules are the site of the germination, maturation, and transportation of the sperm cells within the male testes. Seminiferous tubules are made up of columnar Sertoli cells surrounded by spermatogenic cells on the epithelial interior and stem cells exteriorly The lining of seminiferous tubules is formed by a single layered germinal epithelium. The epithelium has two types of cells, spermatogenic ( primary germ cells) and sertoli cells ( supporting cells), Spermatogenic cells form 4-8 layers. The cells are destined to undergo spermatogenesis and form supermatozoa. Answer : (d)