Penetration of spermatozoan into the egg at fertilisation triggers metaphase-II in the secondary oocyte. This phenomenon is known as .......

The secondary oocyte is arrested at ..... before fertilisation.

The delivery of a foreign DNA fragment into the fertilised egg with a micropipette is known as ………………… .

Consider the following statements. (i) Polyspermy may bring about fertilisation of egg by more than one male nucleus or the supernumerary sperms may fertilise other components of embryo sac much as synergids or antipodals. (ii) In angiosperms, pollen tube is normally an unbranched structure which ususally persists after fertilisation. (iii) Intine is the inner, pectocellulosic layer of pollen grain wall which is destroyed during acetolysis. (iv) Exine layer of pollen grain comprises of an outer non-sculptured layer sexine and an inner sculptured layer tectum. Which of the following combinations of above given statements is correct ?

Identify the statements as correct or incorrect with explanations for your answer (i) FSH acts on the Leydig cells and stimulates synthesis and secretion of androgens. (ii) The increased level of GnRH acts on the anterior pituitary and stimulates the secretion of gonadotropins, i.e. LH and FSH. (iii) The fully grown primary oocyte completes mitotic division producing two daughter nuclei, i.e. secondary oocyte and first polar body. (iv) Ovum is a rounded, motile cell having abundant cytoplasm called ooplasm and a large nucleus termed as germinal vesicle.

On the basis of the functions mentioned below, identify each one correctly (i) It helps in the movement of spermatozoan in a fluid medium. (ii) It contains hydrolytic enzymes and is used to contact and penetrate the egg during fertilisation.

Double fertilisation in an angiosperms plant means (a) fusion of two egg cells with two male gametes (b) fusion of egg cell twice with male gametes (c) fusion of one male gamete with the egg cell and the other male gamete with the synergid (d) fusion of one male gamete with the egg cell and the other male gamete with secondary nucleus