Question

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 such as synergids or antipodals.
(ii) In angiosperms, pollen tube is normally an unbranched structure which usually 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 given statements is correct?

• A. (i) and (iv)
• B. (i) and (iii)
• C. (ii) and (iii)
• D. (ii) and (iv)

Answer 1

The correct option is B (i) and (iii)

Polyspermy refers to a situation where more than two sperms are released in an embryo sac. This may result because of the formation of more than two sperms in a pollen tube or due to the penetration of an embryo sac by more than one pollen tube. In angiosperms, the pollen tube is normally an unbranched structure which collapses soon after fertilization, the pollen tube may persist for as long as three weeks. Intine is the inner, more or less uniform, pectocellulosic layer of pollen grain wall, which is destroyed during acetolysis. Morphologically, the exine is divisible into two distinct layers: (i) an outer sculptured layer called sexine, and (ii) an inner non-sculptured layer, nexine. The sexine further comprises an internal layer of upright rod-like elements, the columellae(bacula) covered over by a roof-like layer, the tectum. The exine is, thus, typically33-layered consisting of tectum, columella, and nexine. The tectum may be smooth or have various types of processes.

So, the correct answer is '(i) and (iii)'.