Question

Crassinucellate ovule has
A. III developed nucellus
B. Partially developed nucellus
C. Well- developed nucellus
D. No nucellus

Answer 1

Hint: Nucellus refers to the central, bulk part of ovule. Depending on the development of the nucellus, the ovules are of various kinds. Crassinucellate ovule, the one in which the archesporium splits into outer parietal cell and inner sporogenous cell, which later becomes the megaspore mother cell. The sporogenous cell is sub-hypodermal because of the development of the parietal cell, which either remains undivided or divides to form parietal tissue.

Complete solution
Option A. III developed nucellus: Nucellus composed of a basal flattened disc or shallow to deeply cup-shaped nucellar pad attenuating distally into a one-cell-thick nuclear membrane that is free or fused to the endotesta or the megagametophyte (Plate III, \[1\] and \[3-6\]). Not a correct option.
Option A is not correct.
Option B. Partially developed nucellus: In Tenuinucellate ovule, the nucellus is partially or poorly developed e.g., Gamopetalae.
Option B is not correct.
Option C. Well-developed nucellus: Crassinucellate ovule possess well developed nucellus. During the early development of the mega sporophyte two or more cell layers are present between the mega sporophyte and the epidermal cells. The mega sporophyte develops into the embryo sac which possesses the egg that, if fertilized and provided with right conditions, will develop into the embryo e.g., Polypetalae and monocots.
Option C is correct.
Option D. No nucellus: Again, the option is incorrect.
Option D is not correct.

Thus Option C is the correct answer

Note:
There is another kind of ovule found, known as “Pseudo-Crassinucellate”, in which the archesporium doesn’t split and the parietal cell is absent. The sporogenous cell is sub-hypodermal due to the development of nucellar tissue by the division of nucellar epidermis.