Q.Choose the correct statement(s) about tenuinucellate ovule

Step 1. Recall the classification basis. Ovules are classed as crassinucellate or tenuinucellate depending on the thickness of the nucellus (the tissue surrounding the embryo sac) and on how the archesporial (sporogenous) cell behaves. In a crassinucellate ovule the hypodermal archesporial cell first cuts off a primary parietal cell (which divides further to build up several nucellar cell layers) before the remaining primary sporogenous cell becomes the megaspore mother cell — giving a thick, multilayered nucellus. In a tenuinucellate ovule, by contrast, the hypodermal archesporial cell functions directly as the megaspore mother cell without cutting off any parietal cell, so the nucellus never builds up extra layers and stays thin (reduced to essentially a single layer besides the epidermis).

Step 2. Evaluate option (a). "Sporogenous cell is hypodermal" — true. The archesporial/sporogenous cell in a tenuinucellate ovule originates from a hypodermal cell (just beneath the epidermis), exactly as in crassinucellate ovules; what differs is that it acts directly as the MMC instead of first producing parietal cells.

Step 3. Evaluate option (b). "Ovules have fairly large nucellus" — false. A fairly large, multilayered nucellus is the hallmark of a CRASSINUCELLATE ovule, the opposite condition to tenuinucellate. …

Compare the defining anatomical features (nucellus thickness and origin of the archesporial/sporogenous cell) of the tenuinucellate …

• Confusing tenuinucellate with crassinucellate and assuming the nucellus is thick/multilayered
• Assuming the sporogenous cell is 'epidermal' because it lies close to the surface, instead of correctly hypodermal …