Question

Pistil is bicarpellary but ovary is unilocular and uniovuled in
A. Lycopersicon
B. Scilla
C. Lepidium
D. Helianthus.

Answer 1

Hint:In Asteraceae, the pistil is bicarpellary, syncarpous, inferior, unilocular with single ovule. That ovule is inverted. Helianthus is a member of the Asteraceae family.

Complete answer:
To answer this question, first, we need to know about different parts of flowers like pistil, ovary etc. The pistil is composed of the ovary, the style, and the stigma. The ovary consists of the growing seeds, and is attached to the pollen-receiving stigma by the style. Flowers commonly consist of a single pistil, but may contain several. Staminate or "male" flowers consist of only stamens and lack pistils entirely. The ovary is usually central to the flower, and supports the other main parts.

In Helianthus, the pistil (female structure) consists of two carpels, which are united to shape a compound ovary with a terminal style. There is commonly a nectar-producing region (nectary) in the form of a minute ring surrounding the style atop the ovary.
The ovary has only one locule (seed cavity), with a single anatropous ovule arising from the base, style simple and long, stigma bifid. The anatropous ovule is a completely inverted ovule which turned back 180° on its stalk. Hence, the pistil is bicarpellary but the ovary is unilocular and uniovuled in Helianthus.

Thus, the correct option is D i.e. Helianthus.

Note: The distinguishing feature of Helianthus is their inflorescence, a kind of specialized, composite flower head or pseudanthium, technically known as a calathium or capitulum that may look superficially like a single flower. The pistil contains two connate carpels. The style has two lobes. Stigmatic tissue may be located in the interior surface or form two lateral lines. The ovary is inferior and has only one ovule, with basal placentation.