NEET repeatedly tests whether you can tell drupe layers apart without swapping them: in mango's pericarp the mesocarp is the thick, fleshy, edible layer and the endocarp is the hard stony one — but in coconut, also a drupe, the mesocarp is fibrous, not fleshy like mango's. Reach for "coconut mesocarp = fleshy" out of habit and you've matched the wrong species to the wrong texture.
A fruit is the mature, ripened ovary formed after fertilisation; when an ovary develops into a fruit without fertilisation, NCERT calls it parthenocarpic — the ovary still matures, only the fertilisation step is skipped, so parthenocarpy is never "no fruit forms at all." When the pericarp is thick and fleshy it differentiates into an outer epicarp, a middle mesocarp and an inner endocarp, as seen in mango and coconut, both one-seeded drupes from monocarpellary superior ovaries.
After fertilisation, ovules develop into seeds — a seed coat around an embryo made of a radicle, an embryonal axis, and one or two cotyledons. In a dicot seed (gram, pea, bean) the seed coat splits into an outer testa and an inner tegmen, with a hilum scar and a micropyle above it; the two cotyledons are often fleshy food stores. Castor keeps its endosperm at maturity (endospermic); gram, bean and pea don't (non-endospermous) — a distinction NEET tests by naming, not describing.
In a monocot seed such as maize, the seed coat is fused to the fruit wall, the endosperm is bulky and separated from the embryo by a proteinous aleurone layer, and the single, shield-shaped cotyledon is called the scutellum — not "the cotyledon." The plumule sits inside a sheath called the coleoptile, the radicle inside the coleorhiza. Mixing up which sheath belongs to which organ, or calling the scutellum a generic cotyledon, is the second recurring trap here.
Watch-out: "endospermic" describes the mature seed, not the ovule — castor's endosperm survives fertilisation as stored food; gram's does not.