Read the given passage and answer the questions that follow:
Seed is often described as a fertilised ovule. Seeds are formed inside fruits. A seed typically consists of seed coat(s), cotyledon(s) and an embryonal axis. Mature seeds may be albuminous or non-albuminous.
What is the persistent nucellus in the black pepper called?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Perisperm
The nucellus is the tissue of the ovule in which the embryo sac develops. In most seeds it does not survive to maturity. In a few seeds, such as black pepper and beet, remnants of the nucellus stay on in the mature seed. This leftover nucellus is called the perisperm.
Option (1) Pericarp — Incorrect. The pericarp is the wall of the fruit. It develops from the wall of the ovary, so it is not a part of the seed at all.
Option (2) Perisperm — Correct. The perisperm is the residual, persistent nucellus. Black pepper and beet are the book’s examples of seeds that keep it.
Option (3) Integuments — Incorrect. The integuments are the protective layers of the ovule. As the seed forms they harden into the seed coats, so they are not the nucellus.
NCERT Extract:
Seed – “… Albuminous seeds retain a part of endosperm as it is not completely used up during embryo development (e.g., wheat, maize, barley, castor). Occasionally, in some seeds such as black pepper and beet, remnants of nucellus are also persistent. This residual, persistent nucellus is the perisperm. Integuments of ovules harden as tough protective seed coats (Figure 1.15a).”
Seed – “… As ovules mature into seeds, the ovary develops into a fruit, i.e., the transformation of ovules into seeds and ovary into fruit proceeds simultaneously. The wall of the ovary develops into the wall of fruit called pericarp.”