Assertion (A): In flowering plants, endosperm development precedes embryo development.
Reason (R): The cells of the endosperm are filled with reserve food materials, which are used for the nutrition of the developing embryo.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Both (A) and (R) are true, and (R) is the correct explanation of (A).
After double fertilisation, the primary endosperm cell (triploid) forms the endosperm, and the zygote forms the embryo. These are post-fertilisation events.
Assertion (A): In flowering plants, endosperm development precedes embryo development. — True. A is about the order of the two events. In flowering plants the endosperm starts to develop first, and the embryo develops after it.
Reason (R): The cells of the endosperm are filled with reserve food materials, which are used for the nutrition of the developing embryo. — True. R is about the job of the endosperm. Its cells are filled with reserve food, and this food nourishes the developing embryo.
Why R explains A? A growing embryo needs a steady supply of food. The endosperm is that food store, so it has to be formed before the embryo starts to grow. The book asks why endosperm develops first and answers it with this food role. So R is the correct explanation of A.
NCERT Extract:
Endosperm – “Endosperm development precedes embryo development. … The primary endosperm cell divides repeatedly and forms a triploid endosperm tissue. The cells of this tissue are filled with reserve food materials and are used for the nutrition of the developing embryo. In the most common type of endosperm development, the PEN undergoes successive nuclear divisions to give rise to free nuclei.”