Question

A researcher compares two embryos, X and Y.

• Embryo X shows equal division of the zygote, forming two cells that are almost identical in size.
• Embryo Y shows an unequal first division and produces a small apical cell and a large basal cell.

(i) Which embryo is likely to develop into a normal dicot embryo?

(ii) What is the fate of: 

1. Apical cell?
2. Basal cell?

Answer 1

1. Embryo Y.
   In dicots, the zygote divides unevenly in its first division, resulting in a big basal cell and a small apical cell. This pattern is matched by Embryo Y.
2. 1. Apical cell: Goes through additional divisions to create the actual embryo (plumule, radicle, and cotyledons).
   2. Basal cell: Creates the suspensor, which anchors the embryo and forces it into the endosperm for nourishment, by going through transverse divisions.