Question

In the embryo of Pinus , the rosette cells lie
A. Above suspensor cells
B. Between suspensor and embryonal cells
C. Between primary and secondary suspensor cells
D. Between embryonic and apical cells

Answer 1

The rosette cells of the rosette tier are formed in the late stages of development when primary and secondary suspensor cells are formed. The rosette cells help in pushing the embryo into the
nutritive region.

Complete answer: In Pinus , the lowermost tier of the proembryo is known as the embryo tier, and the cells above it is known as suspensor cells or suspensor tier. The elongation of suspensor cells results in the formation of secondary suspensor cells. These secondary suspensor cells push the embryo out of the archegonium into the food-laden tissues of the endosperm. The rosette tier is the third tier from the below. All three tiers make up the embryo of the pinus. The nutritive tier helps in the growth of the embryo because it is a food-laden tissue.
Hence, the correct option is Option A-Above suspensor cells.

Note: In the embryo of Pinus , the rosette tier having four cells is formed above the suspensor tier. It mediates between the suspensor tier and the nutritive tier of the embryo. The primary suspensor cell and the secondary suspensor cell elongate and split longitudinally each carrying an embryonal cell. The suspensor cells help to hold the embryo in a fixed position. In the later stages of development, suspensor cells of the embryo deteriorate.