
Concept explainers
To determine: The number of synchronous sets of cell divisions occurred after the first cell division established the embryo and the suspensor.
Introduction: The development of an embryo begins after the fertilization of the egg cell. The pollen tube growing from a pollen grain enters the embryo sac or megagametophyte through the synergid and releases two sperm cells. One out of the two fertilizes the central cell forming zygote and other with polar nuclei resulting in the formation of the endosperm.

Explanation of Solution
The embryogenesis refers to the process taking place after the fertilization of an ovule producing a zygote; the zygote then undergoes repeated divisions to form an embryo. The first cell division leads to the formation of a single row of cells and then begins to divide in different directions.
The cell division produces a three-dimensional ball of cells while the axis of the root and shoot lengthens as cells divide. The zygote is first divided into two cells by the unequal division, and the upper cell is known as vesicular cell, and the lower is the primary embryonal cell. The embryonal cell keeps on dividing to form two more cells while the
Vascular cell remains the same.
After that, suspensor cell is formed, which is 6-18 celled, and the vascular cell remains the same and enlarges to form a four-cell stage and keeps on dividing to form octant (8 celled) and then glomerular embryo (16 celled). The glomerular embryo undergoes repeated division to form a triangular (32 celled), then heart (64 celled) followed by the torpedo and heart-shaped embryo (128 celled). After the first cell division, the embryo undergoes almost six repeated divisions and forms double the number of cells in the previous stage.
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Chapter 40 Solutions
Biology
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