Suspensor formation in Sagittatia occurs at ............ celled stage.
Correct answer: (d)
Solution: In general, zygote divides into two unequal cells, larger suspensor cell towards micropyle and a smaller embryonal cell towards antipodal region. The suspensor cell undergoes transverse divisions forming 6 to 10 celled long suspensor. The first cell of the suspensor is large and is called as haustorium or vesicular cell. The last cell of suspensor is known as hypophysis. It forms a radicle tip. Whereas in Sagittaria type: the early development of dicot and monocot embryos are similar upto octant stage. Later on the differentiation starts. Suspensor is single celled. The zygote of oospore divides transversely producing a vesicular suspensor cell towards micopylar end and embryo cell towards chalazal end. The embryo divides transversely again into a terminal and a middle cell. The terminal cell divides vertically and transversely into globular embryo. It forms a massive cotyledon and a plumule. Growth of cotyledon pushes the plumule to one side. Remains of second cotyledon occur in some grasses. It is called epiblast. The single cotyledon of monocots is called scutellum.