Question

Cleavage polyembryony occurs in
A)Pinus
B)Mini Cycas
C)Cycas
D)Ephedra

Answer 1

Hint: The process by which more than one embryo is developed from a single fertilised egg is called polyembryony. The cleavage polyembryony commonly occurs in the gymnosperms. The archegonium is fertilised which gives rise to many embryos.

Complete answer:
To solve this question, we must know about the process of cleavage polyembryony.
The cleavage polyembryony commonly occurs in gymnosperms. In case of the coniferous plants, all the four cells of the young embryo develop into four embryos. The three wither off and the one completely develops into a new plant. For example, Pinus.
Cycas- In cycas, the polyembryony is simple in which two adjacent archegonia of the same ovule develops into two embryos.
Ephedra- In this the suspensor tube develops into an embryo which results in formation of many embryos.

There are two types of polyembryony.
True polyembryony- the embryos arise from the embryo sac either through cleavage of the zygote or from synergids and antipodal cells.
False polyembryony- It is the fusion of many nuclei or many embryo sacs developed in the same nucellus.
Rosette polyembryony- It this many embryos develop from the rosette cells.

Hence, the correct answer is option (A)

Note: The polyembryony can be experimentally induced or can occur naturally. In conifers, the simple polyembryony occurs but the pine shows cleavage polyembryony. In humans, the polyembryony leads to identical twins which are very rare.