Question

The root cell of a wheat plant has 42 chromosomes. What would be the number of chromosomes in the synergid cells?
A) 7
B) 14
C) 21
D) 28

Answer 1

Hint: Synergids are associated with the female gametophyte of a flowering plant. Synergids are the two specialised cells which are present in the embryo sac and are present adjacent to the egg cells. These cells guide the entry of the pollen tube in the ovary and also nourishes the ovum. Synergids are haploid.

Complete answer:
The synergids are the part of the egg apparatus. They are present near the micropyle of the embryo sac. These are responsible for the reproduction in angiosperms. The synergids help in the fertilisation. These cells are two in number and are present along with the egg. The pollen grains enter the ovary by the help of the pollen tube. The synergids help the pollen tube to enter the ovary. The pollen tube enters into one of the synergids, breaks and releases the sperm cell during fertilisation. Thus, the synergids help in entering the pollen tube in the embryo sac. They also form a filiform apparatus at the micropylar end. As soon as the pollen tube enters, the tube tip breaks and the sperm cells are released.

The synergids are sterile cells and are haploid in nature. In the case of wheat plants, the total number of chromosomes are 42. As the synergids are haploid, they will have the half number of chromosomes that is 21.

Thus, the correct answer is option ‘C’.

Note:
- Synergids function is to guide the entry of pollen tubes and release of sperm cells.
- After the sperm enters the embryo sac, the fertilisation takes place. The double fertilisation generates the embryo and the endosperm. This leads to the formation of the seed and the fruit.