Question

Group of specialized thickened nucellar cells between embryo sac and chalaza is

• A. Hypostase
• B. Epistase
• C. Tapetum
• D. Endothelium

Answer 1

The correct option is A Hypostase

• In some ovules such as those of Zostera and Umbelliferae, a group of thickened cells is found in the chalazal region just below the embryo sac. It is called hypostase. It helps in the transport of food to embryo sac and also produces enzymes and hormones.
  
• When a group of specialised cells is found in the nucellar region just above the embryo sac, it is called epistage such as in Costus.
  
• Tapetum is a single layer of uninucleate, binucleate or multinucleate cells which surrounds the microspore mother cells in anthers. The cells of tapetum provide various enzymes, hormones, amino acids and other nutritive materials to the dividing microsporocytes.
  
• Endothecium forms the single layer of cells with fibrous thickenings inner to the epidermis of anther. These cells remain thin walled and help in the dehiscence of anther during maturity.
  

Thus, the correct answer is option A.