Question

In an angiosperm the free nuclear division takes place during the formation of which of the following ?
1. Gametes
2. Flower
3. Endosperm
4. Embryo

Answer 1

Correct Answer - Option 3 : Endosperm

Concept: 

• The endosperm is the food-laden tissue formed during the development of angiospermous seed which provides essential nutrients to the growing embryo and also to the young seedling at the time of seed germination. 
• In angiosperms, the endosperm develops from a triploid (3n) primary endosperm nucleus which is formed as a result of the fusion of a male gamete with the secondary nucleus of the central cell.
• Based on the first and subsequent divisions of the primary endosperm nucleus, the endosperm is of three types nuclear, cellular and helobial.

Explanation:

• In the nuclear type of endosperm development, the primary endosperm nucleus divides by repeated free nuclear divisions without the formation of walls.
• It results in the formation of a large number of free nuclei in the central cell of the embryosac. A big central vacuole develops in the embryosac pushing all the nuclei to the peripheral cytoplasm.
• The nuclear endosperm is the most common type of endosperm.

• Gametes are the reproductive cells. There are two types of gametes that are involved in reproduction, the male gamete, and the female gamete.
  Each gamete carries one copy of the chromosome from the respective parents and they combine together to form the fertilized egg called the zygote. 
• The flower is the reproductive organ of plants. It consists of sepals, petals, androecium, and gynoceium.
• Sepals and petals are the accessory appendages while androecium represents the male sex organ and gynoecium the female sex organ.
• The embryo is the result of the fertilization of male and female gamete. Embryo differentiates to form the complete organism