Describe the development of monrospric embryo sac.

Explain the development of a Dicot embryo.

Assertion : The method of development of embryo sac from a single functional megaspore is termed as monosporic development. Reason : In monosporic (Polygonum) type of embryo sac development, usually the megaspore which is situated towards micropylar end remains functional.

Type of development of dicot embryo …………….. .

An embryologist interested in studying the morphogenetic movements in chick embryo, during 3 cells layer stage of the embryo, added some vital stains as embryonic fate markers (embryonic fate markers usually stain the cells and in future development of embryo the stained cells differen tiate into developing organ. Thus the movement of the cell can be traced). He gave the upper layer green colour, middle layer orange and innermost layer blue. a. Name the 3 layers mentioned above. b. Based on your knowledge regarding the development of an embryo predict three organs with these respective colours.

Describe the structure of a typical embryo sac found in flowering plants . Why is it generally referred to as monosporic ?

Assertion : Embryogenesis is the development of embryo from the zygote. Reason : Cell division increase the number of cells in the developing embryo.

During the development of embryo, which of the following occurs first?

Describe the process of development and birth in humans.

In these animals, the female retain the eggs inside its body after fertillisation and allows the development of embryo inside the body without providing extra nourishment ot the developing embryo as the placenta is absent. Such animlas are called as

(A) Draw the embryo sac of a flowering plant and label (i) central cell (ii) chalazal end of the embryo sac and (iii ) synergids. (b) Name the cell that develops into the embryo sac and explain how this cell leads to the formation of embryo sac. Also mention the role played by the various cells of the embryo sac .