Q7 of 56 Page 1

State the role of placenta in the development of embryo.

(b) What happens when the egg is not fertilized?

(a) The embryo gets nourishment inside the mother’s body by a disc-like tissue placenta which gets developed between the uterus well and the embryo during the implantation. The nutrients, Oxygen and waste products are exchanged through this tissue.


(b) If the egg is not fertilized, then the thick and soft inner lining along with the dead egg and blood vessels, of uterus gets out of vagina in bleeding form. This process is known as Menstruation. It occurs when sperms are not available in female body.


More from this chapter

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5

Choose from the following:

6C, 8O, 10Ne, 11Na, 14Si


(i) Elements that should be in the same period.


(ii) Elements that should be in the same group. State reason for your selection in each case

 6

An element 'X' belongs to 3rd period and group 17 of the periodic table. State its (i) electronic configuration, (ii) valency. Justify your answer with reasoning.

 8

To construct a ray diagram, we use two light rays which are so chosen that it is easy to know their directions after reflection from the mirror. List these two rays and state the path of these rays after reflection. Use these rays to locate the image of an object placed between centre of curvature and focus of a concave mirror.

 9

(a) Draw a labelled ray diagram to illustrate the dispersion of a narrow beam of white light when it passes through a glass prism.

(b) A star appears slightly higher (above) than its actual position in the sky. Illustrate it with the help of a labelled diagram.