Question

In Nymphaea, placentation is
A. Basal
B. Apical
C. Parietal
D. Superficial

Answer 1

The female reproductive structure if the plant is called gynoecium. It is made up of one or more carpels that consist of three parts namely- stigma, style and ovary. Each ovary has one or more ovules attached to a flattened, cushion-like placenta.
Placentation is defined as the arrangement of the ovules within the ovary.

Complete answer:
Placentation is of different types namely- marginal, parietal, basal, central and free central etc.
Basal placentation
In this type, the ovary is unilocular and a single ovule is borne at the base of the ovary. For example, sunflowers, rice, wheat, etc. have basal placentation.
Apical placentation
In this type of placentation, the ovules are borne at the apex of the ovary.
Parietal placentation
It is the type of placentation in which the gynoecium is formed by the fusion of two or more carpels by their adjacent margins.
The ovary is unilocular in this case and has two or more longitudinal placenta on the inner wall of the ovary, e.g. Cucurbita, Brassica, etc.
Superficial placentation
In superficial placentation, the gynoecium is multicarpellary syncarpous and a large number of ovules are borne on the walls of the loculi without specific order.
Nymphaea (Water lily) has superficial placentation.
Marginal placentation
It is found in the monocarpellary or each carpel of the multicarpellary apocarpous gynoecium, there is a single placenta that develops along the junction of two fused margins.
Free central
In free central, the ovary is unilocular and the ovules are borne on the axis in the center of the ovary.

Note: Placenta has various functions like-

It transfers nutrients, respiratory gases and water and minerals from maternal tissues to growing embryos.
It also helps in the removal of waste from the embryo.