Question

Placentation in tomato and lemon is
Option A- Parietal
Option B- Marginal
Option C- Free central
Option D- Axile

Answer 1

Placentation is defined as the arrangement of the ovules in the ovary of the plant. The arrangement of placentation varies in different plants differently. The function of placentation is to help in the transportation of the nutrients, water, gases from mother to the developing embryo.

Complete answer:
As we know clearly about placenta in mammals specially human beings, in the same way placentation is found in plants also. Basically it is the arrangement of the ovules in the ovary of the plant. Placentation has various arrangements like; axile placentation, marginal placentation, parietal placentation, basal placentation and superficial placentation.

Option A- Parietal Placentation: This is found in unilocular ovary as in cucumber. It is multi carpellary and carpels are fused by their margins. The placenta develops where fusion of two carpels takes place. This is parietal placentation present in cucumbers.

Option B- Marginal Placentation: This type of placentation occurs in monocarpellary plants where ovules are arranged along the junction of two margins of the carpel. For example- Fabaceae.

Option C- Free central placentation: This resembles the axile placentation in that the column is not connected by partitions to the ovary wall and hence formation of locules occurs. For example- Dianthus.

Option D- Axile placentation: This is seen in multi carpellary or bi carpellary ovary. These carpels walls meet in the centre of the ovary and ovules attached to the centre of the placenta in each locule like in lemon and tomato as these are multilocular plants.

So our correct answer is Option D- Axile Placentation.

Note: There are basal placentation as well as superficial placentation also. In basal there is bicarpellary syncarpous. The placenta develops directly and a single ovary at the base of ovule is present whereas in superficial placentation ovules are attached on the inner surface of the partition wall for example in Nymphaeaceae.