Question

Ovary is one-chambered but it becomes two-chambered due to the formation of false septum in
A. Brassica
B. Pisum
C. Hibiscus
D. Dianthus

Answer 1

Hint: In flowering plants, the ovary is a female reproductive organ of the flower or gynoecium, which is a basal part of the pistil and contains ovules that further develop into seeds after fertilization. On maturation, the ovary develops into a dry or fleshy fruit.

Complete answer:
 The septum is a thin partition which generally separates two chambers from each other. Chambers usually terms as locules that are located within the ovary of a flower or plant, these locules contain seeds or ovules, and depending upon the number of ovules present in the ovary, the fruits (ripened ovary) can be classified as unilocular, bi-locular, trilocular, etc. These locules or chambers are separated by the septum which modifies it into a one-chambered or two-chambered ovary.
In the Brassicaceae family primarily known as the mustard family, parietal placentation is seen. Placentation refers to the arrangement of ovules within the ovary, and when ovules develop on the inner wall of the ovary it is known as parietal placentation. In brassica, the ovary is superior, syncarpous, bicarpellary, unilocular but due to the formation of the replum which is a thin false septum present in some fruits such as siliques, etc which grows during the dehiscence (it is the splitting at maturity in a plant to release out its content) in the fruit, and it separates the two valves or walls of the fruits from which these valves fall aways at maturity. Therefore, due to the extending of one parietal placenta to another by dividing the ovary cavity into two locules resulting in the formation of a bilocular ovary/two-chambered ovary becomes a characteristic feature of the family Brassicaceae. Plants listed in this family are cabbage, broccoli, common radish, etc.

While in the case of:
Pisum (Family- Fabaceae), gynoecium-monocarpellary, one-chambered ovary with ovules in two series, superior and elongated, and the placentation are marginal.
Hibiscus (Family- Malvaceae), gynoecium- pentacarpellary syncarpous, superior ovary which is pentalobular with axile placentation.
Dianthus (Family- Caryophyllaceae), gynoecium- syncarpous, superior ovary, unilocular with free-central placentation.

Hence, the correct answer is option (A).

Note: Species which are belonging to this Brassicaceae family are usually annual, biennial, or perennial plants. Some of them are dwarf shrubs or shrubs, while a few of them are vines. From an economical view, this family includes important agricultural crops, involving many vegetables (cauliflower, turnip, etc.).