Correct option is A
The correct answer is (a). The CYCLOIDEA (CYC) and DICHOTOMA (DICH) genes in snapdragons are involved in determining flower symmetry.
CYCLOIDEA is a gene that helps establish bilateral symmetry (zygomorphic) in flowers, and DICHOTOMA also plays a role in the specification of bilateral symmetry in flower development.
Loss-of-function mutations in these genes lead to a loss of bilateral symmetry and result in the transformation of a bilaterally symmetric flower (where the flower is symmetrical along one plane) to a radially symmetric flower (where the flower is symmetrical around a central axis).
This alteration in symmetry occurs because without the function of these genes, the flower adopts a more primitive radial symmetry, a characteristic commonly seen in early-diverging plant species.
Information Booster:
- Bilateral symmetry (zygomorphic symmetry) in flowers is common in the core eudicots, like snapdragons, and is controlled by specific genes such as CYC and DICH.
- Radial symmetry (actinomorphic symmetry) is when parts of the flower are symmetrical along several planes, and is considered the ancestral flower shape.
- CYCLOIDEA (CYC) is involved in controlling the patterning of petals and helps restrict the symmetry to bilateral in snapdragon flowers.
- DICHOTOMA (DICH) acts together with CYC to establish this bilateral symmetry in the upper part of the flower.
- Mutations in either gene disrupt the formation of bilateral symmetry, causing the flower to revert to the radial symmetry that is characteristic of other plant species.
Additional Information:
- (b) Conversion of radially symmetric flower to a bilaterally symmetric flower: Incorrect — Mutations in CYC and DICH result in the opposite, i.e., the conversion of bilateral to radial symmetry, not vice versa.
- (c) Conversion of bisexual flower to a male flower: Incorrect — The loss of CYC and DICH affects flower symmetry, not sex determination in the flower.
- (d) Conversion of bisexual flower to a female flower: Incorrect — Flower sex determination is independent of symmetry and controlled by other genes.
