Question

Life cycle of Ectocarpus and Fucus respectively are
a. Haplodiplontic, Haplontic
b. Haplontic, Diplontic
c. Diplontic, Haplodiplontic
d. Haplodiplontic, Diplontic

Answer 1

Hint: Haplodiplontic means when the genetic material develops from diploid eggs and haploid sperms. Haploid means when there is only one set of single chromosomes. Diploid means when there is a pair of chromosomes each out of the two from each parent.

Complete answer:
Ectocarpus — it undergoes both asexual and sexual reproduction.
The asexual reproduction takes by the biflagellate zoospores. These are produced in sporangia. The unilocular sporangia produces a haploid type of zoospores. The plurilocular sporangia produces diploid types. In case of sexual—

Ectocarpus is mostly anisogamous. It has motile flagellated gametes produced in the plurilocular gametangia. The life cycle of Ectocarpus is Haplodiplontic.

Fucus (rockweed) has a diplontic life cycle. Fucus has dichotomous branches which have heart shaped swollen reproductive tips. These branch ends are called receptacles. These receptacles have a small pore in the centre which is known as ostiole. These bumps are a house for both male and female gametangia. These contain antheridia which resemble small trees. These antheridia secrete sperms.

Oogonia are globular structures which are divided into sections leading to formation of eggs. These sperms fuse with eggs swimming through ostiole leading to a formation of diploid zygote. This zygote is released into the water and fully develops focus over time.

Hence, the correct answer is option (D).

Note: Ectocarpus undergoes both sexual and asexual reproduction. It has a Haplodiplontic life cycle. The fucus has a diplontic life cycle. Both the male and female fuse in the ostiole of the bump.