Question

Which one of the following shows isogamy with non-flagellated gametes?
A. Sargassam.
B. Ectocarpus.
C. Ulothrix.
D. Spirogyra.

Answer 1

Hint: Gametes are reproductive cells that result from the parent body, male gametes (sperm) form male and female gametes (ovum) from the female body. The isogamy has represented the form of sexual reproduction in which gametes of similar appearance like shape and size cannot be classified as male and female due to similar appearance.

Complete answer: In sexual reproduction, male and female gametes are formed in different organs of the body of the organism and they are haploid. Both gametes fuse to form diploid cells which form new individuals later.
a) Spirogyra:- It is green algae also known as water silk or blanket weed. It is filamentous and possesses helical chloroplasts. These algae show isogamy and non-flagellated gametes and can reproduce both sexually and asexually. In the sexual mode of reproduction, the conjugation process takes place between two non- flagellated morphologically similar cells.
b) Sargassum:- it is a genus of brown algae that belong to the class of Phaeophyceae which is seaweed, free-floating in shallow water and coral. Here, sexual reproduction shows oogamous and does not possess isogamy.
c) Ectocarpus:- it is also filamentous brown algae, which act a model organism, it reproduces via sexual and asexually by the formation of biflagellate zoospores which are haploid or may be diploid but it shows anisogamy.
d) Ulothrix:- Ulothrix is filamentous non-branching green algae that reproduce sexually and asexually via fragmentation and conjugation process respectively. The gametes that are formed inside the body of the Ulothrix are bi flagellated.
Hence, the correct answer is option D.

Note: Reproduction is a process that gives rise to new young ones which carry hereditary character that is transferred from parent to offspring. Reproduction is of two types such as asexual reproduction, in which not gametes formation and fusion take place newborn are identical to its parent, while, in case of sexual reproduction, gametes are formed and fusion takes place and the newborn carry both characters of the parent.