Question

Which of the following is the wrong statement?
A. Isogametes are similar in structure, function, and behaviour.
B. Anisogametes differ either in structure, function, or behaviour.
C. In oomycetes, the female gamete is smaller and motile, while the male gamete is larger and non-motile.
D. Chlamydomonas exhibits both isogamy and anisogamy and Fucus shows oogamy.

Answer 1

Isogamy is a sexual reproduction involving the fusion of similar gametes called isogametes. Anisogametes are gametes opposite to isogametes. These gametes are opposite to each other. Oomycetes are water mould species. They reproduce sexually by contact between hyphae and oogonia and Chlamydomonas is an alga that reproduces by both similar and opposite gametes. Fucus is also an alga that reproduces by fusion of motile male and non-motile female gametes.

Complete answer: Oomycetes are fungus-like eukaryotic microbes. They reproduce both sexually and asexually. They include many pathogenic species of plants. For example, the blight of potato, sudden oak death, etc. Oomycetes produce two different types of spores. The female gametes are large and non-motile in sexual spores. On the other hand, the male spore or gamete is motile and small in size.
a) Isogametes are gametes that have similar morphology and physiology. Isogamy is a type of sexual reproduction that involves isogametes fusion. The isogametes have similar structure, function, and behaviour. Many algal and fungal species exhibit isogamy. Such gametes are found generally in lower or primitive types of organisms.
b) Anisogametes are opposite of isogametes. These are morphologically as well as physiologically distinctive. Anisogametes are usually represented by female gametes being quite large and have a very different appearance than the male gamete. The anisogametes differ greatly in structure, function, and behaviour.
d) Chlamydomonas and Fucus are both algae species. Chlamydomonas reproduces both sexually and asexually. Sexual reproduction takes place by isogamy as well as anisogamy. In Fucus , the male gamete is small and the motile and female gamete is the opposite.
Therefore, the right answer is option C.

Note: Oomycetes are filamentous, absorptive organisms that are microscopic in nature. These fungus-like organisms can undergo both types of lifestyles including saprophytic and pathogenic lifestyles. The main reproduction is through asexual self-motile spores that are termed as zoospores. sexual spores are translucent and spherical. Also, these are double-walled cells that can survive harsh environmental conditions.