Question

Given figures labelled by A and B represent

| A| B
---|---|---
(1)| Isogametes of Rhizopus| Heterogametes of Fucus
(2)| Isogametes of Cladophora| Heterogametes of Pinus
(3)| Isogametes of Rhizopus| Heterogametes of angiosperms
(4)| Isogametes of Chara| Heterogametes of Synchytrium

Answer 1

Iso means similar. Therefore isogametes means gametes that are similar in size and form to the one that unites during the time of fertilization. No difference is seen in terms of size, sex or structure. Heterogametes do differ in size and form. Hence, they are morphologically dissimilar and so the male and female gametes can be distinguished.

Complete answer:
As the hint suggests, the isogametes are the same in appearance. So, the picture on the left is a depiction of isogamy whereas the picture on right is heterogametic.

1. Isogametes of Rhizopus and Heterogametes of Fucus- Rhizopus is a saprophytic fungus which can grow as filamentous branching hyphae. In oomycetes of Fucus, large non-motile female fuses with motile male gametes. This option is the most suitable one in terms of appearance and the definition as well.

2. Cladophora is reticulated filamentous green algae. In this, the sexual reproduction is isogamous. Pinus looks like a cone and they are the largest genus of conifers.

3. Angiosperms make up the majority of all plants on Earth. They are vascular plants. Their seeds can be found in a flower.

4. Chara is a freshwater green algae which can be found in submerged shallow water. Synchytrium is simple parasitic fungi. It is unicellular in nature.

Therefore option 1 is the most appropriate and correct option.

Note: Rhizopus are cosmopolitan in nature which can be commonly found in soil, decaying fruit and vegetables. Rhizopus has many different species. There are some morphological characteristics like the sporangia diameter, length of rhizoids, shape, size and texture which helps to differentiate each of its species.