Biology: Oogonium and Antheridium Formation

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Questions and Answers

What is the structure that attaches to the oogonial wall or a nearby cell and germinates into a small filament?

Androspore

Oogonium

Antheridium

Dwarf male plant (correct)

How does the zygote develop after liberation from the oogonial wall?

It undergoes rapid divisions to form multiple cells

It immediately germinates into a mature plant

It fuses with the oogonial wall

It undergoes a resting period before germinating by producing zoospores (correct)

What type of reproduction is characterized by the fusion of identical motile gametes?

Isogamous reproduction (correct)

Heterogamous reproduction

Autocoenobium formation

Vegetative fragmentation

What is the term for a small, filamentous structure that develops from an androspore?

Dwarf male plant Signup and view all the answers

What is the term for the process by which an organism breaks into smaller pieces that can grow into new individuals?

Vegetative fragmentation Signup and view all the answers

What is the term for a spore that is motile and capable of moving towards a fertilization site?

Zoospore Signup and view all the answers

What is the outcome of zygote germination in certain algae?

Four polyhedral cells that produce a mother colony Signup and view all the answers

What is the primary method of asexual reproduction in certain algae?

Formation of autocoenobia Signup and view all the answers

What type of reproduction occurs in certain algae, resulting in the fusion of gametes?

Isogamous reproduction Signup and view all the answers

What is a characteristic of zoospores in certain algae?

They can be biflagellate or quadriflagellate Signup and view all the answers

How do certain algae reproduce vegetatively?

Through fragmentation Signup and view all the answers

What is the shape of the chloroplast in certain algae?

Ring- or girdle-shaped Signup and view all the answers

What is the characteristic of the zygote in the life cycle of Ulothrix?

It is the only diploid phase Signup and view all the answers

What is the characteristic of the zoospores produced by the zygote in Ulothrix?

They are quadriflagellate Signup and view all the answers

What is the term for the gametes in isogamous reproduction?

Isogametes Signup and view all the answers

What is the term for the aplanospores that acquire thick walls and dark pigments in unfavorable environmental conditions?

Hypnospores Signup and view all the answers

What is the mode of vegetative reproduction in Oedogonium?

Fragmentation Signup and view all the answers

What is the characteristic of the filaments in Oedogonium?

They are unbranched and uniseriate Signup and view all the answers

What is the function of the holdfast in Oedogonium?

It attaches the filament to a substratum Signup and view all the answers

What is the term for the residual portions of cells that divide to bring about intercalary growth in Oedogonium?

Caps Signup and view all the answers

Study Notes

Oogonium Formation

Formed by enlargement of a cap cell, becoming spherical and bright orange

Antheridium Formation

Can occur in two ways:
- In macrandrous species, small flattened antheridia are formed by successive rapid divisions of cap cells
- In nannandrous species, antheridia are formed from an antheridial-like cell, releasing swarmer (androspores) that do not fuse with the oogonium

Androspores and Dwarf Male Plant

Androspores are released from an androsporangium and swim towards the oogonium, but do not fuse with it
Instead, they become attached to the oogonial wall or a nearby cell and germinate into small two- or three-celled filaments
The distal end of the filament functions as the antheridium

Zygote Development

Develops a two- or three-layered wall
After liberation, undergoes a resting period before germinating by producing zoospores

Cell Structure

Cells are cylindrical with many nuclei in the peripheral cytoplasm
Chloroplasts are reticulate with pyrenoids

Ulothricales

Order III: Ulothricales
Family: Ulothricaceae
Members found in freshwater, marine, and soil habitats
Algae reproduce vegetatively by fragmentation, asexually by zoospores, aplanospores, or sexually by isogametes or anisogametes

Ulothrix

Unbranched, uniseriate cylindrical filament that grows attached to solid objects
Cells have single chloroplasts that may be ring- or girdle-shaped with one or many pyrenoids
Reproduction:
- Vegetatively through fragmentation
- Asexually by zoospores, aplanospores, or hypnospores
- Sexually by isogametes
- Zoospores are either biflagellate or quadriflagellate

Oedogoniales

Order IV: Oedogoniales
Family: Oedogoniaceae
Only family in this order, comprising three genera: Oedogonium, Bulbochaete, and Oedocladium

Oedogonium

Unbranched, uniseriate filament with uninucleate cells
Occurs in freshwater, attached by means of a basal holdfast as an epilithic or epiphytic alga
Chloroplasts possess many pyrenoids
Nucleus lies in the periphery of the cell
Filaments are polar due to the presence of a holdfast
Reproduction:
- Vegetative: through fragmentation
- Asexual: by zoospores, akinetes, or aplanospores
- Sexual: by oogamy
- Oogonia and antheridia may be on separate filaments (heterothallic) or on the same filament (homothallic)

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Description

This quiz tests your understanding of the formation of oogonium and antheridium in certain species. Learn about the different ways antheridia can occur and the different species that exhibit distinct characteristics.