Botany Chapter on Thallus and Gemmae

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Questions and Answers

What are the cup-shaped structures formed by thallus called?

Gemmae (correct)

Capsules

Follicles

Cortices

How are granular gemmae dispersed to new habitats?

Animal ingestion

Wind

Soil erosion

Raindrops (correct)

What process do gemmae undergo to form new gametophytes?

Binary fission

Cloning

Mitosis (correct)

Meiosis

Which phylum do hornworts belong to?

Anthocerophyta Signup and view all the answers

What is declared about the origin relationships of hornworts?

They are uncertain. Signup and view all the answers

Which statement accurately describes the age of hornwort fossils?

The oldest known fossils date back to the Cretaceous period. Signup and view all the answers

In terms of sophistication, how are hornworts characterized within their phylum?

As the most advanced Signup and view all the answers

Which feature is suggested to be reminiscent of the first land plants in hornworts?

Their reproduction mechanism Signup and view all the answers

What is the maximum diameter of the largest species thallus mentioned?

20 cm Signup and view all the answers

What is the prominent developmental form of the organism described?

Thallus Signup and view all the answers

What adaptation is mentioned for moving to land?

Presence of cuticle Signup and view all the answers

Which of the following accurately describes the gametophyte growth forms?

Either leafy or thallose Signup and view all the answers

What is the most well-known genus mentioned in the content?

Marchantia Signup and view all the answers

What characteristic is true for some species in terms of thallus structure?

Can be structurally differentiated and complex Signup and view all the answers

Which statement about the species present in the content is accurate?

More than 8500 species exist. Signup and view all the answers

What is the significance of thick cell walls mentioned in the content?

They are a sign of adaptation to land. Signup and view all the answers

What is the function of the operculum in the sporophyte?

It protects the developing spores until maturity. Signup and view all the answers

How does the sporophyte obtain nutrients?

From the parent gametophyte. Signup and view all the answers

What is the structure that grows vertically out of the gametophyte?

Sporophyte Signup and view all the answers

What process do spore mother cells undergo to produce spores?

Meiosis. Signup and view all the answers

What type of tissue is relatively small in the sporophyte?

Sporogenous tissue Signup and view all the answers

What happens after spores are released into a suitable environment?

They germinate to form new gametophytes. Signup and view all the answers

What is the shape of the sporophyte in hornworts?

Cylindrical Signup and view all the answers

What defines the phylum Hepatophyta?

It is monophyletic with a common ancestor. Signup and view all the answers

The name 'Hepatophyta' is derived from what resemblance?

Resemblance to human liver. Signup and view all the answers

What unique feature do hornwort cells possess?

A single plastid per cell Signup and view all the answers

How is the sporophyte attached to the gametophyte?

Via a lobed foot Signup and view all the answers

What characterizes the smallest species of liverworts?

They appear as miniature filaments. Signup and view all the answers

The term 'seta' refers to what part of the sporophyte?

The stalk that supports the capsule. Signup and view all the answers

What surrounds the basal foot of the sporophyte?

A collar-like outgrowth of the thallus Signup and view all the answers

Which group of plants is distinguished by having a single chloroplast per cell?

Hornworts Signup and view all the answers

What is the zygote's fate in relation to the sporophyte?

It develops into the sporophyte Signup and view all the answers

What is the role of meristem at the base of the sporophyte?

To allow for continuous growth Signup and view all the answers

What shape does the layer forming at the top of the young sporophyte take during sporangia development?

Dome-shaped Signup and view all the answers

What do multicellular elaters develop from?

Sporogenous mother cells Signup and view all the answers

What is the primary feature that distinguishes the sporophyte from the gametophyte in certain non-vascular phyla?

Sporophyte is semi-independent Signup and view all the answers

What process do mother cells undergo to form haploid spores?

Meiosis Signup and view all the answers

Which of the following structures is found at the center of a sporangium?

Columella Signup and view all the answers

What type of cells do elaters resemble but do not contain in this context?

Spiral thickenings Signup and view all the answers

What characteristic gives the sporophyte an advantage in certain non-vascular phyla?

Longer lifespan compared to gametophyte Signup and view all the answers

Study Notes

Thallus and Gemmae

Thallus forms cup-shaped structures called gemmae.
Granular gemmae are outgrowths of thallus located within gemmae-cups.
Gemmae are dispersed by raindrops to new habitats.

Gemmae Development

Gemmae divide via mitosis to create new gametophytes.

Phylum Anthocerophyta (Hornworts)

Considered one of the most advanced among non-vascular plants due to its sporophyte structure.
Relationships to other plant groups are uncertain, with similarities to original land plants.
Oldest hornwort fossils date back to the Cretaceous period (65-145 million years ago).
Gametophyte is flat, while the sporophyte is linear, growing vertically from the gametophyte.
Diploid zygote develops into a thin, cylindrical sporophyte with a small amount of sporogenous tissue.
Sporophyte is embedded within the parent gametophyte and has a lobed foot surrounded by collar-like thallus outgrowths.
Hornwort cells contain a single chloroplast per cell; pyrenoids are present, resembling those in green algae.

Sporophyte Characteristics

Contains peristome teeth covered by an operculum, which dehisces when spores mature.
The foot of the sporophyte remains embedded in the parent gametophyte, dependent on it for nutrients.
Spore mother cells (2n) undergo meiosis in the sporangium to produce spores.
Spores germinate in suitable environments to form new gametophytes via mitosis.

Phylum Hepatophyta (Liverworts)

A monophyletic phylum derived from a common ancestor, showcasing significant diversity.
Name reflects the superficial resemblance of some liverworts to human liver.
The smallest species has a filament length of 10-5 mm, while the largest species can exceed 20 cm in diameter.
Prominent gametophyte develops a cuticle and thick cell walls, adaptations for terrestrial living.
Over 8,500 species exist, with gametophytes forming either "leafy" or thallose growths.
Marchantia is a well-known genus with a flattened, ribbon-shaped thallus, demonstrating simple or complex structures.
Some species are semi-independent from the gametophyte and are fully photosynthetic.
Sporophyte typically lives longer than the sporophyte of other non-vascular phyla.

Sporophyte Development

Sporangia development starts with a dome-shaped layer in the young sporophyte's topmost part.
Sporophyte growth occurs via continuous intercalary meristem at the base.
The sporangium differentiates into a hollow cylinder with a central column of sterile cells (columella).
Multicellular elaters, known as pseudo-elaters, form between sporogenous mother cells, leading to haploid (n) spores after meiosis.

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Description

Explore the fascinating structures formed by thallus in botany, particularly focusing on cup-shaped gemmae. This quiz delves into the formation and significance of granular gemmae within gemmae-cups. Test your knowledge on these essential plant structures!