40 Questions
What is the first stage in the diploid sporophytic generation?
Zygote
What is the orientation of the first division of the zygote?
Transverse
What gives rise to the Embryo?
Outer cell
What is the function of Elaters in the capsule?
To disperse the spores
How do the spores disperse after leaving the capsule?
By wind
What is the role of bryophytes in ecological restoration?
Pioneer species in succession
What do some mosses indicate about the soil?
All of the above
What can the presence of some mosses in a dry area indicate?
The area receives running water during some part of the year
What is the main role of rhizoids in plants?
Anchorage and absorption
What type of cells are absent in all phases of the gametophytic plant body?
Thick-walled and lignified cells
What is the characteristics of the sporophytic generation?
Short-lived and nutritionally dependent on the gametophyte
What is the function of antheridia and archegonia?
Containing male and female sex cells
What is the result of the fusion of male and female sex cells?
Formation of zygote
What is the term for the asexual reproduction method in liverworts?
Production of gemmae in gemmae cups
What is the term for the structure that develops from the embryo in the sporophytic generation?
Sporophyte
What is the characteristic of the sporophyte in moss?
It is a projecting structure from the gametophytic tissue
What is the purpose of the waxy coating on the surface of the epidermis of the thallus?
To prevent water loss and protect against desiccation
What is the function of the stomata-like structures in bryophytes?
To facilitate gas exchange
Why are the sex organs of bryophytes surrounded by sterile jackets?
To protect them from drying out
What happens to the zygote after fertilization in bryophytes?
It is left inside the archegonium to provide nutrition for sporophyte development
What is the characteristic feature of the life cycle of bryophytes?
Alternation of heteromorphic generations
What is the role of the gametophyte in the life cycle of bryophytes?
It produces gametes
What is the dominant phase in the life cycle of bryophytes?
Gametophyte
What is the characteristic of the gametophyte in primitive or lower forms of bryophytes?
It is undifferentiated, prostrate and thalloid
What is the origin of the name 'bryophyte'?
From 'Bryon' meaning moss and 'Phyton' meaning plant
What is a characteristic of bryophytes that is similar to green algae?
They have chlorophyll a as their primary photosynthetic pigment
What inhibits the development of the gemma in the cup?
Lunularic acid
What is the generation of bryophytes that produces spores?
Sporophyte
What is the primary method of asexual reproduction in hornworts?
Fragmentation
What is the type of reproduction exhibited by bryophytes?
Oogamous (sexual reproduction)
What type of sexual reproduction do hornworts exhibit?
Oogamous
Where can bryophytes be found growing?
In a wide variety of habitats, including cold arctics, hot deserts, and wet rainforests
What is the function of the sterile jacket in the male sex organ?
To protect the fertile cells
What is a characteristic of the gametophyte generation?
It produces male and female sex cells
What is the purpose of the gametophyte generation?
To produce male and female sex cells
What is the shape of the female sex organ in hornworts?
Flask-shaped
What is necessary for fertilization in hornworts?
Water
What is the type of life cycle exhibited by bryophytes?
Alternation of heteromorphic generations
What is the result of the fusion of an antherozoid with an egg in hornworts?
Diploid zygote
What is the role of chemotaxis in fertilization in hornworts?
Attracting antherozoids to the archegonium
Study Notes
Introduction to Bryophytes
- Bryophytes are the simplest and most primitive non-vascular land plants.
- The name "bryophyte" is derived from the words "Bryon" meaning moss and "Phyton" meaning plant.
General Characteristics of Plants
- Bryophytes share common characteristics with green algae, such as:
- Chlorophyll a as the primary photosynthetic pigment
- Chlorophyll b and carotenoids as accessory pigments
- Bryophytes have a well-developed alternation of heteromorphic generations (sporophyte/gametophyte)
Alternation of Generations
- Bryophytes exhibit an alternation of generations, with the gametophyte being the dominant phase
- The sporophyte generation produces spores that germinate into the gametophyte
- The gametophyte generation produces male and female sex cells (gametes) that fuse during sexual reproduction to form a zygote
Habitat
- Bryophytes can be found in a wide variety of habitats, including:
- Different temperatures (cold arctics to hot deserts)
- Elevations (sea-level to mountains)
- Moisture levels (dry deserts to wet rainforests)
- Many bryophytes grow in bogs and marshy areas, while some are epiphytic or epiphyllous
Life Cycle
- The life cycle of bryophytes involves an alternation of generations
- The sporophyte generation produces spores that germinate into the gametophyte
- The gametophyte generation produces male and female sex cells (gametes) that fuse during sexual reproduction to form a zygote
Gametophytic Generation
- The gametophytic generation is the dominant phase in the life cycle
- It is long-lived, green, and fleshy
- In primitive forms, the gametophyte is undifferentiated and thalloid
- In advanced forms, the plant body is erect, differentiated into stem-like axis, lateral appendages (leaf-like structures), and rhizoids (root-like structure)
Sporophytic Generation
- The sporophytic generation is short-lived and completely dependent on the gametophyte
- The sporophyte develops from the embryo and is the first stage in the diploid sporophytic generation
- The sporophyte is differentiated into foot, seta, and capsule
Reproduction
- Bryophytes reproduce both sexually and asexually
- Vegetative reproduction occurs through:
- Fragmentation of thallus
- Production of gemmae in gemmae cups
- Sexual reproduction is oogamous and involves the fusion of male and female sex cells (gametes) to form a zygote
Economic Importance of Bryophytes
- Bryophytes play a crucial role in ecological restoration, as they are pioneers of succession and create conditions that favor the growth of other organisms
- Some bryophytes can be used as biological indicators of soil conditions, such as calcium-rich soils or acidic soils
Learn about the general characteristics of bryophytes, the simplest and most primitive non-vascular land plants. Discover their unique features and importance in the plant kingdom.
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