Bryophyta Flashcards
What are the three main classes of Bryophyta?
The three main classes are mosses (Bryopsida), liverworts (Hepaticopsida), and hornworts (Anthocerotopsida).
Where are bryophytes commonly found?
Bryophytes are found on damp banks, trees, logs, bare rocks, and frozen alpine slopes.
How do bryophytes absorb water?
Water is absorbed through the surface of the plant as bryophytes lack a vascular system.
What is alternation of generations in bryophytes?
It is the life cycle involving a haploid gametophyte phase that produces gametes and a diploid sporophyte phase that produces spores.
Which phase is dominant in the life cycle of bryophytes?
The gametophyte phase is dominant in bryophytes.
What type of cell wall is found in bryophytes?
Bryophytes have cell walls made of cellulose.
Describe the thallus structure in bryophytes.
Bryophytes are thalloid, with undifferentiated bodies resembling leaves or stems but lacking true roots.
Why do bryophytes require external water for reproduction?
External water facilitates the movement of flagellated sperm to reach the egg in the archegonium.
What are the two main types of liverworts?
Liverworts are categorized into thalloid and leafy liverworts.
What is a notable characteristic of thalloid liverworts?
They have a dorsiventrally flattened thallus and grow prostrate.
How does Marchantia polymorpha reproduce asexually?
It reproduces via gemmae, which are specialized bud-like structures found in gemma cups on the thallus.
What are gemmae, and where are they located?
Gemmae are bud-like propagules found in gemma cups on the thallus surface.
What structures develop male and female sex organs in Marchantia?
Male and female gametangia develop on antheridiophores and archegoniophores, respectively.
What is the role of the seta in Marchantia?
The seta is a stalk that suspends the sporophyte, aiding in spore dispersal.
Describe the process of spore release in liverworts.
The capsule splits open, and elaters twist and untwist to release spores, which are dispersed by wind.
What are elaters, and how do they function in liverworts?
Elaters are hygroscopic cells that help in spore dispersal by twisting and untwisting in response to humidity.
What is the function of the calyptra in bryophytes?
The calyptra is a protective cap that shields the young sporophyte.
How do leafy liverworts differ from thalloid liverworts?
Leafy liverworts have overlapping leaves, while thalloid liverworts have flattened, lobed structures.
Where are leafy liverworts most abundant?
They are abundant in tropical forests.
What is the protonema, and how does it relate to the life cycle of bryophytes?
The protonema is an early gametophyte stage that develops into a mature gametophyte.
Describe the sporophytes of hornworts.
Hornwort sporophytes are elongated, green to black rods that grow from gametophytes.
What is the function of rhizoids in bryophytes?
Rhizoids anchor bryophytes to substrates and aid in nutrient absorption.
How do hornworts reproduce sexually?
Archegonia and antheridia develop under the gametophyte’s upper surface, where fertilization occurs.
What is unique about the chloroplasts in hornwort cells?
Hornwort cells contain one large chloroplast with pyrenoids, similar to green algae.
How do bryophytes reproduce asexually?
They reproduce by fragmentation or through structures like gemmae and tubers.
Which environmental conditions favor bryophyte growth?
Moist, shaded environments with adequate water availability favor bryophyte growth.
What is the significance of pyrenoids in hornwort chloroplasts?
Pyrenoids assist in carbon fixation, enhancing photosynthesis efficiency.
Compare haploid and diploid phases in the bryophyte life cycle.
The haploid gametophyte produces gametes, while the diploid sporophyte generates spores.
How do hydroids and leptoids contribute to bryophyte physiology?
Hydroids conduct water, while leptoids transport nutrients in some bryophytes.
Why are bryophytes considered pioneers in ecological succession?
Bryophytes colonize bare surfaces, aiding in soil formation and facilitating plant succession.
What are the genral characteristics of bryophyta?
