L10, bryophytes Flashcards
what are bryophytes?
land plants, no vasculature, no seeds. they were the initial colonizeres of land along with lichen
what are some other characteristics of bryophytes?
they thrive in diverse environments, they significantly contribute to biodiversity and carbon sink, and are sensitive to pollution
what is the morphology of bryophytes?
thalloid structure, small and flat, undifferentiated, not organized into tissues/organs, and lack vasculature and stomata. instead of stomata they have pores
instead of roots, what do bryophytes use?
rhizoids that extend out into the media (soil, earth, water) and uptake nutrients and provide anchoring
due to lack of vasculature, how do bryophytes transport substances?
through the plasmodesmata, more specifically the desmotubule that connects the ER of two adjacent plant cells
what generation stage is dominant in bryophytes?
gametophyte (n) stage - produces gametes (n) that come together to form sporophytes (2n)
explain the life cycle of marchantia
starts with meiosis since it is initially in the gametophyte stage, releasing spores NOT seeds. spores germinate forming gametophytes in which the male gametophyte produces reproductive structure known as antheridia (sperm) and the female produces archegonia (egg)
what is the structure of antheridia (male)?
spherical/elongated, contains a sterile jacket layer of cells and houses spermatogenous cells
what is the structure of archegonia (female)?
flask-shaped, long neck and swollen basal portion, and has a venter that houses a single egg. they also have neck canal cells that produces a passage for entry of sperm as they disappear
during the life cycle of marchantia, what occurs after gametophytes mature?
fertlization - mobile sperm reaches the egg and the two gametes form a 2n zygote
zygote (2n) - after fertilization, zygote remains in archegonium nourished by maternal gametophyte - form of nutrition known as matrotrophy
what are embryophytes?
a multicellular embryo housed within a female gametophyte
what happens after the embryo is formed?
turns into a developing sporophyte that grows inside the calyptra, hanging off the underside of the larger gametophyte plant
the zygote divides by …
mitosis, forming the embryo and then the sporophyte
what is the sporophyte composed of?
a foot, seta/stalk, and a capsule/sporangium
what is the interface between the sporophyte and gametophyte?
the placenta
