25 XMSS Flashcards
(8 cards)
Characteristics of Cyanobacteria
- Photosynthetic prokaryotes,
- oxygenic photosynthesis,
- chlorophyll a,
- live in diverse environments,
- some fix nitrogen (heterocysts),
- can be filamentous, unicellular, or colonial
Cyanobacteria are also known as blue-green algae and play a significant role in aquatic ecosystems.
History of Land Plants
- Evolved from green algae (charophytes) ~470 million years ago;
- began as non-vascular plants;
- vascular plants evolved later;
- seeds and flowers developed over time.
The transition from water to land was a crucial event in plant evolution.
Purpose of Stomata
- Allow gas exchange (CO2 in, O2 out);
- control water loss through transpiration.
Stomata are surrounded by guard cells that regulate their opening and closing.
Function of Xylem
- Transports water and minerals from roots upward;
- provides structural support with lignified cell walls.
Xylem consists of tracheids and vessel elements that facilitate water movement.
Function of Phloem
Transports sugars and nutrients from leaves to the rest of the plant.
Phloem consists of sieve tube elements and companion cells.
Characteristics of Ferns
- Vascular plants;
- reproduce via spores;
- large, divided fronds;
- dominant sporophyte stage;
- require moist environments for reproduction.
Ferns are part of the Pteridophyta division.
Alternation of Generations
Life cycle with two multicellular stages:
* Sporophyte (diploid, makes spores by meiosis) and
* Gametophyte (haploid, makes gametes by mitosis).
This process is crucial in the life cycles of plants, fungi, and some algae.
Characteristics of Charophytes
- Green algae;
- cellulose-rich cell walls;
- chlorophyll a and b;
- similar reproductive traits to land plants;
- mainly freshwater habitats.
Charophytes are considered the closest relatives to land plants.
