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Protist
A diverse group of eukaryotic organisms that are not plants, animals, or fungi.
Algae
A diverse group of photosynthetic protists.
Green algae
Archaeplastida paraphyletic group, composed of chlorophytes and charophytes.
Which green algae group is more related to the land plants?
Charophytes.
Many characters found in land plants are found in a variety of protist clades, mostly the plant-like protists algae. What are the three characters that land plants have that they only share with charophytes?
Rings of cellulose-synthesizing proteins.
Unique flagellated sperm structure.
Formation of a phragmoplast.
What is a cell wall, what is its function, and what is it made of?
Structure surrounding plant cell membrane and gives the plant structure and rigidity, made of the carb cellulose.
How do the cellulose-synthesizing proteins of land plants and charophytes differ from those in other organisms, like algae?
Noncharophyte algae have linear sets of cellulose-synthesizing proteins, while charophytes and land plants have rings of cellulose-synthesizing proteins.
Phragmoplast
Cell structure forming in late cytokinesis in plants and charophytes, guiding the assembly for the cell plate across the midline of the dividing cell, which later turns into the cell wall.
What are the four challenges when charophytes moved to land? Which were probably the most challenging?
Scarcity of water, lack of overall body support, exposure of light, and predation. The first two were the most challenging.’
What did the challenges that the charophytes face, give rise to? How so?
The land plants. Land plants diversified as adaptations evolved, enabling them to dominate their challenges.
What are land plants also called?
The embryophytes.
What are the SDCs of land plants?
Alternation of generations.
Apical meristems.
Multicellular gametangia.
Multicellular dependent embryos.
Walled spores produced in sporangia.
What does “alternation of generation” mean, and what are the generations that are being referred to?
The plant goes through two different phases or “generations.” The referred generations are the haploid or gametophyte generation and the diploid or sporophyte generation.
What is a meristem? Heck, what are the two apical meristems present in embryophytes?
A meristem is a point of growth. The two meristems are the shoot apical meristem (SAM) and the root apical meristem (RAM).
Formally, what is an apical meristem?
Localized region of cell division at tips of roots and shoots.
Why are spores needed to be walled?
To keep spores from drying out and protect the spores from harsh environments.
What does “multicellular dependent embryo” mean?
Multicellular embryos are dependent on a “mother” plant.
What are 7 typical (not shared) characters of plants?
Autotrophic, making its own food.
Bodies are made of three organ types.
Cell walls made of cellulose.
Storage carb is starch.
Presence of cuticle.
Presence of stomata.
Presence of haplodiplontic life cycle.
What are the three organ types and three tissue types in plants?
Organs: Roots, stem, and leaves.
Tissues: Ground, vascular, dermal.
Haplodiplontic life cycle
Plant life cycle with a haploid generation and a diploid generation, both having different multicellular mature body plans.
Cuticle
Covering consisting of wax and other polymers, helping prevent excessive water loss from the above-ground plant organs, while also providing some protection from microbial attack.
Stomata
Specialized pores supporting photosynthesis by allowing exchange of CO2 and O2 between outside air and plant.
Gametophyte
Multicellular haploid body form of plants producing gametes via mitosis.
Sporophyte
Multicellular diploid body form of plants producing spores via meiosis.
What’s the difference between a spore and gamete?
A spore is a reproductive cell that can grow into a new organism without fusing with another cell. In contrast, gametes are cells that fuse during fertilization.
Sporocyte
Diploid cell that will undergo meiosis to make haploid spores.
Sporangia
Multicellular organs producing spores.
Gametangia
Multicellular organs producing gametes.
Antheridia
Male gametangia, producing sperm to be released into the environment.
Archegonia
Female gametangia, producing eggs to be retained within.
Lignin
A polymer filling spaces between cellulose fibres, strengthening and waterproofing the cell wall, thus providing the plant more rigidity and structural support.
Explain the step-by-step process of the typical plant life cycle.
Fertilization: Gametes (1N) fuse, creating a zygote sporophyte.
Mitosis: Zygote sporophyte undergoes mitosis to grow into a young sporophyte and then into an adult sporophyte.
Sporogenesis and meiosis: Sporophyte produces spores via meiosis from sporocytes.
Germination: Spore grows into gametophyte.
Gametogenesis: Gametophyte produces gametes via mitosis, with the gamete depending on the plant’s gametangium.
When does a spore germinate?
Until ideal conditions are met, such as temp., pH, moisture, daylight, et cetera.
What is another way to describe the gametophyte body plan?
The gametophyte body plan is at a thallus level of organization.
Differentiation
A process through which meristematic cells undergo permanent change to form specialized cells and thus specialized tissues and organs.
Including that thallus level of organization, what are the three ways to describe a gametophyte body plan?
The thallus level of organization.
No vascular tissue.
No waxy cuticle.
Why does the gametophyte generation lack vascular tissue?
It’s small, and it doesn’t need a complex system of tissues.
Why does the gametophyte generation lack a waxy cuticle?
The gametophyte generation is short-lived. Why spend energy on something when you’re gonna die anyways?
Does a sporophyte typically have vascular tissue and cuticles? Why yes or why no?
A typical yes to both! In regards to vascular tissue, they’re bigger than the gametophyte and in need of a complex system of tissues. In regards to the cuticle, they have plant organs.
What are the walls of spores made of? What is its function?
Sporopollenin - a biochemically inert polymer protecting spores from environment.
What are the two types of vascular tissue found in land plants?
Xylem and phloem.
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