Growth & Development in Plants
How does age vary from the innermost to outermost layers of secondary xylem (wood)?
It varies by growth rings, with each respective ring representing one year.
What are rhizomes and their function?
A rhizome is a stem that grows underground and is utilized for vegetative production and storage.
What is a monophyletic group?
A group that includes a common ancestor and all of its descendants.
What is sporopollenin and why is it significant?
Sporopollenin is a durable polymer in spore and pollen walls, protecting against desiccation?
What is a sporocyte?
A diploid cell that undergoes meiosis to produce spores.
Which tissue layer is youngest in the secondary phloem?
The innermost layer.
How is a tuber different from a rhizome?
Tubers are a storage organ and a modified underground stem, while a rhizome is a growing stem.
What is a synapomorphy? What is its importance in phylogeny?
A synapomorphy is a shared trait defining a clade, found only in that monophyletic group.
What is the function of multicellular gametangia?
They protect gametes from drying out with a layer of sterile cells.
What is a strobilus, and what role does it play?
A strobilus is a cluster of reproductive structures at the stem’s tip, producing spores.
How often does a new layer of periderm form?
Once per year, during the growth season.
What is a prop root?
Prop roots stabilize plants, especially those in loose or oversaturated soils or lacking a growing stem.
Chlorophyll b and starch as a carbohydrate.
What adaptation in plants allowed gas exchange while reducing water loss?
Stomata and cuticle
What are homosporous and heterosporous plants (in terms of sporangia)?
Homosporous plants have one sporangium type; heterosporous plants have megasporangia and microsporangia.
Why do growth rings form in wood during secondary growth?
Growth slows or halts in the wintertime and resumes in the spring, which forms visible layers.
What is the difference between a bulb and a corm?
Bulbs store energy in thickened leaves, whereas corms store energy in thickened stems.
What does the presence of mitochondria indicate on the phylogenetic tree?
It marks the origins of eukaryotes.
How did mutualistic associations with fungi help early land plants?
Fungi helped plants absorb essential nutrients from the soil.
What is circinate vernation?
The coiled formation of new fronds in ferns.
What is the difference between earlywood and latewood within a growth ring?
Earlywood is made up of larger, thin-walled tracheid cells with wide lumens (rings) formed in spring, and latewood made up of smaller, thick-walled tracheid cells with narrow lumens (rings) formed during summer or autumn.
What is a cladophyll and phyllode?
A cladophyll is a leaf-like stem for photosynthesis, whereas a phyllode is a leaf-like petiole adapted for photosynthesis.
Which homoplastic trait evolved independently in fungi, heterokonts, and archaeplastida?
Cell walls.
It is due to the fact that they retain and nourish developing embryos within a protective structure made of the tissues of the parent gametophyte, which aids in terrestrial adaptation.
What are the two types of elaters and their roles?
In Equisetophyta, elaters attach to spores for dispersal, while in liverworts, elaters help burst the sporangium. Both respond to moisture.