botany 2
What does the term 'gymnosperm' literally mean? 'Naked seed' (referring to seeds that develop on the surface of scales or leaves without being enclosed inside a fruit).
How do extant gymnosperms compare to angiosperms in terms of species richness? Gymnosperms have approximately extant species, whereas angiosperms comprise roughly extant species.
What fundamental structural evolution defines the seed plant ovule? A megasporangium (nucellus) enclosed by protective tissue layers called integuments, with a small opening known as the micropyle.
How does the fate of the functional megaspore in seed plants differ from that in seedless vascular plants? In seed plants, the functional megaspore is retained inside the megasporangium and is no longer released into the environment.
What are the ploidy levels of the three main components of a mature gymnosperm seed? "1. Seed coat: Diploid (, derived from maternal sporophyte integument)
2. Stored food supply: Haploid (, female gametophyte tissue)
3. Embryo: Diploid (, new sporophyte generation)"
In seed plants, what structure represents the microspore that has developed into a mature male gametophyte? The pollen grain.
Why is free water no longer required for fertilization in gymnosperms? Pollen grains are transferred directly to the ovule by wind or animals, and pollen tubes deliver sperm directly to the egg.
Which male gametangial structure found in seedless vascular plants is completely lost in gymnosperms and angiosperms? Antheridia.
What is polyembryony in gymnosperm reproduction? The production or presence of multiple embryos within a single seed, occurring because the megagametophyte produces several archegonia.
How does sperm motility differ between Ginkgo/cycads and conifers/gnetophytes? Ginkgo and cycads produce flagellated, motile sperm, whereas conifers and gnetophytes produce non-motile sperm.
What tissues are produced by a bifacial vascular cambium? Secondary xylem (wood) toward the inside and secondary phloem toward the outside.
What type of fossil plant is Pertica varia, and in which geological period did it exist? It is an early Trimerophyte that grew to about tall during the Devonian period.
Why is the extinct genus Archaeopteris classified as a progymnosperm? It produced gymnosperm-like secondary xylem (wood) and a eustele, but reproduced via spores rather than seeds.
What evolutionary role did seed ferns (*Pteridosperms*) serve in plant history? They represented transitional seed plants evolving from progymnosperms toward early true gymnosperms.
What distinctive leaf structure is characteristic of the extinct gymnosperm genus Cordaites? Elongated leaves with secondary xylem and leaf veins running parallel with the long axis of the leaf.
Which extinct Mesozoic gymnosperm group possessed cycad-like leaves, flower-like reproductive structures, and produced the chemical oleanane? Bennettitales.
What are the four extant phyla of gymnosperms? "1. Cycadophyta
2. Ginkgophyta
3. Coniferophyta
4. Gnetophyta"
Which three primary meristems arise directly from the apical meristem? "1. Protoderm
2. Ground meristem
3. Procambium"
Which primary tissue system originates from the protoderm? Epidermis (dermal tissue system).
Which primary tissue types are produced by the ground meristem? Parenchyma, collenchyma, and sclerenchyma (ground tissue system).
Which primary tissues develop from the procambium? Primary xylem and primary phloem (vascular tissue system).
How do apical meristems and lateral meristems differ in their contribution to plant growth? Apical meristems drive primary growth (length/extension), whereas lateral meristems drive secondary growth (girth/girth expansion).
Which secondary tissues are formed by the activity of the vascular cambium? Secondary xylem and secondary phloem.
Which protective secondary tissue is generated by the cork cambium? Periderm.
What are the primary structural characteristics and metabolic functions of parenchyma cells? They are living cells with thin primary cell walls that function in photosynthesis and storage of sugars and starches.
What structural role does collenchyma tissue perform in growing plant organs? It provides flexible structural support to young, growing stems and leaves via unevenly thickened primary cell walls.
What defines the cellular state and wall composition of sclerenchyma tissue at functional maturity? Sclerenchyma cells are dead at functional maturity and feature thick, heavily lignified secondary cell walls.
How do tracheids differ structurally from vessel elements in xylem tissue? Tracheids are tapered cells connected via lateral pits, whereas vessel elements are wider, barrel-shaped cells stacked end-to-end with open perforation plates.
What conducting cells and nucleated helper cells constitute the phloem of angiosperms vs gymnosperms? "1. Angiosperms: Sieve-tube elements associated with companion cells.
2. Gymnosperms: Sieve cells associated with albuminous cells."
How are palisade mesophyll and spongy mesophyll structurally specialized for leaf function? Palisade mesophyll consists of columnar cells packed with chloroplasts for light capture; spongy mesophyll has loose, airy cell arrangements for gas exchange.
What pair of specialized epidermal cells controls gas exchange and water loss through stomata? Guard cells.
During which geological period did angiosperms originate and undergo rapid diversification? Cretaceous period ().
What is the age, geographic discovery location, and habitat of the early fossil angiosperm Archaeofructus? Dated to , discovered in semi-aquatic fossil beds in Northern China.
Which perianth features are notable by their absence in the primitive fossil angiosperm Archaeofructus? It lacks both petals and sepals.
Which genus represents the single sister lineage to all other living flowering plants (basal angiosperm)? Amborella (notably lacking vessel elements in its xylem).
How do monocots and eudicots differ in cotyledon count within the seed embryo? Monocots have one cotyledon; eudicots have two cotyledons.
How does leaf venation typically differ between monocots and eudicots? Monocots display parallel leaf venation, whereas eudicots exhibit reticulate (net-like) venation.
How are stem vascular bundles arranged in monocots versus eudicots? In monocots, vascular bundles are scattered throughout ground tissue; in eudicots, they are arranged in a distinct outer ring.
What distinct pollen grain aperture morphology serves as a major defining synapomorphy for eudicots? Tricolpate pollen (pollen grains featuring three elongate apertures).
What term describes the specialized composite inflorescence (head) of the family Asteraceae? Capitulum.
What is the pappus in Asteraceae flowers, and what is its function? It is a modified calyx (sepals) reduced to bristles or scales that aids in seed dispersal by wind or animals.
In Gametophytic Self-Incompatibility, what enzyme synthesized in the style degrades RNA to block incompatible pollen tubes? S-RNase.
What broad evolutionary trend occurs in the alternation of generations from non-vascular bryophytes to angiosperms? Progressive reduction of the gametophyte generation () alongside increasing dominance and independence of the sporophyte generation ().
What are the four concentric floral whorls ordered from outermost to innermost? "1. Calyx (sepals)
2. Corolla (petals)
3. Androecium (stamens)
4. Gynoecium (carpels/pistil)"
What term is used for flower perianth parts when sepals and petals are structurally identical and non-differentiated? Tepals.
How many cells comprise a mature angiosperm microgametophyte (pollen grain) prior to fertilization? Three cells (one tube cell and two sperm cells).
What is the cell and nuclear count of a standard mature angiosperm megagametophyte (embryo sac)? Seven cells containing eight nuclei (3 antipodal cells, 1 central cell with 2 polar nuclei, 2 synergid cells, and 1 egg cell).
Why is pollination in angiosperms referred to as 'indirect pollination'? Pollen lands on the stigma surface rather than directly on the micropyle or ovule.
In double fertilization, what product is formed by the first sperm fusion event? A diploid zygote (), formed by the fusion of one haploid sperm () with the haploid egg cell ().
In double fertilization, what tissue is formed by triple fusion, and what is its ploidy level? Endosperm (), formed by the fusion of the second haploid sperm () with the two polar nuclei () of the central cell.
What seed structure is formed from the integuments of the ovule post-fertilization? Seed coat.
What plant organ develops directly from the ovary wall following fertilization in angiosperms? Fruit.
Which female gametangial structures present in gymnosperms are completely absent in angiosperms? Archegonia.
In pine needle cross-sections, what tissue immediately surrounds the vascular bundles inside the endodermis? Transfusion tissue.
What characteristic pitting pattern is visible on the secondary xylem tracheids of progymnosperms like Archaeopteris? Pitted tracheids organized in longitudinal groups within the secondary xylem.