Plant Kingdom Flashcards
What types of organisms were previously included in the Plantae kingdom but are now excluded?
Fungi, Monera, and Protista with cell walls.
What are cyanobacteria commonly referred to as, and how has their classification changed?
Cyanobacteria are also called blue-green algae, but they are no longer classified as ‘algae’.
Which plant groups are described under Plantae in this chapter?
Algae, Bryophytes, Pteridophytes, Gymnosperms, and Angiosperms.
What did the earliest systems of classification use to categorize plants?
Gross superficial morphological characters such as habit, color, number, and shape of leaves.
What were some limitations of the early classification systems?
They were artificial, separated closely related species, and gave equal weight to vegetative and sexual characteristics.
What is the basis of natural classification systems?
Natural affinities among organisms, considering both external and internal features.
Who developed a natural classification system for flowering plants?
George Bentham and Joseph Dalton Hooker.
What does phylogenetic classification assume about organisms in the same taxa?
They have a common ancestor.
What role does numerical taxonomy play in classification?
It assigns numbers and codes to observable characteristics, processing data with equal importance given to each character.
What information does cytotaxonomy use for classification?
Cytological information such as chromosome number, structure, and behavior.
What does chemotaxonomy use to resolve classification issues?
Chemical constituents of plants.
What characteristics define algae?
Chlorophyll-bearing, simple, thalloid, autotrophic, and largely aquatic organisms.
Where can algae be found besides aquatic environments?
On moist stones, soils, wood, and in association with fungi and animals
What forms and sizes can algae exhibit?
Colonial forms like Volvox, filamentous forms like Ulothrix and Spirogyra, and massive marine forms like kelps.
How does vegetative reproduction occur in algae?
Through fragmentation, where each fragment develops into a new thallus
What are the types of asexual reproduction in algae?
Production of different types of spores, especially zoospores, which are flagellated and motile.
How does sexual reproduction occur in algae?
Through the fusion of gametes, which can be isogamous, anisogamous, or oogamous.
What is isogamous reproduction in algae?
Fusion of two gametes that are similar in size.
What is anisogamous reproduction in algae?
Fusion of two gametes that are dissimilar in size
What is oogamous reproduction in algae?
Fusion of a large, non-motile female gamete with a smaller, motile male gamete.
How do algae benefit humans?
They fix carbon dioxide, increase dissolved oxygen, serve as primary producers, and provide food and commercial products like algin, carrageen, and agar.
What are the three main classes of algae?
Chlorophyceae (green algae), Phaeophyceae (brown algae), and Rhodophyceae (red algae).
What are the defining features of Chlorophyceae (green algae)?
Green color due to chlorophyll a and b, various forms (unicellular, colonial, filamentous), and pyrenoids in chloroplasts.
What are the main reproductive methods of Chlorophyceae?
Vegetative reproduction by fragmentation, asexual reproduction by flagellated zoospores, and sexual reproduction which can be isogamous, anisogamous, or oogamous.
Where are Phaeophyceae (brown algae) primarily found?
In marine habitats.
What pigments and food storage forms are associated with Phaeophyceae?
Chlorophyll a, c, carotenoids, xanthophylls, and complex carbohydrates like laminarin or mannitol.
How does sexual reproduction in Phaeophyceae differ?
It can be isogamous, anisogamous, or oogamous, with gametes being pyriform and bearing two flagella.
What are the defining features of Rhodophyceae (red algae)?
Red pigment r-phycocyanin, mostly marine, and food stored as floridean starch.
How do Rhodophyceae reproduce?
Vegetatively by fragmentation, asexually by non-motile spores, and sexually by non-motile gametes with complex post-fertilization developments.
Examples of rhodophyceae
Polysiphonia
Porphyra
Gelidium
Gracilaria
Describe what an antheridiophore is
An antheridiophore is a structure in
bryophytes that bears antheridia, the male
reproductive organs.
Define archegoniophore
An archegoniophore is a structure in
bryophytes that bears archegonia, the female
How is a gemma cup used in bryophytes?
A gemma cup is a structure that produces
gemmae, which are asexual reproductive
structures used for vegetative propagation.
Do rhizoids have a specific function in
bryophytes?
Rhizoids in bryophytes anchor the plant to the
substrate and absorb water and nutrients.
Describe the structure of an antheridial
capsule
An antheridial capsule is the structure
containing antheridia, which produce sperm (spores) through meiosis
in bryophytes. Part of sporophyte that is non photosynthetic.
Define sporophyte in bryophytes
The sporophyte in bryophytes is the diploid
phase of the plant that produces spores
through meiosis.
How do leaves contribute to bryophytes?
Leaves in bryophytes are structures that aid
in photosynthesis and gas exchange.
Do branches play a role in bryophytes?
Branches in bryophytes help in the spread of
the plant and provide additional surface area
for photosynthesis.
Describe the main axis in bryophytes
The main axis in bryophytes is the central
stem-like structure that supports the plant
and connects various parts like leaves and
branches.
Define gametophyte in bryophytes
The gametophyte in bryophytes is the haploid
phase of the plant that produces gametes
through mitosis.
What are bryophytes commonly found growing?
In moist shaded areas in the hills.
Why are bryophytes called amphibians of the plant kingdom?
They can live in soil but are dependent on water for sexual reproduction.
What role do bryophytes play in plant succession?
They help in plant succession on bare rocks/soil.
How is the plant body of bryophytes differentiated from algae?
It is more differentiated, thallus-like, and can be prostrate or erect with unicellular or multicellular rhizoids for attachment.
What structures do bryophytes lack?
True roots, stems, or leaves.
What is the main plant body of a bryophyte called and what is its ploidy?
Gametophyte, and it is haploid.
What are the male and female sex organs in bryophytes called?
Male: antheridium; Female: archegonium
They are multicellular
Anthrezoid are and egg is
Biflagellated ; non motile
How do antherozoids and eggs interact in bryophytes?
Antherozoids swim to the archegonium and fuse with the egg to form a zygote.
What does the zygote develop into in bryophytes?
A multicellular sporophyte.
How does the sporophyte obtain nourishment in bryophytes?
It is attached to the gametophyte and derives nourishment from it.
What happens to some cells of the sporophyte?
They undergo meiosis to produce haploid spores.
What is the economic importance of some bryophytes?
Mosses provide food for animals, peat for fuel, and packing material.
How do mosses and lichens contribute ecologically?
They colonize rocks, decompose them, and reduce soil erosion.
What are the two main groups of bryophytes?
Liverworts and mosses.
Where do liverworts typically grow?
In moist, shady habitats such as stream banks, marshy ground, and tree bark.
What is the structure of a liverwort’s plant body?
Thalloid, with a dorsiventral thallus closely appressed to the substrate.
How does asexual reproduction occur in liverworts?
By fragmentation or formation of gemmae in gemma cups.
What are gemmae in liverworts?
Green, multicellular asexual buds that detach and germinate into new individuals.
What are the structures of the sporophyte in liverworts?
Foot, seta, and capsule.
What stages are involved in the moss life cycle?
Protonema stage and leafy stage.
What characterizes the protonema stage in mosses?
It is a creeping, green, branched, and filamentous stage
What characterizes the leafy stage in mosses?
Upright, slender axes bearing spirally arranged leaves.
How does vegetative reproduction occur in mosses?
By fragmentation and budding in the secondary protonema.
What structures are involved in sexual reproduction in mosses?
Antheridia and archegonia at the apex of the leafy shoots
What does the sporophyte in mosses consist of?
Foot, seta, and capsule, and it is more elaborate than in liverworts.
What are some common examples of mosses?
Funaria, Polytrichum, and Sphagnum.
What plants are included in the Pteridophytes?
Horsetails and ferns
What are some uses of Pteridophytes?
Medicinal purposes, soil-binders, and ornamentals.
What is the evolutionary significance of Pteridophytes?
They are the first terrestrial plants to possess vascular tissues – xylem and phloem.
Where are Pteridophytes typically found?
In cool, damp, shady places, though some can grow in sandy-soil conditions
What is the dominant phase in the life cycle of Pteridophytes?
sporophyte phase
What are the main plant body organs of Pteridophytes?
True root, stem, and leaves
What types of leaves do Pteridophytes have?
Small (microphylls) like in Selaginella, or large (macrophylls) like in ferns.
What are sporophylls in Pteridophytes?
Leaf-like appendages that subtend sporangia.
What are strobili or cones in Pteridophytes?
Distinct compact structures formed by sporophylls in some Pteridophytes.
How are spores produced in Pteridophytes?
By meiosis in spore mother cells within sporangia.
What do spores of Pteridophytes develop into?
Inconspicuous, small, multicellular, free-living, mostly photosynthetic gametophytes called prothallus.
Where do prothallus gametophytes require to grow?
Cool, damp, shady places.
What are the male and female sex organs in Pteridophytes called?
Male: antheridia; Female: archegonia.
What is necessary for the transfer of antherozoids to the archegonium in Pteridophytes?
Water
What does the fusion of male gametes with the egg in the archegonium produce?
A zygote
What does the zygote in Pteridophytes develop into?
A multicellular, well-differentiated sporophyte.
What are homosporous Pteridophytes?
Plants where all spores are of similar kinds.
What are heterosporous Pteridophytes?
Plants like Selaginella and Salvinia that produce two kinds of spores: macro (large) and micro (small).
What do megaspores and microspores produce in heterosporous Pteridophytes?
Female and male gametophytes, respectively
What do megaspores and microspores produce in heterosporous Pteridophytes?
Female and male gametophytes, respectively.
What is a significant evolutionary step observed in some Pteridophytes?
The development of zygotes into young embryos within female gametophytes, a precursor to the seed habit.
Into how many classes are Pteridophytes classified?
Into how many classes are Pteridophytes classified?
Four
Name the four classes of Pteridophytes.
Psilopsida, Lycopsida, Sphenopsida, and Pteropsida
Give examples of plants in the class Psilopsida.
Psilotum
Give examples of plants in the class Lycopsida.
Selaginella, Lycopodium.
Give examples of plants in the class Sphenopsida.
Equisetum
Give examples of plants in the class Pteropsida.
Dryopteris, Pteris, Adiantum.
What does “gymnosperm” mean?
Naked seed
In gymnosperms, how are ovules and seeds positioned?
Ovules are not enclosed by any ovary wall and remain exposed; seeds are naked.
What types of plants are included in gymnosperms?
Medium-sized or tall trees and shrubs
Name a notable gymnosperm and its characteristic.
Giant redwood tree Sequoia, one of the tallest tree species.
What type of root system do gymnosperms generally have?
Tap roots.
What are mycorrhizae in gymnosperms, and give an example?
Fungal associations; example: Pinus.
What are coralloid roots, and which gymnosperm has them?
Specialized roots associated with N2-fixing cyanobacteria; example: Cycas.
Describe the stems of gymnosperms
Stems may be unbranched (e.g., Cycas) or branched (e.g., Pinus, Cedrus)
How are the leaves of gymnosperms adapted to environmental extremes?
Needle-like leaves reduce surface area; thick cuticle and sunken stomata reduce water loss.
Are gymnosperms homosporous or heterosporous?
Heterosporous.
What are the two types of spores produced by gymnosperms?
Microspores and megaspores.
Where are microspores and megaspores produced in gymnosperms?
Within sporangia on sporophylls.
What are the male strobili in gymnosperms called?
Microsporangiate or male strobili.
What does a pollen grain develop from in gymnosperms?
Microspores.
What does a pollen grain develop from in gymnosperms?
Microspores.
What are the female strobili in gymnosperms called?
Macrosporangiate or female strobili.
How do male and female cones differ in Cycas compared to Pinus?
In Cycas, male cones and megasporophylls are borne on different trees; in Pinus, they may be on the same tree.
From where is the megaspore mother cell derived?
From a cell of the nucellus.
What is the structure that protects the nucellus and contains eggs?
The ovule.
How many megaspores are formed from the megaspore mother cell?
Four
What develops from one of the megaspores within the megasporangium?
A multicellular female gametophyte.
What does the multicellular female gametophyte bear?
Two or more archegonia (female sex organs).
In gymnosperms, do male and female gametophytes have independent free-living existence?
No, they remain within the sporangia retained on the sporophytes.
How are pollen grains transported to ovules in gymnosperms?
Carried by air currents.
What happens after pollen grains contact the ovules?
The pollen tube grows towards the archegonia, discharging male gametes near the archegonia.
What develops following fertilisation in gymnosperms?
The zygote develops into an embryo, and the ovules develop into seeds.
How are ovules and pollen grains developed in angiosperms?
In specialized structures called flowers.
How are ovules and pollen grains developed in angiosperms?
In specialized structures called flowers.
What encloses the seeds in angiosperms?
Fruits.
What is the range of sizes in angiosperms?
From the smallest Wolffia to tall trees like Eucalyptus
What commercial products do angiosperms provide?
Food, fodder, fuel, medicines, and other commercially important products
Into what two classes are angiosperms divided?
Dicotyledons and monocotyledons.
What characterizes dicotyledons?
Seeds with two cotyledons, reticulate venation in leaves, and tetramerous or pentamerous flowers
What characterizes monocotyledons?
Seeds with a single cotyledon, parallel venation in leaves, and trimerous flowers.
What is the male sex organ in a flower?
The stamen.
What does each stamen consist of?
A slender filament with an anther at the tip
How are pollen grains formed in angiosperms?
Pollen mother cells in the anther divide by meiosis to produce microspores, which mature into pollen grains.
What is the female sex organ in a flower called?
The pistil.
What are the components of a pistil?
A swollen ovary, a long slender style, and a stigma
What occurs inside the ovary of a pistil?
Ovules are present, each with a megaspore mother cell that undergoes meiosis to form megaspores
How many megaspores are formed from the megaspore mother cell, and what happens to them?
Four megaspores are formed; three degenerate, and one divides to form the embryo sac.
What does each embryo sac contain?
A three-celled egg apparatus (one egg cell and two synergids), three antipodal cells, and two polar nuclei.
What happens to the polar nuclei in the embryo sac?
They fuse to produce a diploid secondary nucleus
What is pollination?
The transfer of pollen grains from the anthers to the stigma of a pistil.
What happens after pollen grains germinate on the stigma?
Pollen tubes grow through the stigma and style to reach the ovule
What occurs during double fertilisation in angiosperms?
One male gamete fuses with the egg cell (syngamy) to form a zygote, and another male gamete fuses with the secondary nucleus to form the triploid primary endosperm nucleus (PEN).
What is the outcome of double fertilisation?
The zygote develops into an embryo, and the PEN develops into endosperm to nourish the embryo.
What happens to the synergids and antipodals after fertilisation?
They degenerate.
What do ovules and ovaries develop into after fertilisation?
Ovules develop into seeds, and ovaries develop into fruit.
In plants, what types of cells can divide by mitosis?
Both haploid and diploid cells
What does the haploid plant body produce by mitosis?
Gametes.
What is the plant body called that represents the haploid phase?
Gametophyte
What is the plant body called that represents the haploid phase?
Gametophyte.
What does the diploid zygote develop into after fertilization?
A diploid sporophytic plant body
How are haploid spores produced in the plant life cycle?
By meiosis in the diploid sporophytic plant body.
What happens to haploid spores after they are produced?
They divide by mitosis to form a haploid plant body again.
What is the term for the alternation of generations in the plant life cycle?
Alternation of generations between gamete-producing haploid gametophyte and spore-producing diploid sporophyte.
What characterizes the haplontic life cycle?
The sporophytic generation is represented only by the one-celled zygote, with no free-living sporophytes. The dominant phase is the free-living gametophyte.
Which plants exhibit a haplontic life cycle?
Many algae such as Volvox, Spirogyra, and some species of Chlamydomonas.
What characterizes the diplontic life cycle?
The diploid sporophyte is the dominant, photosynthetic, independent phase, and the gametophytic phase is represented by a single to few-celled haploid gametophyte.
Which alga represents the diplontic life cycle?
Fucus sp.
What type of life cycle do seed-bearing plants (gymnosperms and angiosperms) follow?
Diplontic life cycle with some variations.
What type of life cycle do bryophytes and pteridophytes exhibit?
Haplo-diplontic.
In bryophytes, what represents the dominant phase in the haplo-diplontic life cycle?
A haploid gametophyte that is independent, photosynthetic, and either thalloid or erect.
In pteridophytes, what represents the dominant phase in the haplo-diplontic life cycle?
A diploid sporophyte that is independent, photosynthetic, and vascular.
What is the term for the life cycle in which both haploid and diploid phases are multicellular?
Haplo-diplontic life cycle.
Which algae exhibit a haplo-diplontic life cycle?
Ectocarpus, Polysiphonia, and kelps.
What type of life cycle does the alga Fucus have?
Diplontic.
