Yellow-green algae

Key takeaways

Yellow-green algae belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Yellow-green algae to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Yellow-green algae from memory before moving on to harder problems.

Reference excerpt

Yellow-green algae or the Xanthophyceae (xanthophytes) are an important group of heterokont algae. Most live in fresh water, but some are found in marine and soil habitats. They vary from single-celled flagellates to simple colonial and filamentous forms. Xanthophyte chloroplasts contain the photosynthetic pigments chlorophyll a, chlorophyll c, β-carotene, and the carotenoid diadinoxanthin. Unlike other Stramenopiles (heterokonts), their chloroplasts do not contain fucoxanthin, which accounts for their lighter colour. Their storage polysaccharide is chrysolaminarin. Xanthophyte cell walls are produced of cellulose and hemicellulose. They appear to be the closest relatives of the brown algae.

Classifications The species now placed in the Xanthophyceae were formerly included in the Chlorophyceae. In 1899, Lüther created the group Heterokontae for green algae with unequal flagella. Pascher (1914) included the Heterokontae in the Chrysophyta. In 1930, Allorge renamed the group as Xanthophyceae. The monadoid (unicellular flagellates) and also sometimes the amoeboid species have been included by some authors in the Protozoa or Protista, as order Heterochloridina (e.g., Doflein and Reichenow, 1927–1929), as class Xanthomonadina, with orders Heterochloridea and Rhizochloridea (e.g., Deflandre, 1956), as order Heterochlorida (e.g., Hall, 1953, Honigberg et al., 1964), as order Heteromonadida (e.g., Leedale, 1983), or as subclass Heterochloridia (e.g., Puytorac et al., 1987). These groups are called ambiregnal protists, as names for these have been published under either or both of the ICZN and the ICN.

AlgaeBase (2020) Xanthophyceae have been divided into the following five orders in some classification systems:

Dictyosphaeriopsis Groenlandiella Halosphaeropsis Pelagocystis Polyedrium Pseudopleurochloris Raphidosphaera Sphaerochloris Tiresias Order Botrydiales Schaffner 1922 Family Botrydiaceae Rabenhorst 1863 e.g. Botrydium Order Mischococcales Fritsch 1927 Family Botrydiopsidaceae Hibberd 1980 e.g. Botrydiopsis Family Botryochloridaceae Pascher 1938 e.g. Ilsteria Family Centritractaceae Pascher 1937 e.g. Centritractus Family Characiopsidaceae Pascher 1938 e.g. Characiopsis, Chlorothecium Family Chloropediaceae Pascher 1931 e.g. Chloropedia Family Gloeobotrydaceae Pascher 1937 e.g. Gloeobotrys Family Gloeopodiaceae Pascher 1938 e.g. Gloeopodium Family Mischococcaceae Pascher 1912 e.g. Mischococcus Family Ophiocytiaceae Lemmermann 1899 e.g. Ophiocytium Family Pleurochloridaceae Pascher 1937 e.g. Meringosphaera, Pleurochloris Family Trypanochloridaceae Geitler ex Pascher 1938 e.g. Trypanochloris Order Rhizochloridales Pascher 1925 Family Myxochloridaceae Pascher 1937 e.g. Myxochloris Family Rhizochloridaceae Pascher 1925 e.g. Rhizochloris Family Stipitococcaceae Pascher ex Smith 1933 e.g. Stipitococcus Order Tribonematales Pascher 1939 Family Heterodendraceae Pascher 1939 e.g. Heterodendron Family Heteropediaceae Hibberd 1982 e.g. Heterococcus, Heteropedia Family Neonemataceae Ettl 1977 e.g. Neonema Family Tribonemataceae West 1904 e.g. Tribonema Family Xanthonemataceae Silva 1980 e.g. Xanthonema Order Vaucheriales Nägeli ex Bohlin 1901 Family Vaucheriaceae (Gray) Dumortier 1822 e.g. Vaucheria

Lüther (1899) Classification according to Lüther (1899):

Class Heterokontae Order Chloromonadales Order Confervales

Pascher (1912) Classification according to Pascher (1912):

Heterokontae Heterochloridales Heterocapsales Heterococcales Heterotrichales Heterosiphonales

Fritsch (1935) Fritsch (1935) recognizes the following orders in the class Xanthophyceae:

Order Heterochloridales Family Heterochloridaceae (e.g., Heterochloris) Family Heterocapsaceae (e.g., Chlorogloea) Family Mischococcaceae (e.g., Mischococcus) Family Heterorhizidaceae (e.g., Rhizolekane) Order Heterococcales Family Halosphaeraceae (e.g., Halosphaera) Family Myxochloridaceae (e.g., Myxochloris) Family Chlorobotrydaceae(e.g., Chlorobotrys) Family Chlorotheciaceae (e.g., Chlorothecium) Family Ophiocytiaceae (e.g., Ophiocytium) Order Heterotrichales Family Tribonemataceae (e.g., Tribonema) Family Heterocloniaceae (e.g., Heterodendron[?]) Order Heterosiphonales Family Botrydiaceae (e.g., Botrydium)

Smith (1938) In the classification of Smith (1938), there are six orders in the class Xanthophyceae, placed in the division Chrysophyta:

Order Heterochloridales (e.g., Chlorochromonas) Order Rhizochloridales (e.g., Chlorarachnion) Order Heterocapsales (e.g., Chlorosaccus) Order Heterotrichales (e.g., Tribonema) Order Heterococcales (e.g., Botrydiopsis) Order Heterosiphonales (e.g., Botrydium)

Pascher (1939) Pascher (1939) recognizes 6 classes in Heterokontae:

Class Heterochloridineae Class Rhizochloridineae Class Hetcrocapsineae Class Heterococcincae Class Hetcrotrichineae Class Heterosiphonineae

Copeland (1956) Copeland (1956) treated the group as order Vaucheriacea:

Kingdom Protoctista Phylum Phaeophyta Class Heterokonta Order Vaucheriacea Family Chlorosaccacea Family Mischococcacea Family Chlorotheciacea Family Botryococcacea Family Stipitococcacea Family Chloramoebacea Family Tribonematacea Family Phyllosiphonacea

Ettl (1978), van den Hoek et al. (1995) In a classification presented by van den Hoek, Mann and Jahns (1995), based on the level of organization of the thallus, there are seven orders:

Order Chloramoebales (e.g., Chloromeson) - flagellate organisms Order Rhizochloridales (e.g., Rhizochloris, Myxochloris) - ameboid organisms Order Heterogloeales (e.g., Gloeochloris) - palmelloid (tetrasporal) organisms Order Mischococcales (e.g., Chloridella, Botrydiopsis, Characiopsis, Ophiocytium) - coccoid organisms Order Tribonematales (e.g., Tribonema, Heterococcus, Heterodendron) - filamentous organization Order Botrydiales (e.g., Botrydium) - siphonous organization; sexual reproduction isogamous or anisogamous Order Vaucheriales (e.g., Vaucheria) - siphonous organization; sexual reproduction oogamous These are the same orders of the classification of Ettl (1978), an updated version of the classic work by Pascher (1939). Ultrastructural and molecular studies shows that the Mischococcales might be paraphyletic, and the Tribonematales and Botrydiales polyphyletic, and suggests two orders at most be used until the relationships within the division are sorted.

Maistro et al. (2009) Informal groups, according to Maistro et al. (2009):

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Yellow-green algae

Start with the simplest possible case. Write down what Yellow-green algae claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Yellow-green algae before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Yellow-green algae ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Yellow-green algae

In research: Yellow-green algae appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Yellow-green algae in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Yellow-green algae is common in secondary-school and first-year university syllabi. It links to neighbouring topics Xanthophyceae, so understanding it makes those chapters shorter.
In everyday life: Look for Yellow-green algae outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Yellow-green algae in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Yellow-green algae means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Yellow-green algae out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Yellow-green algae in simple terms?

Yellow-green algae or the Xanthophyceae (xanthophytes) are an important group of heterokont algae. Most live in fresh water, but some are found in marine and soil habitats.

Why does Yellow-green algae matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Yellow-green algae?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Yellow-green algae.