What is Parenchymatous form of algae?
Parenchymatous (tissuelike) forms, such as the giant kelp (Macrocystis), can measure many metres in length. Coenocytic forms of algae, such the green seaweed Codium, grow to fairly large sizes without forming distinct cells.
What is parenchymatous thallus?
Parenchymatous forms The formation of a parenchymatous thallus occurs when cells of the primary filament divide into two or more planes. The parenchymatous organization may be foliose (e.g., Ulva), tubular (e.g., Enteromorpha), or highly developed structure (e.g., Chara, Fucus, Laminaria, etc.).
Is Ulva Parenchymatous algae?
I. Ulva flexuosa (filamentous and plant-like alga), a parenchymatous alga forming large macroscopic tubes or sacs.
What is pseudo Parenchymatous cell of fungus?
A tissue that superficially resembles plant parenchyma but is made up of an interwoven mass of hyphae (in fungi) or filaments (in algae). Examples of pseudoparenchymatous structures are the fruiting bodies (mushrooms, toadstools, etc.) of certain fungi and the thalli of certain red and brown algae.
What is Parenchymatous cell?
Parenchyma is a type of simple permanent tissue that makes a major part of ground tissues in plants, where other tissues like vascular tissues are embedded. They are non-vascular and composed of simple, living and undifferentiated cells, which are modified to perform various functions.
Which algae has Parenchymatous thallus?
In the case of parenchymatous algae, cells of the primary filament divide in all directions and any essential filamentous structure is lost. This tissue organization is found in Ulva (Chlorophyta) and many of the brown algae.
What type of algae is Ulva?
sea lettuce, (genus Ulva), genus of green algae (family Ulvaceae) usually found growing on rocky shores of seas and oceans around the world. Some species also grow in brackish water rich in organic matter or sewage and can accumulate heavy metals.
Why Ulva is called sea lettuce?
It is also known as sea lettuce because of its expanded leaf-like structures, which resemble a garden lettuce. Marked seasonal variations can be seen in the morphology of Ulva, ie, young plants are dark green in color and soft to the touch, whereas older thalli become light green and their surface becomes slimy.
What is common name of spirogyra?
Spirogyra (common names include water silk, mermaid's tresses, and blanket weed) is a filamentous charophyte green alga of the order Zygnematales, named for the helical or spiral arrangement of the chloroplasts that is characteristic of the genus.
What is the parenchyma?
Definition of parenchyma 1 : the essential and distinctive tissue of an organ or an abnormal growth as distinguished from its supportive framework.
What is parenchyma made of?
parenchyma, in plants, tissue typically composed of living cells that are thin-walled, unspecialized in structure, and therefore adaptable, with differentiation, to various functions.
What is Siphonaceous algae?
siphonaceous (siphoneous) Applied to algae in which the thallus is not divided up by septa, i.e. the many nuclei are not compartmentalized into cells. The typical siphónaceous alga has a large central vacuole surrounded by a layer of protoplasm, containing nuclei and chloroplasts, which lines the cell wall.
What does parenchymal mean in medical terms?
Medical Definition of parenchyma : the essential and distinctive tissue of an organ or an abnormal growth as distinguished from its supportive framework.
What is the function of parenchyma cells in plants?
Parenchyma forms the bulk of plant ground tissue, where they may be specialised to function in photosynthesis, storage, or transport. Parenchyma is integral to vascular tissue, where it provides a route of exchange for materials within and between the xylem and the phloem.
Where is parenchyma found?
Parenchyma is a versatile ground tissue that generally constitutes the "filler" tissue in soft parts of plants. It forms, among other things, the cortex (outer region) and pith (central region) of stems, the cortex of roots, the mesophyll of leaves, the pulp of fruits, and the endosperm of seeds.
What is parenchyma Sclerenchyma and Collenchyma?
Parenchyma – They are living cells and walled, soft in nature due to the presence of thin-walled cells. Collenchyma – These are characterized by uneven thick-walled living cells. Sclerenchyma – They have cells with thickened lignified walls, providing them strength and making them waterproof.
What are the unicellular types of algae?
The range of thallus organization in algae may be classified as follows: 1. Unicellular. Motile and non-motile. ADVERTISEMENTS:
Why are structural and cellular organizations important in the classification of algae?
Structural and cellular organizations are important characters in the classification of algae and in establishing the inter-relationship among them. Similarities of some morphological structures are seen among various classes of algae.
Where is mucilage produced in dendroids?
A variation of the palmelloid condition is seen in dendroid colonies. Here the mucilage is produced locally, generally at the base of the cell. This polarity differentiates the two habits. Dendroid forms are seen e.g. Prasinocladus (Chlorophyceae), Mischococcus (Xanthophyccae) and in Chrysophyceae and Euglenineac (Fig. 5 A, B).
What is the unicellular plant body?
The unicellular plant body may be spherical, oblong or pear-shaped and sometimes elongated (Fig. 2); and approximately circular in cross section. In some cases, the plain body proper and peripheral layer is separated by a space. This envelope is spherical, rigid, variously shaped and is provided with apertures for the protrusion of the flagella.
How are aggregations formed?
Aggregates are formed by the collection of single cells to make thallus. Unlike the coenobium the aggregation of cells does not have fixed number of cells shape or size. The cells are aggregated into more or less irregular colony like mass. When the cells divide, the daughter cells remain in same gelatinous mass.
How many flagella are there in a protoplast?
The number of flagella may be one or more, usually two or in multiples of two. The cells may have a rigid cell-wall or the outer layer of the protoplast forms do the ‘periplast ‘ giving a definite shape to the cell or may allow changes in shape (rhizopodial or amoeboid type).
Which cell type is absent in Cyanophyceae?
Flagellated vegetative cells are absent in Cyanophyceae, Phaeophyceae, Rhodophyceae, Bacillariophyceae. Nature of flagellation, type and number of flagella and the attachment of flagella, is an important character in classification.
Unicellular form of thallus organisation in algae
This type of algal plant body consists of a single cell. The organisms are rounded, pear-shaped, oblong-shaped, or spherical in structure. Some unicellular algae are motile, while others are non-motile.
Unicellular motile forms
These are motile forms of unicellular algae. The thalli contain either flagella or rhizopodia and pseudopodia for locomotion.
Unicellular non-motile forms
These are non-motile forms of unicellular algae without having flagella or any other locomotory organs.
Multicellular form of thallus organisation in algae
This type of algal thallus is formed by multi cells or aggregated unicellular algae.
Colonial forms
The colonial thallus is the unicellular form of algae which may be compact or loosely arranged and form a colony-like structure.
Coenobial forms
The coenobial colony is composed of a definite number of cells arranged in a specific manner.
Aggregated forms
The aggregated thalli are formed by irregularly aggregated cells and are of various sizes and shapes.
What is green algae?
GREEN ALGAE. The term algae is used to collectively refer to a wide range (20,000-30,000 spp.) of very simple photosynthetic organisms. While this term is no longer used as a taxonomic grouping, it is still useful for referring informally to these photosynthetic protists. (Protists are diverse eukaryotes which are neither fungi, ...
What distinguishes algae from land plants?
There are 3 features which distinguish algae from land plants;-. Body plan: There is no specialisation of the algal body into root, stem etc. The photosynthetic portion of the alga is a thallus while the attachment portion comprises hair-like rhizoids.
Why do corals have algae?
Corals contain microscopic algae in a mutualistic relationship which fix carbon dioxide to provide a fuel source for the animals that build the coral reef. Secondly, the exoskeletons of coralline macro-algae often become incorporated into a reef after the alga dies.
What is the body plan of algae?
These algae are coenocytic which means they undergo repeated nuclear division without the accompanying formation of cell walls. These have a tubular structure with the multinuclear cytoplasm lining the thallus (the Greek word for tube is siphon ).
What is the name of the organism that grows on bare rock?
Crustose lichen on rock. Fruticose lichen. On land, algae are often pioneer organisms, growing on bare rock (provided there is moisture). The rock weathers and crumbles, the algae die and the remains of both contribute to formation of soil.
What is the economic significance of algae?
Economic Significance of Algae. Algae are primary producers, i.e. they are the start of the food chain. Phytoplankton are responsible for more than 45% of the Earth's annual primary production. Algae - "oilgae"- are seen as a source of next generation biofuels .
What are the other major groups of terrestrial algae?
The other major group of terrestrial algae are those in lichensymbioses.
What is the parenchyma?
Parenchyma is a type of simple permanent tissue that makes a major part of ground tissues in plants, where other tissues like vascular tissues are embedded. They are non-vascular and composed of simple, living and undifferentiated cells, which are modified to perform various functions. The other simple permanent tissues are:
What are the characteristics of parenchyma?
The main characteristics of parenchyma are: They are living permanent tissues that have the ability to divide at maturity and help in the regeneration and healing of wounds. Parenchyma cells are the foundation of a plant as reproductive cells (spores, gametes) are parenchymatous in nature.
What cells help in gas exchange?
Gas Exchange: Aerenchyma cells help in the gas exchange. Protection: In gymnosperms, the parenchymatous cell have spiny projections that help in the protection from predators. Totipotent: Parenchyma cells have an ability to transform to the other types of cells and act as a precursor for other types of cells.
What are the different types of parenchyma cells?
Parenchyma cells can be categorised based on their structure, location and functions performed. The main parenchyma tissues are: Chlorenchyma: Cells which have chloroplast and perform photosynthesis. The mesophyll cells in leaves which differentiate into palisade and spongy cells.
What is the function of parenchyma cells?
Parenchyma cells form the ground tissue of plants. Parenchyma tissues perform various important functions: Storage : Parenchyma cells have large intercellular space which is ideal for storage. High amount of starch is present in the tubers of potato and cassava.
Where do parenchyma cells occur?
Parenchyma cells occur in the form of continuous masses as homogeneous parenchyma tissues e.g. in pith and cortex of stems and roots, mesophyll of leaves, the flesh of succulent fruits and in the endosperm of seeds
Which cell may have thick xyloglucan walls?
Storage parenchyma cells may have thick xyloglucan walls e.g. in the endosperm of the date palm. The sugar is used during germination and walls become thin
Overview
Algae is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular microalgae, such as Chlorella, Prototheca and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to 50 metres (160 ft) in length. Most are aquatic and autotrophic (they generate food internally) and lack many of the distinct cell …
Etymology and study
The singular alga is the Latin word for 'seaweed' and retains that meaning in English. The etymology is obscure. Although some speculate that it is related to Latin algēre, 'be cold', no reason is known to associate seaweed with temperature. A more likely source is alliga, 'binding, entwining'.
The Ancient Greek word for 'seaweed' was φῦκος (phŷkos), which could mean either the seawee…
Classifications
The committee on the International Code of Botanical Nomenclature has recommended certain suffixes for use in the classification of algae. These are -phyta for division, -phyceae for class, -phycideae for subclass, -ales for order, -inales for suborder, -aceae for family, -oidease for subfamily, a Greek-based name for genus, and a Latin-based name for species.
Relationship to land plants
The first land plants probably evolved from shallow freshwater charophyte algae much like Chara almost 500 million years ago. These probably had an isomorphic alternation of generations and were probably filamentous. Fossils of isolated land plant spores suggest land plants may have been around as long as 475 million years ago.
Morphology
A range of algal morphologies is exhibited, and convergence of features in unrelated groups is common. The only groups to exhibit three-dimensional multicellular thalli are the reds and browns, and some chlorophytes. Apical growth is constrained to subsets of these groups: the florideophyte reds, various browns, and the charophytes. The form of charophytes is quite different from those of r…
Physiology
Many algae, particularly members of the Characeae species, have served as model experimental organisms to understand the mechanisms of the water permeability of membranes, osmoregulation, turgor regulation, salt tolerance, cytoplasmic streaming, and the generation of action potentials.
Phytohormones are found not only in higher plants, but in algae, too.
Symbiotic algae
Some species of algae form symbiotic relationships with other organisms. In these symbioses, the algae supply photosynthates (organic substances) to the host organism providing protection to the algal cells. The host organism derives some or all of its energy requirements from the algae. Examples are:
Lichens are defined by the International Association for Lichenology to be "an a…
Lifecycle
Rhodophyta, Chlorophyta, and Heterokontophyta, the three main algal divisions, have lifecycles which show considerable variation and complexity. In general, an asexual phase exists where the seaweed's cells are diploid, a sexual phase where the cells are haploid, followed by fusion of the male and female gametes. Asexual reproduction permits efficient population increases, but less variation is possible. Commonly, in sexual reproduction of unicellular and colonial algae, two spe…