HEYA GUYS!! WASSUP??define kingdom protista. And also define the characteristics of chrysophytes, protozoans,dinoflagellates,slime moulds and euglenoids.
Answers
Answer:
Kingdom Protista
Euglena, a eukaryotic protist
The term ‘Protista’ is derived from the Greek word “protistos”, meaning “the very first“. These organisms are usually unicellular and the cell of these organisms contain a nucleus which is bound to the organelles. Some of them even possess structures that aid locomotion like flagella or cilia.
Scientists speculate that protists form a link between plants, animals, and fungi as these three kingdoms diverged from a common protist-like ancestor, billions of years ago. Though this “protists-like” ancestor is a hypothetical organism, we can trace some genes found in modern animals and plants to these ancient organisms.
Therefore, these organisms are traditionally considered as the first eukaryotic forms of life and a predecessor to plant, animals, and fungi.
Detailed Insight: Eukaryotic Cells
Characteristics of Kingdom Protista
The primary feature of all protists is that they are eukaryotic organisms. This means that they have a membrane-enclosed nucleus. Other characteristic features of Kingdom Protista are as follows:
These are usually aquatic, present in the soil or in areas with moisture.
Most protist species are unicellular organisms, however, there are a few multicellular protists such as kelp. Some species of kelp grow so large that they exceed over 100 feet in height. (Giant Kelp).
Just like any other eukaryotes, the cells of these species have a nucleus which is bound by organelles.
They may be autotrophic or heterotrophic in nature. An autotrophic organism can create their own food and survive. A heterotrophic organism, on the other hand, has to acquire nutrition from other organisms such as plants or animals to survive.
Symbiosis is observed in the members of this class. For instance, kelp (seaweed) is a multicellular protist that provides otters protection from predators amidst its thick kelp. In turn, the otters eat sea urchins that tend to feed on kelp.
Parasitism is also observed in protists. Species such as Trypanosoma protozoa can cause sleeping sickness in humans.
Protists exhibit locomotion through cilia and flagella. A few organisms belonging to kingdom Protista have pseudopodia that help them to move.
Protista reproduces by asexual means. The sexual method of reproduction is extremely rare and occurs only during times of stress.
Read more: Kingdom Protista
Classification of Protista
Kingdom Protista is classified into the following:
Classification of Protista
Classification of Protista has resulted in 3 subdivisions, namely protozoans, algae and moulds
Protozoa
Protozoans are unicellular organisms. These are also called animal protists. All protozoans are heterotrophic, i.e., they feed on other organisms to obtain nutrition.
There are also parasitic protozoans which live in the cells of larger organisms. Most of the members do not have a predefined shape. For instance, an amoeba can change its shape indefinitely but a paramecium has a definite slipper-like shape. The most well-known examples of protozoans are an amoeba, paramecium, Sporozoa, euglena etc.
The protozoans can be divided into four major groups:
Amoeboid protozoans – Mostly found in water bodies, either fresh or saline. They have pseudopodia (false feet) which help to change their shape and in capturing and engulfing food. Eg., Amoeba
Flagellated protozoans – As the name suggests, the members of this group have flagella. They can be free-living as well as parasitic. Eg., Euglena
Ciliated protozoans – They have cilia all over their body which help in locomotion as well as nutrition. They are always aquatic. Wg., Paramecium
Sporozoans – These organisms are so-called because their life cycle has a spore-like stage. For example, the malarial parasite, Plasmodium.
Moulds
Moulds are saprophytic organisms (they feed on the dead and decaying matter). They are basically divided into two types viz. slime moulds and the water moulds. These are tiny organisms that have many nuclei.
Usually, moulds are characterized by the presence of spores and are even visible to the naked eye.
Read more:Slime moulds
The Chrysophyceae, usually called chrysophytes, chrysomonads, golden-brown algae or golden algae are a large group of algae, found mostly in freshwater. Golden algae is also commonly used to refer to a single species, Prymnesium parvum, which causes fish kills. Wikipedia
Kingdom: Chromista
Scientific name: Chrysophyceae
Phylum: Ochrophyta
Class: Chrysophyceae; Pascher, 1914
Rank: Class
Higher classification: Ochrophyta
Lower classifications: Chrysosphaerales, Ochromonadales
The dinoflagellates are single-celled eukaryotes constituting the phylum Dinoflagellata. Usually considered algae, dinoflagellates are mostly marine plankton, but they also are common in freshwater habitats. Their populations are distributed depending on sea surface temperature, salinity, or depth. Wikipedia
Scientific name: Dinoflagellata
Rank: Phylum
Higher classification: Alveolate
Answer:
We place all single-celled eukaryotes under Protista. However, the boundaries of this kingdom are not well defined. Members of Protista are primarily aquatic. This kingdom forms a link with the others dealing with plants, animals and fungi. Being eukaryotes, the protistan cell body contains a well-defined nucleus and other membrane-bound organelles.
Some have flagella or cilia. Protists reproduce asexually and sexually by, the process involving cell fusion and zygote formation. It may be photosynthetic or holotrophic. These could also be saprotrophic, parasitic and symbionts. On the other hand, some could have mixotrophic nutrition (holotrophic + saprobic). Phytoplanktons are photosynthetic, floating protists. Zooplanktons are free-floating, holozoic protozoans. Chrysophytes.
This group comprises of the diatoms and golden algae (desmids). We find them in fresh water as well as in marine environments. They are microscopic. These organisms float passively in water currents (plankton).
Dianoflagellates
These organisms are usually marine and photosynthetic. They have an appearance of various colours like yellow, green, brown, blue or red. Their colour is influenced and decided by the main pigments present in their cells. The cell wall has stiff cellulose plates on its outer surface. These organisms usually have two flagella; one lies longitudinally and the other transversely in a furrow between the wall plates.
Euglenoids
These are mostly freshwater organisms. We can find them in stagnant water. They do not have a cell wall. Rather, they are built with a protein-rich layer, pellicle that makes their body flexible. They have two flagella. One is short and the other is a long one. The two flagella join with each other at a swelling called paraflagellar body.
Euglena is a connecting link between animals and plants. Nutrition in Euglena is mixotrophic, when the light is available it is photosynthetic, in darkness, it is saprophytic absorbing food from surrounding water.
Slime Moulds
Slime moulds are saprophytic protists. Their body is capable of moving through decaying twigs and leaves engulfing organic material. Under suitable conditions, they form an aggregation called Plasmodium which may grow and spread over several feet. During unfavourable conditions, the plasmodium differentiates and forms fruiting bodies bearing spores at their tips.
The spores possess true walls. The spores are dispersed by air currents. They are extremely resistant to changes in the atmosphere. They are capable of surviving for many years, even under adverse conditions.
Protozoans
All protozoans are heterotrophs and live as predators or parasites. They are believed to be primitive relatives of animals. There are four major groups of protozoan:
Hope it helps friend