"Fire algae" belongs to group :-
Pyrrophyta is reddish brown unicellular dinoflagellates with/without cellulosic cell wall. Dinoflagellates are the bioluminescent algae. They have pigment luciferin which is acted upon by the enzyme luciferase causing production of light without any heat, thus the name fire algae. Euglenophyta are unicellular autotrophic algae characterized by absence of cell wall and presence of pellicle, they are not bioluminescent. Bacillariophyta includes unicellular autotrophic algae (diatoms) with characteristic silicon cell wall and are responsible for formation of diatomaceous earth. Rhodophyta includes mostly multicellular algae (red algae) characterized by presence of calcium carbonate in cell wall which forms coral reefs.
In euglenoids, the stored food is paramylum which is a :-
Paramylon is a carbohydrate similar to starch. The chloroplasts found in Euglena contain chlorophyll which aids in the synthesis of carbohydrates to be stored as starch granules and paramylon. Paramylon is made in the pyrenoids of Euglena. The euglenoids have chlorophylls a and b and they store their photosynthate in an unusual form called paramylon starch, a B-1,3 polymer of glucose. The paramylon is stored in rod like bodies throughout the cytoplasm, called paramylon bodies, which are often visible as colorless or white particles in light microscopy. Their shape is often characteristic of the Euglenaspecies that produces them.
"Naked fungi" (Slime moulds) are naked :-
Slime molds are placed under myxomycetes and are characterized by presence of different morphology at different life stages. The vegetative stage of cellular slime molds is a haploid amoeboid cell and is known as pseudoplasmodium and that of acellular slime molds is multinucleate diploid amoeboid mass, known as plasmodium. Plasmodium is wall less mass of multinucleate protoplast surrounded by slime; hence the name “naked fungi”. This makes option D incorrect and B correct. Sexual reproduction under favourable condition in slime molds produces sporangia on fruiting bodies (sporocarp) which carry haploid spores. Spore formation includes cytoplasmic division of multinucleated protoplasm of sporangia to form uninucleate segments, each surrounded by cell wall. Thus reproductive phase of slime molds is not “wall-less/naked” but has cell wall. This makes options A and C incorrect.
Type of nutrition in slime mould is :-
After the food molecules become small they pass through the walls of intestine and go in to blood. This process is called absorption.
Holozoic is a mode of nutrition in which organisms eat solid food. The food may be a plant product or animal product. In this process, an organism ingests the complex organic food material into its body and then digests the food which is then absorbed into the body cells. The unabsorbed food is thrown out of the body of the organisms by the process of egestion. Man, cat, dog, bear, giraffe, fog, fish, etc., have holozoic mode of nutrition.
Multinucleated acellular slime molds are :-
The slime molds warrant their own classification within Protista because of their unusual morphology. At some stages in their life cycle, they show clearly protozoan characteristics, but at other stages they become almost fungus-like. Slime molds fall into two distinct groups that are not closely related: the cellular slime molds and the true, or acellular, slime molds. A distinguishing morphological difference between the two groups is the vegetative state of cellular slime molds in a haploid amebiod cell, whereas the vegetative state of acellular slime molds is a multinucleate diploid ameboid mass called a plasmodium.
Dinoflagellates are called fire algae due to which character :-
Dinoflagellates are the bioluminiscent algae. They have pigment luciferin, which is acted upon by the enzyme luciferase causing production of light without any heat, thus the name fire algae. The enzymatic reaction of pigment produces light; pigment itself does not impart the fire-like appearance.
Toxins (Saxitoxins) secreted by some dinoflagellates enter the body of human beings through food chain and result in :-
Saxitoxin is secreted by dinoflagelate(gymnodium and gaunulax) causes paralysis in human
Diatoms float in water due to :-
Diatoms are phytoplanktons that float on water surface. They are the primary photosynthetic producers in marine food chains and store their food as oil or lipids and polysaccharide leucosine.
Dead remains of Diatoms at sea bed are called
Cells of Diatoms are surrounded by the cell wall, frustules, which has silica deposits. Shells of diatoms are highly resistant to decomposition due to the presence of silica and are deposited in ocean beds leading to the formation of the diatomaceous earth. Extraction, grounding, sieving and sinteration of diatomaceous earth obtain Kieselguhr which is used in filtration techniques.
Protists should be better termed as :-
Kingdom Protista includes diverse kinds of eukaryotic and unicellular microorganisms. Phylogenetically, protists act as a link between the prokaryotic Monera and multicellular eukaryotes such as Fungi, Plantae, and Animalia. Protists possess membrane-bound distinct cell organelles like nucleus, mitochondria, and chloroplasts (in photosynthetic protists). Because they share several characteristics with multicellular organisms, protists should be better termed multicellular.
Unicellular algae which produce "Auxospores" and have soap box like cell wall are :–
Auxospore is produced by diatom and soap box like cell wall have diatoms made of by silica.
Which of the following eucaryotes are devoid of histone proteins :-
Chrysophytes are characterized by presence of yellow and brown carotenoids which impart them golden colour; hence the name golden algae; Option A is incorrect answer as histone proteins are present in them. Dinoflagellates are the only eukaryotes that have no histone protein in their DNA, which is always in condensed form. They are luminescent algae; their pigment luciferin is acted upon by the enzyme luciferase causing production of light without any heat, thus the name fire algae. Option C is correct. Euglenoids are unicellular biflagellated algae which are characterized by euglenoid movement but have histone proteins. Slime molds are fungus like protists, characterized by presence of plasmodium at a stage of their life cycle; they have histone proteins. Option D is incorrect. Thus, the correct answer is option C.
Which of the following algae secrete "Saxitoxins" :-
Genus Gonyaulax of dinoflagellates secretes neurotoxin saxitoxins which are the causative agents of paralytic shellfish poisoning (PSP). Mollusks such as mussels and clams feed on large number of dinoflagellates; human consumption of those mollusks causes paralysis. Option A is correct. Oscillatoria is a filamentous cyanobacterium which makes option B incorrect as Saxitoxins are secreted by dinoflagellates. Noctiluca, the Night Light, is a colourless dinoflagellate which exhibits characters like dinoflagellates (holozoic nutrition and bioluminescence) and like that of protozoans (absence of armoured cell wall, a characteristic feature of dinoflagellates, and presence of pellicle); it does not secrete saxitoxins. Option C is incorrect. Pyrocystis genus includes mostly spindle shaped dinoflagellates that do not secrete Saxitoxins.
In which of the following cell wall is divided in two half parts :-
In diatoms call wall is arranged in the form of lid like soap bar. So it's cell wall has divided in two parts.
The diatomaceous earth is used for insulating boilers and steam pipes because -
Cells of Diatoms are surrounded by the cell wall, frustules, which has silica deposits. Shells of diatoms are highly resistant to decomposition due to the presence of silica and are deposited in ocean beds leading to the formation of the diatomaceous earth. Diatomaceous earth is used as a filtration aid, mild abrasive in products including metal polishes and toothpaste, mechanical insecticide, absorbent for liquids, matting agent for coatings, a stabilizing component of dynamite and a thermal insulator as it is a bad conductor of heat.
An example of a dimorphic protozoan is
1. It is a marine protozoan common on sea shores.
2. Body enclosed in a many chambered shell and each chamber is perforated with numerous pores.
3. Chambers are arranged in a spiral fashion.
4. Ectoplasm gives rise to numerous thread like extensions-the reticulopodia, which project out of the pores.
5. Adults exhibit dimorphism and alternation of generation between a microspheric and a megalospheric form.
In which of the following, the body is an aggregation of amoeboid cells :-
Cellular slime moulds behave as individual Amoeba and use pseudopods for locomotion and capturing bacteria and other smaller organisms. Unfavourable conditions, like food scarcity, induce the formation of a mass of aggregates of organisms, that stop moving and grow vertically into spore-containing mass, the sorocarp. In the sorocarp, the individual amoebas become encysted as spores, hence they are called as an aggregate of amoeboid cells.
Class Gymnomycota includes :-
Gymnomycota are slime molds; organisms having a noncellular and multinucleate creeping vegetative phase and a propagative spore-producing stage: comprises Myxomycetes and Acrasiomycetes; in some classifications placed in the kingdom Protoctista.
Diatoms perform which type of movement in water :-
Diatoms are phytoplankton that floats on the water surface. They are the primary photosynthetic producers in marine food chains and store their food as lipids and polysaccharide leucosine. Since lipids have a lesser density than that of seawater, diatoms store oil or lipids in their vacuoles to maintain the buoyancy and thereby to float on water.
Protist used for the construction of sound proof rooms, is -
Cell of Diatoms are surrounded by cell wall having two parts or frustules; frustules make two overlapping halves (the epitheca and the hypotheca). Presence of numerous tiny pores in frustules connects the protoplast of the cell with the outside environment. The pectin substance of cell wall is richly impregnated with silica, which creates patterns of minute perforations and striations. Around 90 percent of diatomaceous cell wall is silica. Shells of diatoms are highly resistant to decomposition due to presence of silica and are deposited in ocean beds leading to formation of porous diatomaceous earth. It serves as porous acoustic material i.e. a solid material with cavities/channels to facilitate the entry of sound waves and their absorption with very little reflection. This makes option B correct. Dinoflagellates have armoured cellulosic cell wall while euglenoids lack cell wall but have pellicle which is a semi-rigid proteinaceous structure. Zooflagellates are protozoans that lack cell wall.
One of the following dinoflagellate is called night light :-
Dinoflagellates are characterized by the presence of pigment luciferin, which is acted upon by the enzyme luciferase, causing the production of light without any heat; the bioluminescence. Noctiluca is a dinoflagellate. It is a colourless phototroph in which bioluminescence was reported. It carries out photosynthesis in day and exhibits bioluminescence in the night as regulated by circadian rhythm; hence it is called as “night light”.
Auxospores are formed by -
Diatoms produced by a special type of spores which r know as auxospores. Dinoflagellates and euglenoids produce by binary fission, spore formation does not take place.
Protists which are diploid reproduce sexually by the process of -
Zygotic meiosis is meiosis of a zygote immediately after karyogamy, which is the fusion of two cell nuclei. This way, the organism ends its diploid phase and produces several haploid cells. These cells divide mitotically to form either larger, multicellular individuals, or more haploid cells.
Which is found in slime molds but not in fungi ?
Resembling an amoeba specifically in moving or changing in shape by means of protoplasmic flow. Amoeboid movement is the most common mode of locomotion in eukaryotic cells. It is a crawling-like type of movement accomplished by protrusion of cytoplasm of the cell involving the formation of pseudopodia ("false feet") and posterior uropods.
Photosynthetic protists are mainly -
Unicellular organisms fall into two general categories: prokaryotic organisms and eukaryotic organisms. Prokaryotes include bacteria and archaea. Many eukaryotes are multicellular, but the group includes the protozoa, unicellular algae, and unicellular fungi.
'Red tides' are produced by -
Dinoflagellate contains red pigment peridinin , on explosive growth of dinoflagellates the sea appears red.
Nucleus of Noctiluca is :-
A haploid organism carries the chromosomes number as is present in gametes of that organism, gametes contain half the chromosomes of the somatic cells. Option A is incorrect.
Noctiluca, a dinoflagellate, is a colourless phototroph which exhibits bioluminescence. Since, individual diatoms are diploids, hence, Noctiluca is a diploid protist carrying two complete sets of chromosomes. Option B is the correct answer.
A triploid organism carries three complete sets of chromosomes while a tetraploid organism carries four copies of complete chromosomal set. Options C and D are incorrect.
Therefore, the correct answer is option B.