Practice Questions

Ivanowsky discovered viruses as micro-organisms on tobacco plant and are smaller than bacterium. Later M W Beijerinek termed them as “Viruses” which means venom or poison. W M Stanley for the first time proved that viruses are crystalline like structures and these crystals are made of protein rich sheaths.

Viruses can’t perform any of the metabolic activities when outside a living host. So, they are non-living organisms. Viruses don’t even consist of a cell and so acellular. They are in fact smaller than that of a bacterium and can even infect them.

Viruses can perform all of their metabolic activities except

Unlike organisms in the other five kingdoms which are living, viruses are non-living organisms. They don’t even have basic unit of life i.e. cell. Hence, they are not categorized in any of the kingdoms.

There are already more than thousands of organisms in the five kingdoms and hence, no space to include viruses

Viruses reproduce rapidly which is in fact weird and therefore they are not classified under any of the five kingdoms

Viruses are so small that they can’t be studied

Viruses that infect plants called as plant viruses have single stranded RNA. Animal viruses contain a single/ double stranded RNA or a double stranded DNA. Bacteriophages have double stranded DNA

Viruses are smaller when compared to bacterium. Viruses can infect bacterium are called bacteriophages. Bacteriophages contain double stranded DNA (Deoxy ribonucleic acid).

Coenocytic hyphae are also known as nonseptate hyphae and hence have no septa.

The hyphal walls of fungi consist of microfibrils composed for the most part of hemicellulose or chitin; true cellulose occurs only in the walls of lower fungi.

Fungi are eucaryotic spore-bearing protists that lack chlorophyll. They are of great practical and scientific interest to microbiologists.

Oidia or arthrospores are single-celled spores formed by disjointing of hyphal cells.

Basidiospores are single-celled spores borne on a club-shaped structure called a basidium.

Rhizopus also called as bread mold belongs to Phycomycetes or conjugation fungi. Other well known examples of Phycomycetes or Conjugation fungi are Mucor and Albugo (Mustard fungi).

Asexual spores in Ascomycetes are called Conidia and are produced exogenously by conidiocarps. Sexual spores in Ascomycetes are called Ascospores and are produced endogenously in asci present inside Ascocarps.

Non-motile spores in Phycomycetes are called as Aplanospores and motile spores are known as Zoospores. Fusion of similar or dissimilar gametes through sexual mode results in Zygospores.

Puccina is also called as Rust fungi and is an example of Basidiomycetes. Albugo is also known as Mustard fungi and is an example of Phycomycetes. Rhizopus which is an example of Phycomycetes is also called as Bread mold.

Pencillium belongs to Ascomycetes. Other well-known examples of Ascomycetes comprise of yeast, aspergillus and Neurospora. Pencillium is also used in preparation of drugs like Penicillin.

Budding is an asexual mode of reproduction where an outgrowth from the parent splits to form the daughter organism. Fragmentation is another mode of asexual reproduction where the parent organisms splits into fragments and then develops into a new organism. Binary fission is an asexual mode of reproduction where cytoplasm and nuclei splits into two equal parts to form two daughter nuclei.

an asexual mode of reproduction where an outgrowth from the parent splits to form the daughter organism

an asexual mode of reproduction where the parent organisms splits into fragments and then develops into a new organism

an asexual mode of reproduction where cytoplasm and nuclei splits into two equal parts to form two daughter nuclei

Lice in humans are example of exo-symbiosis. Fungi are heterotrophic and can be either saprophytic or parasitic. Some of the parasitic fungi can cause diseases in humans. Lichens are an example of obligative symbiosis. Cell wall of fungi is made of chitin and polysaccharides.

Some parasitic fungi can cause disease in humans

Lichens are an example of obligative symbiosis

Lice in humans are example for endo-symbiosis

Cell wall of fungi is made of polysaccharides

symbiotic existence of blue-green algae and fungi

symbiotic existence of rhizobium bacteria in the roots of leguminous plants

co-existence of coral reef with zooxanthellae

existence of mycorrhiza along with leguminous plants

Mycology is the study of fungus organ sums that cause disease in humans. 
Micology also has important applications in the diary, wine and baking industries and in the production of dyes and inks

Some mushrooms are poisonous and symptoms range from mild gastrointestinal discomfort to death. For example, a wild species of mushroom, Amanita phalloides, famously known as the ‘death cap,’ contains amatoxins that cause severe gastroenteritis and hepatic necrosis

Dikaryon is formed due to karyogamy. Sexual cycle of fungi comprises of 3 main steps: Plasmogamy, Karyogamy and Meiosis. Fungus prefers sexual reproduction over asexual reproduction during adverse environmental conditions. Initially, the cytoplasm of both the cells fuse which is called plasmogamy and followed by fusion of nuclei to form a diploid zygote called dikaryon. Later dikaryon undergoes meiosis in order to produce haploid spores.

Dikaryon is formed by fusion of two nuclei

Dikaryon is haploid nuclei formed due to fusion of two nuclei

It further undergoes meiosis to form haploid cells

Dikaryon is formed only during adverse environmental conditions

The word “coeno” means common and “cytic” means cytoplasm. Therefore the word “coenocytic” means sharing of common cytoplasm. Aseptate fungi have multiple nuclei in a common cytoplasm.

During reproduction of fungus through fragmentation, Mycelium separates into pieces which in turn grow to form new mycelium. Fragmentation is one of the most common modes of asexual reproduction in Basidiomycetes.

Mycelium separates into pieces which in turn form new one

Germ cells separate into pieces which in turn form new one

Zoospores are formed which further germinates to form new mycelium

Zygospores are formed which further germinates to form new mycelium

Diploid cell refers to the cells with two set of chromosomes. Haploid cells refer to the cells that have only a single set of chromosomes. The number of chromosomes in a haploid cell is half that of a diploid cell. Germ cells are haploid.

The word “karyo” means nucleus and “gamy” means fusion. Therefore the word “karyogamy” refers to the fusion of nuclei. In the sexual cycle of fungus to form spores, plasmogamy is followed by karyogamy and then by meiosis.

Fungus reproduces through asexual mode during favourable conditions and opts sexual mode of reproduction only during adverse situations. Budding, fragmentation and spore formation are different modes of asexual reproduction. Zoospores and zygospores are produced by phycospores for asexual and sexual odes of reproduction respectively.

Red tide is caused by a rapid increase in the population of microscopic algae, or phytoplankton, in coastal waters. This phenomenon is also known as an algal bloom.

Whirling whips are a type of protist known as dinoflagellates, which are named for the way their two flagella beat in opposite directions to produce a whirling motion

Chrysophytes, also known as golden algae, are a type of algae that are commonly found in lakes. They are often unicellular and have a flagellum that helps them move in water. Some species of chrysophytes are colorless, but most are photosynthetic.

Diatoms are photosynthesising algae, they have a siliceous skeleton and are found in almost every aquatic environment including fresh and marine waters, soils, in fact almost anywhere moist.

Diatoms are primarily produced in the oceans

Diatoms are microscopic and float passively in the water

Diatomaceous earth is formed by the cell walls of diatoms

Binary fission:
Paramecium reproduces asexually through binary fission, where the parent cell splits into two cells along its middle.
Conjugation:
Paramecium reproduces sexually through conjugation, where two Paramecia exchange genetic material. In this process, one Paramecium uses a thread-like structure called a pilus to transfer DNA to the other Paramecium.

Diatoms store food as oil. Plants store their food as starch. Diatoms are the main food producing bodies in oceans. They prepare food by photosynthesis.

Dianoflagellates have a complex cell wall made up of cortex. They also possess light sensitive organelle in their cell. Eye spot is found in some of them. Erythropsidium is known to have smallest eye.

Chrysophytes comprise of diatoms and golden algae (desmids). Desmids are unicellular eukaryotes and can prepare their own food by photosynthesis. Desmids reproduce both by sexually and asexually.

Red tide is the coloration of water due to very rapid multiplication of red dianoflagellates like Gonyaulax. Chemicals released due to this rapid growth are harmful for aquatic life.

Red tide is the coloration of water due to very rapid multiplication of red dianoflagellates. Chemicals released due to this rapid growth are harmful for aquatic life.

Accumulation of cell wall deposits of red algae is called red tide

Coloration of water due to rapid multiplication of red dianoflagellates

Spread of chrysophytes due to rapid reproduction

Chrysophytes are found in aquatic habitats. They are present in fresh water as well as marine. Chrysophytes Are microscopic in nature and float in water currents like planktons.

Diatomaceous earth is used in pest control and grain storage. This is because they are abrasive in nature which snatches out lipids from the outermost layer of pests called cuticle and makes them dry which results in their death.

it contains silica which is poisonous for pests when eaten and therefore they die

it snatches out lipids from the outermost waxy layer of pests called cuticle and makes them dry which results in their death

it acts as anesthesia when given in minor quantities but pests die when large quantities are in taken

Diatoms are grouped under Chrysophytes. Chrysophytes comprise of golden algae, diatoms and plant like protists etc. It’s because of the golden-yellow color of the species they are named as Chrysophytes.

Since, Protozoans are mobile and can ingest food into their body they resemble animals. Some of the protozoans follow holozoic nutrition like that of animals. Therefore, Protozoans are animal like protists.

Escherichia coli is a rod-shaped bacterium present in the digestive tract of warm-blooded animals like human beings and is responsible for the indigestion problems in humans.

Vibrio are aquatic microorganisms that are gram-negative, highly motile, and have a single polar flagellum

Organisms that are found in the dead sea withstand High salinities. These organisms are referred to as Halophiles.

A virus infects a bacteria, releases viral particles that carry some of the bacterial genetic material, and then transfers that genetic material to another bacterial cell. This process is mediated by a bacteriophage, which is a bacterial virus.

transfer of genes from one to another bacteria by conjugation

transfer of some genes from one to another bacteria through virus

bacteria obtained DNA from other external sources

bacteria obtain its DNA from the mother cell

• 1972 ൽ കണ്ടെത്തിയ ANWJ ആൻറിജൻ ഗ്രൂപ്പിൽ നടത്തിയ ഗവേഷണത്തിലാണ് പുതിയ രക്തഗ്രൂപ്പ് കണ്ടെത്തിയത് 

• രക്തഗ്രൂപ്പ് കണ്ടെത്തിയത് - ബ്രിട്ടനിലെ NHS Blood and Transplant ലെ ശാസ്ത്രജ്ഞർ 

• ബ്രിസ്റ്റോൾ സർവ്വകലാശാലയുടെ പിന്തുണയോടെയാണ് ഗവേഷണം നടത്തിയത്

Mycoplasma
Mycoplasma is a bacteria that can infect different parts of our body. Which body part is affected our Lungs, skin or urinary tract depends on which type of mycoplasma bacteria is causing our infection. 
All mycoplasma infections have one thing in common though. Unlike other bacteria, mycoplasma do not have a cell walls. They are also very small compared  to other bacteria.That's important because many antibiotics kill bacteria by weakening those walls. Since mycoplasma bacteria don't have them, some antibiotics, like penicillin, won't work against them.

Parasites obtain food from the host. Heterotrophs obtain food from autotrophs. Saprophytes feed on dead and decay matter. Autotrophs prepare their own food either by using light energy or chemical energy. Pseudomonades are Heterotrophs.

Archaebacteria have a rigid cell wall which helps them to survive in extreme conditions like high salt concentration (halophiles) and very high temperature (thermophiles).

complex metabolic reactions in their body

fact that they are the oldest life forms on the earth

Cyanobacteria contain chlorophyll which helps to perform photosynthesis and in turn enrich the oxygen levels in the atmosphere. The word “cyano” in cyanobacteria means blue-green algae and therefore they are also called as blue-green algae.

The word cyano means greenish-blue because of which cyanobacteria is also called as blue-green algae

The colour of cyanobacteria is due to presence of chlorophyll

Cyanobacteria are chemosynthetic autotrophs

Cyanobacteria help in enriching oxygen levels in the atmosphere

Bacteria adopt different modes of nutrition like photosynthetic, chemosynthetic, saprophytic and parasitic. Chemosynthetic autotrophs prepare their own food by obtaining energy from organic substances.

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