Types of microorganisms - class-X

Hens egg is a single cell structure inside the shell before the fertilization that can be seen by naked eyes. But after fertilization, the cells fused and divide into two cells inside the shell.

Hence, option B is correct.

Bacteria are prokaryotes grouped in Kingdom Monera. Prokaryotes have a pro or primitive karyon. Thus the true nucleus is absent in bacteria. The chromosome, a single, continuous strand of DNA, is localized, but not contained, in a region of the cell called the nucleoid. All the other cellular components are scattered throughout the cytoplasm.

Nucleic acids constitute the genetic material and help in cellular expressions in bacteria, while proteins are important for constitutive activities in the bacterial cells. 15% of bacterial cell is protein, while 7% nucleic acids (DNA and RNA).
So answer is -'nucleic acid and proteins'.

An organism made of just one cell is called an unicellular organism. Bacteria, Amoeba,  Paramoecium and Euglena are some examples of unicellular organisms.

The mucilage capsule present in bacteria serving as an extra covering is present outside the cell because it is a temporary layer surrounding the cell wall and protects the bacteria from antibiotics and dessication.

Bacteria exhibit diverse metabolic types regarding oxygen requirements. They include strictly aerobic, strictly anaerobic, facultative anaerobic, and microaerophilic forms, encompassing both aerobic and non-aerobic categories.

Oidia are asexual spores in fungi that resemble yeast cells and undergo fermentation similarly.

Yeast cells are typically killed by alcohol concentrations around 12-14 percent, not 31 percent. Prolonged fermentation does not indefinitely increase alcohol content because the yeast dies.

Bacterial genome as that of a bacteria E.coli consists of Double-stranded DNA (ds DNA) which is circular which means it doesn't have ends like eukaryotic chromosomes. E.coli consists of 4.6 x 10$^6$ base pairs(bp).

In ascomycetes fungi, which include yeasts, sexual spores are produced endogenously inside a sac called an ascus and are known as ascospores. These spores are nonmotile.

• Eukaryotic cilia and flagella have similar organization-
• They possess a central bundle of microtubules called the axoneme which contain nine outer doublet microtubules surrounded by a central pair of singlet microtubules.
• This characteristic 9 + 2 arrangement of microtubules is seen when the axoneme of eukaryotic flagella.
  
• The correct answer is OPTION B.

Peptidoglycans (or mucopeptide or glycopeptide or murein) are the structural elements of almost all bacterial cell walls. They constitute as much as 95% of the cell wall in some Gram positive bacteria to as little as 5 to 10% in Gram negative bacteria. Peptidoglycans are made up of a polysaccharide backbone consisting of alternating muramic acid and glucose amine residues in equal amounts.

Monascus purpureus produces statins which act as blood-cholesterol lowering agents. Aspergillus niger produces citric acid, and Trichoderma polysporum produces cyclosporin-A used as an immunosuppressive agent.

Myxobacteria are a group of bacteria that typically lack flagella and move by gliding over surfaces, often forming complex multicellular fruiting bodies. Spirochetes move via axial filaments, and eubacteria frequently possess flagella.

Bacteroids are the differentiated, non-motile form of Rhizobium bacteria found within the root nodules of legumes, where they fix nitrogen.

Membrane bound organelles are absent in prokaryotes. As compared to a eukaryotic cell, the only comparable organelles present in prokaryotes are ribosomes which are naked nucleoprotein particles. Plasmodium is a unicellular eukaryotic organism which belongs to Kingdom Protista. Saccharomyces is also a unicellular eukaryotic organism which belongs to Kingdom Mycota or Fungi. Streptococcus is a unicellular prokaryotic organism which belongs to Kingdom Monera. Chlamydomonas is a unicellular eukaryotic organism, previously classified under Kingdom Plantae as Chlorophyceae but has now been moved to Kingdom Protista. Of the given options only Streptococcus is a prokaryotic organism. Hence, membrane bound cell organelles are missing in Streptococcus.

Yeasts are single-celled eukaryotic microorganisms classified as members of the kingdom Fungi. They are distinct from bacteria (prokaryotes) and protozoa.

An Amoeba is a type of organism belongs to kingdom Protista. They have the ability to alter its shape, primarily by extending and retracting pseudopods. Amoeba has contractile vacuole which expels excess water from the cell. The various processes which are involved in the nutrition of Amoeba are:
Ingestion, digestion, absorption, assimilation and egestion. Amoeba has not excretory organs. The undigested food collects inside the Amoeba is thrown out of the body by the cell membrane. Thus, the correct answer is option A.

Leukemia is a cancer of the blood-forming tissues and does not typically form a solid tumor mass like other cancers.

  E. coli , a gram negative rod shaped bacteria has since the time of discovery have been commonly used for biological lab experiment and research. The simple cell structured E. coli has one circular chromosome and a ds circular DNA molecule with 4.6 million base pairs in length and 4288 protein coding genes.

The cell walls of bacteria are composed of a macromolecule peptidoglycan which is a repeating framework of long glycan chains having alternate N-acetyl glucosamine and N-acetyl muramic acid; these glycan chains are cross-linked by short peptide fragments to provide a strong but flexible support framework. This makes option A correct. The green algal cell wall is composed mainly of cellulose which makes option B incorrect. Chitin is common constituent of cell walls of all type of fungi; option C is incorrect. The yeast cell wall itself is mainly composed of glucans ($\beta$$-glucans), mannoproteins and chitin; option D is incorrect. Thus, the correct answer is option A.

Amoeba is a protozoan belonging to the kingdom Protista. They are unicellular eukaryotic organisms and thus, made up of single cell.

Microorganisms are the organisms that we cannot see by our naked eyes. It can be prokaryotic unicellular like bacteria, eukaryotic unicellular like protozoa, eukaryotic multicellular like fungi and algae and even acellular like viruses.

Thus, the correct answer is option C.

Unicellular organisms are made up of a single cell and perform all the life processes for survival and independent existence.  Hence, the cell is called as the fundamental structural and functional unit of life.

Pili are minute hair like appendages, that emerges from suface of Gram -ve bacteria. They have similar structure as flagella and often involved in attachment to surface and making of biofilm. They also help in DNA exchange. They are involved in conjugation which results in transfer or exchange of genetic material. 

Escherichia coli is a rod-shaped, gram-negative bacterium that is typically 1-3 micrometers in length.

The reproduction in amoeba is asexual, called binary fission, where it replicated its cells by mitosis and its cell divide in two equal daughter cells. Amitosis is similar to binary fission. Meiosis does not take place in amoeba.

The correct answer is B. 

Amoeba takes its food by the method of phagocytosis (i.e ingesting or engulfing the food particles), also by means of pinocytosis (wherein amoeba wraps around its membranes around the food forms vesicles and pinch it inside the membrane and then gradually digests it) and by endocytosis (in which the outermost the membrane of amoeba either stretches inwards or projects outwards to obtain nutrition.

The correct answer is D.

Amoeba is a unicellular organism; therefore, it lacks the complex histological differentiation found in multicellular organisms like Hydra, cockroaches, or earthworms.

Some bacteria, such as cyanobacteria, are photosynthetic and contain chlorophyll, which led to their historical classification as plants.

In bacteria the site for respiratory activity is found in mesosomes. Mesosomes are folded invaginations in the cell membrane of bacteria. They increases the surface area required for respiration. They contain respiratory enzymes. It is the site of respiratory activity.

F-factor is also called as fertility factor. It is the sex factor of bacteria. It allows the transfers of genes from one bacterium carrying the factor to another bacterium lacking the factor by the process of conjugation. It is found in some bacteria only.

The bacterial cell wall is made up of Peptidoglycan or murein. It is a polymer that is made up of sugars and amino acids. The sugar component is made up of alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM). NAM is then attached to an amino acid chain of L-alanine, D-glutamic acid, diaminopimelic acid (DAP) and D-alanine. 

Bacteria is a unicellular prokaryotic organism. It has a cell wall around the cell membrane. The bacterial cell membrane is made up of proteins and phospholipids. the proteins in are randomly distributed in the phospholipid bilayer of the cell membrane.

Teichoic acids are characteristic components of the cell wall of Gram-positive bacteria. Pneumococcus is a well-known Gram-positive bacterium, whereas the others listed do not possess this specific cell wall structure.

Some bacteria have a capsule outside cell wall. It is made up of mucopolysaccharide. The functions of mucopolysaccharide are;

• Bacterial capsule usually consists of a polysaccharide layer that lies outside the cell envelope. The capsule is found in both gram-positive and gram-negative bacterium.
• The capsule is considered as virulence factor because it enhances the ability of bacteria to cause disease. It protects the bacterial cell from engulfment by macrophages.
• Capsules also contain water which protects the bacterium from desiccation.

The ageing is very slow or is not seen with the human eye in unicellular organisms but they do age. They undergo constant spontaneous DNA damage that can lead to the death of cells when it no longer able to reproduce. Plants and parrot are multicellular organisms with the higher level of complexity. The complexity is such that cell divisions are limited and when the cell is not able to divide, it ages with the decay of organelles and finally dies. So these organisms do age and die after a perticular period of time. but Hydra is the only species that does not age and lose its capability to reproduce. So we can say that ageing is slow or absent in hydra.

Bacterial ribosomes are 70S, consisting of 30S and 50S subunits. The statement claiming they are 30 nm by 50 nm is incorrect as these numbers refer to the Svedberg units of the subunits, not the physical dimensions in nanometers.

• Mesosomes are absent in eukaryotes.
• Mesosomes refers to the folded invaginations in the plasma membrane of prokaryotes or bacterial cells.
  
• Its main function is to increase the surface area of the plasma membrane. 
• When the surface area of the membrane is increased it helps to carry out the cellular respiration more efficiently.
  
• So, the correct answer is 'Mesosome'.

Escherichia coli is a Gram-negative, facultatively anaerobic bacteria. It is found in the intestine of warm-blooded organisms. It has one circular chromosome. The chromosome contains double-stranded DNA. It may contain some circular plasmids as well as extrachromosomal material.

• Mitochondria are absent in bacteria and blue-green algae.
  
• A prokaryotic cell lacks membrane-bound cell organelles and nucleus whereas, a eukaryotic cell consists of membrane-bound cellular organelles and well-defined nucleus.
  
• Red algae, green algae and brown algae have eukaryotic cells (well-defined nucleus and cellular organelles).
• So, the correct answer is 'Bacteria'.

Acetabularia is a single-celled green photosynthetic algae which contain chloroplasts of the photosynthetic function. Being unicellular it has a complex shape and has been a model organism for the study of gene expression with morphogenesis. It has a large nucleus which contains a genetic material. Because of the presence of nucleus which is absent in prokaryote, these algae is classified in eukaryotes. hence algae Acetabularia is a unicellular eukaryote.

A. Amphitrichous bacteria have flagella (single or multiple) extending from both ends of the cell.

Amphitrichous bacteria possess a single flagellum or a tuft of flagella at both poles of the cell. This distinguishes them from peritrichous (all over) or lophotrichous (tuft at one end) arrangements.

Amoeba is a unicellular organism. The main waste material in amoeba ammonia (NH$ _3$) along with carbon dioxide (CO$ _2$). The waste material is excreted through body surface (plasmalema) by the process of diffusion. In this process, contractile vacuoles play important role.

Entamoeba histolytica is a protozoan protist. It is pathogenic in nature. It resides in the upper part of the human large intestine and causes the disease known as amoebic dysentery or amoebiasis. The symptoms of the disease are abdominal pain, repeated motions with blood and mucus. Entamoeba histolytica is transmitted through food or water contaminated with cysts. A mature cyst is called quadri-nucleate cyst. It has four nuclei and two chromatid bodies. Quadrinucleate cyst is the infective stage.

Entamoeba histolytica is a protozoan protist. It is pathogenic in nature. The type of nutrition present in Entamoeba is parasitic. The parasite is generally with one pseudopodium. The contractile vacuole is absent as there is no need of osmoregulation. It feeds on red blood corpuscles by damaging the wall of the large intestine and reaching the blood capillaries. It produces ulcers. It resides in the upper part of the human large intestine and causes the disease known as amoebic dysentery or amoebiasis. Entamoeba histolytica is transmitted through food or water contaminated with cysts. A mature cyst is called quadri-nucleate cyst. It has four nuclei and two chromatid bodies. Quadrinucleate cyst is the infective stage. Only one young Amoeba with four nuclei hatches out from a cyst of Entamoeba histolytica. However, single cyst of Entamoeba histolytica produces eight Amoebae.

Carl Woese proposed the three-domain system based on ribosomal RNA sequences, which serves as a measure of genetic relatedness (phylogeny) among organisms.

Rhodopseudomonas and Rhodospirillum are photosynthetic bacteria that belong to the group of purple non-sulphur bacteria, which use organic compounds as electron donors.

Yeast perform alcoholic fermentation primarily to regenerate NAD+ from NADH, which is essential for the continuation of glycolysis and the production of ATP under anaerobic conditions.

Cell division is the process in which a parent cell divides into two or more daughter cells. The unicellular organism divides and results in the formation of daughter cells and hence, cell division is a type of reproduction in unicellular organisms. Thus, the correct answer is option A.

Bacteria have three mechanism for genetic information transfer without undergoing reproduction-
1. Transformation- take up free fragment of DNA floating in medium. 
2. Transduction- transfer of DNA by a virus bacteriophage.
3. Conjugation- direct cell to cell transfer of DNA mediated by plasmid. So, option C is correct, all other options depend on reproduction for exchange of genetic material.

Amoeba and Paramecium are both unicellular protists. Similarly, Rhizopus (a fungus) and Chlamydomonas (an alga) are both eukaryotic microorganisms, though the relationship is broader than the original pair.

Glycocalyx is the outermost layer of the cell envelope. Cell wall lies between plasma membrane and glycocalyx.

Amoeba and yeast undergo asexual reproduction via fission and budding, respectively, because they are single-celled (unicellular) organisms. Multicellular organisms typically have more complex reproductive strategies.

Bentinckia nicobarica is an endangered palm endemic to the Nicobar Islands, and the red panda is an endangered mammal found in the Himalayas, making this pair represent endangered organisms in India. Other options mix widespread or different conservation status species.

Superbugs is a term used to describe strains of bacteria that are resistant to the majority of antibiotics commonly used today. These resistant bacteria can cause pneumonia, urinary tract infections, skin infections and many other diseases that are difficult to treat and may be fatal.

An anaerobic organism or anaerobic bacteria is any organism that does not require oxygen for growth. It may react negatively or even die if oxygen is present. Mitochondria, Golgi body and ER are organelles of eukaryotic organisms. Since anaerobic bacteria is prokaryotic, they are absent in anaerobic bacteria.

Denitrifying bacteria convert nitrates in the soil to free atmospheric nitrogen, nitrogen-fixing bacteria are heterotrophs.

Viruses can be made into a crystalline form. TMV became the first virus to be crystallized in 1935. One crystal of viruses consists of thousands of viruses. The crystallization of viruses was first done by Stanley. Algae, Amoeba and Sperm cannot be crystallised.

The correct answer is C.

All viruses live inside host cell, they cannot function outside the cell. Unlike bacteria which rarely live in the host cell. Therefore, (c) is the correct answer.

Virus is the microorganisms which have properties of living and non-living both. They have a specific structure which consists of head and tail. Head is composed of several protein units known as capsomeres which enclose the genetic material made up of RNA or DNA. They have a lipid envelope derived from the host cell membrane which lies outside the capsomere. They occur in crystalline form outside the body of the host but as it enters the host cell it injects its genetic material which replicates vigorously. The replicated materials are further packed in the new protein coat formed using host protein and is thrown out by the lysis of cell membrane.

There are $5$ codes of nomenclatures:- 

A virus is a small infectious agent, that replicates only inside the living cells of other organisms. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. All viruses are obligate parasites; i.e., they lack metabolic machinery of their own to generate energy or to synthesize proteins, so they depend on host cells to carry out these vital functions. Thus, option C is correct.
Viruses do not possess their own metabolic system. So, depends on host machinery. Thus, option A is wrong.
All viruses contains either DNA or RNA as genetic material but, not both. Thus, option B is wrong.
The protein coat of virus is called as capsid. Thus, option D is wrong.

Viruses play an important role in horizontal gene transfer and genetic diversity. The evolution history showcases the origin of viruses as to have evolved from plasmids when pieces
of DNA moved between cells. As
big bits of cellular DNA became independent and some DNA stuck with cell genomes. Thus, the correct answer is option D.

• A virus is an organism that can be considered both living and non-living. 
• It can be considered as living when it is inside any host (bacterium) as the virus infects the host cell and replicates inside it making several copies of it. 
• When it is outside the host cell, it is non- living as it can not carry out its life- processes of either reproducing or digestion etc.
• Thus, option A is correct here.

Viruses are non-cellular organisms and replicate only when they infect the host cell. 

Reproducing is one of the characteristics of the living organisms. Viruses definitely multiply. Viruses must use host cells to create more virions. Since viruses don’t have organelles, nuclei or even ribosomes, they don’t have the tools they need to copy their genes and create whole new virions. Instead, viruses enter living cells and then hijack the host’s cellular equipment to copy viral genetic information, build new capsids and assemble everything together. So, the correct answer is 'They can reproduce'.

The algae posses the chlorophyll pigments in the cells which allow these organisms to prepare the food by the process of photosynthesis. They are autotrophic because they can prepare the food on their own. The fungi are the heterotrophic or saprophytic organisms as they do not possess the chlorophyll pigments. They cannot prepare the food and depend on the other sources for food. 

An organism that is capable of synthesizing its own food from inorganic substances using light or chemical energy is called as autotrophic organism. It includes green plants, algae and certain bacteria. Algae are photoautotrophs meanings they use light as the source of energy to prepare their food.

Viruses are obligate filterable parasites capable of independent existence and when they enter inside the body of the host they start utilising the host machinery for its own reproduction. 

The answer is option A "It can carry out photosynthesis"
Because organisms that carry out photosynthesis to make their own food are called autotrophic. Algae contain chlorophyll pigments which helps them to trap energy from sunlight to form glucose (food) on their own.
While option B represents a feature of heterotrophs and option C for carnivores that eat insects.

Algae are single-celled, aquatic, microscopic plants. As they can make their own food, they are considered as plants. They contain photosynthetic pigment, chlorophyll-like plants. However, they do not have root, leaves and stems, unlike plants.

Creutzfeldt-Jakob disease (CJD) is caused by infectious protein particle called prions.

• Approximately around 70% of viruses infecting plant are ssRNA, 20% are ssDNA and rest are either dsRNA or dsDNA.
  
• ssDNA is advantageous due to it's ability to infect and duplicate it's genome faster.
  

The current scientific consensus suggests that viruses may have originated from primitive nucleic acid and protein molecules that evolved to become self-replicating entities.

Restriction endonucleases are enzymes that cut DNA at specific recognition sites and are naturally found in bacteria, where they serve as a defense mechanism against bacteriophage infection.