b. They are the facultative parasites
d. Methanobacterium
The correctly matched pair is: a. Actinomycete – lumpy jaw, b. Mycoplasma – sandal spike, c. Bacteria – crown gall, d. Fungi – late blight. Lumpy jaw is a disease of cattle caused by Actinomycetes. Sandal spike disease affecting sandalwood trees is caused by Mycoplasma. Crown gall, a plant disease characterized by tumor-like growths, is caused by the bacterium Agrobacterium tumefaciens. Late blight of potato is a fungal disease caused by Phytophthora infestans.
a. Teichoic acid absent
a. lack of motile structure
Homoiomerous lichens have algal cells evenly and uniformly distributed throughout the entire thallus, mixed with fungal hyphae in a homogeneous manner without any distinct layering or organization. In contrast, heteromerous lichens display a distinct stratified structure with clearly defined layers: an upper cortex of fungal hyphae, a middle algal layer containing photosynthetic algal cells, and a lower cortex of fungal hyphae, with a medulla of loosely arranged hyphae in between. This structural difference affects their appearance, with homoiomerous lichens appearing more uniform and heteromerous lichens showing visible layering when sectioned.
The kingdom Monera encompasses all prokaryotic organisms, which are characterized by the absence of a true nucleus and other membrane-bound organelles. These organisms are typically microscopic and include diverse forms such as Mycoplasma, bacteria, actinomycetes, and cyanobacteria. Monerans exhibit various modes of nutrition; some are autotrophic, performing photosynthesis or chemosynthesis, while others are heterotrophic, acting as decomposers, parasites, or symbionts. Many bacteria, like Rhizobium, Azotobacter, and Clostridium, play a crucial role in the ecosystem by fixing atmospheric nitrogen into ammonia, making it available for plants. Some bacteria are pathogenic, causing diseases, while others live in symbiotic relationships, benefiting their hosts.
Farmers plant leguminous crops in crop rotations and mixed cropping systems because these plants form symbiotic associations with Rhizobium bacteria in their root nodules. Rhizobium is a nitrogen-fixing bacterium that converts atmospheric nitrogen into nitrates and other nitrogen compounds that enrich the soil and increase its fertility. When leguminous crops such as pulses, beans, or clover are grown alternately with non-leguminous crops like paddy or wheat, the soil nitrogen content is naturally replenished without requiring synthetic nitrogen fertilizers. In mixed cropping, leguminous plants are grown alongside other crops in the same field, simultaneously enriching the soil while other crops benefit from the increased nitrogen availability, thereby enhancing overall yield. This sustainable agricultural practice reduces dependence on chemical fertilizers, lowers farming costs, and maintains soil health over successive growing seasons.
a. Proposed by R.H. Whittaker (American taxonomist)
b. Criteria considered – cell structure, Thallus Organization, Mode of Nutrition, Reproduction, and Phytogenitic Relations.
5 kingdom classifications include: –
a. Monera b. Protista c. Fungi d. Plantae e. Animalia
S. No
Merits:
Demerits:
1.
Based on the complexity of cell structure & organization of thallus
Monera & Protista – Include both autotrophic & heterotrophic organisms
2.
Based on mode of nutrition.
Include cell wall lacking & cell wall
3.
Fungi-kept in a separate category from plants
Bearing organisms.
4.
It shows the phylogeny of the organisms
So the group is more heterogeneous
a. Definition: A symbolic association of algae and Fungi helping each other & living together known as lichens.
b. Partners: Algal partner known as Phycobiont & Fungal partner known as Mycobiont
c. Role of Algal partner – Autotrophic prepare food – give nutrition to fungal partner also
d. Role of fungal partner – gives protection- helps in fixing to the substratum by rhizines.
Classification:
Character
Phycobiont
Mycobiont
1
Asexual reproduction
Akinetes, hormogonia, Aplanospore, etc.
fragmentation soredia, and isidia
2
Sexual reproduction
absent
sexual reproduction by ascocarp & ascospores
Character
Classification of lichens
1.
Habitat
Corticolous – growing on the bark
Lichnicolous – growing on wood
Saxicolous – growing on rock
Terricolous – growing on the ground
Marine – siliceous rock sea
Freshwater – siliceous rocks (freshwater habitat).
2.
Morphology of thallus
Leprose – distinct fungal layer absent Crustose – crust like Foliose – Leaf-like Fruticose-branched pendulous shrub-like
3.
On the basis of the distribution of algae cells
Homoiomerous – Algae cells evenly distributed Heteromerous – A distinct layer of Algae and Fungi present
4.
On the basis of the fungal partner
If it is Ascomycetes – Ascolichen If it is basidiomycetes-Basidiolichen
Economic importance:
Secretion of acids of lichens
Uses
1
Oxalic acid
Weathering of rocks Pioneers in xerosere
2
Usnic acid
Antibacterial
II. a. Pollution Indicators – Lichens sensitive to air pollutants- (pollution indicators)
b. Rocella Montagne – Produces a dye used in litmus paper (acid-base indicator)
c. Cladonia rangiferina – Food for animals in tundra regions
Part – II.
11th Bio Botany Guide Living World Additional Important Questions and Answers
Choose The Right Answer:
- (a) 3.3
- (b) 5.6
- (c) 4.6
- (d) 5.9
(c) 4.6
c. Worker bees
- (a) Bacteria
- (b) Blue-green algae
- (c) Oedogonium
- (d) Nostoc
(c) Oedogonium
c. sexual reproduction
- (a) W.M. Stanley
- (b) Adolf Mayer
- (c) Robert Koch
- (d) Edward Jenner
(d) Edward Jenner
a. Chickenpox
d. Bacillus thuringiensis
- (a) 10 -9
- (b) 10 -6
- (c) 10 -5
- (d) 10 -12
(a) 10 -9
c. Monotropa
b.Penicillium camémberti
- (a) ss (or) ds
- (b) use of RT
- (c) capsid
- (d) sense or antisense
(c) capsid
d. Nucleic acids
C. Yoghurt
- (a) ssDNA
- (b) dsDNA
- (c) ssRNA
- (d) dsRNA
(a) ssDNA
Bacterial chlorophyll is also known as Chloridin. Unlike the chlorophyll found in plants, bacterial chlorophyll is a type of bacteriochlorophyll that absorbs light at longer wavelengths, typically in the infrared spectrum. This allows photosynthetic bacteria to utilize light energy that is not accessible to plants. Chloridin is the specific term used for this type of photosynthetic pigment found in certain bacteria.
Penicillin is the drug also known as the wonder drug. Discovered by Alexander Fleming in 1928, penicillin was the first widely used antibiotic and revolutionized medicine by effectively treating bacterial infections that were previously fatal. Its discovery marked the beginning of the antibiotic era and saved countless lives, earning it the designation of wonder drug due to its remarkable effectiveness and impact on human health.
- (a) host
- (b) ghost
- (c) capsid
- (d) capsomeres
(b) ghost
b. citrus canker
c. Bio-pesticide
- (a) viroids
- (b) virusoids
- (c) prions
- (d) viruses
(c) prions
b. Halobacterium
Budding is a unique feature of Schizosaccharomyces, a genus of yeast fungi. In budding, a small outgrowth or bud forms on the parent cell, which gradually enlarges and eventually separates to form a new independent daughter cell. This is an asexual mode of reproduction characteristic of certain yeasts and is distinct from the other reproduction methods seen in Aspergillus, Penicillium, and Neurospora.
- (a) blue-green algae
- (b) bacteria
- (c) fungi
- (d) cyanobacteria
(c) fungi
d. Heterocyst
c. Plasmid
- (a) Copeland
- (b) Theophrastus
- (c) Linnaeus
- (d) Haeckel
(d) Haeckel
d. It constantly changes its form
The correct arrangement of viruses according to shape and symmetry (cuboidal, spherical, helical, and complex respectively) is: III. a. Herpes (cuboidal/icosahedral), b. HIV (spherical), c. Influenza (helical), d. Vaccinovirus (complex). Herpes simplex virus has an icosahedral capsid structure. HIV is a spherical enveloped virus. Influenza virus has a helical nucleocapsid structure. Vaccinovirus is a complex brick-shaped virus with a complex internal structure.
Growth is an intrinsic property of all living organisms through which they increase in cell number and cell mass. It is an irreversible increase in size and dry weight of an organism resulting from the synthesis of new protoplasm and accumulation of biomass. Growth involves cell division and cell elongation, leading to an increase in the overall dimensions and complexity of the organism.
1796: Edward Jenner developed the first vaccine, using cowpox to provide immunity against smallpox. 1886: Adolf Mayer demonstrated that the sap from tobacco mosaic disease-infected leaves was infectious, suggesting a transmissible agent. 1892: Dimitry Ivanowsky provided evidence that viruses were smaller than bacteria by showing that the infectious agent could pass through fine porcelain filters that retained bacteria. 1898: Martinus Beijerinck independently confirmed Ivanowsky's findings and coined the term 'contagium vivum fluidum' (contagious living fluid), proposing that viruses were a distinct form of living agent. 1901: Karl Landsteiner and Erwin Popper discovered the first human virus, poliovirus. 1917: Felix d'Herelle discovered bacteriophages, viruses that infect bacteria. 1935: Wendell Stanley isolated and crystallized the Tobacco Mosaic Virus (TMV), showing it to be composed of nucleic acid and protein. 1953: James Watson and Francis Crick described the double helix structure of DNA, which was crucial for understanding viral genetic material. 1957: Robert Shane and colleagues identified the first human retrovirus, HTLV. 1960s: The development of electron microscopy allowed for the direct visualization of viruses. 1983: Luc Montagnier and Robert Gallo independently discovered the Human Immunodeficiency Virus (HIV), the causative agent of AIDS. 1990s: The advent of molecular biology techniques, including PCR and gene sequencing, revolutionized virology, enabling rapid identification and characterization of viruses.
The structure of Tobacco Mosaic Virus (TMV) consists of three main components: the nucleic acid, which is single-stranded RNA (ssRNA) forming the genetic material at the core; capsomeres, which are individual protein subunits that form the protective coat; and the capsid, which is the complete protein coat or shell composed of multiple capsomeres arranged in a helical pattern around the RNA core. The capsid provides protection to the genetic material and determines the overall helical shape characteristic of TMV.
Reproduction is the biological process and tendency of a living organism to perpetuate its own species and produce offspring. It is a fundamental characteristic of all living organisms. There are two main types of reproduction: asexual reproduction, in which a single parent produces genetically identical offspring without the fusion of gametes, and sexual reproduction, in which two parents contribute genetic material through the fusion of gametes to produce genetically diverse offspring.
Although bacteria are often associated with diseases in plants, animals, and humans, they are indeed beneficial organisms that play crucial roles in day-to-day life and various industries. In the dairy industry, lactic acid bacteria such as Lactobacillus acidophilus and Lactobacillus lactis are used to ferment milk and produce curd, butter, cheese, and yogurt, which are nutritious food products consumed worldwide. Beyond dairy, bacteria are essential in agriculture for nitrogen fixation through symbiotic relationships with leguminous plants, in biotechnology for producing antibiotics and vaccines, in waste decomposition and nutrient cycling, and in the production of various fermented foods and beverages. Bacteria also play vital roles in maintaining human gut health and digestion. These beneficial applications demonstrate that bacteria are indispensable microorganisms that contribute significantly to human welfare, food production, and environmental sustainability, making them true friends despite their disease-causing potential.
Ascomycetes, a diverse group of fungi, produce their sexual spores (ascospores) within specialized sac-like structures called asci. These asci are typically enclosed within fruiting bodies known as ascocarps. Four distinct types of ascocarps are recognized based on their structure and mode of development: Cleistothecium, which is a completely closed, spherical ascocarp; Perithecium, a flask-shaped ascocarp with a distinct opening called an ostiole; Apothecium, an open, cup-shaped or saucer-shaped ascocarp; and Pseudothecium, which resembles a perithecium but develops within a stroma.
- To relate on the basis of common features
- To define, on the basis of salient features
- To know the relationship among different groups.
- To understand evolutionary relationship.
- Ruggerio etal in 2015-published-7-kingdom system of classification
- It is an extension of Cavalier’s 6 – Kingdom Scheme’Include 2 superkingdom
In the lysogenic cycle, the injected phage DNA becomes circular and integrates into the bacterial chromosome through recombination. The integrated DNA of the phage within the bacterial chromosome is known as a prophage. The prophage remains dormant and replicates along with the bacterial chromosome during cell division. When the prophage is induced by certain environmental stresses or stimuli, it excises from the bacterial chromosome and enters the lytic cycle, leading to the production of new phage particles and lysis of the host cell. This integration and dormancy phase is a crucial part of the lysogenic life cycle of temperate bacteriophages.
Cyanophage
Mycophage
1
Vims infecting blue green Algae are known as
Cyanophage
Vims allacking fungi are called Mycovimses or
Mycophage
2
1st reported by Safferman and Mores(1963)
1st reported by Holling(1962)
3
Eg. Lyngbuya, Plectonema
Eg. Myc ovims attacking Mushrooms
Prokaryotic flagella are relatively small, measuring 20 to 30 nanometers in diameter and 15 micrometers in length. They have a simple structure composed of a single fibril made of the protein flagellin arranged in a helical pattern. Prokaryotic flagella can be present in many different positions on the cell surface, including peritrichous, lophotrichous, monotrichous, and amphitrichous arrangements. In contrast, eukaryotic flagella are much larger in size and have a complex internal structure. In cross-section, eukaryotic flagella contain nine pairs of microtubules arranged in a circle around two central microtubules, forming the characteristic 9+2 arrangement. Eukaryotic flagella are typically present in fewer numbers, usually one or two per cell. Despite these structural differences, both prokaryotic and eukaryotic flagella serve the same primary function of locomotion, enabling cells to move through their environment.
Photolithotrophs are organisms that derive energy from light and use inorganic compounds as electron donors for their metabolic processes. A key example is the green sulfur bacteria, such as Chlorobium, which utilize hydrogen sulfide (H₂S) as the hydrogen donor and possess bacterioviridin as their photosynthetic pigment, often located within chlorosomes. Purple sulfur bacteria are another type, using thiosulphate as the electron donor and employing bacterial chlorophyll. Photoorganotrophs, on the other hand, also utilize light for energy but obtain electrons from organic compounds. Purple non-sulfur bacteria, like Rhodospirillum, exemplify this group, using organic acids or alcohols as hydrogen donors. They possess bacterial chlorophyll within chlorosomes, similar to other photosynthetic bacteria.
Endospore formation is not a true reproduction method because it does not result in an increase in the number of organisms. Rather, endospores are resting spores formed by certain bacteria during unfavorable environmental conditions such as nutrient depletion, extreme temperatures, or desiccation. The bacterial cell develops a thick, protective wall around its DNA and cytoplasm to survive these harsh conditions. When favorable conditions return, the endospore germinates and develops back into a vegetative bacterial cell. Since one endospore produces only one bacterium upon germination, there is no multiplication of cells, which is a defining characteristic of reproduction. Therefore, endospore formation is better classified as a survival mechanism rather than a reproductive process.
Sexual reproduction in bacteria, unlike in higher organisms, does not involve the formation and fusion of gametes. Instead, genetic recombination, which leads to variations in the bacterial population, occurs through three primary mechanisms: conjugation, transduction, and transformation. Conjugation involves the direct transfer of genetic material from one bacterium to another through cell-to-cell contact, often mediated by a pilus. Transduction is the process where bacteriophages (viruses that infect bacteria) transfer bacterial DNA from one bacterium to another. Transformation occurs when a bacterium takes up free DNA from its environment, which may have been released by other lysed bacteria. These processes allow for the exchange of genetic information and contribute to bacterial evolution and adaptation.
- The type of bacteria oxidise in organic compound to release energy
- Eg Sulphur bacteria – Thiobacillus thio oxidants
- Iron bacteria – Ferrobacillus ferro oxidants
- Hydrogen bacteria – Hydrogenomonas
The diagram shows a bacterial cell undergoing conjugation. The labeled parts are: 1. F-plasmid: This is an extrachromosomal DNA molecule that carries genes essential for conjugation, including those for pilus formation. 2. Conjugation pilus: This is a protein appendage extending from the donor cell (F+ cell) to the recipient cell (F- cell), facilitating the transfer of genetic material. 3. Chromosome: This refers to the main bacterial chromosome, which is a circular DNA molecule located in the nucleoid region. 4. F+ cell: This designation indicates the donor bacterium, which possesses the F-plasmid and can initiate conjugation.
Escherichia coli is a bacterium that lives in the human intestine and produces large quantities of vitamin K and B-complex vitamins. These vitamins are synthesized by the bacteria and are beneficial to the host organism. Clostridium acetobutylicum is another important vitamin-yielding bacterium that produces vitamin B2. This bacterium is utilized in industrial fermentation processes where vitamin B2 is prepared through the fermentation of sugar substrates. Both of these bacteria are commercially and medically significant for their ability to synthesize essential vitamins.
Two bacterial diseases affecting potato plants are ringrot and scab. Ringrot is caused by the bacterium Clavibacter michiganensis subspecies sepedonicus. This disease causes necrotic lesions in the vascular tissues of the potato tuber, creating a ring-like pattern when the tuber is cut in cross-section. Scab is caused by the bacterium Streptomyces scabies. This disease produces rough, corky lesions on the surface of potato tubers, making them unsuitable for market. Both diseases are economically important and can significantly reduce potato yield and quality.
- Microorganism such as lactobacillus bifidobacterium when consume as a dietary supplement help to maintain or restores beneficial bacteria to the digestive tract. They are called friendly or good bacteria. They keep our gut healthy
- They help to increase the immunity of the body
- Eg: Probiotic Yoghurt
- Probiotie tooth paste.
- Actinomycetes are called as ray fungi due to their mycelia like growth
- They are anaerobic or facultative anaerobic
- They are gram + ve
- Don’t produce aerial mycelium
- DNA contain high guanine and cytosine content Eg strepotmyces
The figure shows the structure of mycoplasma, which is one of the smallest free-living prokaryotic organisms. The main structural components visible in the diagram are the cell membrane, which forms the outer boundary of the cell; ribosomes, which are the sites of protein synthesis; DNA strands, which contain the genetic material of the organism; and the cytoplasm, which is the gel-like substance filling the interior of the cell. Mycoplasmas lack a cell wall, having only a cell membrane, which distinguishes them from most other bacteria. This structural simplicity is one of the reasons mycoplasmas are among the smallest cellular organisms capable of independent reproduction.
Several renowned mycologists have made significant contributions to the field of mycology. Arthur H.R. Buller and John Webster are prominent Western mycologists known for their extensive work on fungi. D.L. Hawksworth and G.C. Ainsworth are also notable mycologists who have contributed substantially to fungal taxonomy and classification. In India, B. Mundkur, K.C. Mehta, C.V. Subramanian, and T.S. Sadasivam are recognized as important mycologists. E.J. Butler is regarded as the father of Indian mycology and made pioneering contributions to the study of fungi in India. These scientists have collectively advanced our understanding of fungal diversity, classification, and ecology.
The diagram illustrates asexual reproduction in Penicillium, specifically the formation of conidia. Conidia are asexual spores produced at the tips of specialized hyphae called conidiophores. The labeled parts are: Conidiophores, which are the erect, branching hyphae that bear the conidia; Ramus (plural: Rami), which are branches arising from the main conidiophore; Metula (plural: Metulae), which are branches arising from the ramus, bearing sterigmata; Sterigma (plural: Sterigmata), which are small projections from the metulae where conidia are attached; and Conidium or Conidiospore, which is the asexual spore itself.
Homeostasis is the property of self-regulation and the tendency of living organisms to maintain a relatively stable internal environment despite changes in the external environment. It involves the regulation of various physiological parameters such as body temperature, pH, osmotic pressure, and concentration of various ions and nutrients. Homeostasis is essential for living organisms because it allows them to maintain optimal conditions for biochemical reactions and metabolic processes. Without homeostasis, fluctuations in internal conditions would disrupt enzyme function and cellular processes, making survival impossible. For example, maintaining a constant body temperature allows enzymes to function at their optimal rates, and regulating blood pH ensures proper functioning of proteins and cellular processes. Homeostasis enables organisms to adapt to changing external environments and maintain the stability necessary for life processes to continue efficiently.
- Citric acid& Gluconic acid – Aspergillus niger
- Itaconicacid – Aspergillus terreus
- Kojicacid – Aspergillus oryzae
- Puffballs,
- Toadstools,
- Birds nest’s fungi,
- Bracket fungi,
- Smuts
- Rusts,
- Smuts.
Aflatoxins are carcinogenic toxins produced by certain fungi, particularly Aspergillus flavus. These fungi are commonly involved in the spoilage of food materials, especially dried foods such as grains, nuts, and seeds. Aspergillus flavus infests these dried food products and produces aflatoxins as secondary metabolites. Aflatoxins are highly toxic compounds that can cause serious health problems in humans and animals, including liver damage, immune suppression, and cancer. Other fungi such as Aspergillus parasiticus, Polyporus, Mucor, and Penicillium species are also involved in food spoilage, though Aspergillus flavus is the primary producer of aflatoxins. The presence of aflatoxins in food is a significant food safety concern, and proper storage conditions and food handling practices are essential to prevent fungal contamination and aflatoxin production.
- Trichophyton
- Tinea
- Microsporum
- Epidermophyton are some fungi causing skin problems
The question asks to order the systems of classification. While the provided answer 'a. C-D-B-A' is a selection, without the actual options for C, D, B, and A, it's impossible to provide a definitive explanation. However, generally, classification systems are ordered chronologically or by complexity. The two-kingdom system (Plantae and Animalia) is the oldest, followed by the three-kingdom system (adding Protista), then the four-kingdom system (often including Monera), and finally the five-kingdom system (Monera, Protista, Fungi, Plantae, Animalia) proposed by Whittaker, which is widely accepted. A correct ordering would typically reflect this progression.
The question asks to order specific biological terms. The provided answer 'b. D-A-B-C' is a selection. Without the actual options for D, A, B, and C, a precise explanation cannot be given. However, if we consider the terms: I. Genophore (bacterial chromosome), II. Bacteria (the organism), III. Extra Chromosomal DNA (like plasmids), and IV. Fimbrial (referring to fimbriae, which are hair-like appendages on bacteria), a logical ordering might relate to the structure and components of a bacterial cell. For instance, one might order them from the basic genetic material to the organism itself, or from internal structures to external ones.
The correct matching is: Plasmid corresponds to A (a small, circular, double-stranded DNA molecule found in bacteria), Heterocyst corresponds to B (a specialized nitrogen-fixing cell in cyanobacteria), Glycocalyx corresponds to D (a layer of polysaccharides surrounding the cell wall), and Mesosome corresponds to C (an infolding of the bacterial cell membrane involved in DNA replication and respiration). The answer is B-A-D-C.
The correct evaluation of these statements is: (i) Poly-B hydroxybutyrate is indeed a microbial plastic produced by certain bacteria and is biodegradable, making this statement True. (ii) Transduction refers to the transfer of DNA from one bacterium to another via bacteriophages, not direct bacterial transfer, making this statement False. (iii) Micrococcus is an obligate aerobe that requires oxygen to survive, making this statement True. (iv) Spirulina is rich in proteins and other nutrients, not primarily carbohydrates, and is used as a nutritional supplement and alternative food source, making this statement False. The correct answer is True, False, True, False.
Examining each statement: Chloromycetin from Streptomyces venezuelae is used to treat bacterial infections but not specifically tuberculosis. Bacitracin from Bacillus mycoides is used primarily for topical infections, not urinary tract infections. Aureomycin obtained from Streptomyces aureofaciens is indeed used to treat whooping cough and eye infections, making this the correct statement. Streptomycin from Streptomyces griseus is used to treat tuberculosis, not typhoid fever. Therefore, the correct answer is that Aureomycin got from Streptomyces aureofaciens is used to treat whooping cough and eye infections.
Sac fungi is the common name for Ascomycetes, which are characterized by their ascus-shaped spore-bearing structures. Club fungi is the common name for Basidiomycetes, which are characterized by their club-shaped basidium structures. Deuteromycetes and Phycomycetes have different common names and characteristics. Therefore, the correct answer is (i) a and b, referring to Ascomycetes and Basidiomycetes respectively.
Evaluating each statement: (i) Toadstools are actually poisonous or inedible mushrooms, not edible ones, making this False. (ii) Volvariella volvaceae and Agaricus bisporus are edible and cultivated mushrooms, not poisonous, making this False. (iii) Claviceps purpurea produces ergot, which contains ergotamine alkaloids used as a vasoconstrictor in medical applications, making this True. (iv) Aspergillus flavus infests dried foods and produces aflatoxin, a carcinogenic mycotoxin, making this True. The correct answer is False, False, True, True.
Mycoplasma are very small pleomorphic organisms measuring 0.1 to 0.5 micrometers, and they are gram-negative or gram-variable microorganisms. In culture, they characteristically appear with a boiled egg-like structure due to their lack of a cell wall. Mycoplasma cause diseases such as little leaf disease in tomato and witches' broom in Solanum species. Mycoplasma are also known as mollicutes because they lack a rigid cell wall. The correct statement is that Mycoplasma are very small (0.1-0.5 mm) pleomorphic gram-negative microorganisms, and all the other characteristics mentioned are also correct features of these organisms.
The recurrence of fungal skin diseases is primarily due to two factors. Dormant spores present in the skin can become active when favorable conditions such as warmth and humidity return, allowing the infection to recur. Additionally, moisture in the skin environment favors fungal mycelium growth and spread, creating conditions that support fungal proliferation. While antibiotic resistance and drug availability are considerations in bacterial infections, the main reasons for fungal disease recurrence are the activation of dormant spores and the moisture-rich environment that promotes fungal growth. The correct answer is (iii) b and d.
Regarding Tobacco Mosaic Virus (TMV), the correct statement is that the first visible symptom of TMV infection is the discoloration of leaves along the veins, characterized by a distinctive yellow and green mottled or mosaic pattern. This mosaic symptom is the hallmark of TMV infection and appears as irregular patches of light and dark green coloration on the leaves. While other statements may contain partial truths, the most accurate and complete description of TMV symptoms is the appearance of this characteristic mosaic pattern on infected leaves. The correct answer is b.
The question asks to identify symbiotic associations from the given options. Symbiosis refers to a close and long-term interaction between two different biological species. Option (a), nitrogen-fixing bacteria on leguminous plants, is a classic example of mutualism, a type of symbiosis where both partners benefit. Option (c), lichens on rocks, represents a symbiotic association between fungi and algae or cyanobacteria. Option (d), mycorrhizal roots, involves a mutualistic relationship between fungi and plant roots. Option (b), rhizoids of Neprolepis, are root-like structures for anchorage and absorption and do not represent a symbiotic association between different species. Therefore, the correct choice identifying symbiotic associations would include (a), (c), and (d). The provided answer 'VII. Find out the wrong statement' suggests that the original question might have been different, or this is a misinterpretation of the provided options and answer.
b. They are infectious particles of lipoprotein
Ribosomes are cellular structures that serve as the sites of protein synthesis in all cells. Statement (a) is true because ribosomes are indeed where translation occurs and proteins are synthesized. Statement (c) is true because prokaryotic ribosomes are 70S type consisting of two subunits, a 50S large subunit and a 30S small subunit. Statement (d) is true because multiple ribosomes attach to a single mRNA molecule and are held together by the mRNA, forming polyribosomes or polysomes, which allow simultaneous translation of the same mRNA. However, statement (b) is false because the number of ribosomes per cell is not limited to 1000 to 1500; cells can contain thousands to millions of ribosomes depending on the cell type and its protein synthesis activity. Therefore, the false statement is (b).
b. B-D-A-C
c. Methane bacteria
b. Citrus canker
d. Wound tumour virus
c. yeast
VIII. Read the following Assertion A and Reason R. Find the correct Answer
a. A & R correct R is explaining A.
c. A is true but R is wrong.
c. A is true but R is wrong
d. A is true but R is not explaining A.
I. Additional 2 Marks