bacteria Flashcards

Question

What is the purpose of the decolorizer in the Gram staining procedure?

Answer 1

Differentiates between gram-positive and gram-negative bacteria ## Footnote Gram-positive bacteria retain the crystal violet-iodine complex, while gram-negative bacteria are decolorized.

Answer 2

Purple ## Footnote Gram-positive bacteria retain the primary stain.

Answer 3

Pink ## Footnote Gram-negative bacteria are stained by the counter stain safranin after decolorization.

Answer 4

Classifying viruses according to their genomes and mode of replication ## Footnote It creates seven groups of viruses based on common genetics and biology.

Answer 5

Naked viruses and enveloped viruses ## Footnote Naked viruses consist only of nucleic acid and capsid, while enveloped viruses have a lipid layer.

Answer 6

The specific species of organisms that a virus can infect ## Footnote Most viruses infect only specific hosts and cell types.

Answer 7

Viruses that infect bacteria ## Footnote The term 'phage' comes from the Greek word meaning 'devour'.

Answer 8

It surrounds the viral genome and is made of protein subunits called capsomeres ## Footnote Capsids protect the viral genetic material and aid in the infection of host cells.

Answer 9

* Bacillus (rod shape) * Coccus (spherical shape) * Spirilla (spiral shape) * Vibrio (curved shape) ## Footnote These shapes help in the identification and classification of bacteria.

Answer 10

* Infectious, acellular pathogens * Obligate intracellular parasites * DNA or RNA genome (never both) * Lack genes for many products needed for reproduction ## Footnote These characteristics define the unique nature of viruses compared to living organisms.

Answer 11

* Monotrichous * Lophotrichous * Amphitrichous * Peritrichous ## Footnote These distributions describe the arrangement of flagella on bacterial cells.

Answer 12

* Mechanical transmission * Biological transmission ## Footnote Mechanical transmission occurs via physical contact, while biological transmission involves the pathogen being carried within the arthropod.

Answer 13

Allow the virus to attach and enter a host cell ## Footnote Spikes are protein structures extending from the capsid of some viruses.

Answer 14

Classifies viruses into families and genera based on genetics, chemistry, morphology, and multiplication mechanism ## Footnote ICTV has classified known viruses into seven orders, 96 families, and 350 genera.

Answer 15

* Staphylococci (clusters) * Streptococci (chains) * Diplococci (pairs) ## Footnote These arrangements aid in the identification of bacterial species.

Answer 16

* Zygospores (sexual) * Sporangiospores (asexual) * Ascospores (sexual) ## Footnote These spores are used in the classification of fungal species.

Answer 17

Thick peptidoglycan layer with wall teichoic acids ## Footnote This structure contributes to the retention of the crystal violet stain.

Answer 18

Viruses with a lipid layer surrounding the nucleic acid-packed capsid ## Footnote Enveloped viruses often have additional glycoproteins on their surface.

Answer 19

Zygospores

Answer 20

Sporangiospores

Answer 21

Without septa/coenocytic hyphae

Answer 22

Ascospores

Answer 23

By conidiospores

Answer 24

Saccharomyces

Answer 25

Basidiospores

Answer 26

By conidia, budding or fragmentation

Answer 27

Imperfect fungi

Answer 28

Asexually by conidia

Answer 29

Trichoderma

Answer 30

* Saprophytic * Parasitic * Symbiotic

Answer 31

Dead organic substances

Answer 32

Living organisms (plants or animals)

Answer 33

An interdependent association with other species where both benefit

Answer 34

A reproductive cycle involving both sexual and asexual phases

Answer 35

Chlorophyll

Answer 36

Teleomorph

Answer 37

Dikaryophase

Answer 38

Purple or violet

Answer 39

Pink or red

Answer 40

A method to describe characteristics of an individual colony of fungi

Answer 41

* Form * Size * Elevation * Margin/border * Surface * Opacity * Colour

Answer 42

Filamentous structure made of hyphae

Answer 43

A mesh-like structure formed by hyphae

Answer 44

Made up of chitin and polysaccharides

Answer 45

Unicellular prokaryotic organisms

Answer 46

By binary fission

Answer 47

Crystal violet ## Footnote Crystal violet stains both gram-positive and gram-negative bacteria purple.

Answer 48

It acts as a mordant to form an insoluble crystal violet-iodine complex ## Footnote This complex enhances the retention of the primary stain in bacteria.

Answer 49

Differentiates between gram-positive and gram-negative bacteria ## Footnote Gram-positive bacteria retain the crystal violet-iodine complex, while gram-negative bacteria are decolorized.

Answer 50

Purple ## Footnote Gram-positive bacteria retain the primary stain.

Answer 51

Pink ## Footnote Gram-negative bacteria are stained by the counter stain safranin after decolorization.

Answer 52

Classifying viruses according to their genomes and mode of replication ## Footnote It creates seven groups of viruses based on common genetics and biology.

Answer 53

Naked viruses and enveloped viruses ## Footnote Naked viruses consist only of nucleic acid and capsid, while enveloped viruses have a lipid layer.

Answer 54

The specific species of organisms that a virus can infect ## Footnote Most viruses infect only specific hosts and cell types.

Answer 55

Viruses that infect bacteria ## Footnote The term 'phage' comes from the Greek word meaning 'devour'.

Answer 56

It surrounds the viral genome and is made of protein subunits called capsomeres ## Footnote Capsids protect the viral genetic material and aid in the infection of host cells.

Answer 57

* Bacillus (rod shape) * Coccus (spherical shape) * Spirilla (spiral shape) * Vibrio (curved shape) ## Footnote These shapes help in the identification and classification of bacteria.

Answer 58

* Infectious, acellular pathogens * Obligate intracellular parasites * DNA or RNA genome (never both) * Lack genes for many products needed for reproduction ## Footnote These characteristics define the unique nature of viruses compared to living organisms.

Answer 59

* Monotrichous * Lophotrichous * Amphitrichous * Peritrichous ## Footnote These distributions describe the arrangement of flagella on bacterial cells.

Answer 60

* Mechanical transmission * Biological transmission ## Footnote Mechanical transmission occurs via physical contact, while biological transmission involves the pathogen being carried within the arthropod.

Answer 61

Allow the virus to attach and enter a host cell ## Footnote Spikes are protein structures extending from the capsid of some viruses.

Answer 62

Classifies viruses into families and genera based on genetics, chemistry, morphology, and multiplication mechanism ## Footnote ICTV has classified known viruses into seven orders, 96 families, and 350 genera.

Answer 63

* Staphylococci (clusters) * Streptococci (chains) * Diplococci (pairs) ## Footnote These arrangements aid in the identification of bacterial species.

Answer 64

* Zygospores (sexual) * Sporangiospores (asexual) * Ascospores (sexual) ## Footnote These spores are used in the classification of fungal species.

Answer 65

Thick peptidoglycan layer with wall teichoic acids ## Footnote This structure contributes to the retention of the crystal violet stain.

Answer 66

Viruses with a lipid layer surrounding the nucleic acid-packed capsid ## Footnote Enveloped viruses often have additional glycoproteins on their surface.

Answer 67

Zygospores

Answer 68

Sporangiospores

Answer 69

Without septa

Answer 70

Ascospores

Answer 71

By conidiospores

Answer 72

Saccharomyces

Answer 73

Basidiospores

Answer 74

By conidia, budding or fragmentation

Answer 75

Imperfect fungi

Answer 76

Asexually by conidia

Answer 77

Trichoderma

Answer 78

* Saprophytic * Parasitic * Symbiotic

Answer 79

Dead organic substances

Answer 80

Living organisms (plants or animals)

Answer 81

An interdependent association with other species where both benefit

Answer 82

A reproductive cycle involving both sexual and asexual phases

Answer 83

Chlorophyll

Answer 84

Teleomorph

Answer 85

Dikaryophase

Answer 86

Purple or violet

Answer 87

Pink or red

Answer 88

A method to describe characteristics of an individual colony of fungi

Answer 89

* Form * Size * Elevation * Margin/border * Surface * Opacity * Colour

Answer 90

Filamentous structure made of hyphae

Answer 91

A mesh-like structure formed by hyphae

Answer 92

Made up of chitin and polysaccharides

Answer 93

Unicellular prokaryotic organisms

Answer 94

By binary fission

Answer 95

The site for nutrients in the bacterial cytoplasm is the cytoplasmic inclusions or storage granules. These structures store excess nutrients in the form of: Glycogen (energy storage) Polyhydroxybutyrate (PHB) or polyhydroxyalkanoates (PHA) (carbon storage) Volutin granules (metachromatic granules) (phosphate storage) Sulfur granules (used by sulfur-oxidizing bacteria) Magnetosomes (iron storage for magnetotaxis) These inclusions help bacteria survive in fluctuating environmental conditions by providing energy and essential elements when external nutrients are scarce.

Answer 96

The site for nutrients in the cytoplasm is the cytoplasmic inclusions or storage granules. These structures store essential nutrients, including: Glycogen granules – Store glucose for energy. Lipid droplets – Store fats for long-term energy. Polyphosphate granules – Store inorganic phosphate for ATP synthesis. Sulfur granules – Store sulfur for metabolism in some bacteria. Gas vesicles – Help in buoyancy control in aquatic bacteria.

Answer 97

The gap between the outer membrane and plasma membrane in Gram-negative bacteria is called the periplasmic space or simply the periplasm. Key Features of the Periplasmic Space: Found only in Gram-negative bacteria (Gram-positive bacteria lack an outer membrane, so they do not have a true periplasmic space). Located between the outer membrane and the plasma (inner) membrane. Contains a thin layer of peptidoglycan, providing structural support. Filled with periplasmic enzymes, such as: Hydrolytic enzymes (break down nutrients). Transport proteins (facilitate nutrient uptake). Detoxifying enzymes (e.g., β-lactamase, which breaks down antibiotics like penicillin). This space plays a critical role in nutrient processing, transport, and defense against toxic substances.

Answer 98

The polysaccharide that helps bacteria in adherence to surfaces is called the glycocalyx. It exists in two main forms: Capsule – A well-organized, tightly attached polysaccharide layer. Slime layer – A loosely attached, more diffuse polysaccharide layer. Functions of Glycocalyx in Bacterial Adherence: Attachment to surfaces (e.g., host tissues, medical devices, biofilms). Protection against desiccation and immune system evasion. Formation of biofilms, which enhance bacterial survival in harsh environments. For example, Streptococcus mutans uses its glycocalyx to stick to teeth and contribute to dental plaque formation.

Answer 99

Bacteria are prokaryotic microorganisms, meaning they lack a nucleus enclosed by a membrane. Instead, their genetic material exists in a nucleoid region, a region of naked DNA within the cell. Bacteria are classified into two major groups: Eubacteria (true bacteria) – Found in diverse environments and include most known bacterial species. Archaea – Ancient bacteria-like organisms that thrive in extreme environments such as hot springs and deep-sea hydrothermal vents.

Answer 100

Bacteria typically consist of: Cell membrane – Controls the passage of substances. Cytoplasm – Contains ribosomes and other cellular components. Ribosomes – Responsible for protein synthesis. Nucleoid – The region containing bacterial DNA.

Answer 101

Capsule – A protective outer layer aiding in adhesion and immune evasion. Flagella – Tail-like structures used for movement. Fimbriae (Pili) – Hair-like projections that help bacteria attach to surfaces.

Answer 102

Most bacteria range in size from 0.5 to 5 μm in diameter. They exhibit autotrophic (self-feeding) or heterotrophic (feeding on other sources) nutrition. Saprophytic bacteria play a crucial role as decomposers in ecosystems, helping to recycle carbon. Some bacteria, such as nitrogen-fixing bacteria, convert atmospheric nitrogen into biologically usable forms, supporting plant growth and maintaining the nitrogen cycle.

Answer 103

Bacteria are categorized into three main shapes: Cocci – Spherical bacteria (e.g., Staphylococcus, Streptococcus). Bacilli – Rod-shaped bacteria (e.g., Escherichia coli, Bacillus species). Spirochetes and Curved Bacteria – Spiral-shaped bacteria, further divided into: Vibrio – Comma-shaped (e.g., Vibrio cholerae). Spirochetes – Flexible, helical-shaped bacteria (e.g., Treponema pallidum). Helicobacter – Helical-shaped with flagella (e.g., Helicobacter pylori).

Answer 104

Bacteria can be grouped based on how they obtain energy: Autotrophic Bacteria – Produce their own food through photosynthesis or chemosynthesis (e.g., Cyanobacteria). Heterotrophic Bacteria – Depend on external organic sources for nutrition, further divided into: Saprophytic Bacteria – Decompose dead organic matter (e.g., Bacillus subtilis). Parasitic Bacteria – Depend on a host for survival and may cause diseases (e.g., Mycobacterium tuberculosis).

Answer 105

Bacteria are classified based on their need for oxygen: Aerobic Bacteria – Require oxygen to survive: Obligate aerobes – Cannot survive without oxygen (e.g., Mycobacterium tuberculosis). Microaerophilic bacteria – Require oxygen but at lower levels than atmospheric concentrations (e.g., Helicobacter pylori). Anaerobic Bacteria – Do not require oxygen and may be harmed by it: Facultative anaerobes – Can survive with or without oxygen (e.g., Escherichia coli). Aerotolerant anaerobes – Do not use oxygen but can tolerate its presence (e.g., Lactobacillus). Obligate anaerobes – Cannot survive in the presence of oxygen (e.g., Clostridium botulinum).

Answer 106

Bacteria are also classified based on their optimal temperature for growth: Psychrophiles (Cold-loving bacteria) – Thrive in cold temperatures (0–15°C), e.g., Pseudomonas syringae. Mesophiles (Moderate-temperature bacteria) – Grow best at normal temperatures (20–45°C), e.g., Escherichia coli. Thermophiles (Heat-loving bacteria) – Thrive at high temperatures (45–80°C), e.g., Thermus aquaticus

Answer 107

Binary fission occurs in four key steps: DNA Replication and Cell Elongation – The bacterial chromosome replicates, and the cell grows longer. Formation of a Septum (Dividing Membrane) – A new membrane begins to form in the middle of the cell. Formation of a New Cell Wall – The septum becomes a new cell wall, separating the two DNA copies. Cell Division and Separation – The cell splits into two identical daughter cells. Each daughter cell is genetically identical to the parent cell.

Answer 108

The generation time of bacteria depends on the species and environmental conditions. Most bacteria divide every 20 to 30 minutes under optimal conditions. Some bacteria, like Mycobacterium tuberculosis, have a much slower generation time of 18 to 20 hours.

Answer 109

Cocci (spherical bacteria) divide along different planes, leading to various arrangements: Diplococci – Pairs (e.g., Neisseria). Streptococci – Chains (e.g., Streptococcus). Staphylococci – Clusters (e.g., Staphylococcus). Tetrads – Groups of four. Sarcinae – Cube-like structures.

Answer 110

The speed of bacterial reproduction is influenced by: Temperature – Optimal growth varies by species. Nutrients – Availability of essential elements. pH Levels – Most bacteria thrive at neutral pH (~7.0). Oxygen Levels – Some bacteria need oxygen, while others thrive without it.

Answer 111

A. Leeuwenhoek Antonie van Leeuwenhoek (1632–1723) was the first person to observe and describe bacteria using a simple microscope. In 1676, he reported his findings of tiny "animalcules" (now known as bacteria) in water samples. His discovery laid the foundation for microbiology.

Answer 112

Micrococcus refers to single, isolated cocci (spherical bacteria) that exist individually rather than in chains or clusters. These bacteria are non-motile, Gram-positive, and commonly found in soil, water, and on human skin. Other options explained: B. Streptococcus – Forms chains of cocci. C. Tetracoccus – Forms groups of four cocci. D. Staphylococcus – Forms grape-like clusters of cocci.

Answer 113

Extrachromosomal material Plasmids are small, circular, double-stranded DNA molecules that exist outside the main bacterial chromosome (extrachromosomal). They can replicate independently and often carry genes that provide advantages, such as: Antibiotic resistance (e.g., R plasmids). Toxin production. Metabolic advantages. Other Options Explained: B. Main DNA – Incorrect; the main bacterial DNA is the nucleoid, not the plasmid. C. Non-functional DNA – Incorrect; plasmids contain functional genes that can benefit the bacteria. D. Repetitive genes – Incorrect; plasmids do not necessarily contain repetitive genes.

Answer 114

A. Intracellular Parasitic bacteria are predominantly intracellular, meaning they live and reproduce inside the host's cells. These bacteria rely on the host for nutrients and protection from the immune system. Examples of Intracellular Parasitic Bacteria: Obligate intracellular parasites (must live inside host cells) Rickettsia (causes typhus) Chlamydia (causes chlamydia infections) Mycobacterium leprae (causes leprosy) Facultative intracellular parasites (can live inside or outside cells) Salmonella Listeria monocytogenes Other Options Explained: B. Intercellular – Incorrect; bacteria are not typically found between cells, but rather inside them. C. Obligate – Partially correct, but not all parasitic bacteria are obligate intracellular parasites. D. None of the above – Incorrect; intracellular bacteria are the most common parasitic bacteria.

Answer 115

The reproductive cycle of bacteria is generally shorter than that of the host Explanation: Parasitic bacteria reproduce rapidly, often doubling in number within minutes to hours, whereas their hosts (e.g., humans, animals) have much longer reproductive cycles, ranging from days to years. This rapid reproduction allows bacteria to: Accumulate mutations faster, leading to quicker evolution. Adapt to environmental changes and host defenses more rapidly. Develop antibiotic resistance more quickly. Other Options Explained: A. Bacteria face greater choices than their hosts – Not a direct factor in evolutionary speed. B. Bacteria have less DNA than the host – While true, the amount of DNA does not directly affect the speed of evolution. C. Bacteria reproduce primarily sexually – Incorrect; bacteria mainly reproduce asexually (binary fission), although they can exchange genetic material via conjugation, transformation, or transduction.

Answer 116

Denitrifying bacteria convert nitrates (NO₃⁻) into nitrogen gas (N₂), reducing nitrogen availability in the soil and completing the nitrogen cycle. Key Denitrifying Bacteria: Pseudomonas spp. (e.g., Pseudomonas denitrificans) Paracoccus denitrificans Thiobacillus denitrificans (though mainly involved in sulfur oxidation, some species contribute to denitrification) Other Options Explained: A. Micrococcus denitrificans – Does not exist; Micrococcus species are not involved in denitrification. C. Thiobacillus – Some species participate in denitrification, but it is primarily known for sulfur oxidation rather than nitrogen reduction. D. All of the above – Incorrect, as Micrococcus is not a denitrifier.

Answer 117

D. Diphtheria, Leprosy, Plague These are all bacterial diseases: Diphtheria – Caused by Corynebacterium diphtheriae. Leprosy – Caused by Mycobacterium leprae. Plague – Caused by Yersinia pestis. Other Options Explained: A. Malaria, mumps, polio – Incorrect; Malaria – Caused by a protozoan (Plasmodium). Mumps – Caused by a virus (Mumps virus). Polio – Caused by a virus (Poliovirus). B. Cholera, typhoid, mumps – Incorrect because mumps is viral. Cholera – Bacterial (Vibrio cholerae). Typhoid – Bacterial (Salmonella typhi). Mumps – Viral. C. Tetanus, TB, malaria – Incorrect because malaria is caused by a protozoan. Tetanus – Bacterial (Clostridium tetani). TB (Tuberculosis) – Bacterial (Mycobacterium tuberculosis). Malaria – Protozoan (Plasmodium).

Answer 118

B. Mitochondria Explanation: Bacteria resemble mitochondria due to their similar structure and evolutionary origin. According to the endosymbiotic theory, mitochondria are thought to have evolved from ancient prokaryotic bacteria that were engulfed by a larger cell. Similarities Between Bacteria and Mitochondria: Both are prokaryotic in nature (no nucleus). Both have circular DNA (similar to bacterial plasmids). Both have 70S ribosomes (similar to bacterial ribosomes, unlike eukaryotic 80S ribosomes). Both reproduce via binary fission. Both have a double membrane, with the inner membrane resembling bacterial membranes. Other Options Explained: A. Nostoc species – Incorrect; Nostoc is a cyanobacterium, which is a photosynthetic prokaryote, not directly resembling all bacteria. C. Chlamydomonas – Incorrect; Chlamydomonas is a unicellular eukaryotic algae, which has a nucleus and does not resemble bacteria. D. None of the above – Incorrect, since mitochondria are the closest resemblance to bacteria.

Answer 119

S. typhi (Salmonella typhi) Explanation: Salmonella typhi is a motile bacterium because it possesses peritrichous flagella (flagella all around its body), allowing it to move. It causes typhoid fever and moves actively in the intestines. Other Options Explained: B. K. pneumoniae (Klebsiella pneumoniae) – Non-motile, does not have flagella. C. B. anthracis (Bacillus anthracis) – Non-motile, although Bacillus species are often motile, B. anthracis lacks flagella. D. Shigella – Non-motile, does not have flagella. Thus, Salmonella typhi is the only motile bacterium in this list

Answer 120

C. Bacilli Explanation: Bacilli are rod-shaped bacteria. Examples: Escherichia coli Bacillus subtilis Salmonella typhi Other Options Explained: A. Vibrio – Comma-shaped bacteria (e.g., Vibrio cholerae). B. Cocci – Spherical-shaped bacteria (e.g., Staphylococcus, Streptococcus). D. Spirilli – Spiral-shaped bacteria (e.g., Spirillum).

Answer 121

Explanation: Gram-positive bacteria have a unique cell wall structure that includes: Many Layers of Peptidoglycan (A is correct) The peptidoglycan layer is thick and multilayered, providing structural strength. Thicker Cell Wall Compared to Gram-Negative Bacteria (B is correct) Gram-positive bacteria have a thicker cell wall (20–80 nm) than gram-negative bacteria, which have a thin peptidoglycan layer. Presence of Teichoic Acids (C is correct) Teichoic acids are unique to Gram-positive bacteria and help with: Cell wall maintenance Ion transport Antigenic properties

Answer 122

Bacteriophages Explanation: Bacteriophages (or phages) are viruses that specifically infect and replicate within bacteria. They attach to bacterial cells, inject their genetic material, and hijack the bacterial machinery to produce new viruses. Some well-known examples include T4 phage (infects Escherichia coli) and λ (lambda) phage. Other Options Explained: A. Bacterial viruses – This is a vague term; the correct term is bacteriophages. B. Bacterial pathogens – Incorrect; bacterial pathogens are disease-causing bacteria, not viruses. D. Various – Too broad and incorrect in this context.

Answer 123

Protoplasmic outgrowth of donor cells Explanation: Pili (singular: pilus) are hair-like projections on the bacterial surface, primarily involved in conjugation (gene transfer between bacteria). They are protoplasmic outgrowths from the donor cell that attach to the recipient cell during bacterial conjugation, allowing the transfer of genetic material (such as plasmids). Other Options Explained: A. Extra chromosomal genetic element – Incorrect; pili are protein structures, not genetic elements. C. Small flagella – Incorrect; pili are not used for motility like flagella. D. Special bacterial cilia – Incorrect; bacteria do not have cilia, only pili and flagella.

Answer 124

Explanation: Bacteria reproduce asexually through binary fission, a simple and rapid process where a single bacterial cell divides into two identical daughter cells. The process includes: DNA replication – The bacterial chromosome duplicates. Cell elongation – The cell grows, and the chromosomes move apart. Septum formation – A dividing wall forms in the middle. Cell separation – The bacterial cell splits into two. Other Options Explained: A. Mitosis – Incorrect; bacteria do not undergo mitosis since they lack a nucleus. B. Meiosis – Incorrect; meiosis occurs in eukaryotic cells for sexual reproduction, not in bacteria. C. Conjugation – Incorrect; conjugation is a gene transfer method, not a form of reproduction.

Answer 125

A. Cell wall Explanation: The primary difference between Gram-positive and Gram-negative bacteria is in their cell wall structure, which affects their staining properties in the Gram stain test.

Answer 126

Reproduction of genetic material in extreme environments Explanation: Bacteria found in salt lakes and hot springs are typically extremophiles, specifically Archaea (such as halophiles and thermophiles). These organisms are adapted to extreme environments and can: Survive and reproduce under high temperatures (thermophiles) or high salt concentrations (halophiles). Replicate their genetic material and carry out cell division in conditions that would be lethal to most other organisms. Other Options Explained: B. Sensitive to penicillin – Incorrect; many extremophiles, especially Archaea, lack peptidoglycan in their cell walls, making them resistant to penicillin. C. Does not undergo fission reproduction in extreme environments – Incorrect; these bacteria still reproduce by binary fission even in harsh conditions. D. No cell wall – Incorrect; many extremophiles do have a cell wall, but its composition differs from typical bacteria (e.g., Archaea have pseudopeptidoglycan or protein-based walls instead of peptidoglycan).

Answer 127

B. Cell wall Explanation: The cell wall is responsible for maintaining the shape of a bacterial cell by providing structural support and rigidity. It is composed primarily of peptidoglycan, which gives the cell its specific shape and protects it from osmotic pressure. Other Options Explained: A. Capsule – Incorrect; the capsule is a protective outer layer made of polysaccharides but does not determine shape. C. Cell membrane – Incorrect; the cell membrane controls transport and metabolic functions but does not provide rigid structural support. D. Slime layer – Incorrect; the slime layer helps in adherence and protection but does not contribute to bacterial shape.

Answer 128

D. All of these Explanation: Methanogens are anaerobic bacteria that break down cellulosic material and produce methane (CH₄), carbon dioxide (CO₂), and hydrogen (H₂) as metabolic byproducts. They belong to the domain Archaea and thrive in environments like swamps, sewage, and the digestive tracts of ruminants (e.g., cows and termites). Examples of Methanogens: Methanobacterium – Found in sewage, wetlands, and animal intestines. Methanobrevibacter – Common in the gut microbiota of humans and ruminants. Methanococcus – Found in marine sediments and deep-sea hydrothermal vents.

Answer 129

Pili - Respiration (Mismatched) Explanation: Pili are hair-like appendages found on the surface of bacterial cells. Their primary functions include: Attachment to surfaces (fimbriae-type pili). Gene transfer during conjugation (sex pili). Biofilm formation. Pili are NOT involved in respiration, which occurs in the cell membrane of bacteria. Other Options Explained (Correctly Matched): A. Glycocalyx – Maybe capsule or slime layer ✅ Glycocalyx is an external polysaccharide layer that can exist as: Capsule (organized, tightly bound). Slime layer (loose, unorganized). C. Cell wall – Protective, determines shape, prevents from bursting ✅ The cell wall provides structural integrity, prevents osmotic lysis, and maintains shape. D. Flagella, Pili, and Fimbriae – Surface structures of bacterial cells ✅ These structures are all external appendages that assist in movement (flagella), attachment (fimbriae, pili), and genetic exchange (sex pili). Final Answer: ✅ B. Pili - Respiration (Mismatched)

Answer 130

Nucleus Explanation: Bacteria are prokaryotic organisms, meaning they lack a true nucleus. Instead of a nucleus, bacteria have a nucleoid region, where their circular DNA is located without a nuclear membrane. Other Options Explained (Part of Basic Bacterial Structure): A. Flagella ✅ – Many bacteria have flagella for movement (e.g., Escherichia coli). C. Plasmid ✅ – Extrachromosomal DNA, often carrying antibiotic resistance genes. D. Cell wall ✅ – Provides structural support, prevents osmotic lysis, and maintains shape (Gram-positive bacteria have thick peptidoglycan, Gram-negative have a thinner layer).

Answer 131

Splitting of centromeres Explanation: Bacteria reproduce asexually through binary fission, which does not involve centromeres. Centromeres are structures found in eukaryotic chromosomes, where spindle fibers attach during mitosis and meiosis. Since bacteria lack a nucleus and linear chromosomes, centromeres do not exist in bacterial cells, and therefore, their splitting does not occur. Other Options Explained (All Occur in Bacterial Reproduction): B. DNA replication ✅ – Bacteria duplicate their circular DNA before dividing. C. Cell wall formation ✅ – A new cell wall forms during binary fission to separate the daughter cells. D. Protein synthesis ✅ – Essential for bacterial growth and reproduction, occurring in ribosomes (70S). Final Answer: ✅ A. Splitting of centromeres (Does not occur in bacterial reproduction).

Answer 132

Bacterial inheritance often occurs through mutation, horizontal gene transfer (HGT) (transformation, transduction, and conjugation), and binary fission, which do not follow Mendelian inheritance seen in sexually reproducing organisms.

Answer 133

Usually asexual reproduction Explanation: Mendel’s laws of inheritance primarily apply to sexually reproducing organisms, where traits are inherited from two parents through meiosis and fertilization. However, bacteria: ✔ Reproduce asexually through binary fission, meaning offspring are genetically identical clones of the parent (except for mutations or genetic exchange). ✔ Do not undergo meiosis or independent assortment, which are fundamental to Mendelian genetics. ✔ Genetic variation in bacteria occurs through mutation and horizontal gene transfer (conjugation, transformation, and transduction), not Mendelian inheritance. Other Options Explained (Incorrect Choices): A. Genetic material is not DNA ❌ Incorrect Bacteria DO have DNA as their genetic material. B. Genetic material is not on chromosomes ❌ Incorrect Bacteria have a single, circular chromosome, though not enclosed in a nucleus. D. No nucleus ❌ Incorrect While bacteria lack a nucleus, this is not the main reason why Mendelian laws don’t apply. Final Answer: ✅ C. Usually asexual reproduction (Bacteria do not follow Mendel’s laws due to lack of sexual reproduction).

Answer 134

Outside the nucleocapsid, there is an envelope composed of polysaccharides, proteins, and lipids (False Statement) Explanation: ✔ A. It has the structure of cell wall, cell membrane, cytoplasm, and nucleoid ✅ (True) Bacillus anthracis is a prokaryotic bacterium, meaning it has: A cell wall (Gram-positive, thick peptidoglycan layer). A cell membrane (for transport and metabolic functions). Cytoplasm containing ribosomes and other components. A nucleoid region (circular bacterial DNA, no nucleus). ✔ B. Reproduction by binary fission ✅ (True) Like all bacteria, Bacillus anthracis reproduces asexually by binary fission. ❌ C. Outside the nucleocapsid, there is an envelope composed of polysaccharides, proteins, and lipids ❌ (False) This statement is incorrect because: Bacillus anthracis does not have a viral nucleocapsid (nucleocapsids are found in viruses, not bacteria). Instead, it has a capsule (composed of poly-D-glutamic acid, not polysaccharides, proteins, and lipids). This capsule helps in immune evasion by protecting the bacteria from phagocytosis. ✔ D. Assimilation type is chemoheterotrophy ✅ (True) Bacillus anthracis is chemoheterotrophic, meaning it: Obtains energy from organic compounds (does not produce its own food). Requires external nutrients for survival. Final Answer: ✅ C. Outside the nucleocapsid, there is an envelope composed of polysaccharides, proteins, and lipids (False Statement).

Answer 135

A multicellular prokaryotic organism (Incorrect Statement) Explanation: ✔ B. Usually composed of branched hyphae ✅ (True) Actinomycetes form filamentous, branched structures resembling fungal hyphae, but they are bacteria, not fungi. ✔ C. Intrabasal mycelium is related to nutrient absorption ✅ (True) The substrate (intrabasal) mycelium helps in nutrient absorption from the environment. ✔ D. Aerial hyphae are associated with sporogenesis ✅ (True) Aerial hyphae rise above the surface and are involved in spore production (sporogenesis), which aids in reproduction and dispersal. ❌ A. A multicellular prokaryotic organism ❌ (False Statement) Actinomycetes are prokaryotic bacteria, but they are not truly multicellular. They form filamentous colonies that resemble fungi, but each filament is composed of chains of individual bacterial cells, not a true multicellular structure. Final Answer:

Answer 136

The Role of Iodine in Gram Staining In the Gram staining process, iodine serves as a mordant. Function of Iodine in Gram Staining: ✔ Mordant – Iodine binds to the crystal violet dye and forms a large crystal violet-iodine complex (CV-I complex) inside the bacterial cell. ✔ Fixes the Dye – The CV-I complex becomes trapped in the thick peptidoglycan layer of Gram-positive bacteria, preventing it from being easily washed away during decolorization. ✔ Enhances Contrast – Strengthens the binding of the dye to bacterial cells, making the Gram stain more effective. Gram Staining Process: Crystal Violet – Primary stain (colors all cells purple). Iodine – Mordant (fixes crystal violet in Gram-positive bacteria). Alcohol/Acetone (Decolorizer) – Gram-positive: Retains purple color (thick peptidoglycan traps CV-I complex). Gram-negative: Loses the purple color (thin peptidoglycan allows CV-I complex to wash out). Safranin – Counterstain (stains Gram-negative bacteria pink/red). Final Answer: ✅ Iodine acts as a mordant in Gram staining, forming a crystal violet-iodine complex that helps retain the dye in Gram-positive bacteria.

Answer 137

The ability of bacteria to change their morphological form frequently is called: ✅ Pleomorphism Explanation: Pleomorphism refers to the ability of some bacteria to alter their shape or size in response to environmental conditions. This characteristic is common in bacteria that lack a rigid cell wall or have an irregular cell wall structure. Examples of Pleomorphic Bacteria: ✔ Mycoplasma spp. – Completely lacks a cell wall, making it highly pleomorphic. ✔ Corynebacterium spp. – Can appear in various shapes, from rods to club-shaped forms. ✔ Helicobacter pylori – Can transition between spiral, coccoid, and rod-shaped forms. Why is Pleomorphism Important? ✔ Helps bacteria evade the immune system. ✔ Enhances survival in different environments. ✔ Increases resistance to antibiotics targeting cell wall synthesis (e.g., Mycoplasma is resistant to beta-lactam antibiotics). Final Answer: ✅ Pleomorphism (The ability of bacteria to frequently change their morphological form).

Answer 138

The ability of bacteria to change their morphological form frequently is called: ✅ Pleomorphism Explanation: Pleomorphism refers to the ability of some bacteria to alter their shape or size in response to environmental conditions. This characteristic is common in bacteria that lack a rigid cell wall or have an irregular cell wall structure. Examples of Pleomorphic Bacteria: ✔ Mycoplasma spp. – Completely lacks a cell wall, making it highly pleomorphic. ✔ Corynebacterium spp. – Can appear in various shapes, from rods to club-shaped forms. ✔ Helicobacter pylori – Can transition between spiral, coccoid, and rod-shaped forms. Why is Pleomorphism Important? ✔ Helps bacteria evade the immune system. ✔ Enhances survival in different environments. ✔ Increases resistance to antibiotics targeting cell wall synthesis (e.g., Mycoplasma is resistant to beta-lactam antibiotics). Final Answer: ✅ Pleomorphism (The ability of bacteria to frequently change their morphological form).

Answer 139

The Surface Structures of Bacteria for Cell-Cell Attachment The bacterial surface structures responsible for cell-cell attachment include: ✅ 1. Pili (Fimbriae) – Primary attachment structures Short, hair-like appendages on the bacterial surface. Help in adhering to host cells, surfaces, or other bacteria. Example: Neisseria gonorrhoeae uses pili for attachment to human cells. ✅ 2. Glycocalyx (Capsule or Slime Layer) – Protective and adhesive Capsule: A thick, organized layer that enhances adherence and immune evasion. Slime layer: A loose, unorganized layer that helps in biofilm formation. Example: Streptococcus mutans forms a glycocalyx to stick to teeth (causing dental plaque). ✅ 3. Biofilm Formation – Community attachment Bacteria within biofilms attach to each other and surfaces via extracellular polymeric substances (EPS). Example: Pseudomonas aeruginosa forms biofilms in medical devices and lungs of cystic fibrosis patients. Final Answer: ✅ Pili (Fimbriae), Glycocalyx (Capsule or Slime Layer), and Biofilms are bacterial surface structures for cell-cell attachment.

Answer 140

Structure of the Bacterial Chromosome Unlike eukaryotes, which have multiple linear chromosomes inside a nucleus, bacteria have a single, circular, double-stranded DNA molecule located in the nucleoid region of the cell. This DNA contains all the genetic information necessary for bacterial survival and reproduction. Key Features of the Bacterial Chromosome ✅ 1. Circular and Double-Stranded DNA The bacterial chromosome is circular (not linear like eukaryotic chromosomes). It is made up of double-stranded DNA (dsDNA). Example: Escherichia coli has a single, circular chromosome. ✅ 2. Located in the Nucleoid Region The bacterial chromosome is found in the nucleoid, a dense, irregularly shaped region within the cytoplasm. It is not enclosed by a nuclear membrane (prokaryotic feature). ✅ 3. Supercoiled for Compactness Since bacterial DNA is longer than the bacterial cell, it is supercoiled by enzymes like DNA gyrase and topoisomerase. This compaction allows it to fit inside the small bacterial cell. ✅ 4. No Histones (Unlike Eukaryotic DNA) Bacteria lack histone proteins found in eukaryotic chromosomes. Instead, nucleoid-associated proteins (NAPs) help in DNA packaging. ✅ 5. Replication is Bidirectional DNA replication starts at a single origin of replication (OriC). It proceeds bidirectionally around the circular chromosome until completion. ✅ 6. No Introns or Splicing Bacterial DNA is mostly coding sequences (no large non-coding regions like introns in eukaryotes). Genes are often arranged in operons (clusters of functionally related genes). ✅ 7. May Contain Plasmids (Optional, Extrachromosomal DNA) Many bacteria also have plasmids, which are small, circular DNA molecules separate from the main chromosome. Plasmids can carry genes for antibiotic resistance, virulence, and metabolic functions.

Answer 141

Membranous Infoldings in Bacteria That Initiate DNA Replication: ✅ Answer: Mesosomes Explanation: Mesosomes are membrane infoldings of the plasma membrane found in some bacteria. They are believed to play a role in DNA replication, cell division, and respiration. These structures increase the surface area of the plasma membrane, facilitating metabolic activities. Functions of Mesosomes: DNA Replication Initiation – Mesosomes help in the attachment of the bacterial chromosome (nucleoid) to the plasma membrane, assisting in DNA replication. Cell Division – They are involved in septum formation during binary fission. Respiration and Metabolism – In aerobic bacteria, mesosomes contain enzymes for ATP production (similar to mitochondria in eukaryotes). Enzyme Secretion – Involved in the secretion of extracellular enzymes. Debate on Mesosomes: Some researchers argue that mesosomes are artifacts formed during the preparation of bacterial cells for electron microscopy. However, their role in DNA replication and metabolic activities has been studied in certain bacterial species. Final Answer: ✅ Mesosomes (Membranous infoldings in bacteria that help initiate DNA replication).

Answer 142

C. A prokaryotic cell is similar to a eukaryotic organelle Explanation: Prokaryotic cells and certain eukaryotic organelles (such as mitochondria and chloroplasts) share similarities, supporting the endosymbiotic theory. Mitochondria and chloroplasts in eukaryotic cells resemble prokaryotic cells because they: Have their own circular DNA (like bacteria). Possess 70S ribosomes (similar to prokaryotes, while eukaryotes have 80S ribosomes). Reproduce independently by binary fission, like bacteria. Have a double membrane, suggesting they originated from engulfed prokaryotic cells. Why Other Options Are Incorrect: A. Shape of DNA ❌ – Prokaryotes have circular DNA, while eukaryotic nuclear DNA is linear. B. Number of chromosomes ❌ – Prokaryotes usually have one circular chromosome, while eukaryotes have multiple linear chromosomes. D. Cell wall ❌ – While some eukaryotes (plants, fungi, algae) have a cell wall, their composition (cellulose or chitin) is different from the peptidoglycan-based bacterial cell wall. Final Answer: ✅ C. A prokaryotic cell is similar to a eukaryotic organelle (Supports the endosymbiotic theory).

Answer 143

Explanation: Mycolic acid is a waxy, lipid-rich fatty acid found in the cell walls of acid-fast bacteria, such as Mycobacterium tuberculosis and Mycobacterium leprae. It makes the bacterial cell wall hydrophobic and resistant to decolorization during the acid-fast staining (Ziehl-Neelsen stain) test. Acid-Fast Staining Process: Carbol fuchsin (primary stain) penetrates the thick, waxy cell wall. Acid-alcohol (decolorizer) is applied: Acid-fast bacteria (e.g., Mycobacterium) retain the red color due to mycolic acid. Non-acid-fast bacteria lose the stain. Methylene blue (counterstain) colors non-acid-fast bacteria blue. Why Other Options Are Incorrect: B. Teichoic acid ❌ – Found in Gram-positive bacteria, but does not affect acid-fast staining. C. Malic acid ❌ – A metabolic acid, not related to bacterial cell walls. D. Tartaric acid ❌ – Found in food products, not in bacterial cell walls. Final Answer: ✅ A. Mycolic acid (Helps acid-fast bacteria retain color during the acid-fast test).

Answer 144

Gram-Positive Bacteria: Retain crystal violet stain due to their thick peptidoglycan layer. Appear purple under the microscope. Gram-Negative Bacteria: Lose the crystal violet stain after alcohol/acetone decolorization due to their thin peptidoglycan. Take up safranin counterstain, appearing pink/red under the microscope. Summary of Key Differences ✔ Gram-positive bacteria have a thick peptidoglycan layer, no outer membrane, and retain crystal violet (purple color). ✔ Gram-negative bacteria have a thin peptidoglycan layer, an outer membrane (with LPS), and stain pink/red due to safranin.

Answer 145

two bacteria of the same species attach to each other and combine their genetic material.

Answer 146

uses organisms such as bacteria, to clean up environmental pollution.

Answer 147

Pasteurization

Answer 148

The correct answer is: D) imperfect fungi Explanation: Slime molds, water molds, and downy mildews are all funguslike protists — they resemble fungi in some ways (like decomposing organic material), but they are not true fungi. Imperfect fungi, on the other hand, are true fungi (from the kingdom Fungi) that do not have a known sexual reproductive stage — hence the name imperfect. So, imperfect fungi is NOT a funguslike protist — it's an actual fungus.

Answer 149

The correct answer is: C) toadstools Explanation: Club fungi belong to the phylum Basidiomycota, and they are named for their club-shaped reproductive structures called basidia. Toadstools (a common term for mushrooms) are examples of club fungi. ✅ Algae and kelp are protists, not fungi. Basidia refers to the structure in club fungi, not the organism itself. So, C) toadstools is your best answer.

Answer 150

The correct answer is: B) Penicillium Explanation: Imperfect fungi are fungi that do not have a known sexual reproductive stage. Penicillium is a classic example of an imperfect fungus — it's where the antibiotic penicillin comes from. Mushrooms are club fungi (Basidiomycota). Yeast is usually a sac fungus (Ascomycota). Proterospongia is not a fungus at all — it's a protozoan, part of a group of protists. ✅ So, B) Penicillium is the correct answer.

Answer 151

Explanation: Zygospore fungi (phylum Zygomycota) produce spores in structures called sporangia. These are spore-producing sacs usually found at the tips of specialized hyphae. The other options are unrelated to fungi: Pigments – related to color. Cilia – used for movement in some protists and animals, not fungi. Eyespots – found in some protists for detecting light, not in fungi. ✅ So, the correct answer is D) sporangia.

Answer 152

The correct answer is: B) Hyphae Explanation: Hyphae are the threadlike tubes that make up the body of a fungus. They help in absorbing nutrients from the environment and can form complex networks called mycelium. Let’s look at the other options: Heterotrophs – organisms that get their food from other sources (not specific to fungi). Spores – reproductive cells in fungi. Lichens – a symbiotic relationship between fungi and algae or cyanobacteria. ✅ So, the correct answer is B) Hyphae.

Answer 153

D) mycorrhiza Explanation: Mycorrhiza is a mutualistic relationship between fungi and plant roots, where the fungus helps the plant absorb water and nutrients, especially phosphorus, and in return, the plant provides the fungus with sugars from photosynthesis. Orchids often depend heavily on mycorrhizal fungi to grow, especially early in their life cycle. Let’s break down the wrong options: Pseudopods – extensions of cytoplasm used by some protists (like amoebas) for movement and feeding. Dinoflagellates – single-celled protists, some of which cause red tides. Arteries – blood vessels found in animals, not plants. ✅ So, the correct answer is D) mycorrhiza.

Answer 154

Explanation: Yeast is a fungus used in baking to make bread rise through the process of fermentation, where it produces carbon dioxide and alcohol. The carbon dioxide forms bubbles in the dough, making it light and fluffy. Let’s look at the other choices: Euglenoids – single-celled protists that can photosynthesize. Protozoans – single-celled animal-like protists, not used in baking. Amoeba – a type of protozoan, also not used in baking. ✅ So, the correct answer is definitely D) yeast.

Answer 155

Explanation: Sac fungi (phylum Ascomycota) produce their spores in a sac-like structure called an ascus (plural: asci). Each ascus typically contains 8 spores, known as ascospores. Let’s break down the incorrect options: A) Mycorrhiza – a symbiotic relationship between fungi and plant roots, not a spore-producing structure. C) Nucleus – the control center of a cell, not where spores are made. D) Algae – a separate group of organisms, not involved in the spore production of fungi. ✅ So, the correct answer is B) in the ascus.

Answer 156

C) Amastigomycota Explanation: Ascomycetes (sac fungi) fall under the division Amastigomycota in older classification systems. The term Amastigomycota refers to fungi without flagellated cells (i.e., non-motile spores), which includes both Ascomycetes and Basidiomycetes. Modern classification often places Ascomycetes under the phylum Ascomycota, but in traditional systems, they are grouped within Amastigomycota. ✅ So, the correct answer is C) Amastigomycota.

Answer 157

B) sori Explanation: In slime molds, the fruiting bodies (structures that produce and release spores) are called sori. These sori often appear as small, clustered spore-producing structures on the surface of decaying materials. Let’s rule out the other options: A) Acervulus – a type of asexual fruiting body found in certain fungi (especially in plant pathogens). C) Apothecium – a cup-shaped fruiting body found in some Ascomycete fungi, not slime molds.

Answer 158

The correct answer is: C) are sensitive to SO₂ Explanation: Lichens are extremely sensitive to sulfur dioxide (SO₂) pollution, which is why they are often used as bioindicators of air quality. SO₂ damages the delicate symbiotic relationship between the fungus and the alga (or cyanobacterium) that make up the lichen. In areas with high SO₂ levels, lichens tend to disappear or decline sharply, making their presence (or absence) a useful sign of air purity. Let’s rule out the rest: A) is true about lichens, but it doesn’t explain SO₂ sensitivity. B) Lichens actually grow very slowly. D) They do not flourish in SO₂-rich environments — they struggle or die off. ✅ So, the correct answer is C) are sensitive to SO₂

Answer 159

B) Puccinia graminis tritici Explanation: Black rust of wheat (also called stem rust) is a serious fungal disease caused by Puccinia graminis f. sp. tritici. It affects wheat plants, leading to black pustules (uredinia and telia) on stems and leaves, which can severely reduce crop yield. Let’s clarify the other options: A) Albugo candida – causes white rust in cruciferous plants. C) Melampsora lini – causes rust disease in flax (linseed). D) Claviceps purpurea – causes ergot disease in rye and other cereals. ✅ So, the correct answer is B) Puccinia graminis tritici.

Answer 160

Explanation: Basidiomycetes are fungi that produce spores on a structure called a basidium. Bird’s nest fungi and puffballs are classic examples of Basidiomycetes. Puffballs release spores in a cloud when mature. Bird’s nest fungi have spore-containing structures that resemble tiny eggs in a nest. Let’s break down the incorrect options: A) Puffballs and Claviceps – Claviceps belongs to Ascomycetes. B) Peziza and stinkhorns – Peziza is an Ascomycete. C) Morchella and mushrooms – Morchella is an Ascomycete, mushrooms are Basidiomycetes, so it’s a mixed pair. ✅ Correct pair from Basidiomycetes: D) Bird’s nest fungi and puffball.

Answer 161

The correct answer is: B) Myxomycetes Explanation: Myxomycetes are also known as acellular slime molds or plasmodial slime molds. They exist as a giant multinucleated cell (plasmodium) without distinct cell walls — hence acellular. They move like amoebas and engulf food particles, eventually forming fruiting bodies to release spores. Let’s rule out the others: A) Acrasiomycetes – cellular slime molds (not acellular). C) Oomycetes – water molds, fungus-like protists, not slime molds. D) Ascomycete – a division of true fungi, not related to slime molds. ✅ So, the correct answer is B) Myxomycetes.

Answer 162

B) lichens Explanation: Lichens are highly sensitive to sulfur dioxide (SO₂) and are often used as bioindicators of air quality. In areas with high SO₂ pollution, lichens disappear or are greatly reduced, making them reliable indicators of clean vs. polluted air. Let’s break down the incorrect options: A) Mosses – more tolerant of pollutants than lichens. C) Mushrooms – not used as air pollution indicators. D) Puffballs – fungi, not used for indicating air quality. ✅ Correct answer: B) lichens.

Answer 163

The correct answer is: A) green algae and ascomycetes Explanation: Lichens are symbiotic associations between a fungus (usually from the phylum Ascomycota) and a photosynthetic partner, typically green algae or sometimes cyanobacteria (blue-green algae). In most lichens, the fungal component is an ascomycete, and the photosynthetic partner is a green alga. Let’s rule out the incorrect options: B) Brown algae and higher plant – not involved in lichens. C) Blue green algae and basidiomycetes – rare combination, not typical. D) Red algae and ascomycetes – red algae are not usually found in lichens. ✅ So, the correct answer is A) green algae and ascomycetes.

Answer 164

The correct answer is: A) mechanical pressure and enzymes Explanation: Fungi penetrate their host tissues using a combination of: Mechanical pressure to physically push through the host surface. Enzymes (like cellulases and pectinases) to break down cell walls and soften the tissue. This dual action allows the adhesive pads or appressoria of parasitic fungi to invade host cells effectively. Let’s rule out the other options: B) Hooks and suckers – found in parasitic animals like helminths, not fungi. C) Softening by enzymes – partially true, but mechanical pressure is also required. D) Only by mechanical pressure – insufficient alone; enzymes are needed too. ✅ So, the correct answer is A) mechanical pressure and enzymes.

Answer 165

The correct answer is: D) a symbiotic relationship with alga Explanation: Lichens are a classic example of a symbiotic relationship between: A fungus (usually from Ascomycota), and An alga (typically a green alga or a cyanobacterium). In this mutualistic relationship: The alga performs photosynthesis and provides food (sugars). The fungus offers protection, moisture retention, and a suitable structure for the alga to live in. Let’s break down the wrong choices: A) Saprophytic – feeding on dead organic matter, not the case here. B) Epiphytic – living on the surface of a plant, not a mutual relationship. C) Parasitic – one benefits, the other is harmed; this is not true for lichens. ✅ So, the correct answer is D) a symbiotic relationship with alga.

Answer 166

The correct answer is: C) A, D and E only Explanation: For Mucor (a common bread mold) to grow well on bread, it requires: A) Temperature of about 25°C ✅ Mucor grows best at warm, room-like temperatures. Around 25°C is ideal for its growth. D) Relative humidity of about 95% ✅ Fungi like Mucor thrive in moist environments, and high humidity encourages spore germination and mycelial growth. E) A shady place ✅ Mucor prefers dark or shaded environments, as direct light can inhibit spore development. Incorrect choices: B) Temperature of about 5°C ❌ — too cold for optimal growth. C) Relative humidity of about 5% ❌ — far too dry; Mucor needs moisture. F) A brightly illuminated place ❌ — light can hinder mold growth. ✅ Correct answer: C) A, D and E only

Answer 167

The correct answer is: D) Claviceps Explanation: Ergot of rye is a fungal disease caused by Claviceps purpurea. It infects the flowering heads of rye and other cereals, producing dark, hard structures called sclerotia (ergots) that replace the grains. These sclerotia contain toxic alkaloids that can cause ergotism in humans and animals if consumed. Let’s rule out the others: A) Uncinula – causes powdery mildew. B) Ustilago – causes smut diseases in crops like corn. C) Phytophthora – a water mold that causes late blight in potatoes, not ergot. ✅ So, the correct answer is D) Claviceps.

Answer 168

Explanation: Oomycetes (also known as water molds) produce motile cells (zoospores) that have two flagella: One tinsel-type flagellum (with side hairs) that pulls. One whiplash-type flagellum that pushes. These flagella are inserted laterally, and this is a key identifying feature of Oomycetes. Let’s go through the other options: A) Chytridiomycetes – have motile cells, but typically with a single posterior whiplash flagellum. B) Zygomycetes – do not produce motile cells. C) Deuteromycetes – known as imperfect fungi, with no sexual stage identified; also lack motile cells. ✅ So, the correct answer is D) Oomycete.

Answer 169

The correct answer is: A) binary fission Explanation: Schizosaccharomyces is a fission yeast, meaning it reproduces asexually by binary fission — the parent cell divides into two equal-sized daughter cells. This is different from Saccharomyces cerevisiae, the more common budding yeast, which reproduces by budding. Let’s eliminate the other options: B) Budding – used by Saccharomyces, not Schizosaccharomyces. C) Fragmentation – not typical for yeast. D) Spore formation – occurs during sexual reproduction, not asexual. ✅ So, Schizosaccharomyces reproduces asexually by A) binary fission.

Answer 170

The correct answer is: B) fungi Explanation: Fungi exhibit absorptive heterotrophic nutrition, which means they: Secrete digestive enzymes onto organic matter. Break it down externally, and then Absorb the nutrients through their cell walls. Let’s break down the other options: A) Algae – are mostly autotrophic, performing photosynthesis. C) Bryophytes (e.g., mosses) – are autotrophic land plants. D) Pteridophytes (e.g., ferns) – are also autotrophic. ✅ So, the correct answer is B) fungi.

Answer 171

Explanation: A zygospore is a thick-walled, resistant structure formed by zygomycete fungi (like Rhizopus) during sexual reproduction. After formation, the mature zygospore lies dormant under unfavorable conditions, often for 1 to 3 months, before germinating when the environment becomes favorable again (e.g., adequate moisture, temperature, and nutrients). Let’s rule out the others: A) 4–5 days and D) 20 days – too short for proper dormancy. C) 1 year – possible in extreme conditions but not typical. ✅ Correct answer: B) 1–3 months.

Answer 172

The correct answer is: C) Class Explanation: In fungal taxonomy, the suffix “-mycetes” is used to denote a class. For example: Ascomycetes – class of fungi under phylum Ascomycota Basidiomycetes – class under Basidiomycota Let’s clarify the other options: A) Division – ends in -mycota (e.g., Ascomycota). B) Subdivision – ends in -mycotina (e.g., Saccharomycotina). D) Order – ends in -ales (e.g., Mucorales). ✅ So, the correct answer is C) Class.

Answer 173

The correct answer is: A) these grow very rapidly (2 cm per day) Explanation: This statement is wrong because lichens grow very slowly, typically at a rate of a few millimeters per year, not centimeters per day. Let’s review the correct statements: B) They show fungal and algal symbiotic relationships ✅ Lichens are a symbiosis between a fungus and an alga or cyanobacterium. C) Some of its species are eaten by reindeers ✅ Especially in Arctic regions, reindeer feed on lichens like Cladonia (reindeer moss). D) These are pollution indicators ✅ Lichens are highly sensitive to air pollution, particularly sulfur dioxide (SO₂). ❌ So, the incorrect (and thus correct answer to the question) is: A) these grow very rapidly (2 cm per day).

Answer 174

Explanation: Rhizopus stolonifer, commonly known as black bread mold, belongs to the class Zygomycetes. It is characterized by: Fast-growing, filamentous hyphae. Zygospore formation during sexual reproduction. Asexual reproduction via sporangia that release spores. Let’s rule out the others: A) Acrasiomycetes – cellular slime molds, not true fungi. C) Ascomycetes – sac fungi like Penicillium or Saccharomyces. D) Deuteromycetes – fungi with no known sexual stage ("imperfect fungi"). ✅ So, Rhizopus stolonifer belongs to B) Zygomycetes.

Answer 175

B) Amastigomycota Explanation: Amastigomycota is a division of fungi that lack flagella at all stages of their life cycle — neither their spores nor gametes have flagella. This group includes fungi like Ascomycetes and Basidiomycetes, which reproduce through non-motile spores. Let’s break down the other options: A) Mastigomycota – fungi-like organisms with flagellated cells (e.g., Chytrids). C) Gymnomycota – an outdated or rarely used term, not a widely recognized fungal division. D) Basidiomycetes – a class within Amastigomycota, and yes, they lack flagella, but the broader division is Amastigomycota. ✅ Correct answer: B) Amastigomycota.

Answer 176

The correct answer is: B) zygospore Explanation: In Rhizopus stolonifer (black bread mold), the zygospore is the thick-walled, resistant structure that contains the zygote nucleus formed after the fusion of gametangia during sexual reproduction. It serves as a dormant stage, surviving unfavorable conditions and later germinating to produce a new fungal organism. Let’s clarify the other options: A) Progametangia – early structures that give rise to gametangia, not where the zygote is housed. C) Suspensor cell – supports the developing zygospore, but doesn't contain the zygote nucleus itself. D) Coenozygote – an uncommon or obsolete term, not standard for describing fungal reproductive structures. ✅ Correct answer: B) zygospore.

Answer 177

B) symbiosis Explanation: Mycorrhiza is a mutualistic (symbiotic) association between the roots of a plant and a fungus. The fungus helps the plant absorb water and nutrients (especially phosphorus). In return, the plant provides sugars and carbohydrates to the fungus. This relationship benefits both partners, which is the essence of symbiosis. Let’s rule out the others: A) Parasitism – one benefits, the other is harmed. C) Antagonism – one organism suppresses or harms another. D) Endemism – refers to species being restricted to a specific geographic area, not a type of interaction. ✅ So, mycorrhiza exhibits B) symbiosis.

Answer 178

The correct answer is: B) symbiotic relationship between fungi and roots of some higher plants Explanation: Mycorrhiza is a mutualistic (symbiotic) association between: The roots of higher plants, and Certain fungi (often from phyla like Glomeromycota or Basidiomycota). The fungus helps the plant absorb nutrients and water, especially phosphorus, while the plant supplies sugars to the fungus. Let’s rule out the incorrect options: A) Parasitic association – ❌ Incorrect, because both partners benefit. C) Symbiosis of algae and fungi – ❌ That describes lichens, not mycorrhiza. D) Relation of ants with the stem of some trees – ❌ Irrelevant to mycorrhiza. ✅ So, the correct description is: B) symbiotic relationship between fungi and roots of some higher plants.

Answer 179

A) telia on wheat leaves Explanation: Puccinia graminis tritici, the fungus that causes black stem rust of wheat, has a complex life cycle involving two hosts: wheat (primary host) and barberry (alternate host). On wheat, it forms: Uredia (producing uredospores – the repeating stage). Telia (producing teliospores – the overwintering stage). Let’s examine the other options: B) Aecia on barberry leaves ✅ (Correct, but not the answer to this question). C) Pycnia on barberry leaves ✅ (Also correct, but not the answer here). D) Aecia on wheat leaves ❌ (Incorrect – aecia are formed on barberry, not wheat). ✅ So, the correct answer is A) telia on wheat leaves.

Answer 180

1. Decomposition - nutrient and carbon recycling. 2. Biosynthetic factories. The fermentation property is used for the industrial production of alcohols, fats, citric, oxalic and gluconic acids. 3. Important sources of antibiotics, such as Penicillin. 4. Model organisms for biochemical and genetic studies. Eg: Neurospora crassa 5. Saccharomyces cerviciae is extensively used in recombinant DNA technology, which includes the Hepatitis B Vaccine. 6. Some fungi are edible (mushrooms). 7. Yeasts provide nutritional supplements such as vitamins and cofactors. 8. Penicillium is used to flavour Roquefort and Camembert cheeses. 9. Ergot produced by Claviceps purpurea contains medically important alkaloids that help in inducing uterine contractions, controlling bleeding and treating migraine. 10. Fungi (Leptolegnia caudate and Aphanomyces laevis) are used to trap mosquito larvae in paddy fields and thus help in malaria control.

Answer 181

1. Destruction of food, lumber, paper, and cloth. 2. Animal and human diseases, including allergies. 3. Toxins produced by poisonous mushrooms and within food (Mycetism and Mycotoxicosis). 4. Plant diseases. 5. Spoilage of agriculture produce such as vegetables and cereals. 6. Damage the products such as magnetic tapes and disks, glass lenses, marble statues, bones and wax

Answer 182

1. They are eukaryotic; cells contain membrane bound cell organelles including nuclei, mitochondria, golgi apparatus, endoplasmic reticulum, lysosomes etc. They also exhibit mitosis. 2. Have ergosterols in their membranes and possesses 80S ribosomes. 3. Have a rigid cell wall and are therefore non-motile, a feature that separates them from animals. All fungi possess cell wall made of chitin. 4. Are chemoheterotrophs (require organic compounds for both carbon and energy sources) and fungi lack chlorophyll and are therefore not autotrophic. 5. Fungi are osmiotrophic; they obtain their nutrients by absorption. 6. They obtain nutrients as saprophytes (live off of decaying matter) or as parasites (live off of living matter). 7. All fungi require water and oxygen and there are no obligate anaerobes. 8. Typically reproduce asexually and/or sexually by producing spores. 9. They grow either reproductively by budding or non-reproductively by hyphal tip elongation.

Answer 183

All fungi have typical eukaryotic morphology. They have rigid cell wall composed of chitin, which may be layered with mannans, glucans and other polysaccharides in association with polypeptides. Some lower fungi possess cellulose in their cell wall. Some fungi such as Cryptococcus and yeast form of Histoplasma capsulatum possess polysaccharide capsules that help them to evade phagocytosis. Inner to the cell wall is the plasma membrane that is a typical bi-layered membrane in addition to the presence of sterols. Fungal membranes possess ergosterol in contrast to cholesterol found in mammalian cells. The cytoplasm consists of various organelles such as mitochondria, golgi apparatus, ribosomes, endoplasmic reticulum, lysosomes, microtubules and a membrane enclosed nucleus. A unique property of nuclear membrane is that it persists throughout the metaphase of mitosis unlike in plant and animal cells where it dissolves and re-forms. The nucleus possesses paired chromosomes

Answer 184

1-Cell wall components  Two major types of components o Structural polymers - polysaccharide fibrils that provide rigidity/integrity of the wall o Matrix components - cross-link the fibrils as well as coat/embed them  Main wall components differ between the major taxonomic groups of fungi [see Table 3.1, Deacon] o Chitin - straight chain polymers of b-1,4-linked N-acetylglucosamine residues; 4 chitosan is de-acetylated chitin o Glucan - polymers of b-1,3-linked glucose residues with short b-1,6-linked side chains o Cellulose - b-1,4-linked glucans o Matrix polymers - Glucouronic acids - Mannoproteins - mannose attached to protein

Answer 185

 Septa occur at generally regular intervals along a length of a hypha  Perforations allow cytoplasm to flow from one cell to another  When a cell is damaged, a Woronin body or coagulated cytoplasm serves a plug to prevent loss of cytoplasm  Coenocytic fungi are more susceptible to cellular damage  Functions of septa  Structural support of the hypha  Enables differentiation by dividing hypha into different cells that can undergo separate modes of development  Types of septa  Simple  Dolipore

Answer 186

 Double membrane bound organelle ranging in size from 1-2 µm to 20-25 µm in diameter  Unique features of fungal nucleus  Membrane remains intact during mitosis  No clear metaphase plate  Various types of spindle-pole bodies (microtubule-organizing centers) depending upon species  Ploidy  Most fungi are haploid with the number of chromosomes ranging from 6 to 20  Some fungi are naturally diploid  Others alternate between haploid and diploid states

Answer 187

 Plasma membrane - phospholipid bilayer  Involved in uptake of nutrients 5  Differs in that it contains ergosterol - Site of action for certain antifungal drugs - Oomycota contain plant-like sterols  Secretory system  Consists of the following: - Endoplasmic reticulum (ER) - Golgi apparatus (or equivalent) - different in than those found in animals, plants, and the Oomycota in that they lack cisternae - Membrane-bound vesicles  Involved in fungal tip growth  Chitosomes - microvesicles that are capable of synthesizing chitin  Vacuoles  Functions - Storage - Recycling of materials - Contain proteolytic enzymes - Regulation of cellular pH - Possible role in cellular expansion/growth  Shape - Round - Tubular - may be involved in material transpor

Answer 188

Both are microscopic organisms. Fungi and bacteria have a cell wall made up of polysaccharides. Although the components of the cell walls are different, all species of bacteria and fungi have a true cell wall. Some bacteria like Lactobacillus are used as probiotics, Staphylococcus epidermidis as normal skin flora that protects skin from infection, and Escherichia coli in the gut benefit humans. Likewise, yeast is helpful in the production of alcohol and bakery items. Some species of both phyla can cause serious illness. Like aspergilloma (fungus ball) by Aspergillus species, a fungus that can seriously damage the lungs of an infected human. Likewise, cholera by Vibrio cholerae and typhoid by Salmonella species are some of the life-threatening water-borne bacterial diseases. Both of the organisms can be saprophytic or parasitic. E coli and Spirochetes are saprophytic bacteria, whereas almost all fungi are saprophytic. Both bacteria and fungi are heterotrophs, meaning they can grow and feed on plants and animals. Both bacteria and fungi require heat, nutrition, and moisture for growth. The optimum temperature for bacteria and fungi that can cause human infections is 37℃

Answer 189

Fungi can be defined as nucleated, achlorophyllous, osmotrophic, spore-bearing organisms that typically reproduce both sexually and asexually and whose usually branching, filamentous bodies are surrounded by cell walls composed of cellulose, chitin or both.

Answer 190

Kingdom Fungi (Myceteae) ## Footnote Other references may divide them between the kingdoms Chromista and Eumycotina.

Answer 191

Without chlorophyll

Answer 192

Chemoheterotrophs

Answer 193

By dumping digestive enzymes into their environments

Answer 194

* Yeasts * Molds * Fleshy fungi

Answer 195

Thallus or soma

Answer 196

Microscopic, thread-like filaments that make up the body of fungi

Answer 197

A filamentous mass formed by multiplying hyphae

Answer 198

* Vegetative mycelium * Aerial mycelium

Answer 199

Septate hyphae have crosswalls or septa, while aseptate hyphae do not

Answer 200

Cells of septate hyphae containing two separate, haploid nuclei

Answer 201

Specialized hyphae produced by parasitic fungi that penetrate host cells to absorb nutrients

Answer 202

Specialized hyphae that form mutualistic relationships with plant roots

Answer 203

* Plasmogamy * Karyogamy * Meiosis

Answer 204

The joining of protoplasm from two fungi

Answer 205

The joining of two haploid nuclei resulting in a diploid zygote

Answer 206

A process involving separation of chromosomes and division of the diploid nucleus into haploid parts

Answer 207

Fungal induced diseases occurring in humans and other animals

Answer 208

* Dutch elm disease * Chestnut blight * Potato blight * Apple scab * Peach leaf curl * Corn smut * Rusts * Mildew

Answer 209

* Decomposers that break down dead materials * Form mycorrhizae aiding plant nutrient uptake * Serve as a food source * Used in food processing * Source of antibiotics * Produce enzymes for industrial processes

Answer 210

Eukaryotic

Answer 211

Some fungi are pathogens responsible for diseases

Answer 212

Fungal induced diseases occurring in humans and other animals ## Footnote Mycosis is the singular form of mycoses.

Answer 213

* Widespread use of antibiotics and antimicrobial drugs * Increased use of chemotherapeutic agents * HIV infection and damage to the immune system

Answer 214

The state of that individual's immune system

Answer 215

Mycoses occurring on the body surface caused by fungi infecting skin, hair, and nails

Answer 216

Tinea pedis or athlete's foot

Answer 217

Ringworm of the scalp, caused by Microsporum or Trichophyton

Answer 218

Dermatophytes, including genera such as Epidermophyton, Trichophyton, and Microsporum

Answer 219

Mycoses involving damage to tissue layers just below the skin

Answer 220

A type of subcutaneous mycosis caused by Sporothrix schenckii

Answer 221

A chronic subcutaneous mycosis caused by various black molds

Answer 222

Mycoses involving fungi that enter deep tissues and travel throughout the body

Answer 223

Coccidioides immitis, a type of soil fungus

Answer 224

Flu-like symptoms

Answer 225

Histoplasma capsulatum

Answer 226

Toxic substances produced by fungi

Answer 227

Causes severe liver damage and sometimes death when ingested

Answer 228

A potent mycotoxin produced by Aspergillus flavus

Answer 229

Ergot, which can cause convulsive ergotism and hallucination

Answer 230

Black mold

Answer 231

opportunistic mycoses

Answer 232

Compromised immune function

Answer 233

Candida albicans

Answer 234

It can cause a potentially fatal form of meningitis

Answer 235

Lung infections in immunocompromised individuals

Answer 236

AIDS patients

Answer 237

Headache, dizziness, and reduced immune function

Answer 238

Eukaryotic cells ## Footnote Eukaryotic cells have a nucleus and organelles, and many fungi can maintain two distinct nuclei per cell.

Answer 239

Fungi are heterotrophic and derive energy from consuming carbon compounds from living or dead organisms.

Answer 240

Absorptive nutrition ## Footnote Fungi secrete enzymes into their environment to digest food and absorb simple nutrients.

Answer 241

Chitin ## Footnote Chitin is similar to cellulose but contains nitrogen in its molecular structure.

Answer 242

By budding

Answer 243

A network of hyphae ## Footnote Mycelium is the vegetative part of the fungus and can secrete digestive enzymes and absorb nutrients.

Answer 244

Structures that look like plant roots and enable fungi to grow quickly over surfaces.

Answer 245

Rock-like masses that allow fungi to survive difficult environmental conditions.

Answer 246

* Meiospores (sexual) * Mitospores or conidia (asexual)

Answer 247

They produce spores, which are used for identification and classification of fungi.

Answer 248

Candida albicans

Answer 249

Chytriomyces hyalinus

Answer 250

Fusarium oxysporum

Answer 251

Agaricus bisporus

Answer 252

Multicellular fruiting bodies

Answer 253

Teleomorph refers to the sexual phase, while anamorph refers to the asexual phase.

Answer 254

Through sexual and asexual reproduction on multiple hosts.

Answer 255

Single-celled spermatia and receptive hyphae.

Answer 256

Fusion of nuclei to form a diploid cell.

Answer 257

It can produce reproductive structures and undergoes karyogamy to form spores.

Answer 258

* Describe the unique and common features of named fungal groups. * Describe the various reproductive life cycles associated with fungi.

Answer 259

The study of fungi ## Footnote Mycology derives from the Greek word 'mykes' meaning mushroom.

Answer 260

Eukaryotic, spore-bearing, heterotrophic organisms that produce extracellular enzymes and absorb their nutrition

Answer 261

Absorptive heterotrophs

Answer 262

80,000 species described, with 1,700 new species described each year

Answer 263

1.5 million species of fungi estimated

Answer 264

* Decomposition and nutrient recycling * Biosynthetic factories * Sources of antibiotics * Model organisms for studies * Edible mushrooms * Nutritional supplements * Flavoring for cheeses * Medicine from alkaloids * Malaria control

Answer 265

* Destruction of food and materials * Animal and human diseases * Toxins from poisonous mushrooms * Plant diseases * Spoilage of agricultural produce * Damage to various products

Answer 266

* Eukaryotic with membrane-bound organelles * Have ergosterols in membranes * Rigid cell wall made of chitin * Chemoheterotrophs * Osmotrophic * Require water and oxygen * Typically reproduce asexually and/or sexually

Answer 267

Kingdom - Subkingdom - Phyla - Subphyla - Class - Order - Family - Genus - Species

Answer 268

* Filamentous (hyphal) * Single-celled (yeast)

Answer 269

Structures that occur at regular intervals along a hypha

Answer 270

Membrane remains intact during mitosis, no clear metaphase plate

Answer 271

* Fragmentation * Budding * Fission * Sclerotia * Rhizomorphs

Answer 272

Asexual spores formed by conidiogenesis

Answer 273

Anamorph is the asexual form, while teleomorph is the sexual form of the same fungus

Answer 274

Involved in the uptake of nutrients and contains ergosterol

Answer 275

Asexual reproduction

Answer 276

* Spiral hyphae * Pectinate body * Favic chandelier * Nodular organ * Racquet hyphae * Rhizoides

Answer 277

Thick-walled resting cells produced by some fungi

Answer 278

A chain of elongated cells formed by yeasts when buds fail to detach

Answer 279

It differs from cholesterol found in mammalian cells and is the site of action for certain antifungal drugs

Answer 280

Sexual reproduction

Answer 281

Structures that remain dormant under unfavourable conditions and germinate into new mycelia under favourable conditions ## Footnote Sclerotia are a survival mechanism for fungi.

Answer 282

Rope-like structures formed by interwoven hyphae in some higher fungi that resume growth under favourable conditions ## Footnote Rhizomorphs facilitate nutrient transport and colonization.

Answer 283

A type of reproduction involving the formation of special reproductive structures called spores or propagates ## Footnote Asexual reproduction allows for rapid population increase.

Answer 284

Flagellated, motile spores produced inside zoosporangia, lacking a cell wall, found in lower fungi ## Footnote Examples include Achyla and Saprolegnia.

Answer 285

Non-motile spores produced inside sporangia, dispersed by wind, found in fungi like Rhizopus and Mucor ## Footnote Sporangiospores play a key role in fungal reproduction.

Answer 286

Thick-walled resting spores that arise from hyphal cells and store reserve food ## Footnote They allow the fungus to survive unfavourable conditions.

Answer 287

Spore-like structures formed by the breaking up of hyphal cells, do not store reserve food ## Footnote Oidia are produced in Rhizopus.

Answer 288

Non-motile spores produced singly or in chains at the tips of conidiophores, found in fungi like Aspergillus and Penicillium ## Footnote Conidia are important for asexual reproduction.

Answer 289

A reproductive process involving fusion of gametes, gametangia, or hyphae, excluding Fungi imperfecti ## Footnote It includes processes like plasmogamy and karyogamy.

Answer 290

A phase in the fungal life cycle where hyphae remain dikaryotic, often following karyogamy in higher fungi ## Footnote This phase allows for genetic diversity.

Answer 291

Fusion of motile gametes called planogametes, which can be isogamous, anisogamous, or heterogamous ## Footnote Examples include Synchytrium (isogamy) and Allomyces (anisogamy).

Answer 292

When gamete-bearing structures called gametangia come close and develop a fertilization tube for male gamete migration ## Footnote Examples include Phytophthora and Albugo.

Answer 293

Formation of tiny unicellular spore-like structures called spermatia that are transferred to female gametangia ## Footnote Found in fungi like Puccinia.

Answer 294

Fusion between two somatic cells resulting in dikaryotic hyphae, involving only plasmogamy ## Footnote Examples include Agaricus.

Answer 295

Homothallism involves fusion between genetically similar strains, while heterothallism involves genetically different mating types ## Footnote Heterothallism promotes genetic diversity.

Answer 296

✅ c) Chitin Explanation: Unlike plants (which have cellulose), fungi have cell walls primarily made of chitin, a tough, flexible compound also found in insect exoskeletons.

Answer 297

b) Absorbing dissolved organic material Explanation: Fungi are absorptive heterotrophs. They secrete enzymes to break down complex organic materials in their surroundings and absorb the dissolved nutrients.

Answer 298

✅ a) Mycelium Explanation: The mycelium is the network of hyphae that forms the main body of a fungus, often hidden in soil or decaying matter.

Answer 299

✅ d) Zygospore Explanation: Zygomycota (like Rhizopus stolonifer) reproduce sexually by forming zygospores, which are thick-walled, resistant spores formed by the fusion of two gametangia.

Answer 300

✅ b) Prevents desiccation Explanation: Sporopollenin is an extremely resilient and chemically stable polymer found in the outer walls of spores and pollen. Its main function is to protect the spore from drying out (desiccation) and other environmental stresses.

Answer 301

✅ b) Diffusion across hyphae Explanation: Fungi lack vascular tissues (like xylem and phloem found in plants). Instead, they transport water and nutrients by diffusion across their hyphal networks.

Answer 302

✅ b) Ergosterol Explanation: Ergosterol is the primary sterol in fungal cell membranes. It plays a role similar to cholesterol in animal cells, maintaining membrane fluidity and integrity. This is also why many antifungal drugs (like azoles and amphotericin B) target ergosterol synthesis.

Answer 303

✅ c) Chytridiomycota Explanation: Chytridiomycota are the only true fungi that produce motile zoospores with flagella. These spores can swim, which is unique among fungi.

Answer 304

✅ b) Ascus Explanation: The defining feature of Ascomycota is the production of spores in a sac-like structure called an ascus. Typically, each ascus contains 8 ascospores.

Answer 305

Explanation: A dikaryotic cell (common in Ascomycota and Basidiomycota) contains two separate haploid nuclei from different parent strains. These nuclei share the same cytoplasm but do not fuse immediately, leading to a unique n + n condition.

Answer 306

b) Anchoring and nutrient absorption Explanation: Rhizoids are root-like structures found in fungi (like Rhizopus). They anchor the fungus to its substrate and help in absorbing nutrients, but they are not true roots

Answer 307

✅ d) Ascomycota Explanation: Most yeasts, including Saccharomyces cerevisiae, belong to the phylum Ascomycota. They reproduce mainly by budding or fission and produce ascospores in an ascus during sexual reproduction.

Answer 308

b) Externally, before absorption Explanation: Fungi are absorptive heterotrophs. They secrete digestive enzymes into their surroundings to break down complex organic matter externally, then absorb the nutrients.

Answer 309

✅ b) Basidiospores Explanation: Basidiomycota produce basidiospores on a club-shaped structure called a basidium. These spores are characteristic of mushrooms, puffballs, and bracket fungi.

Answer 310

✅ a) Coenocytic Explanation: Coenocytic hyphae are continuous tubes filled with cytoplasm and multiple nuclei, lacking septa (cross-walls). Common in Zygomycota.

Answer 311

✅ a) Flagellated spores Explanation: Chytridiomycota are the only fungi that produce motile, flagellated zoospores, allowing them to swim in water.

Answer 312

✅ c) Hyphae Explanation: Hyphae are the thread-like filaments of fungi that penetrate the substrate and absorb nutrients through their walls via diffusion and active transport

Answer 313

Explanation: In fungi, meiosis occurs after the fusion of haploid nuclei (karyogamy), leading to the production of haploid spores that ensure genetic variation.

Answer 314

✅ b) Ascomycota Explanation: Ascomycota are called sac fungi because they form spores inside a sac-like structure called an ascus. Common examples include yeasts, morels, and Penicillium.

Answer 315

✅ b) They lack a known sexual reproductive stage Explanation: Deuteromycota, also known as imperfect fungi, are grouped together because their sexual stage has not been observed. Once the sexual form is discovered, they are usually reclassified into Ascomycota or Basidiomycota.

Answer 316

✅ b) Saprophytes Explanation: Saprophytic fungi feed on dead and decaying organic matter, helping decompose and recycle nutrients in ecosystems.

Answer 317

✅ b) Glycogen Explanation: Unlike plants (which store starch), fungi store carbohydrates in the form of glycogen, similar to animals.

Answer 318

✅ b) Penicillium Explanation: Penicillium notatum (and related species) produces the antibiotic penicillin, discovered by Alexander Fleming. It's one of the most important antibiotics in history.

Answer 319

✅ b) Club-shaped structures Explanation: Basidiomycota are named for their club-shaped structure called a basidium, where basidiospores are produced. These include mushrooms, puffballs, and bracket fungi.

Answer 320

✅ b) Histoplasma capsulatum Explanation: Dimorphic fungi can exist in two forms: as mold (filamentous) in the environment and as yeast (unicellular) in the host. Histoplasma capsulatum is a classic dimorphic fungus and can cause histoplasmosis in humans.