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Microbiology Flashcards

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1
Q

Microbiology

A

Is the study of organisms that are too small and are not visible clearly to the naked eye or un-aided eye when they exist individually.

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2
Q

Microorganisms general size

A

Less than 0.1mm

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3
Q

Extremophiles

A

Some microorganisms are capable of inhabiting extreme environmental conditions that are unfavourable or even lethal for other organisms.

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4
Q

Thermophiles - condition

A

High temperatures

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5
Q

Psychrophiles - condition

A

Low temperatures

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6
Q

Acidophiles - condition

A

acid pH

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7
Q

Alkaliphiles - condition

A

basic pH

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8
Q

Halophiles - condition

A

require NaCl

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9
Q

Barophiles - condition

A

high pressure

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10
Q

High growth rate of microorganisms

A

Posses a high surface area to volume ratio due to their small size.

Flowing rate of materials in to the inside of the cells and exit of waste materials to the outside of the cells increases and results in high metabolic rate.

Average generation time or the time taken required to double the population of microorganisms is relatively less.

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11
Q

Basic 3 distinct shapes of bacteria

A

Rod shape - Bacillus
Spherical shape - Coccus
Spiral shape - Spirillum

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12
Q

2 morphological varieties found in virus according to the symmetry of protein coats

A

Icosahedral
Helical

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13
Q

4 major nutritional types seen among microorganisms

A

Chemoautotrophs
Chemoheterotrophs
Photoautotrophs
Photoheterotrophs

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14
Q

4 physiological groups of microbes

A

Obligate aerobes
Obligate anaerobes
Facultative anaerobes
Microaerophiles

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15
Q

2 types of nitrogen fixing microbes with examples

A

Free living - Azotobacter sp
Symbiotic - Rhizobium sp. with legume roots

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16
Q

Different forms of coccus bacteria

A

Coccus
Diplococcus
Streptococcus
Tetrad
Sarcinae
Straphylococcus

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17
Q

Coccus

A

Cells divide in 1 plane
Divided cells detach from each other after cell division

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18
Q

Diplococcus

A

Cells divide in 1 plane
Divided cells remain in pairs

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19
Q

Streptococcus

A

Cells divide in 1 plane
Divided cells remain attached in chain like patterns

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20
Q

Tetrad

A

Cells divide in 2 planes producing 4 cells remain attaches together

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21
Q

Sarcinae

A

Cells divide in 3 planes and remain attached in group of 8 cells

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22
Q

Straphylococcus

A

Cells divide in multiple planes and form grape like cluster of cells

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23
Q

Types of bacilli bacteria

A

Single bacillus - Single rod
Diplobacillus - Remain in pairs after cell division
Streptobacillus - Occurs in chain after cell division

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24
Q

Types of spiral bacteria

A

Vibrio - Bacteria look like curved rods
Spirillum - Helical shape, like a corkscrew and rigid body
Spirochete - Helical shape, flexile body

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25
Q

Photoautotrophs (source of energy, source of carbon and examples)

A

Light
CO2
Purple sulfur and green sulfur bacteria

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26
Q

Photoheterotrophs (source of energy, source of carbon and examples)

A

Light
Organic carbon
Purple non sulfur bacteria

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27
Q

Chemoautotrophs (source of energy, source of carbon and examples)

A

Inorganic chemicals
CO2
Nitrobacter, Nitrosomanas, Thiobacillus thiooxidans

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28
Q

Chemoheterotrophs (source of energy, source of carbon and examples)

A

Organic chemicals
Organic carbon
Most bacteria

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29
Q

Obligate aerobic

A

Require O2 for their survival
Generate energy by oxidative phosphorylation

Acetobacter sp.

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30
Q

Obligate anaerobic

A

Cannot survive in the presence of O2
Generate energy by fermentation

Clostridium sp.

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31
Q

Facultative anaerobic

A

Prefer to grow in the presence of O2 producing energy by oxidative phosphorylation
They can also grow in anaerobic environments using fermentation

Escherichia coli

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32
Q

Microaerophilic

A

Can grow only in O2 concentrations lower than those in air

Lactobacilus sp

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33
Q

Reproduction methods of bacteria

A

Mostly undergoes asexual reproduction - Binary fission, fragmentation or budding

Performs conjugation as a sexual method

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34
Q

Unicellular and colonial forms of Cyanobacteria

A

Majority of unicellular forms stay together by copious secretion of mucilage by daughter cells.

In colonial forms cells remain attached by walls or held in a common gelatinous matrix forming a colony of cells. Types - spherical, cubical, square or irregular shape.

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35
Q

2 types of nitrogen fixing cyanobacteria

A

Free living - Nostoc sp.
Symbiotic - Anabaena-Azolla sp

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36
Q

Heterocyst and akinete of Cyanobacteria

A

Nitrogen fixation takes place in special cells called heterocyst. Nitrogen fixation is catalysed by the enzyme nitrogenase. Nitrogenase is sensitive to O2. Heterocyst carry thick cell wall to protect nitrogenase from O2

Akinete is a thick walled resting spore with stored food. Akinete is resistant to drought and high temperatures. They are able to survive during unfavourable environmental conditions although vegetative cells dries out.

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37
Q

Reproduction seen in Cyanobacteria

A

Reproduces only by asexual methods

Single unicellular forms and colonial non-filamentous types by simple cell division

Colonial unicellular and colonial filamentous by fragmentation

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38
Q

sp. meaning in microbiology

A

Species

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39
Q

Nutritional modes seen among fungi

A

Saprophytic (decomposers)
Parasitic (plant and animal pathogens)
Mutualistic (lichens and mycorrhizae)

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40
Q

Reproduction seen in fungi

A

Unicellular fungi reproduce asexually by fission or budding
Filamentous fungi asexually or sexually by producing spores

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41
Q

Pleomorphic meaning

A

Occurring in various distinct forms

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42
Q

Nutritional modes seen among protists

A

Photoautotrophic
Heterotrophic
Mixotrophic

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43
Q

Respiratory modes seen among protists

A

Aerobic
Anaerobic
Facultative anaerobic

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44
Q

Reproduction seen among protists

A

Reproduce sexually by gametes and asexually by fission

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45
Q

Mollicutes

A

Mollicutes are prokaryotes included in the domain Bacteria
Mycoplasma and phytoplasma are considered unique due to the absence of cell walls

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46
Q

Mycoplasma

A

Pleomorphic
Smallest prokaryotic group of microorganisms invisible under the light microscope
Do not contain flagella
Almost all mycoplasma are parasites of humans and animals
Reproduce by budding and binary fission and do not posses spores
Requires high amount of growth factors
Aerobes or facultative anaerobes

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47
Q

Phytoplasma

A

Similar in size to mycoplasma
Only can be seen under the electron microscope
Phytoplasma only infect plants and are generally present in the phloem sap
Cannot grow in artificial media
Transmitted mostly by leafhoppers
Reproduce in both leafhoppers as well as plant body
Reproduce by binary fission and budding
Posses aerobic or facultative anaerobic mode of respiration

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48
Q

Characteristic features of virus

A

Do not show any cellular organisation
Not considered as living organisms
Can only multiply with a host cell (obligate parasites)

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49
Q

Composition of viruses

A

Composed of a central core of nucleic acid and surrounded by a protein coat called the capsid which is made up of a fixed number of protein subunits called capsomeres

May have either DNA or RNA as their genetic material
Depends on the host cell’s protein synthesis machinery

Consists of reverse transcriptase enzymes for reverse transcribing RNA into DNA

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50
Q

4 types of morphological forms of virus and examples

A

Helical viruses- Long rigid or flexible rods e.g: Rabies virus
Icosahedron - Icosahedron symmetry e.g: Aden virus
Complex - Exhibits more than one form of symmetry with additional structures e.g: Bacteriophage
Enveloped viruses - Roughly spherical. Capsid covered by envelopes e.g: Herpes simplex virus

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51
Q

Bacteriophages

A

Are typical group of viruses that are capable of infecting bacteria

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52
Q

2 distinct multiplication mechanisms of viruses

A

Lytic cycle
Lysogenic cycle

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53
Q

Difference between lytic cycle and lysogenic cycle

A

Lytic cycle involves with the lysis of the host cell whereas the lysogenic cycle allows viral DNA incorporating into host DNA and multiply without causing lysis of the host cell

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54
Q

Steps of lytic cycle

A

Attachment
Penetration
Biosynthesis
Maturation
Release

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55
Q

Viroids

A

Consist only of short piece of RNA with no protective layer such as a protein coat
Can only multiply within a host cell
Do not contain any gene and only carry signals for their multiplication
Viroids infect plants, but no other life forms unto date

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56
Q

Prions

A

Are proteinaceous infectious particles.
Smaller this virus
Lack nucleic acid but can replicate with the help of host’s gene that encodes the prion protein
Found as disease causing agents in some birds and mammals
All these diseases are neurological diseases

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57
Q

Diseases caused by prions

A

All are neurological

Transmissible Spongiform Encephalopathies (TSEs) - Large vacuoles develop in the brain giving spongy like appearance

Mad cow disease (emerged in cattle)

Creutzfeldt-Jakob disease (CJD) is one of the human diseases caused by prions

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58
Q

Sterilisation

A

Process of removal or destruction of all forms of microbial life including endospores
2 types as physical and chemical

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59
Q

Physical methods of sterilisation

A

Moist heat sterilisation (done by denaturing proteins under high temperature and pressure)
Dry heat sterilisation - direct flaming, Incineration, Hot-air sterilisation
Pasteurisation
Boiling
Filtration
UV radiation

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60
Q

Moist heat sterilisation

A

Moist heat is used to sterilise culture media, heat stable reagents and laboratory equipments. E.g: autoclaving, pressure cookers

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61
Q

Dry heat sterilisation

A

Dry heat is used to sterilise glassware, Petri dishes, pipettes, inoculation loops and needles and scalpels

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62
Q

Types of pasteurisation

A

High temperature short-time (HTST) - 72 C , 15 s
Low temperature long time (LTLT) - 63 C, 30 min
Ultra high temperature (UHT) - 140 C, less than 5 s

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63
Q

Filtration

A

Used to sterilise heat stable liquids such as enzymes and some culture media. Pore size varies from 0.01micrometers to 0.45 micrometers

64
Q

Major disadvantage of using UV radiation as a sterilisation method

A

Does not penetrate through solid surfaces and coverings such as paper, glass and textile

65
Q

Chemical methods of sterilisation

A

Ethylene oxide kills microorganisms and endospores (highly penetrating)
Chlorine dioxide has been used to fumigate enclosed building areas contaminated endospores of Bacillus anthracis

66
Q

What is used in water treatment prior to chlorination

A

Chlorine dioxide

67
Q

Culture media description

A

Is a material prepared for providing nutrients and anchorage which are essential for the growth of microorganisms under laboratory conditions

Agar is used as a solidifying agent (agar solidifies at temperatures below 40 C). Before microbes are entered glassware and nutrient medium should be sterilised. Prior to observation microbes are stained once on the glass slide for better viewing. e.g: methylene blue, crystal violet and saffranin

68
Q

Commonly used microbial culture media and their components

A

Nutrient agar - peptones, meat extract, NaCl, agar and distilled water. Used to culture bacteria.

Potato-dextrose agar (PDA) - Potatoes, glucose, agar and distilled water. Used to culture fungi.

69
Q

How does humans get in contact with microorganisms for the 1st time

A

Generally humans are free of microbes at birth.
During the birth, newborn first gets in contact with the microbes present on the vagina of mother.
Usually these are Lactobacilli
Lactobacilli colonise the intestine of the new-born. These are called the normal microbiota

70
Q

Microbes and diseases

A

it has been estimated that their are 1014 microbial cells for every 1013 body cells. Most of these microbes are not harmful or even beneficial. e.g: E.coli in low concentrations in the large intestine synthesise vitamin K and B and avoid colonisation of certain disease causing agents such as Salmonella typhi. Probiotics are live microbial cultures which and alleviate diarrhoea and prevent entry of Salmonella enteric during antibiotic therapy.
Most of these microbes colonise on inner surfaces of the body such as mucous membrane of nasal tract, throat, upper respiratory and intestinal and genitourinary tracts. Some are opportunistic (E.coli)

71
Q

Pathogen

A

An organism or entity (non-living entities such as virus and prions) that is capable of causing disease.

72
Q

Host

A

Organism with within which infected pathogens live on or in and multiply.

73
Q

Pathogenicity

A

The ability of a pathogen to cause disease in the host by overcoming the defence of a host

74
Q

Parasite

A

An organism or entity living on or in another living organism (host) and obtain nutrients and other resources from the host.

75
Q

Characteristics of pathogenic microorganisms

A

Having optimal growth conditions(temperature) which corresponds to the body conditions of the host.

Having structures to adhere to host cells and to protect against host’s defence mechanisms. e.g: capsule, pilli

produce toxins

Having enzymes for invasiveness such as phospholipase, lecithinase and hyaluronidase

Having DNase to alter host’s metabolic processes

76
Q

Virulence

A

Is the degree of pathogenicity of the pathogen

77
Q

Virulent factors

A

Certain genes of the pathogenic microorganisms express factors which gives them the ability to infect the host and cause diseases

78
Q

Invasiveness

A

Is the ability of the pathogens to invade tissues by overcoming host’s defence mechanisms and multiply for colonising

79
Q

Toxigenicity

A

Ability of microorganisms to produce biochemical substances known as toxins that disrupt the normal functions of cells. Toxins can be proteins or lipopolysaccharides which are known as biological poisons.

80
Q

Endotoxins

A

Endotoxins are lipopolysaccharides
Thermo-stable toxins which are part of the microbial cell. Endotoxins gets released when the microbial cell dies and the cell walls are broken apart
All endotoxins cause the same symptoms regardless of the species of pathogen which includes chills,fever,weakness, generalized aches and sometimes shock and death
Endotoxins are produces only by gram-negative bacteria
e.g: Lipopolysaccharides of the cell walls of Salmonella typhi

81
Q

Exotoxins

A

Produced inside bacterial cells as part of their growth and metabolism and are secreted to the surrounding after cell lysis
Exotoxins are proteins (thermo-liable), majority are enzymes (inactivated by boiling). Due to the catalytic nature only a small amount will be quite harmful
Commonly produced by gram-positive bacteria and few gram-negative bacteria
3 types as neurotoxins, enterotoxins and cytotoxins

82
Q

3 types of exotoxins, characteristics and examples

A

Neurotoxins - interfere with normal transmission of nerve impulse. e.g: Clostridium tetani and Clostridium botulinum

Enterotoxins - stimulates cells of the gastrointestinal tract in a abnormal way. e.g: Vibrio cholera

Cytotoxins - kills host cells by enzymatic attack. e.g: Corynebacterium diphtheriae

83
Q

Causative agent and affected organ of Chickenpox

A

Herpes virus (varicella-zoster)
Skin

84
Q

Causative agent and affected organ of Rubella

A

Rubella virus
Skin

85
Q

Causative agent and affected organ of Measles

A

Measles virus
Skin

86
Q

Causative agent and affected organ of Conjunctivitis

A

Haemophilus influenza / Adenovirus
Eye

87
Q

Causative agent and affected organ of Bacterial meningitis

A

Streptococcus pneumonia
Haemophilus influenza
Neisseria meningitis

Nervous system

88
Q

Causative agent and affected organ of Tetanus

A

Clostridium tetani

Nervous system

89
Q

Causative agent and affected organ of Rabies

A

Rabies virus
Nervous system

90
Q

Causative agent and affected organ of Rheumatic fever

A

Streptococcus pyogenes

Cardiovascular system

91
Q

Causative agent and affected organ of Tuberculosis

A

Mycobacterium tuberculosis

Respiratory system

92
Q

Causative agent and affected organ of Influenza

A

Influenza virus

Respiratory system

93
Q

Causative agent and affected organ of Pneumonia

A

Streptococcus pneumonia

Respiratory system

94
Q

Causative agent and affected organ of Hepatitis

A

Hepatitis A virus

Digestive system

95
Q

Causative agent and affected organ of Food poisoning

A

Staphylococcus aureus

Digestive system

96
Q

Causative agent and affected organ of Cholera

A

Vibrio Cholera

Digestive system

97
Q

Causative agent and affected organ of Typhoid

A

Salmonella typhi

Digestive system

98
Q

Causative agent and affected organ of Leptospirosis

A

Leptospira interrogans

Urinary system

99
Q

Causative agent and affected organ of Gonorrhea

A

Neisseria gonorrhoea

Reproductive system

100
Q

Causative agent and affected organ of Genital herpes

A

Herpes simplex virus

Reproductive system

101
Q

Causative agent and affected organ of AIDS

A

Human immunodeficiency virus

Immune system

102
Q

Protists

A

Pleomorphic
Different locomotive structures such as pseudopodia, cilia or flagella
Photoautotrophs, heterotrophs or mixotrophs
Aerobes, anaerobes or facultative anaerobes
Symbiotic interactions with lichens
Sexually by gametes or asexually by fission

103
Q

Phospholipase

A

Destroy animal cell membranes

104
Q

Lecithinase

A

Hydrolyses the lecithin component of lipid in cell membranes

105
Q

Hyaluronidase

A

Destroys body tissues by breaking down the hyaluronic acid which is cementing substances between cells

106
Q

Antiseptics and disinfectants

A

Major difference is that antiseptics can be safely directly applied to the human body. Generally formulated as liquids and their effectiveness varies with concentration, duration of exposure, temperature and presence of organic matter.

Antiseptics - ethanol, isopropanol, chloroxylenol
Disinfectants - phenol, hypochlorites (Na and Ca)

107
Q

Microbes which are not destroyed by antiseptics or disinfectants

A

Polio virus, tuberculosis bacterium, spores of bacteria and fungi

108
Q

Various actions shown by antibiotics

A

Inhibition of cell wall synthesis - Penicillin
Inhibition of protein synthesis - Erythromycin, Tetracycline
Disrupting plasma membrane - Daptomycin
Inhibition of DNA/RNA synthesis - Rifampin

109
Q

Vaccines

A

Is a suspension of weakened pathogen or fractions of organisms that are used to induce immunity

110
Q

Live attenuated viruses

A

Contains the live but weakened pathogen. Mimics an an actual infection and provides lifelong immunity. Booster vaccination is not needed. e.g: MMR, Chickenpox

111
Q

Inactivated vaccines

A

Pathogen is inactivated or killed and requires booster doses. e.g: Rabies, influenza, polio and cholera

112
Q

Subunit vaccines

A

Contains only the antigenic fragment of the pathogen that can induce immunity in the recipient. Types as toxoid vaccines and recombinant vaccines. Subunit vaccines requires repeated booster doses.

Toxoid vaccines contain the inactivated toxin derived from pathogens. e.g: Diphtheria and tetanus

Recombinant vaccines are made using genetic engineering. e.g: Hepatitis-B vaccine

113
Q

E.g of using microbes in the early periods

A

Babylonian and Sumerian civilisations used yeast to make alcohol in 6000 BC

114
Q

Advantages of using microbial processes over chemical processes

A

Simple nutritional requirements are sufficient for their growth.

Able to convert a wide range of raw materials

Able to convert cheap raw materials into industrially important products

Due to their high growth rate, raw materials can be converted to products within a short period of time

Growth conditions can be controlled to obtain desired end products

Reactions can be carried out a low temperatures, energy and pressure

Gives higher yield with higher specificity

115
Q

Basic principles of microbial metabolic processes

A

Microbial cells are used as end products. e.g: single cell proteins

Microbial metabolic products are used as end products. e.g: primary end products - alcoholic beverages, secondary end products - antibiotics

Microbial metabolic processes are used as end products. e.g: bioremediation, metal extraction and retting

GM microbes are used to produce end products. e.g: commercial enzymes, vaccines and hormones

116
Q

Single cell proteins

A

Microbial cells grown in large scale as food supplements and are rich in proteins. E.g: Yeast, Chlorella sp and Spirulina sp

117
Q

alcoholic beverages

A

Yeast oxidises simple sugars such as sucrose derived from sugarcane into ethanol and CO2.

118
Q

Production of vinegar

A
  1. Alcoholic fermentation - sugar is fermented by S.cerevisiae. Ethanol is subjected to acetic acid fermentation
  2. acetic acid fermentation - Ethanol undergoes incomplete oxidation to produce acetic acid. Highly aerobic and involves Acetobacter sp and Gluconobacter sp
119
Q

Dairy products

A

Lactic acid producing bacteria converts lactose sugar in milk into lactic acid. e.g: L.bulgaricus, L.lactis and S.thermophillus

120
Q

organic acids

A

Citric acids - sucrose fermented by Aspergillus niger

121
Q

Metal extraction

A

Some metals from ores are extracted with the help of microbes (leaching). e.g: extraction of Cu from low grade Cu ore which other extraction methods are unprofitable, Thiobacillus ferrooxidans recovers Cu from ores that contain Fe and S (about 70%), Uranium and gold can also be leached.

122
Q

Retting

A

Is the process of loosening fibres from woody stems or other plant materials such as coir. Pectinases facilitate loosening.

123
Q

Residues which are not digested naturally

A

Residues of pesticides such as heavy metals, insecticide DDT, herbicide 2,4-D

124
Q

Bioremediation

A

Technology that applies of living organisms to remove, degrade or detoxify pollutants.

Functions - remediate soil and water contaminated with oil spills, toxic metal waste, hazardous organic wastes
Decompose wastewater from food processing and chemical plants

125
Q

Nature, distribution and role of soil microorganisms

A

Soil provides an adequate physical and chemical environment for the growth of microorganisms in terms of space and nutrients such as minerals, water, decaying organic matter and gases such as O2, CO2 and N2. Depth of soil leads to diversity between soil microbes.

Top few cm hv the largest community of microbes. Majority of soil microflora includes bacteria and others such as fungi, algae, protozoa and actinomycetes. Soil microbes are important in decomposing and recycling of materials in biogeochemical cycles

126
Q

Mineralization

A

Is the decomposition of plant and animal residue by using extracellular enzymes of bacteria and fungi.

Mineralization helps to remove plant and animal debris from the earth’s surface allowing other organisms to live. And recycles minerals which are found in limited quantities on earth.

127
Q

Carbon cycle

A

All organisms contains large amount of carbon in their bodies as cellulose, starch, fat and proteins

1st step of the carbon cycle is the fixation of atmospheric CO2 by autotrophs and are made available for chemoheterotrophs and protozoans

Part of the C fixed in autotrophs and heterotrophs are released back into the atmosphere as CO2 through respiration and made available again for autotrophs

Another part of C fixed in chemoheterotrophs is released as faeces which is later decomposed by soil microbes

Rest of C fixed remain in organisms until they die and when they are dies it is decomposed and released back into the atmosphere

Microbes of carbon cycle consumes more than 80% of the methane produced in ocean beds before reaching the atmosphere

128
Q

Ammonification

A

More than 90% of the organic nitrogen of soil exists as proteins. Proteins of dead plants and animals are decomposed by extracellular proteolytic enzymes and are converted to amino acids. These amino acids are taken into microbial cells and undergoes ammonification where the amino groups of amino acids are converted to ammonia and are further converted ammonium once they dissolve in soil water.

129
Q

Nitrification

A

Process of converting ammonium ions to nitrate by nitrifying bacteria

NH4+ is converted NO2- by Nitrosomans
NO2- is converted NO3- by Niitrobacter

130
Q

Denitrification

A

In the absence of O2 certain microbes reduce nitrates to N2. Occurs frequently in water-logged areas (pseudomonas sp) NO3-, NO2-,N2O,N2

131
Q

Nitrogen fixation

A

Process of converting N2 to NH4+

132
Q

Anaerobic bacteria fixing N2

A

Clostridium sp

133
Q

Rhizosphere

A

Symbiotic interaction between plant roots and soil surrounding the root surface for about few mm. This micro-ecological zone is the most bio-diverse and dynamic habitat on earth. Microbes within the rhizosphere competes for space, nutrients and water of which bacteria are the most common (psedomonas,bacillus and Agrobacterium) Both pathogenic and symbiotic fungi inhabit the rhizosphere

134
Q

Mycorrhizae

A

Symbiotic relationship between fungi and plant roots. Almost all land plants are associated with 1 or more mycorrhizal fungi. These fungi increases the surface area over which nutrients and water can be absorbed by the plants, reaches to small pores within soil and increases the uptake of immobile nutrients such as P,Zn,Cu

135
Q

Microbes in improving soil quality

A

Involved in the formation of stable soil aggregates such as fungal filaments, actinomycetes filaments and polysaccharide gums produced by bacteria

136
Q

Major criteria of indicator organisms of water quality

A

Should be present consistently in the human faecal matter in large amounts. e.g: coliforms

137
Q

Coliform bacteria

A

Bacteria which are aerobic or facultative anaerobic, gram negative, non-endospore forming and rod shaped which ferments lactose to gas within 48 hours in a lactose broth at 35 C

138
Q

Water borne diseases

A

Typhoid, paratyphoid, cholera, gastroenteritis and dysentery

139
Q

Steps of urban water treatment

A

Sedimentation and coagulation
Filtration
Disinfection

140
Q

Sedimentation and coagulation

A

If the water is turbid it is allowed to stand in large reservoirs for a holding period to allow settling of particle matter at the bottom. Enhanced by adding alum (aluminium potassium sulphate) which produces a sticky polysaccharide.

141
Q

Filtration

A

Water is sent through beds of fine sand. Protozoan cysts are removed by the surface absorption onto the sand particles. Removes about 99% of bacteria. Some water treatment plants uses activated carbon for the removal of toxic chemicals.

142
Q

Disinfection

A

Done through chlorination or by ozone. O3 is highly reactive and kills microorganisms by oxidation. O3 method is the preferred method as it leaves no taste or odour and has little residual effect.

143
Q

Primary treatment of waste water

A

large floating materials are screened out
removal of sand
removal of oil and grease
solid matter is allowed to settle in sedimentation tanks
sludge collected and removed

No biological activity is used here and through this step about 25%-35% of organic matter is removed

144
Q

Secondary treatment of waste water

A

Waste water is aerated to facilitate growth of aerobic bacteria and rapid microbial oxidation. Activated sludge system or the trickling filter method is used.

In activated sludge vigorous aeration is done mechanically and in tricking filter, waste water is slowly sprayed onto a bed of rocky material and allowed trickle. Microbes grow on the filter bed and oxidises organic matter. (75%-95%) Finally water is disinfected

Sludge remaining from both the treatments are sent to an anaerobic sludge digester and the organic matter in sludge is converted to CH4 and CO2 by anaerobic decomposition. Digested sludge can be used as a fertiliser.

145
Q

Adverse effects of discharging large amounts of waste water

A

Dissemination of pathogenic microbes
Water pollution due to accumulation of biodegradable materials and their decomposition products
Decomposition which cause large consumption of O2 in water which affects aquatic organisms
Anaerobic decomposition leading to bad smells

146
Q

Importance of recycling solid wastes

A

Improper disposal of waste can create breeding sites for mosquitoes, insects and rats which acts as vectors of diseases such as dengue, chickungunya and leptospirosis

creates social problems due to bad smell due to anaerobic decomposition of waste

accumulation of CH4 can cause explosions and fires

transmission of water borne diseases such as typhoid, paratyphoid, cholera, gastroenteritis and dysentery

ground water can be polluted due to leachate of waste (liquid pass through waste)

147
Q

Solid waste management

A

Sorting and recycling
Degradation/ decomposition of organic matter (composting)
Sanitary. land fillings

148
Q

Food spoilage

A

Growth of microorganisms on food changes the physical, chemical and biological components of food making it unfit for consumption

149
Q

Chemical changes taking place in food

A

Putrefaction
Fermentation
Rancidity

150
Q

Putrefaction

A

Proteins in the food source are broken down by proteolytic enzymes secreted by proteolytic microorganisms into amino acids, amines, ammonia and H2S

151
Q

Fermentation

A

Complex carbohydrates are broken down into simple carbohydrates by amylase and then the simple carbohydrates are converted into food acids, alcohol and gases by saccharolytic enzymes

152
Q

Rancidity

A

Lipids present in the food source is converted into fatty acids and glycerol by lipolytic enzymes

153
Q

Physical changes taking place in food

A

Softening of food
Pigmentation
Ropiness
Slime or gum formation
Toxin accumulation

154
Q

External factors influencing food spoilage

A

temperature of storage
R.H of environment
presence and concentration of gases in the environment

155
Q

Internal factors influencing food spoilage

A

pH - most microbes grow best at pH 7, however holds and yeast grow over a wide range (2-10) and bacteria from 5-7

moisture content - high moisture containing food such as meat and fish are spoiled by bacteria and low moisture containing food are spoiled by molds and yeast.

nutrient content - nutrient rich food are easily spoiled

biological structure - outer covering of fruits, egg shells

156
Q

Food borne pathogens

A

Typhoid - Salmonella typhi
Cholera - Vibrio cholera
Food poisoning - Staphylococcus aureus
Dysentery - Shigella
Botulism - Clostridium botulinum
Aflotoxins - Aspergillus flavus

157
Q

Effects of food spoilage

A

Food borne infections - microbes enters into the human body through spoiled food and they grow and replicate producing toxins. Symptoms will be developed after some time. e.g: typhoid, cholera and dysentery

Food intoxications - Indigested spoiled food contains toxins. Symptoms are rapid. e.g: aflatoxins, botulism and food poisoning

Viruses also cause food borne illnesses

Biology (21 decks)

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