CONTENT
• Growth of Microorganisms
• Beneficial and Harmful Effects of Microorganisms
• Diseases Caused by Microorganisms, Symptoms, Mode of Transmission and Control
GROWTH OF MICRO-ORGANISMS
Bacteria reproduce by binary fission in which a single cell divides into two. This process is called asexual reproduction. The time interval required for the cell to divide into two is called generation time. This time varies from one organism to another. It strongly depends upon nutrient availability, temperature, gaseous requirement and pH. There are different phases in the growth of bacteria. These include the (i) lag phase (ii) logarithmic or exponential phase (iii) the stationary phase and (iv) decline or death. The growth of micro-organisms can be measured by using any of these methods:
(a) Turbidity method.
(b) Serial dilution method.
(c) Squared transparent paper or cellophane method.
EVALUATION
1. State four factors that can affect the growth of microorganisms.
2. List three ways of measuring the growth of bacteria.
BENEFICIAL AND HARMFUL EFFECTS OF MICRO-ORGANISMS
BENEFICIAL EFFECTS
1. Bacteria help to digest cellulose in herbivores.
2. In man, they synthesize vitamin K and B12
3. Bacteria and fungi are widely used in the synthesis of antibiotics
4. They are used to manufacture amino acids and vinegar
5. Bacteria are used to process milk into different tastes and flavours
6. They are used to decompose sewage into harmless inorganic compounds.
7. Microbial cultures are used to produce enzymes
8. Yeast is used as a leavening agent in baking industries.
9. Algae play important role in fertilizing the soil.
10. Bacteria are used to produce single-cells protein (SCP).
HARMFUL EFFECTS
1. Bacteria cause decay and spoilage of food items.
2. Materials like wood, paper, textiles, rubber and metals are destroyed by microbes.
3. They cause diseases of different types.
EVALUATION
1. State thee beneficial and three harmful effects of microorganisms.
2. Mention five mention five beneficial and five harmful microorganisms.
DISEASES CAUSED BY MICRO-ORGANISMS
DISEASE CAUSATIVE AGENT SYMPTOMS TRANSMISSION CONTROL
Chickenpox Varicella Virus Fever, tiredness, and an itchy, blistery rash. Contact Isolate patient and use appropriate drugs.
Cholera Vibrio Cholerae • Watery diarrhea, vomiting, leg cramps.
flies, food , faeces,
carriers Personal hygiene.
Common Cold Rhino Virus Cough, runny nose, shivering, etc. Contact Take appropriate medications and avoid contact.
Dengue Dengue Virus (arbovirus) Severe headache, severe eye pain (behind eyes), joint pain, muscle and/or bone pain, rash, mild bleeding (e.g., nose or gum bleed, petechiae, or easy bruising),low white cell count. Aedes Mosquito Drain the water and clear the bushes around.
Diarrhoea Giardia intestinalis Frequent passing of watery faeces, cramps and pains in the abdomen (stomach), nausea and vomiting. contaminated stools Personal hygiene
Diphtheria Corynebacteriumdiptheriae (Bacteria) A sore throat, hoarseness, painful swallowing, swollen glands (enlarged lymph nodes) in your neck, thick, difficulty breathing or rapid breathing, nasal discharge, fever and chills, & malaise. Contact Use antibiotics and avoid contacts.
Leprosy Mycobacterium leprae Disfiguring skin sores, lumps, or bumps (that do not go away after several weeks or months), loss of feeling in the arms and legs, muscle weakness. Long and close contact Use antibiotics and avoid contacts. Patients should be isolated.
Measles Measles virus
(ParaMyxoVirus) A high temperature, sore eyes (conjunctivitis), runny nose, small white spots, harsh dry cough, going off food, tiredness, aches, pains, diarrhoea and/or vomiting. Contact Take appropriate medication and avoid contact.
Pneumonia Diplococcus pneumonia High fever, shaking chills, cough with phlegm (a slimy substance) which doesn’t improve or worsens, shortness of breath, chest pain when you breathe or cough, suddenly feeling worse after a cold, etc. bacteria transmission by
contact. Use of antibiotics and avoidance of contact.
Poliomyelitis Polio Virus or Enterovirus Fever, sore throat, headache, vomiting, fatigue, back pain or stiffness, neck pain or stiffness, pain or stiffness in the arms or legs, muscle weakness or tenderness, & meningitis. houseflies, food and
water Good hygiene and appropriate medication.
Rabies Rhabdovirus Fever, cough, sore throat, etc. mad dog bites Treat dogs and seek urgent medical attention in cases of bites.
Septic Sore
Throat Streptococcus Bacteria Fever, nasal drainage, sore throat, swollen glands, difficulty swallowing, and irritability. Contact Use of antibiotics and avoidance of contact.
Sleeping
Sickness TryponosomaBrucei • Anxiety, drowsiness during the day, fever, headache,
• insomnia at night, mood changes, sleepiness,
• sweating, swollen lymph nodes all over the body,
• swollen, red, painful nodule at site of fly bite. reaches lymph nodes via transmission thru fly bites Clear vegetations around, use insecticides and take appropriate medication.
Smallpox Variola Virus High fever, vomiting, fatigue, backache, a raised spotted rash, etc. Contact Take appropriate medication and avoid contact.
Tuberculosis Mycobacterium tuberculosis Malaise, weight loss, and night sweats. Bacteria transmission by
cough Isolate patients and use appropriate antibiotics.
Tetanus Clostridium tetani Muscle spasms and breathing problems. bacteria in soil thru
wounds Treat wounds urgently.
Typhoid Salmonella Typhi • Abdominal tenderness,
• agitation, bloody stools, chills,confusion, difficulty paying attention, fluctuating mood,nosebleeds,severe fatigue,weakness, etc. Flies, food etc. Treat water before drinking. Maintain personal hygiene. Use appropriate antibiotics.
Whooping cough Hameophilius Pertussis Cough, whooping sound during breathing, etc. coughing and sneezing Isolate patients and use appropriate antibiotics.
Influenza Flu Orthomixovirus fever and muscle aches, cold, runny nose, sore throat, etc. Contact Take appropriate medication and avoid contact.
Malaria Plasmodium chills, headache,muscle aches, tiredness, nausea, vomiting and diarrhea. Bite from female Anophelex mosquitoes Use of drugs, insecticides, etc.
EVALUATION
1. State the causative organisms, symptoms and control of the following diseases (i) Malaria (ii) Cholera (iii) Tuberculosis (iv) Measles (v) Poliomyelities
2. List five airborne and waterborne microorganisms respectively.
GENERAL EVALUATION
1. Mention the observable phases in the growth of microbes.
2. State five uses of microorganisms in industries.
3. Outline four general ways of controlling microorganisms.
4. Mention three microorganisms each that are involved in Nitrogen and Carbon cycle.
5. State three uses of microorganisms in (i) Agriculture (i) Medicine
6. Describe three ways of measuring growth of bacteria.
7. List five ways through which microorganisms can be transmitted.
READING ASSIGNMENT: College Biology, chapter 21, page 467 – 484.
WEEKEND ASSSIGNMENT
1. The growth phase in bacteria in which cells divide steadily at a constant rate is called (a) Exponential phase (b) lag phase (c) stationary phase (d) decline phase
2. Which of the following microbes causes cholera? (a) Virus (b)Bacterium (c) Protozoan (d) Fungus
3. Growth of micro-organisms can be measured by the following methods except___________ method (a) serial dilution (b) turbidity (c) squared transparent paper (d) dry weight
4. The following practices contribute to the control of the spread of diseases except (a) sewage treatment with chemicals (b) proper sewage disposal (c) disinfecting the surrounding (d) using human faeces as manure
5. The vector of the trypanosome parasite is (a) housefly (b) tse-tse fly (c) mosquito (d) black fly
THEORY
1. Define the following phases in microorganisms growth (i) lag (ii) exponential (iii) stationary.
2. State four ways in which each of the following organisms are beneficial to humans. i. Bacteria ii. Fungi
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