MODULE 12

MICROORGANISMS AND THEIR EFFECTS ON LIVING THINGS

CONCEPT MAP

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BACTERIAi. unicellular organismsii. size : 0.1 – 10 umiii. shapes

iv. Reproduction a) Binary fission

b) Conjugation c) Spore formation v. Nutrition : Photosynthetic / Saprophytic / Parasitic vi. Habitat : everywhere

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SHAPE BACTERIA

Spherical

Rod-shaped

Comma-shaped

Spiral or spring-shaped

vibrios

Spirilla

Streptococcus

Coccus Diplococcus

Staphylococcus

Bacillus Diplobacillus Streptobacillus

FUNGI

i. Unicellular or multicellular organisms.ii. Size : 10 – 100 umiii. Reproduction : Spore production / budding / conjugation

buds

iv. Nutrition : saprophytic / parasiticv. Habitat : damp dark places

PROTOZOA

i. Unicellular organisms

ii. Size : 2 – 1000 umiii. Reproduction : Binary fission / conjugationiv. Nutrition : Saprophytic / parasitic / photosyntheticv. Habitat : Marine, fresh water and moist terrestrial habitats.

VIRUSES

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Bread mould/Mucor Yeast

Amoeba Paramecium

Trypanosoma

i. The smallest and simplest organisms.ii. Size : 20 – 400 nm.iii. Contain DNA / RNA and protein coat (capsid)iv. Nutrition : Parasitic. Do not respire,synthesize, eat and excrete.v. Reproduction : Penetrate DNA into living host cells.

vi. Habitat : Living host cells.

ALGAE

i. Unicellular or multicellular organisms.ii. Size : 10 – 10000 um.iii. Examples

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Spirogyra Chlamydomonas

Influenza virus

Tobacco mosaic virus

Bacteriophage

A virus attaches itself to a host cell

Viral DNA

BacterialDNA

The virus injects its DNA into the cell’s cytoplasm

The viral DNA replicates itself

The viral DNA replicates using material in the host cell.The viral DNA then makes its own outer protein coat.

The host cell bursts open releasing hundreds of new viruses which will infect other cells

iv. Nutrition : Photosynthetic v. Reproduction : Binary fission / fragmentation / conjugationvi. Habitat : Aquatic habitats and other moist habitats with low light

intensity.

Factors that affect the growth of microorganismsi. Nutrients ii. Lightiii. Water / humidityiv. Temperaturev. pH

Uses of microorganisms1. Food digestion2. Decaying process3. Medicine4. Agriculture5. Industry

Type of industry Type of microorganism

Products

Food industry Fungi (yeast) Alcoholic drinks Bread

Bacteria or fungi Cheese, cream, yogurt and butterSoya sauce

Bacteria VinegarTea leaves

Rope industry Bacteria RopeLeather industry Bacteria LeatherCleansing or mining industry

Bacteria Purified petroleum and mineral ores

6. In various field – genetic engineering (bacteria or viruses)

Harmful effects of microorganisms1. Tooth decay - bacteria2. Food poisoning – bacteria, fungi3. Diseases – bacteria, fungi, viruses, protozoa (pathogen)Pathogen Examples of diseases

causedSymptoms of the disease

Bacteria Tuberculosis (TB) Chest pain, cough,fever,night sweats, fatigue,weight loss, shortness of breath, loss of appetite, coughing up blood.

Cholera Vomiting,severe diarrhoea, dehydration of body, stomach cramps.

Gonorrhoea Discharge of pus from the genitals, painful urination

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Syphilis Fever, swollen lymph nodes, lesions throughout the body,patchy hair loss on the head

Viruses Common cold Sneezing, runny nose, fever,sore throat,fatigue,headache,general aches and pain.

Dengue fever Headache, high fever, severe pain in joints and muscles, sore throat, skin rashes.

Hepatitis Fever, jaundice ( yellowing of the body), dark-coloured urine, weight loss.

AIDS Swollen lymph nodes, infections by bacteria, viruses and fungi, weight loss, skin rashes, fatigue, fever, diarrhoea.

Fungi Ringworm Ring-shaped infection on the skin, red and scaly patches that itch.

Tinea White spots on the surface of skin, a fine and dry scale on it. Get itch especially when sweating.

Protozoa Malaria Bouts of high fever, sweating and shivering, nausea, muscle pain.

Methods of transmission of diseases Examples of diseasesThrough air Common cold, Tuberculosis (TB )Through water Cholera, Hepatitis AThrough food Cholera, Hepatitis AThrough physical contact Gonorrhoea,syphilis,ringworm,athlete’s

foot, Hepatitis B, AIDSThrough Vectors Cholera, malaria,dengue fever

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Ways to prevent infection caused by microorganisms

1.Control of vectors

a) Mosquitoi. Life cycle

ii. Control

-eliminate the breeding grounds (draining swamps,bury all containers and discarded tyres).

- kill the larvae (Covering the surfaces of ponds and lakes with oil ,use larvae drugs,larvae-eating fish)

- Get rid of the hiding place of mosquitoes by cutting down bushes and mowing tall grass.

b) Houseflies

i. Life cycle

ii. Control -get rid of breeding grounds (rubbish dumps and exposed faeces) -place in rubbish in bins with lids. -use toilets with flush facility

-always keep food covered-kill the adult houseflies by spraying insecticide.

2. Sterilization i. Use heat – Heating, boiling,autoclave/pressure cooker ii. Use chemicals – Antiseptics, disinfectant iii. Use radiation – gamma rays and ultraviolet light.

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Pupae also live in water but they are inactive

Adult female mosquitoes feed on human blood

Mosquitoes lay eggs in stagnant water

The larvae develop in water but come to the surface to breathe

housefly

Egg

Larvae

PupaPupa

4. Immunity

Artificial passive immunity

Artificial active immunity

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Active immunityPassive immunity

NaturalArtificialNaturalArtificial

Immunity

ACTIVITY

1. Complete the diagram below :-

2. Microorganisms are living things which are too small and are only visible under the

--------------------------- 3. Microorganisms are also known as

4. Name the modes of nutrition of : a) protozoa b) Algae a) -------------------------------------------------------------------------------------------------------------

b) --------------------------------------------------------------------------------------------------------------

5. What is a pathogen ? Name an example.

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------------------------------------------------------------------------------------------------------------------ 6. What microorganism is used in bread-making ?

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7. Name an example of a disease that spreads through cantact and name the pathogen involved.

------------------------------------------------------------------------------------------------------------------ 8. What is meant by a disease vector ?

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viruses

algae

-----------------------------

microorganisms

9. State two ways by which we can prevent diseases that are spread by mosquitoes.

i. --------------------------------------------------------------------------------------------------------

ii. -------------------------------------------------------------------------------------------------------- 10.Complete the similariies and differences between active and passive immunity below:

Ways to develop immunity

Time taken to acquire immunity (immediate/takes time)Effects of immunity(long-lasting/short-lived)Body receives(antigens/antibodies)Does the body makes its own antibodies?(Yes/No)Examples

OBJECTIVE ITEMS

1. Which of the following microorganisms cannot reproduce outside living cells? A Bacteria C Fungi B Protozoa D Viruses 2. Mucor reproduces asexually by A binary fission C budding B forming spores D meiosis 3. Which of the following is a favourable condition for the growth of microorganisms? A Bright condition C Dry environment B pH 1 D Temperature of 350C 4. Which of the following activities does not involve microorganisms? A The production of ethanol

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Active immunity Passive immunity

Similarities

differences

B The preparation of vaccine C the preparation of antibiotic D The preservation of food 5. Which of the following substances is suitable for cleaning wounds ? A Antibiotics C Antibodies B Antiseptics D Disinfectants 6. What type of immunity is conferred from a mother to her baby? A Natural active immunity B Artificial active immunity C Natural passive immunity D artificial passive immunity 7. Which of the following diseases spread through droplets released into the air when a patient breathes, coughs or sneezes ? I Common cold II Tuberculosis III Malaria A I and II only C II and III only B I and III only D I,II and III 8. Which pair is correct ?

A B C D 9. Cholera is transmitted from a person to another by I water II food III contact A I and II only C II and III only B I and III only D I, II and III 10. What is vaccine? A A preparation containing an antitoxin B A preparation containing an antiserum C A preparation containing antibodies D A preparation containing weakened or dead pathogens.

STRUCTURED QUESTIONS

Pathogens Diseases causedViruses Dengue feverBacteria MalariaFungi HepatitisProtozoa Syphilis

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1. Table 1 shows the results of an experiment to investigate the effects of temperature on the growth of bacteria in a laboratory.

Table 1Temperature(0C) 10 20 30 37 40 50 60Number of colonies in petri dish after 48 hours

0 11 28 30 28 1 0

a) Name the medium used to culture bacteria in the experiment.

------------------------------------------------------------------------------------------------------ (1 mark)

b) In the above experiment, state two precautions to be taken when handling the experiment.

i) --------------------------------------------------------------------------------------------------

ii)--------------------------------------------------------------------------------------------------- (2marks) c) Based on the results in Table 1, state one inference from the experiment.

----------------------------------------------------------------------------------------------- (1 mark) d) Based on the results in Table 1, sketch a graph of the number of colonies of bacteria against temperature. ( 1 mark )

e) Based on the graph in d), state one conclusion for the experiment.

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No. of colonies

10 20 30 40 50 60 Temperature(0C)

30

25

20

15

10

5

--------------------------------------------------------------------------------------------------------- ( 1 mark )

2.

Explain how you would develop a concept based on the information given. Your explanation of the concept should include the following :

Idenify two common characteristics ( 2 marks ) Develop initial concept (1 mark ) Give other non-examples in relation to this concept. (2 marks ) Explain the actual concept. ( 1 mark )

ANSWER

ACTIVITY

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Events

Pregnancy Breastfeeding Injection of serum

1.

2. Microscope

3. Microbes

4.a) Protozoa : Saprophytic/parasitic/photosynthetic b) Algae : photosynthetic

5. Pathogen is a microorganism which cause diseases. Example: viruses, bacteria,fungi and protozoa.

6. Yeast/ fungi

7. Gonorrhoea/syphilis (bacteria) /AIDS/Hepatitis B (viruses) /Tinea/ringworm (fungi)

8. A disease vector is an animal which transfers pathogens from one host to another.

9. – eliminate the breeding grounds (draining swamps, bury all containers and discarded tyres ) - kill the larvae (covering the surfaces of ponds and lakes with oil, use larvae drugs, larvae-eating fish) - get rid of the hiding place of mosquitoes by cutting down bushes and mowing tall grass.

10. Similarities : - All of them give protection to the person against diseases. - The ability to fight diseases is due to the presence of antibodies in the body.

Differences :

Antibodies are produced by the body itself

Ways to develop immunity Antibodies are obtained from an outside source

Takes time Time taken to acquire immunity (immediate/takes time)

Immediately

Long-lasting Effects of immunity Short-lived

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bacteria viruses

microorganismsalgae fungi

protozoa

(long-lasting/short-lived)Antigens Body receives

(antigens/antibodies)Antibodies

Yes Does the body makes its own antibodies?(Yes/No)

No

Vaccination/recover from the illness (measles,chickenpox,mumps)

Examples Injecting serum/breastfeeding/from the maternal blood

OBJECTIVE ITEMS

1. D 2. B 3. D 4. D 5. B6. C 7. A 8. A 9. A 10. D

STRUCTURED QUESTIONS

1.a) Nutrient broth b) i. Wash hands thoroughly with water and soap before and after the experiment. ii. Use an antiseptic solution to clean all the apparatus and materials used. iii. Wear gloves. c) Bacteria can only grow and reproduce at a suitable temperature.

d) no. of colonies

e) The higher the temperature, the faster the growth rate of bacteria. The fastest rate of growth is at 37 0C (optimum temperature). After this temperature, the rate of growth for bacteria declines to zero.

2. Two common characteristics : All the evens involve transfer of antibodies All the events confer passive immunity.

Initial concept : A person may receive antibodies from the external source (another human being or an animal).This confers passive immunity.

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10 37 60

Temperature (0C)

30

0

Other non-examples in relation to this concept : A person can acquire natural immunity through vaccination. A person can acquire natural immunity by falling sick and recovering from it.

Actual concept : Immunity is the protection against diseases provided by our immune system. We can attain immunity through active immunity and passive immunity. Active immunity is acquired when our body itself produces the antibodies. Passive immunity is acquired when our body receives the antibodies from another human being or animal.

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