Here are potential responses to the questions: 4) You don't always get sick from undercooked meat because not all meat contains harmful bacteria. The bacteria have to be present and in large enough quantities to cause illness. Other factors like your own immune system also play a role in whether or not you get sick. 5) Even when multiple people eat contaminated food, only some may get sick because factors like age, existing health conditions, medication and the size of the bacteria dose can affect the chances of getting an infection. People's individual immune systems also respond differently. 6) It can take time for symptoms of a foodborne illness to appear because the bacteria first have to multiply inside the body until they reach levels high enough to

1. Micro-organisms and
Humans
Internal Assessment 4 Credits
Year 11
Ms Gibellini

3. Microbes and YOU!
• Have you ever had FOOD POISONING?
When, and what happened?
• Name 2 foods that often cause food
poisoning
• You have dirty water. How can you
clean it so it is safe to drink?
• You have fresh chicken. How can you
store it safely?
• Name 2 types of VIRUS
• Name 2 types of BACTERIA
• Name 2 types of FUNGUS
• What should you do to keep good hygiene?
• Have you ever had these infections - YES or
NO:
• Cold
• Pimples
• Vomiting
• Diarrhea
• AIDS
• Measles
• Chicken Pox
• Are you vaccinated?

4. Achievement Standard
Investigate comprehensively involves using findings and biological ideas to make significant links about
the interactions between humans and micro-organisms, including the impacts of this knowledge on
human’s personal actions or everyday life.
Micro-organisms will be selected from: bacteria, fungi and viruses.
The ways that humans use and are affected by micro-organisms may include: disposal of organic wastes,
sewage treatment, composting, food production and preservation, food poisoning, microbial action
on everyday materials (helpful and harmful micro-organisms), disease in humans and animals they
are in contact with, antibiotics, resistance to antibiotics, and origins and control of pandemics.
Biological ideas relating to how humans use and are affected by micro-organisms may include the
following:
• structure and life processes of micro-organisms
• culturing of micro-organisms
• factors that affect the life processes of micro-organisms.

5. Content
• Structures and functions, requirements for survival, life processes (feeding,
reproduction) for bacteria, fungi, viruses
• Factors affecting life processes
• Culturing micro-organisms
• How humans use and are affected by microbes eg:
• helpful/harmful microbe action on everyday materials,
• food preservation and production,
• food poisoning,
• disease in humans and animals they are in contact with,
• antibiotics, resistance to antibiotics.

6. Assessment
This assessment activity involves investigating how humans use, and are affected by, micro-
organisms.
There are two tasks as part of this assessment.
Task One
a) You will carry out an investigation in a small group to discover the ideal growing
conditions for fungi (mould) on bread and answer associated questions.
b) You will then individually discuss how foods can be protected from spoiling.
Task Two
This is an individual research task around causes and effects of food borne illnesses where you
will discuss common causes of TWO food borne illnesses and how recommended food safety
practices affect the life processes of microbes and prevent illness in humans.

7. Microbes are very small living things
and are sometimes called
micro-organisms.
Microbes are so tiny that they cannot be
seen with the naked eye. They can only
be seen using a microscope.
What are microbes?
How many different microbes can
you name?

9. There are three types of microbes:
Different types of microbes
bacteria
viruses fungi
microbes

11. MRS C GREN
• All living organism must carry out the following functions including microbes
M – Movement
R – Respiration
S – Sensitivity
C – circulation/cells
G – growth
R – Reproduction
E – Excretion
N – Nutrition (feeding)
• It is these process that we use to make foods and medicine but can also make us sick

14. Bacteria
• Complete Scipad page 7-9
• http://www.youtube.com/watch?v=pcXdfofLoj0&feature=player_embedded

15. Bacterium structure

16. Structure and Function
Structure Function
Flagellum
Pili
Cell Wall
Ribosomes
Plasma Membrane
Slime Layer/capsule

17. Structure and Function
Structure Function
Flagellum Tail used to swim – move towards food
(M- Movement)
Pili Attach onto food or other organisms
Cell Wall Gives shape to bacteria and protects it
Ribosomes Make proteins (enzymes)
Plasma Membrane Has small holes in and allows entry and exit
of substances
Slime Layer/capsule Protects against attack from white blood
cells and other microbes

18. R – Reproduction in Bacteria
• Bacteria reproduce by splitting in half – Binary
Fission
• In the right conditions (plenty of food, water,
warmth and space) they can do this very very
quickly!
• It is because they can increase in numbers so
quickly that we MUST be careful when storing
food.
• In the assessment you will investigate the
factors that affect the growth rate of fungi
• Complete Scipad pages 10-11

20. R – Reproduction in Bacteria
Experiment 1: Factors affecting Bacterial Growth
Aim: To investigate the effect of temperature on bacterial growth
Method:
1. Inoculate 3 agar dishes with bacteria
2. Seal with celeotapte and label – fridge, room, incubator
3. Put one in fridge, room, incubator
4. After 3 days draw the results

21. Results:
The temperature at which bacteria growth fastest is…..
Discussion:
All microbes contain enzymes which control reactions within cells including DNA replication
and therefore rate of reproduction.
Enzymes are affected by temperatures, too c_______ or too h______ and they do not work
and therefore the rate of reproduction s________ down.
Body temperature (37’C) is the ideal temperature for growth.
Why do you think we stored cooked and uncooked food in a fridge and not the bench?
Complete Scipad page 12
Fridge Room Incubator

22. Results
• Fuzzy = fungi
• Smooth, shiny, slimy, orange = bacteria

24. N – Nutrition/Feeding in Bacteria
• Bacteria feed by extra cellular digestion
• Extra – outside the cell
• Microbes excrete digestive enzymes
• The enzymes break food down into smaller molecules and in
turn make our food ‘go off’ or spoil (making it inedible)
• The small food particles are then absorbed into the microbe
through the cell membrane
• Complete Scipad pages 14-15

25. • http://www.bbc.co.uk/bitesize/ks3/science/organisms_behaviour
_health/disease/activity/
• http://www.bbc.co.uk/schools/scienceclips/ages/10_11/micro_or
ganisms.shtml

26. Harmful Bacteria

28. Useful Bacteria
•Digestion
•Breaking down wastes
•Making cheese, yogurt
•Cycle nutrients

32. Fungi
• Fungi include mushrooms,
moulds and yeast
Complete Scipad pages 17

33. Fungi (yeast) structure

34. Structure and Function
Structure Function
Sporangium
Spores
Sporangiophore
Hyphae
Mycelium

35. Structure and Function
Structure Function
Sporangium Spore producing capsule at the end of the
sporangiophore
Spores Reproductive cells that grow into new fungi
Sporangiophore Holds sporangium up so spores can get
spread as far as possible
Hyphae Thread like structures used for support and
feeding (embedded into food)
Mycelium The entire network of the fungus

36. N – Nutrition/Feeding in Fungi
• Fungi feed by extra cellular digestion
• Extra – outside the cell
• Microbes excrete digestive enzymes
• The enzymes break food down into smaller molecules and in turn make our food ‘go
off’ or spoil (making it inedible)
• The small food particles are then absorbed into the microbe through the cell
membrane
• Complete Scipad pages 19
• http://bugs.bio.usyd.edu.au/learning/resources/CAL/Microconcepts/moviePages/e
xtracellular_digestion.html

37. R – Reproduction in Fungi
• Vertical hyphae grow
• Sporangium with spores inside develop
on the end of the vertical hyphae
• Sporangium bursts releasing spores
over a wide area
• Spores land and grown hyphae and feed
on food source
• Spores will only grow under the right
conditions – warmth, moisture, food
and space.
• Complete Scipad page 20

40. Conditions required for Microbes Growth
• Food availability

41. Temperature
• Set up and complete Scipad page 25-29 Temperature
and Fungal Respiration
• Bacteria can grow well between 4’C -63’C (Danger
Zone)
• Some bacteria can survive in extreme conditions
• What temperature are fridges meant too be set at?
• Why do you boil water untreated before drinking?

42. Toxicity
• Bacteria produce toxins
• It is these toxins that make us sick
• To much of these toxins can also
make the bacteria sick
• Growth also slows as the bacteria
run out of space and food
• Complete Scipad pages 42

44. Moisture and Nutrients
• Bacteria need moisture and food/nutrients to grow
• Lack of moisture does not kill the bacteria only makes them
dormant
• Which lasts longer – powdered milk or liquid? Why?

45. Time
• Microbes need time to grow
• In ideal conditions they can multiply
every 20 minutes
• After two hours at room temperature
there can be enough bacteria to cause
food poisoning

50. Virus structure

51. Protein
Coat
Genetic
Material
• Viruses are not alive they need living cells to survive
Virus

52. Viruses
Host
Cell
1. DNA material injected into cell2. DNA material copied by cell3. Viruses copied by cell4. Viruses emerge from cell
destroying it in the process.

53. How viruses replicate inside cells

56. Summary of Microbes

57. Summary of Microbes
Fungi Bacteria Virus
Example Mushrooms Salmonella Influenza
Size Visible Visible as colonies microscopic
DNA Yes Yes RNA
Cell walls Yes No No
Uses Food, alcohol Yoghurt Genetic modification
Replication Releases spores Binary fission Uses host cell to replicate
Diagram

58. Harmful Microbes
•Microbes can:
• Spoil food
• Cause disease
• Cause food poisoning
•Complete scipad
pages 62-65

59. Which type of microbe?

60. Microbes can enter the body in many different places.
How do microbes enter the body?
eyes
mouth
cuts
nose
ears
How are the diseases caused by microbes spread?
genitals
skin

61. The spreading of microbes and disease is known as
transmission.
How are microbes spread?
A cough or a sneeze can release
millions of microbes into the air
which can then infect somebody
else.
1. Transmission by air
Dirty water can transmit many
diseases, e.g. cholera, which
can be transmitted by drinking.
2. Transmission by water

62. An animal can carry a microbe from
one place to another, e.g. a mosquito
which spreads the malaria parasite.
3. Transmission by animals
Many microbes can be exchanged from one
person to another by direct or indirect contact:
4. Transmission by contact
 direct contact by hand;
 indirect contact, e.g. by walking on a
wet floor already contaminated by
someone else who has athlete’s foot;
 sexual contact.

63.  Transmission via breastfeeding
If a child is being breastfed, he or she
can also pick up microbes from the
mother via the mother’s milk.
If the mother develops the HIV/Aids infection,
it can be passed on to the unborn child
through the placenta.
 Transmission through the placenta
There are other forms of indirect contact,
e.g. the transmission of microbes from
mother to unborn child.
4. Transmission by contact

64. The spread of disease can be prevented by making sure
that good hygiene is used in key places such as bathrooms
and kitchens.
Chemicals called antibiotics can be
used to treat bacterial infections.
People can be immunized against
some diseases by the injection of a
vaccine.
How is the spread of disease stopped?

68. Preventing Microbal Growth - Practical

74. Food Storage

76. Moisture
•Removing water prevents microbes from
growing
•Drying
•Adding salt
•Sealing in bags/jars

77. Food Storage

78. Food Safety

79. 4) Why is it that you do not ALWAYS get sick when you eat undercooked meat?
5) Why is that even though everyone ate the same food only some people get sick?
6) Why does it take so long for symptoms to show up?