Topic 8: Micro-organisms and disease

Question 1

What is a microorganism?

Answer 1

A living organism which is so small that it can only be seen with a microscope.

Question 2

What are the 4 types of microorganism?

Answer 2

Viruses
Bacteria
Fungi
Protists

Question 3

Which type of microorganism is not always a microorganism?

Answer 3

Fungi

Question 4

What is a protist?

Answer 4

An organism belonging to the Kingdom Protista. Many consist of just one cell, which is eukaryotic.

Question 5

What does eukaryotic mean?

Answer 5

Containing a nucleus.

Question 6

What is a pathogen?

Answer 6

A disease causing microorganism.

Question 7

What is a virus?

Answer 7

A microorganism (pathogen) capable of infecting every type of living organism.

Question 8

Why are microorganisms grown by scientists?

Answer 8

In large numbers, they are easier to study and work with.

Question 9

What is put in a petri dish to grow microorganisms?

Answer 9

Agar jelly and the microorganisms themselves.

Question 10

What is a colony?

Answer 10

A (circular) group of bacteria visible to the naked eye.

Question 11

What are the optimum growth rates for bacteria?

Answer 11

between 30-37 degrees. For a petri dish, keep it at 25 to make sure bacteria isn’t harmful to humans (in school).

Question 12

What is aseptic technique used for?

Answer 12

The procedure of growing microorganisms in a way that minimises the risk of contamination.

Question 13

What are the 5 steps to aseptic technique?

Answer 13

1. Loop placed in Bunsen flame to stop contamination.
2. Lid/stopper taken off of bacterial tube and top of tube placed in flame.
3. Loop is dipped into bacteria, tube flamed again.
4. 4 striking patterns on agar jelly, lightly. Petri dish lid partially lifted.
5. Loop flamed again. Petri dish sealed across dish, NOT around (don’t want optimum environment.

Question 14

How often does bacteria reproduce?

Answer 14

Approximately every 20 minutes.

Question 15

What is binary fission?

Answer 15

Asexual reproduction of bacteria in which they copy their DNA and divide into two.

Question 16

What is a culture of bacteria?

Answer 16

Bacteria grown deliberately by humans.

Question 17

What are 4 safety precautions to take when culturing microorganisms?

Answer 17

Wear protective equipment - goggles
Wash hands before and after
Clean all work surfaces
Keep eyes and face away from culture

Question 18

What is an antibiotic?

Answer 18

A chemical used in medicine to destroy bacteria.

Question 19

What do antibiotics not effect?

Answer 19

Viriuses.

Question 20

What type of microorganism is penicillium?

Answer 20

A fungus.

Question 21

What are the 3 optimal conditions for fermentation?

Answer 21

Temperature - 23-28°c
pH - 6.5
Oxygen level - oxygen needed for respiration and growth
Nutrient levels and contamination must be monitored too

Question 22

Label a fermentation diagram.

Answer 22

DO IT

Question 23

How can the amount of original bacteria be estimated from the number of colonies present?

Answer 23

Each bacterium will divide many times to produce a colony, so the number of colonies is usually how many bacterium there were to begin with.

Question 24

Why is counting colonies an inaccurate way of finding the number of original bacteria?

Answer 24

Colonies may clump together

Difficult to count with so many

Question 25

What happens to the rate of bacterial growth if the temperature is increased?

Answer 25

The growth rate increases but if the temp is too high the proteins denature and the bacteria will die.

Question 26

What happens to the rate of bacterial growth if the temperature is decreased?

Answer 26

It will decrease but when the temperature is too low bacteria will stop growing altogether.

Question 27

Why are refrigeration and freezing useful in food storage?

Answer 27

Food will last longer as microorganism growth is limited/stopped.

Question 28

What is a fermenter used for?

Answer 28

To produce large cultures of microorganisms.

Question 29

What does the air intake do?

Answer 29

Allows sterile (for no contamination) air to get in as penicillium is aerobic and requires oxygen.

Question 30

What does the stirrer do?

Answer 30

Mixes the nutrients throughout the fermenter (otherwise they would collect at the bottom).

Question 31

What does the cooling jacket do?

Answer 31

Cools the culture because respiration of the penicillium produces heat.

Question 32

What does the pH probe do?

Answer 32

Monitors pH levels so it can be corrected.

Question 33

What does the pressure relief valve do?

Answer 33

To avoid dangerous levels of pressure, air is allowed out via this valve.

Question 34

What is agar?

Answer 34

A jelly that has nutrients in it to help grow cultures of bacteria.