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Biology GCSE > Topic 8: Micro-organisms and disease > Flashcards

Topic 8: Micro-organisms and disease Flashcards

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1
Q

What is a microorganism?

A

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

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2
Q

What are the 4 types of microorganism?

A

Viruses
Bacteria
Fungi
Protists

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3
Q

Which type of microorganism is not always a microorganism?

A

Fungi

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4
Q

What is a protist?

A

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

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5
Q

What does eukaryotic mean?

A

Containing a nucleus.

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6
Q

What is a pathogen?

A

A disease causing microorganism.

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7
Q

What is a virus?

A

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

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8
Q

Why are microorganisms grown by scientists?

A

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

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9
Q

What is put in a petri dish to grow microorganisms?

A

Agar jelly and the microorganisms themselves.

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10
Q

What is a colony?

A

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

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11
Q

What are the optimum growth rates for bacteria?

A

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

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12
Q

What is aseptic technique used for?

A

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

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13
Q

What are the 5 steps to aseptic technique?

A
  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.
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14
Q

How often does bacteria reproduce?

A

Approximately every 20 minutes.

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15
Q

What is binary fission?

A

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

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16
Q

What is a culture of bacteria?

A

Bacteria grown deliberately by humans.

17
Q

What are 4 safety precautions to take when culturing microorganisms?

A

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

18
Q

What is an antibiotic?

A

A chemical used in medicine to destroy bacteria.

19
Q

What do antibiotics not effect?

A

Viriuses.

20
Q

What type of microorganism is penicillium?

A

A fungus.

21
Q

What are the 3 optimal conditions for fermentation?

A

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

22
Q

Label a fermentation diagram.

A

DO IT

23
Q

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

A

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.

24
Q

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

A

Colonies may clump together

Difficult to count with so many

25
Q

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

A

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

26
Q

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

A

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

27
Q

Why are refrigeration and freezing useful in food storage?

A

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

28
Q

What is a fermenter used for?

A

To produce large cultures of microorganisms.

29
Q

What does the air intake do?

A

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

30
Q

What does the stirrer do?

A

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

31
Q

What does the cooling jacket do?

A

Cools the culture because respiration of the penicillium produces heat.

32
Q

What does the pH probe do?

A

Monitors pH levels so it can be corrected.

33
Q

What does the pressure relief valve do?

A

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

34
Q

What is agar?

A

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

Biology GCSE (9 decks)

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