Microbiology

Question 1

What shape are bacillus bacteria?

Answer 1

Rod shaped

Question 2

What shape are coccus bacteria?

Answer 2

Spherical shaped

Question 3

What shape are spirillum bacteria?

Answer 3

Spiral shaped

Question 4

What are the key organelles in a virus?

Answer 4

1. Flagellum
2. Pilus
3. Plasmid
4. Capsule
5. Circular DNA
6. Ribosome
7. Plasma membrane
8. Cell Wall

Question 5

What is a diplo arrangement of bacteria?

Answer 5

Cells that remain in pairs

Question 6

What is a strepto arrangement of bacteria?

Answer 6

Cells remain attached in chains

Question 7

What is a Tetrads arrangement of bacteria?

Answer 7

Cells arranged in squares

Question 8

What is a Staphylo arrangement of bacteria?

Answer 8

Random planes of division resulting in sheets and clumps.

Question 9

Do prokaryotes have a membrane bound nucleus?

Answer 9

No

Question 10

What is the cell wall of a prokaryote made up of?

Answer 10

Peptidoglycan

Question 11

How to prokaryotes reproduce?

Answer 11

Binary fission

Question 12

What is the function of a virus cell wall?

Answer 12

1. Prevents osmotic lysis
2. Maintains pressure inside cell
3. Maintains rigidity and cell structure

Question 13

What are the structural characteristics of a gram positive bacteria?

Answer 13

A cell wall with a thick layer of peptidoglycan

Question 14

What colour do gram positive bacteria stain?

Answer 14

Purple

Question 15

What dye is held by a gram positive bacteria?

Answer 15

Crystal Violet

Question 16

What are the structural characteristics of a gram negative bacteria?

Answer 16

A complex cell wall with a thin layer of peptidoglycan and a thick outer layer of lipopolysaccharide.

Question 17

What colour do gram negative bacteria stain?

Answer 17

Pink

Question 18

Why do gram negative bacteria stain pink?

Answer 18

The crystal violet stain is removed when rinsed with ethanol.

Question 19

What physical conditions do microbes require?

Answer 19

1. Suitable temperature
2. Suitable pH
3. Oxygen requirements

Question 20

What nutrient conditions do microbes require?

Answer 20

1. Carbon source
2. Nitrogen source
3. Inorganic ions and vitamins

Question 21

What are saprotrophs?

Answer 21

Bacteria with a lower temperature optima

Question 22

What are psychrophiles?

Answer 22

Bacteria that grow down to -15 degrees

Question 23

What are thermophiles?

Answer 23

Bacteria that have an optimum of 80 degrees

Question 24

What is the optimum temperature of pathogens?

Answer 24

Body temperature - 37 degrees

Question 25

Why should it be ensured that a incubation plate is not sealed off from oxygen?

Answer 25

It minimises the chance of the growth of pathogenic bacteria.

Question 26

What is an obligate aerobe?

Answer 26

Bacteria which require oxygen, can only grow in oxygen rich environments

Question 27

What is an obligate anaerobe?

Answer 27

Bacteria that can only survive in the absence of oxygen

Question 28

What is a facultative anaerobe?

Answer 28

Bacteria that can survive in the absence of oxygen but grow best in the presence of oxygen.

Question 29

What is the growth media for bacteria?

Answer 29

Liquid, broth or agar

Question 30

List 5 aseptic techniques and why they are employed

Answer 30

1. Autoclave equipment; kills spores and bacteria 2. Flame inoculation loops, wires and glass spreaders; kills bacteria 3. Open petri dish lids at a small angle; prevents bacteria entering the dish 4. Roaring blue flame; creates convection current to move away contaminated air 5. Keep McCartney caps in hand and flame bottle necks; do not contaminate desk, kills bacteria.

Question 31

What is the total cell count?

Answer 31

Total of all dead and living bacteria

Question 32

What can total cell count be used for?

Answer 32

Calculating turbidity using a colorimeter

Question 33

What is viable cell count?

Answer 33

Total of living cells only

Question 34

Why is it important to estimate population growth?

Answer 34

1. Environmental health monitoring 2. Water Supply 3. Monitoring growth in fermenters

Question 35

What is the problem with serial dilution?

Answer 35

If dilution is not significant, then the colonies will merge and counting is inaccurate.

Question 36

What are the general problems with counting bacteria?

Answer 36

1. They are very small 2. There are lots of them 3. Difficult to tell the difference between dead and alive bacteria?

Question 37

What are the advantages of a viable count method?

Answer 37

1. Counts living cells

Question 38

What are the disadvantages of a viable count method?

Answer 38

1. Possible to under estimate the population 2. Takes a long time to count 3. If a culture is mixed, some may take longer to grow than others

Question 39

What are the advantages to total cell count method?

Answer 39

1. Quick 2. Used on several types of cells 3. Alive or dead is shown

Question 40

What are the disadvantages to total cell count method?

Answer 40

1. Difficult to count clumps 2. Does not always divide living and dead 3. Difficult to count under a microscope