Quick Review Flashcards - Click to flip and test your knowledge!
Question
Why are bacteria classified as prokaryotes?
Answer
They lack a well-defined nucleus and a nuclear membrane.
Question
According to the Five Kingdom classification, why are bacteria not considered plants?
Answer
They are prokaryotic and single-celled rather than eukaryotic and multicellular.
Question
What is the average length of a bacterium?
Answer
The average length is $2\mu\text{m}$.
Question
One micrometre ($1\mu\text{m}$) is equivalent to what fraction of a millimetre?
Answer
It is one-thousandth of a millimetre.
Question
Term: Cocci
Answer
Definition: Bacteria that are spherical in shape.
Question
Term: Bacilli
Answer
Definition: Bacteria that are rod-shaped.
Question
What term describes spiral or twisted bacteria?
Answer
These bacteria are known as Spirilla.
Question
What shape identifies Vibrio bacteria?
Answer
Vibrio bacteria are comma-shaped.
Question
Bacteria that occur in pairs are specifically called _____.
Answer
Diplococci
Question
Bacteria that grow in long chains are referred to as _____.
Answer
Streptococci
Question
What term is used for bacteria that occur in clusters or bunches?
Answer
These are called Staphylococci.
Question
The living substance within a bacterial cell membrane is called the _____.
Answer
Protoplasm (or protoplast)
Question
How does the composition of a bacterial cell wall differ from that of a plant cell wall?
Answer
It is made of peptidoglycan instead of cellulose.
Question
Where is the chromatin (DNA) material located in a bacterial cell?
Answer
It is present in the central region of the cytoplasm.
Question
The bacterial chromosome consists of a single circle of DNA attached to the _____ at one point.
Answer
Cell membrane
Question
What is the function of a capsule in some bacteria?
Answer
It serves as a slimy protective layer outside the cell wall.
Question
Which structures provide active locomotion for bacteria in a liquid environment?
Answer
Whip-like flagella provide locomotion.
Question
Most bacteria are _____, meaning they depend on readymade food from different sources.
Answer
Heterotrophic
Question
Bacteria that draw nourishment from decaying dead organisms are classified as _____.
Answer
Saprotrophic
Question
How do parasitic bacteria obtain their nourishment?
Answer
They draw nourishment from the body of their living hosts.
Question
What is the role of the powerful enzymes secreted by bacteria into their surroundings?
Answer
They make food material soluble so it can be absorbed as a solution.
Question
Bacteria that respire by absorbing atmospheric oxygen are called _____.
Answer
Aerobic
Question
Define anaerobic bacteria.
Answer
Bacteria that need no free oxygen to respire and are killed if exposed to air.
Question
What is the only method of reproduction in bacteria?
Answer
Asexual reproduction by means of fission or cell division.
Question
What occurs to the circular DNA immediately before a bacterial cell divides?
Answer
The DNA duplicates.
Question
Under ideal conditions, how frequently can some bacteria divide?
Answer
They can divide once every half an hour.
Question
What is conjugation in bacteria?
Answer
A highly primitive type of sexual reproduction where DNA is transferred between two bacteria through a hollow tube.
Question
Spore formation in bacteria is a method of escaping _____, not a method of reproduction.
Answer
Unfavourable conditions
Question
List two extreme conditions that bacterial spores can tolerate.
Answer
They can tolerate extreme dryness and the temperature of boiling water.
Question
What is an antibiotic?
Answer
A chemical substance produced by a living micro-organism that stops the growth of or kills disease-producing bacteria and fungi.
Question
Who discovered the first medical antibiotic, penicillin?
Answer
Alexander Fleming discovered it in 1929.
Question
What is the source organism for the antibiotic penicillin?
Answer
The fungus (mould) $Penicillium\ chrysogenum$.
Question
Which bacterium is the source of the antibiotic streptomycin?
Answer
The bacterium $Streptomyces\ griseus$.
Question
Which disease is typically treated with the antibiotic Chlorotetracycline?
Answer
It is used to treat typhoid.
Question
What is a 'broad spectrum' antibiotic?
Answer
An antibiotic able to kill a wide variety of disease-producing micro-organisms.
Question
Why should a good antibiotic not kill the normal bacteria of the host?
Answer
To avoid destroying the beneficial micro-organisms that naturally live in the host's body.
Question
What is a serum?
Answer
Blood plasma from which fibrinogen has been removed, often containing antitoxins.
Question
What is the function of an antitoxin?
Answer
It is a substance produced in animal bodies that reacts with the poison (toxin) produced by invading germs.
Question
How is serum prepared for medical use?
Answer
By injecting small doses of bacterial toxin into a healthy animal and then extracting its blood once antitoxins are produced.
Question
Which hormone was the first human substance produced by genetically modified $E.\ coli$?
Answer
Insulin was the first such substance.
Question
Define a vaccine.
Answer
A preparation consisting of weakened germs or dead germ substances used to develop resistance to a disease.
Question
What is the specific purpose of the BCG vaccine?
Answer
It is used to provide immunity against tuberculosis.
Question
What are toxoids?
Answer
Inactivated toxins of a bacteria that still stimulate the production of antibodies.
Question
Which nitrogen-fixing bacteria are found in the root nodules of leguminous plants?
Answer
The bacteria are of the genus $Rhizobium$.
Question
Name two types of free-living nitrogen-fixing bacteria in the soil.
Answer
$Azotobacter$ and $Clostridium$.
Question
In the process of nitrification, which bacteria first convert ammonia into nitrites?
Answer
$Nitrosomonas$ bacteria perform this conversion.
Question
Which bacteria convert nitrites into nitrates in the soil?
Answer
$Nitrobacter$ bacteria perform this step.
Question
What is the function of denitrifying bacteria such as $Pseudomonas$?
Answer
They break down soil nitrates to release nitrogen gas ($N_{2}$) back into the atmosphere.
Question
Define 'Decay' as caused by bacteria.
Answer
The complete breakdown of organic matter by bacteria without giving out a foul smell.
Question
How does 'Putrefaction' differ from 'Decay'?
Answer
Putrefaction is the incomplete breakdown of organic matter that emits a foul smell.
Question
What role do bacteria play in 'tea curing'?
Answer
They are used to produce the different flavours of tea.
Question
What is the 'retting' process in the industry?
Answer
The use of bacteria to loosen the fibres of hemp and flax by rotting.
Question
How is bacteria used in the leather industry?
Answer
They are used in tanning to break down the soft perishable parts of animal skin.
Question
What is botulism?
Answer
A very serious type of food poisoning caused by a specific bacterium found in tinned and sealed foods.
Question
How does salting preserve food like fish or pickles?
Answer
The high concentration of salt causes plasmolysis and death of any bacteria or mould that creep in.
Question
What are the standard conditions for the pasteurisation of milk?
Answer
Heating to about $60^{\circ}\text{C}$ for a period of 30 minutes, followed by quick chilling.
Question
Why does refrigeration at $0-5^{\circ}\text{C}$ prevent food spoilage?
Answer
Microbes (bacteria and moulds) do not grow or multiply at or below the freezing point of water.
Question
Which chemical is commonly added to tinned foods and squashes as a preservative?
Answer
Sodium benzoate is often used.
Question
Name one common bacterial disease of mustard plants.
Answer
Black rot of mustard.
Question
What is a common bacterial disease that affects cattle lungs and causes a dry husky cough?
Answer
Bovine tuberculosis.