Classification and Viruses

Question 1

Definition: species

Answer 1

a group of organisms that can interbreed and produce fertile offspring

Question 2

The five kingdoms:

Answer 2

1. Monera
2. Protista
3. Fungus
4. Plant
5. Animal

Question 3

Monera:

Answer 3

• are single-celled organisms
• are heterotrophic or autotrophic
• have no cell nucleus
• have no membrane-bound organelles in their cell

Question 4

Protists:

Answer 4

• are mainly single-celled organisms (and the algae)
• obtain food by a large number of different methods
• have a nucleus in their cells
• have membrane-bound organelles

Question 5

Fungi:

Answer 5

• are mainly multicellular (yeast are unicellular)
• are heterotrophs and feed by absorption
• have a nucleus in their cells
• have cell walls made of chitin
• reproduce asexually using spores

Question 6

Viruses:

Answer 6

• do not appear in the classification of living things
• simpler structure than cells
• can replicate and pass on information from one generation to the next
• can only reproduce within the cell of another living organism
• have no organelles or metabolism outside their host

Question 7

Viral structure:

Answer 7

• a core of nuclei acid (either DNA or RNA, never both)

- a coat of proteins (capsid) on its surface

Question 8

obligate parasites

Answer 8

As all viruses can only replicate within other living cells, they are described as obligate parasites.

Question 9

How can a virus infect a cell?

Answer 9

To infect a cell, the surface proteins of the virus must be able to bind with proteins on the surface of the cell. This is ehat causes the specificity of viruses.

Question 10

Bacteriology

Answer 10

the study of bacteria (i. e. Monera kingdom)

Question 11

3 main groups of bacteria:

Answer 11

1. Spherical (cocci): These can be found singly, in cluster, in pairs or in chains
2. Rods: These can occur singly or in chains and may have flagella for movement
3. Spiral: Often contain flagella for movement

Question 12

Stucture of a bacteria

Answer 12

• outside of all bacteria is a cell wall
• some bacteria have a gelatinous sheath around this cell wall, particullarly if they are pathogenic; others may have a dry capsule
• motile bacteria have flagella
• there is a cell membrane between the cell wall and the cytoplasm of all bacteria
• there are no membrane-bound organelles found within the cell but cytoplasm and ribosomes are present
• the nucleic material is a single chromosome of DNA that is not contained within a membrane
• many bacteria also contain other circular pieces of DNA. These small pieces of DNA usually contain only a few genes and are called plasmids.
• manybacteria produce spores, often endospores, in unfavourable conditions. Spores are thick-walled structures which allow the bacteria survive the unfavourableconditions.

Question 13

Reproduction of bacteria

Answer 13

Bacteria reproduce by a simple process called binary fission. This is a form of asexual reproduction.

Question 14

Nutrition of autotrophic bacterias:

Answer 14

1. Autotrophic bacteria make their own food by one of two methods:
   (a) Photosynthetic bacteria
   (b) Chemosynthetic bacteria

Question 15

Nutririon of heterotrophic bacterias:

Answer 15

Heterotrophic bacteria have to take in food produced by other organisms. These are the most commen type of bacteria:

(a) Saphrophytes
(b) There are three types of symbiotic relationships possible:
1. Mutualism
2. Commensalism
3. Parasitism

Question 16

Photosynthetic bacteria

Answer 16

are bacteria that use sunlight to make their own food

Question 17

Chemosynthetic bacteria

Answer 17

are bacteria that are capableof making their own food using energy from a chemical reaction

Question 18

Saphrophytes

Answer 18

are organisms which get their food from dead organisms commonly called decomposers

Question 19

Symbiotic organisms

Answer 19

are organisms of one species that live in close relationship with a second species where at least one organism benefits

Question 20

Mutualism

Answer 20

both organisms benefit

Question 21

Commensalism

Answer 21

one organism benefits but does not harm

Question 22

Parasitism

Answer 22

one organism benefits and harms its host

Question 23

Factors affecting growth

Answer 23

Oxygen, Temperature, pH & Environmental concentration

Question 24

Economic importance of bacteria

Answer 24

• Harmful bacteria can lead to decay where we don’t want decay, i.e. food spoilage
• Bacteria can cause disease in humans and other animals and plants
• Beneficial bacteria are important as decomposers in the treatment of sewage and in the production of compost
• Bacteria can produce antibiotics
• Beneficial bacteria produce cheese and yoghurt

Question 25

Sterility

Answer 25

A substance is sterile if it is free from all microbes.

Question 26

Apsepsis

Answer 26

Apsepsis means excluding microbes from as much of the environment as possible.

Question 27

The continiuous flow method

Answer 27

The continuous flow method of production involves maintaining the microbes in the log phase of growth by the addition of fresh medium

Question 28

The batch flow method

Answer 28

The batch flow method of production is when a fixed amount of nutrients are added to a bioreactor which is emptied of its consistents at the end of production.

Question 29

bioreactor

Answer 29

A bioreactor is a vessel in which cells, organisms or enzymes are placed to manufacture specific products.