Classification

Question 1

What is classification?

Answer 1

Grouping of organisms together basing on the features they have in common

Question 2

Taxonomy is?

Answer 2

The science of classification

Question 3

Define nomenclature

Answer 3

Giving of names to organisms

Question 4

Systematics is?

Answer 4

Placing of organisms into groups basing on their similarities and differences

Question 5

A diagnostic feature of phylum Chordata is?

Answer 5

Presence of a vertebral column

Question 6

What is a species?

Answer 6

A group of organisms with many common features that can breed to produce viable offspring

Question 7

Artificial classification is?

Answer 7

Based on one or a few easily observable characteristics for simplicity and convenience

Question 8

Natural classification?

Answer 8

Considers natural relationships between organisms eg internal and external features

These are;
- Embryology
- Physiology
- Biochemistry
- Cell structure
- Behavior

Question 9

What is phylogenetic classification ?

Answer 9

This is based on evolutionary history (phylogeny) of organisms.

Question 10

Phonetic classification is?

Answer 10

Based on observable characteristics and all characters are considered to be of importance

Question 11

List the five kingdoms

Answer 11

-Prokaryotae
-Protoctista
-Fungi
-Plantae
-Animalia

Question 12

Describe the structure of viruses (akaryotes)

Answer 12

• Simple structure
• Core- inner regional in which the genetic material is found
• Capsid-Protective coat of protein surrounding the core [the capsid is made up of subunits called capsomeres]
• Envelope- Found only in some large viruses
  -Small piece of nucleic acid (DNA or RNA)
  -In most viruses it is surrounded by a protein or lipoprotein

Question 13

Give characteristics of viruses

Answer 13

1. Lack cellular structure
2. Smallest living things
3. Obligate endoparasites
4. Depend on host cells for reproduction
5. Highly specific
6. Most enter hosts by phagocytosis or pinocytosis

Question 14

Why are viruses considered to be living things?

Answer 14

1. Possess genetic material
2. Can mutate hence evolve
3. Carry out protein synthesis in host cells
4. Capable of self replication when inside host cells
5. Transmit characteristics to the next generation

Question 15

Why are viruses considered to be non-living?

Answer 15

1. Can be crystallized
2. Lack enzyme systems
3. Cannot metabolize unless they are inside the host cells

Question 16

Describe the structure of HIV virus

Answer 16

• Spherical
• 2 molecules of single stranded RNA and reverse transcriptase enzyme
• These are surrounded by a cone shaped protein capsid
• The capsid is enclosed by an envelope (composed of lipid and glycoprotein)
• Reverse transcriptase enzyme converts single stranded RNA into double stranded DNA copies .
• The viral DNA made is inserted into the host’s DNA where it directs the production of more viral properties.
• The envelope contains glycoproteins which bind specifically to helper T-cell receptors enabling the virus to enter the helper T-lymphocytes

Question 17

Why is HIV referred to as a retrovirus?

Answer 17

The enzyme reverse transcriptase (found in retroviruses) catalyzes the conversion of viral RNA into DNA (reverse transcription)

Question 18

Viruses in plants?

Answer 18

-Cassava mosaic disease
-Tobacco mosaic disease
-Southern bean mosaic disease
-Tomato bush stunt disease

Question 19

Viruses in animals?

Answer 19

-Small pox
-The Acquired Immuno Deficiency Syndrome
-Rabies
-Measles
-New castle disease

Question 20

The major feature of prokaryotes is?

Answer 20

Genetic material not bound by a nuclear membrane

Question 21

The two groups of members in kingdom prokaryotae are?

Answer 21

Archaea; Organisms grow under extreme conditions

Hyperthermophiles; Organisms grow under very high temperatures

Question 22

Give uses of viruses

Answer 22

1. In preparing antidotes/ vaccine: Pox, mumps, polio, jaundice e.t.c. diseases can be controlled by penetrating using or dead virus in human body as vaccines
2. In controlling harmful animals and
   insects: Some animals and insects which are harmful for humans can be controlled by some special virus
3. Control of disease: T2 bacteriophage virus saves humans from dysentery by spoiling some harmful bacteria, like, e-coli.
4. In laboratory: Virus is used in lab, as the simplest living model. In the research of genetics virus used. It is an important subject in genetic engineering.
5. In the evidence of evolution: Virus plays a vital role to acquire knowledge about the trend of evolution and the process of formation of living organisms because virus contains both living and non-Iiving characteristics.

Harmful roles:

-Virus destroys plenty of bacteria useful for humans Different diseases like common Cold, Influenza, Mumps, Pox, Polio, Yellow fever, Harpies, Aids etc. are caused by the attack of virus.

Question 23

Give methods of preventing spread of viral diseases

Answer 23

1. Vaccination
2. Hygiene and Sanitation: Proper waste water treatment
3. Vector control: Mosquito control is often more effective than vaccination given the sporadic nature of most arboviral (arthropod-borne) diseases.
4. Lifestyle changes: For diseases transmitted sexually and by intravenous drug use, lifestyle change should change transmission patterns if it can be implemented.
5. Eradication:
   The necessary features for eradication are:
   - An effective vaccine that optimally doesn’t require a cold chain and is easily administered
   - No animal reservoir
   - Lack of recurrent infection
   - One or a few stable serotypes
   - No infectivity before symptoms and no unapparent infections, making early containment possible

Question 24

Describe the structure of a bacterial cell

Question 25

Give the economic importance of bacteria

Answer 25

1. They are cultured for research purposes
2. They facilitate the making of foods like yoghurt, cheese and vinegar
3. They are used for making antibiotics, amino acids and enzymes.
4. In humans, vitamin K and B complex are produced by the symbiotic bacteria (E. Coli) while in animals it is used to break down cellulose.
5. They cause decomposition of dead organic matter, hence enabling their disposal.
6. They take part in nutrient recycling e.g. the nitrogen cycle, carbon cycle and the phosphorous cycle.
7. On the other hand, bacteria cause food to get spoilt
8. Bacteria like Thiobacillus and Disulphovibrio produces sulphuric acid which destroys underground metal pipes.

Escherichia coli, a bacteria that is symbiotic with humans and animals produces what in the human gut?
- Vitamin B and K complex in humans
- Cellulose secreting enzymes in ruminants