Unit 2-Parasitism

Question 1

What are the six common parasitic groups?

Answer 1

Protists
Nematodes
Arthopods
Viruses
Platyhelminthes
Bacteria

Question 2

What is a relatively inefficent mechanism of transmission?

Answer 2

Direct Contact

Question 3

Give examples of two key parasites with intermediate hosts

Answer 3

Schistomosoma
Plasmodium

Question 4

How are endoparasites of body cavities transmitted?

Answer 4

Direct Contact
Consumption of Intermediate Host

Question 5

How are ectoparasites transmistted?

Answer 5

Direct Contact

Question 6

Give an example of an endoparasite of the body cavity

Answer 6

Tapeworm

Question 7

Give an example of an endoparasite of the body tissue

Answer 7

Plasmodium

Question 8

How are endoparasites of the body tissue transmitted?

Answer 8

Vectors

Question 9

What is HIV caused by?

Answer 9

A virus

Question 10

Define a virus

Answer 10

Infectious agents that can only replicate inside in a host cell

Question 11

Describe what is in the structure of a virus

Answer 11

Antigens on the surface
Nucleic Acid (RNA/DNA)
Protein Capsid
Outer Envelope

Question 12

What is a protein capside?

Answer 12

Protective protein coat surrounding the nucleic acid

Question 13

What are the two types of nucleic acids found in viruses?

Answer 13

RNA and DNA

Question 14

Why are viruses not classed as living?

Answer 14

Do not carry out any of the normal functions for life except for reproduction, which they can only do in the cell of living organisms

Question 15

Describe the stages in virus reproduction

Answer 15

1. Virus antigens to host cell surface
2. Virus DNA inserted into host cell
3. Virus DNA is replicated by host enzymes
4. Virus genes are transcribed to RNA which is translated to make viral protein coats
5. New virus particles are assembled and burst out of the host cell

Question 16

Give examples of DNA viruses

Answer 16

Chickenpox
Herpes
Small pox

Question 17

Give examples of RNA viruses

Answer 17

Influenza
Hepatitis
Ebola

Question 18

What differs in RNA viruses replication?

Answer 18

Viral RNA genome is replicated directly using an enzyme from the virus

Question 19

Give an example of RNA retroviruses

Answer 19

HIV

Question 20

How do RNA retroviruses replicate?

Answer 20

Use the enzyme reverse transcriptase to form a DNA copy of the virus genome. When virus is reproducing, the DNA copy of the genome will be transcribed to RNA which is then translated to make new viral proteins.

Question 21

What are the two type of first line defences?

Answer 21

Physical Barriers
Chemical Secretion

Question 22

Describe the role of mucus in preventing parasite infection

Answer 22

Mucus in the lungs trap microbial parasites and are moved away from delicate tissues by cilia

Question 23

Describe physical barriers to parasite infection

Answer 23

Skin acts as a tough barrier
Skin is dry so many parasites die on surface
Nasal hair trap parasites

Question 24

How do tears prevent parasites?

Answer 24

Contain antibodies and lysosomes

Question 25

When are second line responses triggered?

Answer 25

After the parasite has entered the body fluid

Question 26

What are the three type of second line defences?

Answer 26

Inflammatory Responses Phagocytes Natural Killer Cells

Question 27

Describe an inflammatory response

Answer 27

Some injured cells release chemicals including histamine Cause local blood vessels to dilate Increases blood flow to the area Stimulating phagocytes to migrate to the area

Question 28

What are phagocytes?

Answer 28

White blood cells which are able to migrate from the blood into tissue fluid

Question 29

What do phagocytes do?

Answer 29

Check surface of the particles for self antigens, if not found, phagocyte engulfs and digests the object

Question 30

What do phagocytes do after digestion of non self objects?

Answer 30

Present the fragments of the foreign antigens on the surface

Question 31

What are natural killer cells?

Answer 31

Type of white blood cells which detect abnormal cell surface proteins

Question 32

What do natural killer cells do?

Answer 32

Attach to cells which have abnormal surface proteins and release chemicals into them triggering apoptosis

Question 33

What are specific cellular defences triggered by?

Answer 33

The antigens on the surface of the parasite

Question 34

What are lymphocytes and where are the typically found?

Answer 34

White blood cells mainly found in the lymph gland

Question 35

What are the two types of lymphocytes?

Answer 35

B and T lymphocytes

Question 36

What are the two roles of T lymphocytes?

Answer 36

1. Stimulate other T lymphocytes and cause B lymphocytes to divide rapidly 2. Destroy infected cells

Question 37

What do B lymphocytes do?

Answer 37

Produce antibodies which attach to pathogens allowing phagocytes to engulf and digest them

Question 38

What is it called when some T and B lymphocytes are kept after parasite infection?

Answer 38

Immunological Memory

Question 39

What is clonal selection?

Answer 39

Response of lymphocytes when they bind to their specific antibodies causing rapid replication

Question 40

What is a benefit of immunological memory?

Answer 40

Faster and bigger response to future parasite infection of the same parasite

Question 41

What are the three ways parasites evade the immune system?

Answer 41

1. Mimic the host antigens 2. Antigenic Variation 3. Modify host's immune system

Question 42

What is Epidemiology?

Answer 42

Study of outbreak and spread of infectious diseases

Question 43

What can the information from epidemiology studies can be used to do?

Answer 43

Plan and evaluate strategies to prevent the spread of parasites in the future

Question 44

What is herd immunity?

Answer 44

Way to prevent the s[read of diseases by vaccinating enough members of a population to limit the spread of parasites

Question 45

What is the herd immunity threshold?

Answer 45

Minimum density of resistant hosts required in a population to prevent the epidemic

Question 46

What are the three problems associated with developing vaccinations?

Answer 46

1. Many parasites are difficult to culture in a lab away from hosts 2. Parasites have very rapid evolution and change surface antigens regularly 3. Host Parasite Interconnection of Metabolism

Question 47

Why is host parasite interconnection a problem in developing vaccinations?

Answer 47

Often vaccinations are highly linked which makes it difficult to find new drug compounds that only target the parasite

Question 48

What are the benefits of improved parasite control?

Answer 48

1. Reduction in child mortality 2. Improvement in child development/intelligence 3. Body is able to use more resources for growth and development

Question 49

What may be the only effective control strategy for parasites?

Answer 49

Target the transmission stage

Question 50

What two things are used to target the transmission stage of a parasites lifecycle?

Answer 50

Civil Engineering Projects Co-ordinated vector control strategy

Question 51

How do civil engineering projects target transmission?

Answer 51

All work to improve sanitation Prevents mixing of drinking water and contaminated water E.g. Clean water supplies, sewerage systems