Chapter 12 Pathogens And Plants

Question 1

What are pathogens? What is communicable disease?

Answer 1

Pathogens- organisms which cause disease
Communicable- caused by pathogens which can be passed between organisms

Question 2

What are bacteria? How are they sorted and cause disease?

Answer 2

Prokaryotes which are classified by shape- e.g rod, corkscrew or by cell wall, gram positive or negative
They secrete toxins, natural waste products produced as part of the bacteria functioning, which break down cell membranes, disrupt enzymes, and interfere with DNA

Question 3

What are viruses and how do they cause disease?

Answer 3

Non living genetic material surrounded by proteins
They invade cells- inserting virus genetic material into the hosts DNA, take over the metabolism/ biochemistry of a cell to make more viruses, burst, then spread
Bacteriophages take over bacteria

Question 4

What are protoctista? How do they cause disease?

Answer 4

Eukaryote which break into cells, steal nutrients, replicate by themselves, and burst the cell open

Question 5

What are fungi and how do they cause disease?

Answer 5

Eukaryotes, saprotrophs, which digest cells to destroy them, and also secrete toxins

Question 6

What is ringrot and what is it caused by?

Answer 6

Disease of potatoes, tomatoes and aubergines
Gram Positive Bacteria

Question 7

What is tobacco mosaic virus and what is it caused by?

Answer 7

Disease of tobacco plants and tomatoes, which stunts growth, no cure
Virus

Question 8

What is potato blight and what causes it?

Answer 8

Affects potatoes
Protoctist, acts like fungi by penetrating host cells, no cure

Question 9

What is black Sigatoka and what causes it?

Answer 9

Disease of banana trees, destroys leaves
Fungus- digest cells, fungicide to help

Question 10

What is tuberculosis?

Answer 10

Disease which damages lung tissue, increased likelihood with low immune system
Bacteria

Question 11

What is meningitis strep?

Answer 11

Bacterial infection of the meninges, can cause blood poisoning so death
Signs= blotchy rash that doesn’t disappear under a glass
Cured via antibiotics and vaccines

Question 12

What is HIV?

Answer 12

Virus that targets T helper cells, gradually destroys the immune system, Virus interacts with host DNA
No vaccine, antivirals slow spread

Question 13

What is influenza?

Answer 13

Disease of ciliated epithelium, often a secondary infection
Virus

Question 14

What is malaria?

Answer 14

Disease caused by a Protoctist, through mosquitoes, spread to human blood via bites
Controlled via controlling spread of mosquitoes
Pathogen called PLASMODIUM

Question 15

Give two examples of fungal diseases for animals?

Answer 15

Ringworm- cattle, cats, scratchy circles. Antifungal cream
Athletes foot- digesting warm skim, antifungal cream

Question 16

What are examples of direct transmission between humans?

Answer 16

Direct contact e.g kissing, skin to skin
Inoculation- through breaks in the skin
Ingestion- from hands in mouth

Question 17

What are examples indirect transmission in animals?

Answer 17

Fomites- sharing bed sheets
Droplets
Vectors- organisms that spread disease without become affected

Question 18

What are examples of transmission in plants

Answer 18

Direct- healthy plant touching unhealthy
Indirect- soil contamination, spores travelling through wind, water,

Question 19

What factors affect transmission of communicable disease?

Answer 19

Overcrowding
Poor nutrition
Climate change
Culture
Variety

Question 20

What is the process of recognising a pathogen in plants?

Answer 20

Receptors respond to chemical from either the pathogens, or from when pathogens attack the cell wall
Stimulates the release of signalling molecules which switches in genes that can produce a cellular response e.g chemical production, alarm other cells

Question 21

What is a plants physical defence mechanism against pathogens?

Answer 21

Produces callose, formed from B-glucose 1,3 and 1,6 linkages
Deposited between cell walls and membranes next to infected to prevent pathogens entering neighbouring cells
Blocks off sieve plates and plasmodesmata to help prevent pathogens spreading

Cellulose cell wall as a physical barrier, lignin for water proofing
Waxy cuticle to prevent water collecting on the surface
Guard cells close stomata

Question 22

What are chemical plants responses to pathogens?

Answer 22

Terpenoids- antibacterial and antifungal
Alkaloids- nitrogenous , prevents being fed on, so less exposure to pathogens

Question 23

How can vaccinations prevent epidemics turning into pandemics ?

Answer 23

At the beginning of an epidemic, mass vaccination , may need to be changed regularly to be effective
Herd immunity, when enough people have it, gives protection to who hasn’t stopping spread

Question 24

Why has malaria and HIV not had a vaccine?

Answer 24

Malaria evasive- hides inside erythrocytes
HIV disables immune system as disrupts T helper cells

Question 25

What are some examples of where medicines come from?

Answer 25

Organisms: Aspirin from Willow bark, Penicillin from mould
Synthesis with help from computers
Modifying current medication

Question 26

Medically, why is biodiversity important?

Answer 26

Lots of new medicines from plants and fungi
Deforestation, loss of coral reefs, loss of habitats
Means there are species which have gone extinct which could have held the key to treating diseases of the future

Question 27

What is pharmacogenetics?

Answer 27

Personalised medicine- a combination of drugs which work on one’s individual genome and disease
e.g Herceptin and HER2 breast cancer gene,

Question 28

What is synthetic biology?

Answer 28

Using genetic engineering to develop bacteria to produce drugs which are otherwise too expensive, rare or unavailable
Or synthesis of new genes/organism
Also nanoparticles to deliver drugs

Question 29

Why is over use of antibiotics a problem?

Answer 29

Antibiotics work by targeting the functioning of a bacteria e.g of translation/transcription/synthesis of DNA/cell wall
If a mutation occurs with a different way of the above, if successful, passes on to daughter cells
To whole population
Especially a problem if not needed, like in feeds

Acts as a selection pressure and so leaves only those resistant surviving which would otherwise not be at an advantage

Question 30

What happened with MRSA and C.difficile?

Answer 30

MRSA in nose, but in body causes problems, treated with antibiotics but now resistant
C difficile in gut, not normally a problem, but antibiotics killed healthy bacteria, so took over gut

Question 31

What is the difference between vaccination and immunisation?

Answer 31

Vaccination- inject antigen
Immunisation- process of developing immunity

Question 32

Outline a method for testing callose in plants at different temperatures.

Answer 32

Baseline callose first.
Aseptic technique
Infect same species of plant, ideally clones, same disease, same time, same pH water, same soil type, same light intensity
20,30,40,50 degrees heaters, set times
Take samples from the plant, multiple and from multiple locations, but same for all 3
Microscope and graticule for amount

Question 33

How do retroviruses replicate?

Answer 33

Insert RNA into cell
Reverse transcriptase to make single stranded DNA from RNA strand, then DNA polymerase to make double strand and helix
Attached to host DNA
Enables synthesis of RNA which can be released