Infection and Response

Question 1

What are pathogens?

Answer 1

Microorganisms that cause diseases which spread between organisms

Question 2

Tell me about rose black spot.

Answer 2

It’s pathogen is a fungus and it is spread by wind and water.
Symptoms are purple/black spots on leaves, can turn yellow and drop off; and reduced growth
Prevention/treatment is removing and destroying infected leaves; fungicides

Question 3

Tell me about malaria.

Answer 3

It’s pathogen is a protist and is spread by mosquito vectors
Symptoms are fever, and can be fatal
Prevention and treatment is mosquito nets or stopping them from breeding

Question 4

Tell me about salmonella (food poisoning)

Answer 4

It’s pathogen is a bacterium and it is spread by eating contaminated food
Symptoms are fever, stomach cramps, vomiting, diarrhoea
Prevention or treatment is vaccination of poultry and hygienic food preparation

Question 5

Tell me about gonorrhoea.

Answer 5

It’s pathogen is a bacterium and it’s spread by sexual contact
Symptoms are pain when urinating and yellow/green discharge from vagina or penis
Prevention or treatment are condoms and antibiotics

Question 6

Tell me about measles.

Answer 6

It’s pathogen is a virus and is spread by airborne droplets (coughs and sneezes)
Symptoms are fever, red skin rash, can be fatal
Prevention or treatment is vaccination of children

Question 7

Tell me about HIV.

Answer 7

It’s pathogen is a virus and its spread by sexual contact or exchanging bodily fluids (blood)
Symptoms are flu-like (initially), then a damaged immune system (late stage infections/AIDS)
Prevention or treatment is condoms, avoiding sharing needles, antiretrovirals

Question 8

Tell me about Tobacco mosaic virus (TMV).

Answer 8

It’s pathogen is a virus and it can be spread by direct contact between plants.
Symptoms are a mosaic pattern leaves, which reduces photosynthesis and growth.
Don’t need to know how it is prevented

Question 9

What are 4 non-specific defence systems against pathogens?

Answer 9

1: Skin - acts as a barrier and secretes antimicrobial substances to kill pathogens
2: Nose - hairs and mucus trap particles containing pathogens
3: Trachea and bronchi - mucus traps pathogens and cilia waft mucus up to the throat so that it can be swallowed
4: Stomach - hydrochloric acid kills pathogens

Question 10

What are the 3 ways a white blood cell attacks pathogens?

Answer 10

1: Phagocytosis (pathogen gets engulfed and digested)
2: Produces antibodies (pathogen has antigens, then the cell produces specific antibodies and attacks the pathogen with them)
3: Produces antitoxins (these counteract the toxins produced by invading bacteria)

Question 11

What do antibiotics do?

Answer 11

Kill bacteria
Specific antibiotics kill specific types of bacteria

Question 12

Why is it hard to develop drugs for viral infections?

Answer 12

Viruses live and reproduce inside cells

Question 13

What do painkillers do?

Answer 13

Treat the symptoms of disease but don’t kill the pathogens

Question 14

Tell me about digitalis.

Answer 14

It is a heart drug that is sourced from foxgloves

Question 15

Tell me about aspirin.

Answer 15

It is a painkiller sourced from willow

Question 16

Tell me about penicillin.

Answer 16

It is an antibiotic and is sourced from penicillium mould

Question 17

What 3 things are drugs tested for?

Answer 17

1: toxicity - how harmful the drug is
2: efficacy - whether the drug works and produces the effect you’re looking for
3: dosage - the concentration that should be given, and how often it should be given

Question 18

What is preclinical testing?

Answer 18

Tests on human cells and tissues; then tests on live animals

Question 19

What are clinical trials?

Answer 19

Tests on healthy volunteers (the dosage is gradually increased from a very low initial dose; tests on ill patients (finding optimum dose); peer review

Question 20

What is a placebo?

Answer 20

Substances that are like the drug being tested but don’t do anything

Question 21

What does a trial being double-blind mean?

Answer 21

It means that not even the doctors know who has the placebo and who has the real drug

Question 22

Tell me about monoclonal antibodies.

Answer 22

They are produced from lots of clones of a single white blood cell (B-lymphocyte)
They are all identical and specific to one protein antigen

Question 23

How do you produce monoclonal antibodies from a mouse?

Answer 23

Mouse injected with chosen antigen
B-lymphocytes from mouse make antibodies but don’t divide easily
This makes a hybridoma
It divides quickly to produce lots of clones that produce the monoclonal antibodies
The antibodies are collected and purified.

Question 24

How do you produce monoclonal antibodies from tumour cells in a lab

Answer 24

These don’t make antibodies but divide lots
B-lymphocytes are fused with a tumour cell
This makes a hybridoma
It divides quickly to produce lots of clones that produce the monoclonal antibodies
The antibodies are collected and purified.

Question 25

What are the 3 uses of monoclonal antibodies?

Answer 25

1: cancer treatment
2: locating specific molecules in research
3: measuring levels of substances in blood or urine

Question 26

What are the 6 signs of plant diseases?

Answer 26

1: stunted growth
2: spots on leaves
3: discolouration
4: patches of decay (rot)
5: malformed stems or leaves
6: abnormal growths (eg, lumps)

Question 27

What can plants be infected by?

Answer 27

Viruses
Bacteria
Fungi

Question 28

What can plants be infested by?

Answer 28

Insects (eg, aphids)

Question 29

What can plants be affected by?

Answer 29

Nitrate deficiency, which stunts growth - nitrate ions are needed to make proteins for growth
Magnesium deficiency, which causes calorosos (yellow leaves) - magnesium ions are needed to make chlorophyll

Question 30

What are the 3 ways to identify plant diseases?

Answer 30

1: Look up the signs in a gardening manual or on a gardening website
2: Take the infected plant to a lab, where scientists can identify the pathogen
3: Use testing kits that identify the pathogen using monoclonal antibodies

Question 31

What are the 3 physical defences of a plant?

Answer 31

1: waxy cuticle on leaves - barrier to pathogens
2: layers of dead cells around stems (bark) - barrier to pathogens
3: cellulose cell walls - barrier to pathogens around cells

Question 32

What are the 3 mechanical defences of a plant?

Answer 32

1: thorns and hairs stop animals touching and eating plants
2: leaves that droop or curl when touched can knock insects off
3: plants mimic other organisms to trick animals into not eating them

Question 33

What are the 2 chemical defences in a plant?

Answer 33

1: antibacterial chemicals kill bacteria and prevent disease
2: some plants produce poisons to deter herbivores