Why Do Plants Make Drugs

Question 1

Gene for gene recognition (3)

Answer 1

Plant gene (R)

Parasite gene (AVR)

Plant produce specific R gene that is resistant to the pathogen that produces the corresponding AVR gene

Question 2

Plant R proteins

Answer 2

Recognise molecule made by product of AVR genes

Activate plant defences by triggering signal transduction pathways

• local hypersensitive response
• general systematic acquired resistance

Question 3

Hypersensitive response (3)

Answer 3

Programmed cell death:

• cell and tissue die
• makes metabolites and toxic proteins
• cell wall changes

Question 4

Systematic acquired resistance (3)

Answer 4

Plant wide non specific response

Causes expression of defence genes and lasting response

Causes expression of defence genes and lasting response

Methylsalicylate made

Question 5

What does Methylsalicylate do? (4)

Answer 5

Carried in phloem
Converted to salicylic acid
Activates TP (triode phosphate in glycolysis)
Makes SAR (systematic acquired resistance)

Question 6

Physical defences (3)

Answer 6

Thorns
Distasteful/toxic
‘Recruit’ predatory animals to defend against specific herbivores (peps)

Question 7

Chemical defences (3)

Answer 7

Lots of chemicals
Secondary special metabolites
-sugars
-amino acids
-fatty acids
-phenolics

Synthesises by one species in specific conditions

Question 8

What are the 5 features and their roles in plants?

Answer 8

Colour:
Flowers-reproduce
Leaves-light

Fragrance:
Flowers- reproduce
Leaves- defence

Flavours:
Defence

Toxins:
Defence

Storage compounds:
Survival and reproduction

Question 9

Example of a secondary metabolite that’s used by humans

Answer 9

Onions and garlic

Question 10

Flavour from onions

Answer 10

Instant volatiles released when tissue is damaged

Question 11

What in it for the onion?

Answer 11

Lots of resources
Causes fast re-growth
Protect bulb during dormancy
Protects leaves during growth

Question 12

Protection and risk of an onion (2)

Answer 12

Protection from pathogens and predators

Susceptible to specialists as volatiles attract germinates

Question 13

What’s in the bulb? (5)

Answer 13

Carbs
Flavour precursors and peptides
Allinase and lachrymatory factor synthase (LF’s)
Lectinm (bind carbs)
Flavonoids

Question 14

How does a plant know defence is needed? (3)

Answer 14

Receptors

Stimulation causes signal down transduction pathway

Response at several levels including metabolites and enzymes. Growth can also be detected.