Toxins and Anti-nutrients 1 and 2

Question 1

Lignin

Answer 1

largely present in higher(tall) plants
adds rigidity to plant cell walls
increases as the plant matures 
provides structure to xylem pathways 
not digested by endogenous digestive enzymes, microbial enzymes or acid hydrolysis 

can be broken down by bracket fungi

Question 2

Suberin

Answer 2

• wax polymer (indigestible lipid)
• hydrophobic. layer in the periderm[most outer layer/ cork]
• also protect roots from losing nutrients and water
  
  • passage cells control water/nutrients going in/out

Question 3

Cutin

Answer 3

wax polymer (indigestible lipid)

• structural component of plant cuticle
• adds another layer between consumer and digestible plant components

Question 4

Silica (Si+O2)

Answer 4

deposition of phytoliths –> mineral deposits in plant tissue
- hard/gritty compound (decrease digestibility, increase tooth abrasion)

Question 5

Secondary Plant Compounds

Answer 5

responsible for chemical interference

• primary role is herbivore deterrence
• most act against all consumers but some are selective

are ALSO toxic to the plant itself so the plant must do 1 of 2 things

1. isolate the compound within the plant
2. store an inactive form that activates upon consumption

Question 6

Options for consumers to adapt to PSC- 1, 2

Answer 6

1. avoidance
2. selectivity
   a. eat new, younger vegetation
   b. younger plants have less physical protection
   c. younger plants have lower concentrations of toxins
   the exception is caffeine which is more prevalent in younger coffee

Question 7

Options for consumers to adapt to PSC- 3

Answer 7

3. microbial detoxification
   a. GIT bacteria can breakdown/detoxify secondary compounds
   b. ruminants/foregut fermenters have the advantage
   c. but bacteria need time to adapt to toxins

Question 8

Options for Consumer to adapt to PSC- 4

Answer 8

metabolic detoxification

a. tissue level detoxification (liver)

Question 9

Options for Consumer to PSC-5

Answer 9

pica

• binding toxins with non-nutritive substances
• ingesting clay/soil (binds toxins, reduces absorption)
• activated charcoal is used in medical practice

Question 10

Coumestrol

Answer 10

Flavonoid
high concentrations in soybeans, clover, alfalfa sprouts
may cause sterility, miscarriages and liver damage

Question 11

Coumarins

Answer 11

high concentrations in sweet grass, sweet clover
may cause hepatotoxicity with prolonged ingestion
vitamin K antagonist- inhibit blood clotting

Question 12

Tannins

Answer 12

high concentrations in grapes, cocoa, rhubarb, legume trees

high concentration in fruit skin/seeds/stems, bark, roots

binds and precipitates proteins (preferentially proline)

mucin in saliva

Question 13

common examples of Alkaloids

Answer 13

nicotine from nightshade plants –> stimulant, psychoactive

morphine from poppies–> sedative, psychoactive

cocaine from coca leaves –> stimulant, psychoactive

caffeine from >60 plant species –> stimulant, psychoactive

psilocin from psilocybin mushrooms –> stimulant, psychoactive

Question 14

Less common examples of alkaloids

Answer 14

strychnine from seeds of strychnine trees –> toxic, lethal

curare from bark fo chondrodendron trees –> toxic, sedative, lethal

coniine from poison hemlock, fools parsley–> toxic, lethal

Ricin from seeds of castor oil plants –> toxic, lethal

Question 15

MONOterpenes

Answer 15

anti-microbial

• citronella from lemongrass
• menthol from mint and peppermint
• pinene from pine resin
• cannabinoids from cannabis
• curcuminoids from turmeric and mustard seeds
• young plants will have lower concentrations

Question 16

DIterpenes

Answer 16

found in plant resins, often highly toxic

gratanotoxin from rhododendron trees- nerve and muscle inactivation –> low heart rate

Question 17

Cyanogenic Glycosides

Answer 17

toxic polysaccharides

• plants store inactive cyanogenic glycosides in vacuoles
• plant is chewed glycosides from cytoplasm exposed
• enzyme cleaves glycoside bond, release active hydrogen cyanide –> very potent and toxic
• amgydalin in seed /pits of peaches, cherries, plums, apples
• linamarin in leaves, roots, of cassava, flax, lima bean plants

Question 18

Cardiac Glycosides

Answer 18

highly toxic polysaccharides

• interferes with membrane potentials (heart CNS)
• digitoxin from digitalis plants

Question 19

Thiaminase

Answer 19

enzyme that breaks down thiamine (B1)
- many live fish contain inactive thiaminase
also found in bracken fern and horsetails

Question 20

Goitrogens

Answer 20

inhibit iodine uptake, disrupts thyroid hormone production

results in enlarged thyroid

Question 21

selenium

Answer 21

‘accumulator’ plants contain toxic concentrations of selenium
examples: milk vetch and wood aster