B11

Question 1

What defence strategies do plants have?

Answer 1

Mechanical protection, complex polymers or silica crystals reduces digestibility. Phytotoxins

Question 2

What mechanical protection do plants have?

Answer 2

Spines, thorns - large animals
trichomes - small animals

Question 3

What are some digestibility reducers?

Answer 3

Cellulose and hemicellulose, pectin, lignins, cutins and waxes, tannins, silica

Question 4

What are phytotoxins?

Answer 4

The active substances are secondary metabolites, biochemical and angiosperm coevolution. Presence of compounds characterises groups and even whole families

Question 5

What is primary metabolism?

Answer 5

Carbon assimilation and nitrogen assimilation

Question 6

What is secondary metabolism?

Answer 6

Lipids (steroids, terpenoids), sugars, nuclei acids, amino acids (alkaloids, nitroaliphatics, cyanogenic compounds), proteins

Question 7

What are some nitrogen based phytotoxins?

Answer 7

Non-protein amino acids - canavine in legumes
Cyanogenic glycosides - form HCN
Glucosinates - N and S
Alkaloids - morphine from poppies
Peptides - short aa polymers
Proteins - ricin from castor oil
Nitroalipahtics - legumes

Question 8

What are some non nitrogen-based phytotoxins?

Answer 8

Iridoids - intermediates in alkaloid synthesis
Terpenoids - menthol, taxol, rubber, cannabinoids
Cardiac glycosides - digoxin in foxglove
Saponins - natural detergents
Furanocoumarins - phytochemicals in parsnips and hogweeds
Isofoavonoids - phytoestrogens
Quinones - derived from phenolic compounds
Polyadetylenes - asteraeae

Question 9

What are some plant toxins?

Answer 9

Nicotine - alkaloid
strychnine - alkaloid
cyanogenic glycosides - release HCN when leaf is damaged
3-nitropropionic acid - inhibits mitochondrial activity
Digitoxin - cardiac glycoside
Ricin - protein

Question 10

Relationship between milkweeds, monarch butterflies and blue jays?

Answer 10

Milkweeds and monarch butterflies. Milkweed produce several cardiac glycosides, very bitter, very toxic. Monarch caterpillars ingest milkweed tissue and sequester the toxins into their own tissues. Toxins survive in tissues into adult butterfly stage. Adult butterfly has aposematic colour warning pattern, blue jays learn to avoid monarchs through recognising aposematic pattern. Only 50% of pop need to be toxic to effect 100% protection to population.

Question 11

Relationship between pyrrolizidine alkaloids, ragworts, moths and butterflies?

Answer 11

As well as ragwort, tiger moths also eat the leaves of foxglove and sequester cardiac glycosides and individual moth may contain both alkaloid and cardiac glycosides in the same body. These moths have aposematic colour warning some danaid butterflies consume pyrrolizidine alkaloids in order to synthesise pheromones.

Question 12

Why do animals eat some plants but not others?

Answer 12

Plant defence theory, plant apparency theory, resource availability theory

Question 13

What is the plant apparency theory?

Answer 13

Long lived, late successional species use quantitative plant defences (digestibility reducers, phytotoxins). Apparent plants are easy to find by herbivores that employ generalist strategies, short lived, early successional species use qualitative toxins, these plants not particularly easy to find and herbivores employ specialist strategies

Question 14

Cyanogenic glycosides in legumes equation?

Answer 14

Cyanogenic glycoside -glucosidase enzyme> unstable product -> ketone + HCN

Question 15

What genes and genotypes are involved in cyanogenesis?

Answer 15

Two genes, G controls synthesis of cyanogenic glycoside, E controls synthesis of the glucosidase. Four genotypes involved : GE - cyanogenic, gE, Ge, ge - not cyanogenic

Question 16

What is the role of plants in medicine?

Answer 16

Plant relied on heavily, 70% of pharmaceuticals are derived from natural products

Question 17

What are some important secondary metabolites?

Answer 17

Alkaloids, steroids, glycosides, oils and resins, polyacetylenes, organic acids, amino acids, peptides, proteins, flavonoids

Question 18

What are some over the counter plant medicines?

Answer 18

Cough mixtures, laxatives, inhalers, pain meds

Question 19

What are some powerful drugs extracted from plants?

Answer 19

Atropine, ephedrine, digitoxin/digoxin, morphine, quinine, reserpine, scopolamine, vincristine
Taxol/paclitaxel

Question 20

What are vincristine and vinblastine?

Answer 20

Rosy perwinkle, Catharanthus roseus. Power anti-cancer properties, vinblastine increased chances of surviving leukaemia. Vincristine is used to treat hogkins disease

Question 21

What strategies are there for surveying plant world medicines?

Answer 21

Screen everything, systematic approach of screening taxonomic groups, ethnopharmacological approach based on ethnobotany

Question 22

What are the advantages or disadvantages of screening everything?

Answer 22

Probably impossible, very expensive, only a few have proven commercially successful.

Question 23

What are the advantages or disadvantages of the systematic approach?

Answer 23

It is based on phytochemistry and chemosystematics. Certain types of chemicals are only found in certain taxa of plants. Many ppl feel approach is unlikely to uncover new drugs.

Question 24

What are some importantly plant families?

Answer 24

Apocynaceae, asclepiadaceae, berberidaceae, liliaceae, moraceae, nyssaceae, papaveraceae, rubiaceae, rutaceae, scrophulariaceae, solanaceae, taxaceae

Question 25

What is the study of plant use by ethnic cultures called?

Answer 25

Ethnobotany, as 80% of people in less developed countries rely on traditional medicines for primary healthcare

Question 26

What is ethnopharmacology?

Answer 26

Study of drugs derived directly from natural sources used by ethnic cultures

Question 27

What are some examples of ethnobotany and ethnopharmacology?

Answer 27

Arrow poisons, curare, a muscle relaxant in poison. Ordeal poisons, phytostigmine, used in eye disorders. Ethnic medicine : prostratin, a deoxy-phorbal derived from bark. Powerful anti-virus compound which does not stimulate tumour development. Potential use in treatment of HIV.

Question 28

What are some more examples of ethnobotany and ethnopharmacology?

Answer 28

Cocaine, from leaves or coca bush, alkaloid structures has been used as model for many synthetic anaesthetics. Steroidal sapogenins, oral contraceptives. Cortisone and hydrocortisone are also steroidal sapogenins.