Phytoalexins defend plants against pathogens. Phytoalexins are produced by plant cells in response to attack by pathogens, and they inhibit the metabolism and growth of the pathogens. Go back to question 9b or go on to question 9c . Unlike most other animals, bees are able to see in the UV, so these guides are visable primarily to bees. Go back to question 9c or go on to question 10a .
Some tannins are also powerful antioxidants.
Go back to question 10a or go on to question 10b . Siderophores are special class of ionophores that bind to Fe ions. They form a lipid-soluble complexes with Fe, thereby facilitating it's movement across the cell membrane into the cell. Ergot alkaloids act by interferring with neurotransmission causing hallucinations or by vasoconstriction. Go back to question 10c or to question 1 or to the top of this exam .