chem222
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can someone help me with question ci and ii
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chem222
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can someone help me with question ci and ii
I was thinking about suckers for ci but not sure how to explain it (markscheme)
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OxFossil
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can someone help me with question ci and ii
No idea what your markscheme requires, but

i) cutting elms near ground level stimulates the roots to throw up many new suckers and rapidly form a thick growth of new shoots. If left to grow, they can form a bush-like thicket, which may result in several harvestable shoots, suitable for uses like fencing. This is called coppicing. If artificially thinned, so as to leave just a single coppice shoot, that remaining new growth will eventually replace the old main trunk.

ii) Dutch Elm disease is caused by a fungus carried by the elm bark beetle. After a fire or storm, the elm is structurally damaged, but can recover through vegetative growth. This new growth is no more vulnerable to further fire or storm damage than the parent stem. But since vegetative propagation does not change the genetic make-up of the new growths (they are simply outgrowths of the parent stock), the new growth will be just as vulnerable to further infection by the Dutch elm fungus as the parent. What's more, the vegetative shoots are still connected to the parent trunk, and the fungus and/or the beetle vector are very likely to still be present in the parent stem, or in nearby trees, so the chance that the new growth will be infected is very high.
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chem222
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(Original post by OxFossil)
No idea what your markscheme requires, but

i) cutting elms near ground level stimulates the roots to throw up many new suckers and rapidly form a thick growth of new shoots. If left to grow, they can form a bush-like thicket, which may result in several harvestable shoots, suitable for uses like fencing. This is called coppicing. If artificially thinned, so as to leave just a single coppice shoot, that remaining new growth will eventually replace the old main trunk.

ii) Dutch Elm disease is caused by a fungus carried by the elm bark beetle. After a fire or storm, the elm is structurally damaged, but can recover through vegetative growth. This new growth is no more vulnerable to further fire or storm damage than the parent stem. But since vegetative propagation does not change the genetic make-up of the new growths (they are simply outgrowths of the parent stock), the new growth will be just as vulnerable to further infection by the Dutch elm fungus as the parent. What's more, the vegetative shoots are still connected to the parent trunk, and the fungus and/or the beetle vector are very likely to still be present in the parent stem, or in nearby trees, so the chance that the new growth will be infected is very high.
excellent answers.. for the ci, my text book says ''elm tree is a plant that uses suckers. these are shoots that grow from sucker buds present on the shallow roots of a parent plant''
would that be sufficient? this is what the markscheme says
''root suckers / basal sprouts ; from , meristem / undifferentiated , tissue ; grow , up around / in circle / between , felled trees ; correct ref. to time ; ''
It also says ignore reference to genetics, what does that mean?
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OxFossil
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excellent answers.. for the ci, my text book says ''elm tree is a plant that uses suckers. these are shoots that grow from sucker buds present on the shallow roots of a parent plant''
would that be sufficient? this is what the markscheme says
''root suckers / basal sprouts ; from , meristem / undifferentiated , tissue ; grow , up around / in circle / between , felled trees ; correct ref. to time ; ''
It also says ignore reference to genetics, what does that mean?
Thanks. I'm afraid I know nothing about markschemes, and what you quote just sounds like a word salad to me. It would be a pure guess to speculate that "correct ref to time" could refer to the idea that the suckers are thrown up after the parent is felled, and takes time to mature to harvestable timber??? Likewise, "ignore reference to genetics" may just mean that it is of no significance to the allocation of marks to mention that shoots produced from suckers are genetically identical to the parent plant. That's fair enough for c) i, but not for c) ii anyway. But what do I know?
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chem222
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Thanks. I'm afraid I know nothing about markschemes, and what you quote just sounds like a word salad to me. It would be a pure guess to speculate that "correct ref to time" could refer to the idea that the suckers are thrown up after the parent is felled, and takes time to mature to harvestable timber??? Likewise, "ignore reference to genetics" may just mean that it is of no significance to the allocation of marks to mention that shoots produced from suckers are genetically identical to the parent plant. That's fair enough for c) i, but not for c) ii anyway. But what do I know?
Thanks a lot anyway
Can I ask one more question?
Pot plants grown for sale at Christmas will not be bought if their leaves drop off, why can this problem be solved by Auxins? Auxins inhibit the growth of side shoots (apical dominance)....
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OxFossil
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Thanks a lot anyway
Can I ask one more question?
Pot plants grown for sale at Christmas will not be bought if their leaves drop off, why can this problem be solved by Auxins? Auxins inhibit the growth of side shoots (apical dominance)....
Frankly, I don't know. I know that apical dominance increases internode distance and as you say, inhibits side shoot growth. So you will have fewer side leaves to drop off. More pertinently, auxins also prevent the formation of abscission scars at side shoots - which obviously directly inhibits leaf drop. But this bit of info may be beyond your curriculum or mark scheme?

One has to suspect that the reference to "Christmas" must be significant here - the non-growing season. But how? I have no idea. Sorry.
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