Insecticides.

Theres this horrible question . The aqa nelson thornes book says its from an AQA 2004 paper but I've searched them and I can't find the mark scheme.

Okay so.
Theres a table showing number of pests against the month while chemical pesticide is in use.

feb 2
march 15
april 3
may 20
june 3
july 16
august 2

Why is the number of pests going up down up down???

The actual question is.

Explain how th echemical control leads to changes in the number of spotted knapweed plants from march to june.

All Ive got is that they develop resistance...its a 3 mark question. Help please.

OP

Anybody?

Original post by Destroyviruses

Anybody?

Does the question say when the insecticide is used?

My first thoughts are that the insecticide is used when the population of pests are high. So when applied, the pests die, and only a few of them remain, but enough of them to be able to colonise again. I would read over your notes again, I'll try and find what the mark scheme says.

(edited 13 years ago)

Reply 3

Eloades11

17

Yep just to confirm what I said was right(sorry if I sound big-headed).

Here is the link to the thread with the mark scheme http://www.thestudentroom.co.uk/showthread.php?t=1234936

scroll down to chapter 5 unit 4, question 5 (b)(ii). Its because the insecticide is washed away after time and plants are able to grow back during that time before the insecticide is re-applied.

Hope this helped

Reply 4

Destroyviruses

OP

13

Original post by Eloades11

Yep just to confirm what I said was right(sorry if I sound big-headed).

Here is the link to the thread with the mark scheme http://www.thestudentroom.co.uk/showthread.php?t=1234936

scroll down to chapter 5 unit 4, question 5 (b)(ii). Its because the insecticide is washed away after time and plants are able to grow back during that time before the insecticide is re-applied.

Hope this helped

Thankyou it helped alot indeed. *HUG*

Insecticides.

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