F215 - Revision thread 13th June 2011

why you gotta say that? I hated plant transport!!!!!!!!!!!!!!!!!!! it can be transported in the xylem too right? all i can remember is plant hormone gets transported by diffusion active transport and mass flow...explain them if you can my knowledge is a bit rusty.....

why you gotta say that? I hated plant transport!!!!!!!!!!!!!!!!!!! it can be transported in the xylem too right? all i can remember is plant hormone gets transported by diffusion active transport and mass flow...explain them if you can my knowledge is a bit rusty.....

for golden rice how much detail do we need to know?

Main aim of it, few of functions of vitamin A, and name of the 2 enzymes, CRT 1 from the bacterium and phytoene synthetase from the daffodil. And I think the 3 points made by green peace who are against GM food. The latter ain't so important but the others I'd say revise.

well yeah I know those ones but like many people have the whole multistep reaction in their notes which is really worrying me. They have info about diff restriction enzymes etc??

for golden rice how much detail do we need to know?

I got a little document of notes about plant transport if you'd like that? I reckon its a long shot for them to test on that. major synoptic things they could probably throw is mitosis, transcription, nervous system synapse (a2), maybe enzymes for immobilising enzymes in biotech. I wouldn't worry about synoptic so much even if its present I doubt there'll be loads of it.

Okay thank you, that's really helpful

haha i'm sorry! i hate plant transport too. i dont think it will come up, hopefully. I cant remember anything about it from AS, but no i dont think plant hormones can be transported in the xylem. all it says in the textbook/revision guide is:
auxins are moved around the plant to control tropism. they move by diffusion and active transport over short distances, and via phloem over long distances.

Yes please send em my way!


if synoptic are on biological molecules i will be happy no other synoptic question just that lol.
quick q. During strenuous exercise the concentration of H+ in muscle tissue increases. A high concentration of H+ ions reduces the ability of Ca+ to bind to protein in the myofibrils. Using this information explain how the increased concentration of hydrogen ions results in a reduction in the force of contraction of a muscle. 5 marks
I haven't got the markscheme for this one gotta look in up in daylight.
but it reminds me of enzymes. Calcium ions bind to troponin but when H+ is around there is less binding because of this the shape of troponin won't change and movement of tropomyosin won't occur. the actin binding site will not be open so myosin head will not bind and cross bridgess won't form. . what ya think

I was just wondering about something. On the meiosis spread it says that during Anaphase 2, the chromatids "randomly segregate". What exactly does this mean? I can't really see why this is said because to me it seems a bit pointless saying that they randomly segregate if you're going to end up with the same amount of chromosomes on each side anyway... if that makes any sense.

Doubt you need to know the enzymes introduced to the cell for the production of beta-carotene but you need to know that:
-Rice plants contain Beta carotene in the inedible parts of the plant like leaves, its a photosynthetic pigment so is required for phososynthesis.
-the endosperm however (the rice grain) doesnt contain Beta carotene and that is the edible part.
- beta carotene is turned into Vitamin A in the gut
- The metabolic pathway for the production of beta carotene in the endosperm was found to only have 2 enzymes missing which via genetic engineering were introduced into the plant.
- now beta carotene is able to be produced in the endosperm and so we can get a supply of beta carotene

this is more signicant to those in developing countries who rely mostly on rice and are defficient in vitamin A

Vitamin A has various functions:

required for
eyesight (it forms part of the visual pigment rhodospin)
cell growth and development (involved in the synthesis of many glycoproteins)
epithelial tissue (needed for maintenacne and differentiation of epethilial cells, helps reduce infections)
bone (essential for growth of bones)

the stuff in brackets i guess is extra so not sure if you need to know it or not

also finally,
golden rice is said to be biofortified which means it contains higher than normal concentrations of a particular nutrient (beta carotene)

hope this helps and correct me if Im wrong

Doubt you need to know the enzymes introduced to the cell for the production of beta-carotene but you need to know that:
-Rice plants contain Beta carotene in the inedible parts of the plant like leaves, its a photosynthetic pigment so is required for phososynthesis.
-the endosperm however (the rice grain) doesnt contain Beta carotene and that is the edible part.
- beta carotene is turned into Vitamin A in the gut
- The metabolic pathway for the production of beta carotene in the endosperm was found to only have 2 enzymes missing which via genetic engineering were introduced into the plant.
- now beta carotene is able to be produced in the endosperm and so we can get a supply of beta carotene

this is more signicant to those in developing countries who rely mostly on rice and are defficient in vitamin A

Vitamin A has various functions:

required for
eyesight (it forms part of the visual pigment rhodospin)
cell growth and development (involved in the synthesis of many glycoproteins)
epithelial tissue (needed for maintenacne and differentiation of epethilial cells, helps reduce infections)
bone (essential for growth of bones)

the stuff in brackets i guess is extra so not sure if you need to know it or not

also finally,
golden rice is said to be biofortified which means it contains higher than normal concentrations of a particular nutrient (beta carotene)

hope this helps and correct me if Im wrong

does crossing over take place in prophase metaphase or anaphase? surely it's all 3 of them? which one do mark schemes specify?
and the same with the random assortment and segregation of bivalents and chromatids?
i know the whole meiosis process, just wanted to clear up, cus from what i can see, it could be all 3 of those