F215 - Revision thread 13th June 2011

hey guys....

don't bother focusing on the second module (the biotech one) as 54% of all the marks in the last paper (jan 2011) came from that module, hence they are very very very very very very unlikely to focus/ask too much on it

EDIT: I know this as I went through it and counted

OUTLINE THE PROCESS INVOLVED IN GENETIC ENGINEERING OF RICE....

If i write this....the two genes from daffodil and one from bacterium eriwina urefovora were inserted in to TI plasmids and taken up by the bacterium agrobacterium tumefaciens. This introduced the genes into rice embryo.The resultin rice plants produced seeds wita beta carotene in the endosperm, which is yellow. Vitamin A can be produced in our bodies from beta carotene...is that an acceptable answer? or am i missing anything imporant??

guys i've been really ill for the last 6 months and started revision last week. any notes for last minute revision?

ok I give up I have a stats exam in the am so need to go and get some papers done for that and will be back after lunch time, but before I go
anyone wanna try a few questions?
1) explain why very wet soils are usually nitrogen deficient. 2marks
2) explain the process of succession in a system of sandunes, or in an area you have studied. 4marks
3) explain why many would prefer the use of biological pest control as preferable to application of insecticides. 5 marks
4) Explain what is meant by the term succession. 4 marks
5) Explain how a fermenter allows continuous culture of chlorella. 6 marks
6) Outline the process of cloning plants from tissue culture 6 marks
All for sport

For biology? Possibly the worst subject to revise - learn the "buzzwords" and the main mechanisms and make sure you're sure on those before getting into the fiddly bits. Also, apply for special consideration.

And drink a lot of coffee, because there's a lot to know so you need ENERGY

1)wet soils make the conditions for bacteria in the soil anaerobic - as no oxygen is available nitrates must be taken up to use as a source of oxygen.
2)Pioneer species that can tolerate high levels of salt etc occupy just above the high water mark - these species stabilize the ground by producing nitrates and making the ground firmer with their roots. Secondary species can now succeed these as the environment becomes more tolerable - community of organisms changes until climax community reached, e.g. a forest.
3)Insecticides contain toxic compounds which could leak into rivers when it rains, and produce knock on effects for the environment - could cause problems if organisms other than insects e.g. birds eat the crop. Biological pest control is more natural and doesn't have knock on effects for the environment? (i dunno im rambling haha)
4)Succession is a directional change in a community of organisms over time, which starts at an uninhabitable area, where pioneer species first occupy, stabilizing the area until a climax community is reached.
5)Continuous culture involves the constant addition of nutrients and oxygen, and removal of waste products and products - chlorella is a form of algae - starter culture added to fermenter, pH temp O2 and nutrient levels at optimum for growth - remove algae at intervals
6)Explant taken (usually) from tip of shoot of plant to be cloned. This is steralized, and then placed on a growth medium to promote cell division, but not cell differentiation - this produces a mass of undifferentiated cells called a callus. Callus is broken up into smaller fragments, and these are placed on another growth medium which promotes shoot growth, then transferred to another growth medium to promote root growth. These plants are then planted in soil in a green house to acclimatize to conditions.

what do i get out of 27? i hate all the ecology stuff haha

I wouldnt go with TI plasmids because, they are insereted into a soil bacterium which is then taken up by the plant, why not refer to maybe microinjection which inserts the genes for the enzymes into the rice genome close to a specific promoter sequence that switiches on the genes for endosperm development so that these enzymes too can take part in developing as part of the metabolic pathway for the endosperm growth (which without the presence of these two enzymes cannot produce beta carotene)

You need to be able to outline the process involved in the genetic engineering of the golden rice, as in 2 extra enzymes are inserted into the genome, but the way in which thats done is not written in the book in detail, so if it was to ask you how do you genetically engineer golden rice, refer to the genetic engineering process of insulin, and instead of saying the mRNA of insulin is taken, refer to the genes coding for the 2 enzymes being placed in vectors etc. because an examiners note said that the genetic engineering process is not just used for insulin but you may be asked how other proteins are genetically engineered like renin which was in a past paper not sure wether it was jun10 or jan11

Hope this helps, i wouldnt worry too much about the way in which the enzymes are inserted into the rice genome, just remember that the genes for the enzymes were placed in the rice genome close to a specific promotor sequence that switches on the genes for endosperm development.

thanks. has anyone posted the jan2011 paper yet and what do people think will come up tomorrow?

thanks. has anyone posted the jan2011 paper yet and what do people think will come up tomorrow?

I answered that question with the whole impulse to cerebrum, etc. but after I looked at the mark scheme, I realised that the whole answer for that question was about the structure of the cerebrum in detail, etc. which we don't need to know. So that particular question won't come up But if something similar to that comes up, I'm guessing you should answer it with a description of formation of action potential in the sensory neurone, followed by impulse to brain, then to effector, etc.

Do you guys think the nitrogen cycle will come up?

Ah awesome, that's exactly how I answered it, so when I saw the mark scheme I was a bit like
Just checking I hadn't missed out a big section!

its on page 12

Are u sure about ure answer to 1