Edexcel BIOLOGY Doubts!!!!

[AbdulKareem]

I have some few questions from unit 4 (A-level):
- Suggest two enviromental conditions that could increase the rate of oxygen production in plants
- Describe how a forest could be managed sustainably in order to ensure a continual supply of timber for the future
-Name a method by which global sea temperatures can be monitored
-Some recovery in the great barrier reef may be taking place at present. Suggest a possible explanation for this, other than change in sea temperature
-HIV positive people were excluded from the data (ie data about number of new TB cases). If they have been included suggest how the data would differ. Give an explanation to your answer.
-Give one example of physical evidence that could be retained from the original investigation of a crime scene and explain why the sample is suitable for a DNA test to be carried out.

SOrry for being thick, answer what u can if u please thanks alot

Here's what I think are some correct answers;
-Any condition which will increase the rate of photosynthesis over respiration so the plant produces more oxygen (e.g. 1.higher temperature 2.brighter sunlight/light... etc.)
-By planting seeds after cutting trees.
-Maybe reducing CO2 emissions? Hmm it's unlikely.. I'm not sure to be honest.
-The increasing acidity of the sea (lower pH because of more CO2 absorption by the sea).
-The number of people affected with TB would have been higher. Explanation: TB is an opportunistic disease which only attacks when your immunity is at its weakest. HIV kills the T-helper cells in your immune system which makes it very weak, and so TB finds the perfect time to attack.
-Blood/Falling hair... etc.
Refer to DNA profiling. I'm sorry but I'm a bit short on time right now.

I hope it helps
Good luck mate!

[Amelia]

-Maybe reducing CO2 emissions? Hmm it's unlikely.. I'm not sure to be honest.

How about sencors?

-Give one example of physical evidence that could be retained from the original investigation of a crime scene and explain why the sample is suitable for a DNA test to be carried out.

check these - http://en.wikipedia.org/wiki/DNA_profiling
                   http://www.answers.com/topic/genetic-fingerprinting

[Amelia]

hey wt about the quadrat/transect experiment? i knw nothin how 2 do it!

Something like this, you mean?

[abuelzouz]

Something like this, you mean?

Thanks  a lot still ddnt check it have 2 open my laptop 2.. my pc has  office 2003 nt 2007 Thanks again

[AbdulKareem]

How about sencors?


check these - http://en.wikipedia.org/wiki/DNA_profiling
                   http://www.answers.com/topic/genetic-fingerprinting

The links have too much general not required information.. They won't help.
Perhaps reading what you post before you post it is a good idea

[Hissa]

Here's what I think are some correct answers;
-Any condition which will increase the rate of photosynthesis over respiration so the plant produces more oxygen (e.g. 1.higher temperature 2.brighter sunlight/light... etc.)
-By planting seeds after cutting trees.
-Maybe reducing CO2 emissions? Hmm it's unlikely.. I'm not sure to be honest.
-The increasing acidity of the sea (lower pH because of more CO2 absorption by the sea).
-The number of people affected with TB would have been higher. Explanation: TB is an opportunistic disease which only attacks when your immunity is at its weakest. HIV kills the T-helper cells in your immune system which makes it very weak, and so TB finds the perfect time to attack.
-Blood/Falling hair... etc.
Refer to DNA profiling. I'm sorry but I'm a bit short on time right now.

I hope it helps
Good luck mate!

Thank u so much, i just wanted to double check if my answers were correct, that gave me confidence
Thanks for ur help.

[Amelia]

The links have too much general not required information.. They won't help.
Perhaps reading what you post before you post it is a good idea

I thank you, for the advice.

[guMnam]

okay....i m tired of finding something to study from for unit 3 & 6...can somebody sugest a book or watever

[hissyfit]

For Edexcel there s CGP   http://www.cgpbooks.co.uk/pages/productDetail.asp?book=BER52&page=%2Fassets%2Fukthumbnails%2FBER52%5Fsample2%5Flge%2Egif

+ other  book,  http://www.amazon.co.uk/Edexcel-Biology-Revision-Guide-Sciences/dp/1846905982/ref=sr_1_1?s=books&ie=UTF8&qid=1296467672&sr=1-1#reader_1846905982

you can find another preview of this book on the pearsonschoolsandfecolleges.co.uk website,couldn t put link as the website isn t working at the moment.

they mainly have the method, +some practice qs
The Letts book doesn t jave anything on the practicals,imo I don t think it s worth buying

[guMnam]

umm Thanks for tht...but i wasnt looking for tht caz i already noe abt 2 of them...wat i want is a book frm pearson..i have a link to two of its pgs but i dont noe the name and where to find the whole thing....

http://www.pearsonschoolsandfecolleges.co.uk/AssetsLibrary/SECTORS/Secondary/PDFs/Science/EdexcelScience/EdexcelA2Biology_Practical63_MostEffectiveAntibiotic_StudentWorksheet.pdf

[hissyfit]

I will ask on The Student Room and see if I get any answers,will post here if I do

[hissyfit]

you can see the replies here : http://www.thestudentroom.co.uk/showthread.php?t=1535284&stat_userid=413917&stat_usergroupid=12&stat_membergroupids=&stat_widgettype=secondary&stat_widgetname=widget_watched_threads
 

[guMnam]

hmm....Thanks for ur help

[hissyfit]

Plant Fibres-why do some stretch more than others?
Any ideas,googling didn t help

Has it got to do with their structure or their composition( materials they are made up of)?
Thanks
+rep

I was given these hints: Think about the molecular structures involved. Proteins and polysaccharides form secondary structures - what are they? What types of forces are involved in them? What about tertiary structures?


My attempts - I have no idea other than the glycosidic bonds in cellulose.I don t know what secondary structures polysaccharides form other than long chains.

I know there are hydrogen bonds in secondary strucure in proteins+varipous bonds in tertiary structure .
I m really stuck plz help!
 

[Deadly_king]

Plant Fibres-why do some stretch more than others?
Any ideas,googling didn t help

Has it got to do with their structure or their composition( materials they are made up of)?
Thanks
+rep

I was given these hints: Think about the molecular structures involved. Proteins and polysaccharides form secondary structures - what are they? What types of forces are involved in them? What about tertiary structures?


My attempts - I have no idea other than the glycosidic bonds in cellulose.I don t know what secondary structures polysaccharides form other than long chains.

I know there are hydrogen bonds in secondary strucure in proteins+varipous bonds in tertiary structure .
I m really stuck plz help!
 

That's for sure.........the molecular structure has a lot to do with this stretching thing about fibers.

Let's get to the root of it........definition of fibers.

Fibers are elongate cells with tapering ends and very thick, heavily lignified cell walls. Fiber cells are dead at maturity and function as support tissue in plant stems and roots. The lumen or cavity inside mature, dead fiber cells is very small when viewed in cross section.

So my first conclusion........lignin certainly has something to with it. i think that the more lignin the fiber possess, the less will it stretch.

Now you should look back at your notes on cell membrane. What is the name of the thing that is responsible for elasticity?

This should certainly give you a hint.

Another point : Plant cell walls are composed essentially of two polymer constituents, a network of highly structured microfibrils embedded in a relatively unstructured matrix.

So now you need to make some research on the components of cellulose as well and how it forms elastic microfibrils.

Hope it helps.