Biology P4 (again) : And stretch your hands to avoid cramp.

As I always say, I'm not Vika. I'm only borrowing his ID (again, lol).

This is a short listings of all (maybe) processes that is involved in our biology lesson.

But in fact, there are so many processes in biology, that this list ended up long, which is a pain for me.

This may (or may not) help you, but it certainly helps me since by writing these points, I remember better, "So why don't I contribute by writing it in the blog? Like killing two birds with a shotgun" I thought.

Whatevs lets just go to the main part.

1. Synaptic Transmission

• Action potential arrives on presynaptic membrane
• It causes uptake of Calcium Ions
• Calcium Ions cause vesicles of Acetylcholine (ACh) to fuse with presynaptic membrane
• ACh released and diffuse across synaptic cleft
• ACh binds with receptors on postsynaptic membrane
• Sodium channel is opened, Sodium Ions enter and depolarisation occur, action potential initiated

2. Action Potentials

• Resting potential is -65 mV (maintained actively by sodiumpotassiumpumps (3 sodium out for 2 potassium in)
• Action potential arrives, Na+ moves in through its voltage-gated channels
• Potential is +40 now because of excess of positive ions (depolarisation)
  
• Na+ channels close, sodiumpotassiumpumps restore resting potential (repolarisation) (briefly becomes more negative than normal)

3. ADH Effect

• ADH arrives through blood and binds to receptors in plasma membranes of the lining-cells of collecting ducts.
• It causes enzyme controlled reactions that produce active phosphorylase enzyme
• active phosphorylase enzyme causes vesicles of water permeable channels to move.
• Vesicles fuse with membrane, and voila! Your collecting duct is now permeable to water..

4. Meiosis Process (Things similar to mitosis will not be mentioned throughoughly (did I spell that right?))

• Meiosis I :
  
• Prophase I : homologous chromosomes pair up, (one pair is called as bivalent), and everything goes like mitosis, except crossing over occurs inbetween bivalent
• Metaphase I : They line up, independent assorment occurs.
• Anaphase I : centromeres DO NOT divide unlike mitosis
• Telophase I : as usual
• Meiosis II :
• Everything is as usual, but this time, the centromeres do break and divide.

5. Photophosphorylation (One of the longest, real word I've ever seen, that I have to copy paste this word through the list, do they ever attempt to abbreviate this word?)
(I strongly reccomend Figure 16.4 of our biology textbook (old edition))

• Photolysis, gives out 2H+, O, and 2 electrons.
• Electrons go to P680 and get excited to higher energy level. (Non cyclic-Photophosphorylation)
• Energy in electrons used to make ATP
• Electrons go to P700, excited again, used to make ATP again, and it cycles. (Cyclic-Photophosphorylation)
• 2 Electrons with the previous 2H+ ions combines with NADP to form reduced NADP.

6. Calvin Cycle (figure 16.6 is reccomended now)
RuBP = ribulose biphosphate, GP = glycerate 3-phosphate, TP = triose phosphate

• CO2 combines with RuBP to form unstable 6C compound
• It breaks to form 2 GP which is 3C compound
• Reduced NADP and ATP used to make GP into TP
• TP is used to make glucose, amino acid, lipids, etc.
• TP can also be used to regenerate RuBP

7. Phosphorylation (figure 15.9 is reccomended)

• Glucose, by using ATP turns into Hexose Phosphate, by using ATP again turns into Hexose Biphosphate, which breaks to 2 Triose Phosphate molecules.
• 2 TP turns into 'intermediates' and give out 2ATP and 2H, that forms 2 reduced NAD.
• 'intermediates' turns into 2 pyruvate molecules.

8. Krebs Cycle (...crap, this is long..I'll use symbols to make it short.) (figure 15.11 is reccomended)
[N] = an NAD molecule turns into reduced NAD during the process, [C] = CO2 is kicked out during the process

• A molecule of pyruvate turns into Acetyl CoA [N][C]
• AcetylCoA combine with oxaloacetate to form citrate (6C)
• citrate (6C) through some process turns into (5C) [N][C]
• Same thing happen to the (5C) molecule again, producing a (4C) molecule [N][C]
• the (4C) molecule turns into oxaloacetate, during this, an FAD is reduced an ATP is formed [N]

9. Anaerobic respiration (a short paragraph for this one) (figure 15.16 & 15.17 is reccomended)

Basically there are 2 types, lactate (in muscles) and ethanol (in bacteria).
The starting process is similar: glucose turns into pyruvate, making ATP and giving 2H in the process. 2H used to make 2 reduced NADs.
This is the difference:

• Lactate: the 2 reduced NADs give out the 2H they previously received to the pyruvate forming lactate.
• Ethanol: pyruvate lose CO2 somehow, becoming ethanal. Then, the 2 reduced NADs give out the 2H they previously received to ethanal which become ethanol.

Notably, reduced NADs are acting as coenzymes in this process. (maybe..)


Ahh there you go.. (letting out a sigh of relief)
Please tell me if I spelled anything wrong or something like that. I'm not perfect, and definitely not a 'dewa'.
There are several points that I purposely do not include like gene technology and sexual reproduction (For those testosteroners dont go "whut no sex?" on me, and flame in the comment box.). But these points are outside the textbook and Ms.Yanti has recently repeatedly taught us about these excluded points.

Yes, yes, I myself am wondering, why the heck would I write this at the night before the test? And on top of it, I wrote this at 10p.m. and finished at 11p.m. Chances are, nobody will ever read this before the test, since they are already asleep, resting properly before tomorrow's test at 7.30 a.m. (except Vika maybe). But at least it benefits me (and Vika maybe) as I've said. Also, as Vika reasoned; " The future generations may need this."

But seriously, I have no idea of why am I doing this.. It just occured..
Ah well, eventhough no one is reading this, but good luck anyways for the Bio P4 tomorrow and Math P3 too.

*abrupt end*

Biology P4: Get Your Pen Ready

First of all, good luck for tomorrow's P6 exam.

Second, let us post more beautiful girls picture (not Reon, Ozawa or Dizon):









Now for the real deal.

Basically the most difficult part in this paper is Part II, which can be surprisingly easy as in our prelim exam. Generally, homeostasis (osmoregulation and blood glucose regulation) is the easiest of all. Why? You mention one condition then you mention the opposite condition then you get a mark or two. Add up the organ and the hormone involved, you get 4 marks. Mention the aftermath, you will get two marks (blood glucose conc. down/water retained). Get it?

The one that gives us a lot of trouble are plant growth regulator (PGH) and our friend Darwin and his theory.

As for PGH, I can't think of any better possible answer other than these:

• Name the hormones and what is the effect
• How does it carry out the effect
• Leaf abscission and apical dominance

Yes, I do realize all of them requires memorizing. So good luck with that. But for some tips, rather than memorizing the steps, try to understand what is really happening. Make a flow chart and try to analyze the function of each hormone.

As for our dearest friend who was stranded in Galapagos Island, my best suggestion is to open wikipedia.org, type his name and just read whatever provided along with the link.

Another good bet is to memorize one type of your preferred sympatric speciation and allopatric speciation. For this reason, I strongly suggest you to read PYP and just take one of the stories. Personally, I find the story about prawn is indeed good.

Another dreaded topic (still from the same guy) is selection and variation. For this two topics, fortunately, the flow answer is always the same. Remember about sickle cell anemia and malaria? Practically, selection and variation question always follow such structure:

• Initially there are two variants (or any number) of phenotype.
• Number of population remain constant/ gene pool remains constant
• Mention about survival of the fittest/competition, depend on question
• Also mention about change in condition or environment
• If they can survive, they will be able to reproduce or the other way round
  
• Those who survive pass on their gene to the next offspring (this phrase never fails to appear in such questions), otherwise they die.
• Such changes happen over time -> result in evolution
• Change in number of gene pool

Those are only guidelines and please do not copy paste above phrases during your exam. Seriously. Above points are only guidelines and may need to be modified when answering question such as artificial selection, importance of variation or roles of human in natural selection.

Personally, I would recommend to take questions regarding ATP production (Kreb's, glycolysis, anaerobic pathway, oxidative phosphorylation), photosynthesis (asking about Calvin Cycle or light-dependent), synaptic transmission, gene technology (recombinant DNA, electrophoresis, PCR, Sanger method) and homeostasis (osmoregulation, blood glucose control). As a general rule, take "how" questions rather than "describe" questions. Think of your answer before you write them. If the questions can be answered in less than 100 words (listing only main points), I say go for it.

Hope this help.



N.B. Above pictures contain one transsexual woman. Do not get infatuated with her unless you accept her whatever she is.

Biology P3 Tips 03

note: I'm using Vika's account since i'm too lazy to make one =_=, for those who failed to guess who am I, I wont tell ^.^

The third one, last but not least.
This post is about the last part of the microscope question, just after the labelled-drawing question, and the things to expect from the practical (just so that we will not be surprised).

Q2: The Drawing Features and Comparisons

So, the last part of the question will give you a picture, and it will ask you to compare and contrast the picture given with the image of a section of the slide. Definitely, absolutely, inevitably, you MUST draw a table. Drawing an appropriate table with correct headings gives you one mark out of a total of five. The second mark is given if you use comparative statements, which means your statements in the table are indicating that you are comparing or contrasting the features on both images (you may want to see the 2008 marking scheme for clarification). That's two marks already. The other three marks are given to correct contents in the table.

That is basically all I can say on this question...

Last Tips and Final Overview Briefing:

These are things I forgot to say, or things that I've just discovered along the way.
In all drawings, you should use more than half the space provided, no matter how large it is, this is just in case that the marking scheme requires you to do so. Oh and by the way, in the new 2008 practical, I think that you will be asked to draw twice, first is the unlabelled drawing, in which you will be asked to draw a section of the image in the slide (you need to draw more than half of the page), and the second one is the labelled drawing (eventhough the question does not ask you to label it, you should, and for this one, the marking scheme does not say anything about drawing for more than half the space, but just in case, if you want to...).

Next, there is also the calibration part. You should all be familliar with the calculations (if not, immediately ask assistance from your teacher or Ms.Yanti, in our current case). In the calibration part, they will tell you to look for a certain part (not necessarily a cell) from the image of the slide, record the value of the divisions blablabla, and simply measure it. Dont forget to write the units, and show a clear working. In the end of the calibration question, they may ask you to identify a source of error in the measurement.

Turn back to question one..

In the experiment question or the test-tube practicals, after the table question, you will be asked do describe and explain on your experiment, which means that you must explain on the theory behind the experiment given. This question worth three marks. After this should be the error and improvements, see my Biology P3 Tips 02 for this. (And I suggest you remember all the 'Common Errors' that I listed)

In the beginning of Graph questions,you will be given a printed table containing the values that you will plot in the graph. Now, some of the values may be obviously missing, this means extra mark for everyone, so don''t fail to notice it. And yet, thankfully, another extra mark follows; there will be a question like: "Explain why that guy discarded the funny value, and repeated the experiment balblalblalbla". Simply answer that the value does not fit the pattern, or the result was an error and it is incorrect, so it is proper to discard and repeat balblabl.

Next is the graph. Plot all the points and use, if possible, all of the space provided. Label the axis properly with correct units. After the graph, there is this funny question that give you a hypothesis/statement. You will be asked to judge whether the hypothesis is supported by the experiment or not, and give a correct hypothesis if the answer is NO. Yes, ladies and gentlemen, this leads to another one of extra mark. Because the question is worth two marks, the answer will obviously be NO. Just say why the experiment does not support that guy's hypothesis and give a new one.

Oh and one or two (usually one) extra pesky question(s) may pop out anywhere in this practical. What I mean by extra pesky question(s) is like those "Suggest why this is like that." These question(s) may give you another extra mark, but that also depends on your knowledge and creativity, of course.

Yay, that's it for my tips and suggestion, I hope it helps. Sorry because I did not put the questions in order. One last thing to say is a quote from Vika's chemistry P3 tips:

"Last but not least doa. Biarpun udah disiapin seperfect mungkin, tapi selalu ada uncertainty. By conducting our experiment accurately and precisely, we should reduce those uncertainty by a great amount. But still, it is always good to have faith."

Woohoo, good luck on your biology practicals. I may be back for P2 and P1 tips (or even A2 biology if Vika forces me to do so (again)).
(Please note that my tips are based on past year papers of 2007 and May/June 2008, so if anything goes mismatch, don't be blame this blog.)

Biology P3 Tips 02

note: I'm using Vika's account (again) since i'm too lazy to make one =_=, for those who failed to guess who am I, I wont tell ^.^

Hey ho, next for the tips.
Did this the day before chemistry practical.
This time I'm going to list a compilation of things to remember about errors and improving-the experiment-questions in biology practicals and just a bit of comments on those labelled drawings and how to draw them.

Q1 part 02:
Error identification and countermeasures
This is it, the valuable list of improvements which I have listed and categorized for the sake of convenience. You can deduce what error they represent by yourself, its pretty obvious.

1. Common Improvements (applicable for almost all kinds of experiment)

• Repeated readings
  
• Keep the temperature constant
• Keep the pH constant
• Same amount of time
• Constant concentration
• Constant volumes of reactants and reagents
  

2. Improvements on tests with serial dilution (like Benedict Dilution and Enzyme Inhibitor test)

• Use colorimeter to identify colour difference more accurately
• Increase range of dilution
• More accurate use of equipments

3. Improvements on potato strip tests

• Thickness and/or width of the strips should be same
  
• Use strips from the same potato
• Weigh the strips
• Increase length of strips

4. Improvements on bubble count experiment

• Measure the volume of the bubbles produced

5. Errors that you cannot improve (haha..), i think you can write these on the sources of error questions.

• Difficult to put enzyme at the same time (in Enzyme Inhibitor serial dilution)
• Inaccurate serial dilution
• Volume of Benedict added is not exactly the same

6. Errors involving measurement of lengths on cells/diagrams etc, that ocassionally pop out on question 2 (these are..real)

• Not viewing the ruler from the right angles / Parallax error
• Thickness of ruler lines affects the reading
• Difficult to focus both ruler and specimen at same time

Well that's basically almost everything I know on errors. Yes, I know and have noticed some unclear or funny things on the list above, like 'Difficult to focus both ruler and specimen at same time' and 'Thickness of ruler lines affects the reading', but these are taken from marking schemes, so its all real. Cambridge sure has its own ways of doing (or marking) things...

Next I'd like to comment on drawing with labels on question 2. On the subject of drawing things that you see on the light microscope, what I've noticed from the marking scheme is that it generally speaks about the drawings should have the right orientation, shape and proportional sizes (like a red blood cell should be smaller than a white blood cell). No shadings or colouring is allowed. Make sure your label lines do not intersect each other. And the lines on your drawing should be clean and continuous (like drawing a smooth plasma membrane). Just a simple and clear drawing is good.

This is all for the second part of the p3 tips. I hope you can benefit from it. Dont panic and try to remember all the things on errors I wrote.. Instead focus on two to three things that you dont know yet or that you find easy to remember, since the questions on errors usually only ask for 2 or 3 points.

Ok then guys, good luck on chemistry and Vika's tips are awesome, hands down.

Biology P3 Basics and Tips 01

(note: I'm using Vika's account since i'm too lazy to make one =_=, for those who failed to guess who am I, I wont tell ^.^)

Finally, a biology section.
Anyways,
Since Vika told me to do biology, and bio p3 is first, so I'd like to share some bio p3 tips.
You can request any clarifications on A Level Biology later, and I or Vika will try our best to answer it.

First, the basics, just for your information.
The practical usually consists of 2 questions. The first one should be some test-tube-practical, and the second one should be microscope-related-practical
Total mark is 40, according to 2009 syllabus it consists of:

• Manipulation, Measurement, and Observation (16 marks or 40% of total mark)
  
• Presentation of Data and Observation (12 marks or 30% of total mark)
• Analysis, Conclusions and Evaluation (12 marks or 30% of total mark)

Well, basically all three is important since their respective marks have the ratio of 40 : 30 : 30 which is well spread. I find the syllabus for the biology practical quite helpful because it simply explains what will happen in the practical. I suggest you take your time to read the practical syllabus. My writings are actually a summary of the syllabus and what I know.

Q1 part 01: The Tedious Test Tube Practicals.

In this practical, the first question will ask you to do certain things with clear set of instructions like put 2cm³ of starch into solution A and then put some inhibitor blablabla, and it will ask you to record your observation in sentences. That is all there is to it, only worth 2 marks.

Ah, the main part. The second question, based on the info given on the first, will tell you to do an experiment and record your observation in a table, you know how it goes. You are given a set of apparatus, but you may or may not use them all. The experiment is repeated with varying sets of values of the factors like time or concentration, and oftenly 3 readings for each value set is enough. Make a neat table to record your observations, label each coloumn, AND DON'T MESS UP THE UNITS ON THE LABEL (and it goes like length/mm or length (mm)). Use pen for your writings.

This is basically manipulation of apparatus, use the apparatus given efficiently and smartly, don't mix up the syringe or beaker, and note that you should read on the meniscus. This question worth 6 marks and should take anywhere from 20-40 minutes depending on the question. DON'T SPEND TOO MUCH TIME IN LEISURE AND COMFORT OR HESITATION, YOU'RE KILLING YOURSELF; RESIST THE TEMPTATION! If the experiment takes a long time you can do the next questions first. Immediately afterwards, they will ask you to draw a conclusion from your results, pretty simple.

Oh before I forget.. I'd like to give some tips on the ultimately-luck-based-ambiguous-colour type test tube practicals, like benedict dilution (i hate this the most, inhibitor comes next on my hate list), use the word 'pale' or 'dark' AND DONT INVENT YOUR OWN COLOUR LIKE PURPLISH GREEN OR PINKISH BLUE, believe me, its written on the syllabus. I'm unsure whether you can use comparison like paler red than at 0.1 mol, but darker than at 0.5 mol. Use precise and simple language for it.

That's it for part one, I wont discuss all aspect of the practical though, i'll just discuss what seems important or tricky to me. Its roughly a week to the actual practical when this is written, expect it to be finished maybe 3 days before the practical. And again, the practical syllabus really helps, just read it.