Monday, November 1, 2010

6BI01 Introduction and Water!


The 6BI01 unit, like all other main units, it worth 120 UMS points. The raw score, like all other main units, is 80 marks. Units 3(B) and 6(B) are worth 60 UMS. Unit 3B's raw score is 40 and 6B's is 50.

In AS, 6BI01 is worth 40% of the total grade earned! In the full A Level, this unit is worth 20%. So, it it clear that this unit is heavily weighted in the AS year so you should try you best to perform well. This is a fairly simple and straightforward unit. If you learn the concepts and familiarise yourself with previous questions and how they are answered you should earn yourself a nice, solid A. I scored 101/120 in this unit, but I had the potential to score 120/120. I underestimated the time factor and omitted lots of raw marks because time ran out. I knew the answers to to the questions I left out! I sat this unit in June 2009 and the time for this paper was 1 hour 15 minutes. The examiners realised that we were pressed for time so they increase the time for this paper to 1 hour 30 minutes. The raw marks remain unchanged.


This unit is called Lifestyle, Transport, Genes and Health. You will study important biological molecules, enzymes, cell membranes, transport, the cardiovascular system, protein synthesis and genetics. You will be asked to objective, short answer and extended response questions. You will have to pay attention to the quality of your written response in some questions. You can be asked to interpret and analyse graphs, draw and label diagrams and fill-in-the-blanks in paragraphs or tables. There's a systematic approach to answering these types of questions and I will cover them as I post content for this unit. Practical-based questions ALWAYS show up and so this is where your core practicals will be important. You may be asked to write out the entire method for a core practical or a practical similar to one you are required to know.

The list of core practicals that you will need to know for this unit:

1.Describe how the effect of caffeine on heart rate in Daphnia can be investigated practically, and discuss whether there are ethical issues in the use of invertebrates.

2.Describe how to investigate the vitamin C content of food and drink.

3.Describe how membrane structure can be investigated practically, eg by the effect of alcohol concentration or temperature on membrane permeability.

4.Describe how enzyme concentrations can affect the rates of reactions and how this can be investigated practically by measuring the initial rate of reaction.

You may want to take a look at this online resource for the core practicals. Keep in mind that I will be posting specific content for the core practicals on this website anyway.

6BI01 kicks off with water!

The importance of water as a solvent in transport, including its dipole nature.
Because it is charged, water is a very good solvent. Charged or polar molecules such as salts, sugars and amino acids dissolve readily in water and so are called hydrophilic ("water loving"). Uncharged or non-polar molecules such as lipids do not dissolve so well in water and are called hydrophobic ("water hating"). Because of water's dipole nature (and so, it's ability to dissolve a wide variety of substances), it is a very important biological solvent. Salts, sugars and amino acids can be dissolved in water and transported in blood around the body. Most of the body's cellular reactions take place in aqueous environments and a solvent (water) is needed to dissolve the reactants so that they can react. Because water molecules can hydrogen bond, they are very cohesive (water can flow). This cohesiveness makes water a good transport solvent.

To get a better understanding of how water's structure contributes to its function, you should do a bit more research on the internet and in your textbook and/or revision guide. Be sure to revise what hydrogen bonds are (with respect to water) and how they form. Here are a few websites which I used:
>http://www.worldofmolecules.com/solvents/water.htm Just read the part about water's dipole nature and it's ability to act as a sovlent

BEWARE: You are NOT required to know about any other functions of water other than it's solvent abilities. You can learn other uses of water if you want, but you will not be tested on anything else other than water's importance as a solvent in transport.

>Here are a few questions that you should be able to answer:
+Water is the universal ________ in living organisms. [solvent]
+Why is water an important solvent in living organisms? [Because most biochemical reactions take place in aqueous solution]
+What is the chemical formula of water? [H20] *You should be able to draw the basic chemical structure of water and identify the partial charge on the atoms found in water.
+Why are water molecules described as polar? [Because they have a slight positive charge at one end of the molecule and a slight negative charge at the other end]
+Why can water molecules form hydrogen bonds with each other? [same answer as above]

Pretty simple beginning!


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