Archive for January, 2010

Vitamin D, iodine and fibre

Monday, January 11th, 2010
Tikar lady with Goitre by superdove on flickr

Tikar lady with Goitre by superdove on flickr

Three of the nutrients that we need to consume in order to maintain a healthy balanced diet are vitamins, minerals and fibre.  We’ll look at one example of a vitamin (D), one example of a mineral (iodine) and then fibre, and aim to answer the following questions:

  • What are the sources of vitamin D in human diets?
  • What are the risks of vitamin D deficiency from insufficient exposure to sunlight vs the risk of contracting malignant melanoma (skin cancer)?
  • What are the benefits of taking dietary supplements to prevent malnutrition? Use iodine as an example.
  • What is the importance of fibre as a component of a balanced diet?

To get you started, here is a short video clip dealing with vitamin D.  I’ll let you research the others yourselves 🙂

Enjoy and learn!

The kidney

Monday, January 11th, 2010
kidney by kidneynotes on flickr

kidney by kidneynotes on flickr

OK – this is the last section of the syllabus before we begin our options.  Here are some of the key points we’ll learn:

  • What is excretion? (And what isn’t)
  • How to draw and label a diagram of the kidney.  We’ll dissect one too.
  • What a nephron is, how to annotate a diagram of one to help explain the processes of ultrafiltration and reabsorption.
  • What is osmoregulation, and what role do hormones play in it?
  • What are the differences between concentrations of various components in blood and urine, and the reasons for those differences.

We’ll again use this wonderful presentation from Mr S Taylor as well as our textbooks.  In addition, once we’ve completed this topic, you could watch this video.  It’s a little complicated, so I wouldn’t recommend watching it at the start, but after we’ve covered some of the theory.

Another useful review powerpoint from Mr Hobbins: 11.3 The Kidney


How much Vitamin C does fruit contain?

Thursday, January 7th, 2010
blood orange by Derek Purdy on flickr

blood orange by Derek Purdy on flickr

For this lab you are going to test a range of fruits (lemon, orange, mango, tomato) and determine their vitamin C content.  Here’s how:

Vitamin C is an antioxidant.  It changes DCPIP (a dye) from blue to colourless. 

  1. Use a pipette to add some of the vitamin C solution, drop by drop to 2cm3 of DCPIP in a test tube.
  2. Shake the tube gently after the addition of each drop.
  3. Continue until the solution is decolourised.
  4. Record the exact volume of vitamin C added.  Repeat and average results.
  5. Calculate the mass of vitamin C required to decolourise 2cm3 of DCPIP, knowing that the vitamin C solution was made to contain 1mg of vitamin C in 1.0cm3 of water.
  6. Using a similar technique, compare the vitamin C contents of several different fruits.
  7. To determine the volume of the fruit, place it in a beaker and cover with water.
  8. Mark the level of the meniscus on the outside of the beaker.
  9. Remove the fruit, make the water up to the mark with water from a measuring cylinder.  The volume of water added is equivalent to the volume of the fruit.

This comes from Practical Advanced Biology by King, Reiss and Roberts.

When you write up your lab report, include the data collected and the processing of it, though I will not award this a separate grade (as I have told you how to do it).  State your conclusions and write a detailed evaluation.  I will grade this according to the IB rubric. Conclusion and evaluation rubric

Here are a some questions for consideration:

  • Vitamin C is derived from a 6-carbon sugar.  Suggest why it is so abundant in fruits and what functions it may serve.
  • A typical adult requires about 10mg of vitamin C per day, though governments recommend between 30 and 60 mg.  To what extent can these needs be met by a single piece of fruit?
  • Can you find out what effect storing or cooking has on the vitamin C content of foods?

Due date for this is Tuesday 19th January 🙂 If you would like me to take a look at your draft then get it to me by 7.30am Monday, the day before.

Specific heat capacity

Thursday, January 7th, 2010
light the match by bikini sleepshirt on flickr

light the match by bikini sleepshirt on flickr

We’ll be looking at heat energy a little more closely and understanding it’s relationship to temperature.  This will lead us on to something called specific heat capacity.  What on earth is that?  Check out this presentation by Mr Hobbins: Specific Heat Capacity

Here is the worksheet we’ll go over in class: Specific heat Capacity questions

We’ll also be doing a lab where we compare different fuels to see which is more efficient.  Different groups will test different fuels, and then pool the data into the following spreadsheet. Comparison of fuels table and graph template

9H Dickinson Copy of Comparison of fuels table and graph template

9D Dickinson Copy of Comparison of fuels table and graph template

Block A Data FUELS heat capacity LAB

Block D Data FUELS heat capacity LAB

For homework you will be required to print out a copy of the table and graph, and then write up your conclusion.  You should also highlight sources of error in the experiment and suggest sensible improvements or alternatives.  This will be due on Friday 15th January.

Options, Options

Monday, January 4th, 2010
Guide to a healthy balanced diet by Leo Reynolds on flickr

Guide to a healthy balanced diet by Leo Reynolds on flickr

So, no we begin the last part of the course, that is the option section.  We’ll start with OPTION A – Human nutrition and health.  I think you will find this a relatively easy option, hopefully interesting, and certainly relevant.  To get started, here is a copy of the syllabus guide. Option A – syllabus outline

More reproduction

Monday, January 4th, 2010
Sertoli cells from google images

Sertoli cells from google images

We covered the basics last semester – now on to the detailed HL stuff to do with reproduction.  Check out this presentation, which has good information and some great links to explore.

We’ll start by reviewing the stucture of egg and sperm. then look at how they are produced.  You can read up on the processes of spermatogenesis and oogenesis in your textbooks on pages 265/6.  We’ll take a more detailed look at the process of fertilization, pregnancy and childbirth.

You can also use this powerpoint from Mr Hobbins 🙂 Reproduction Higher

What is energy?

Monday, January 4th, 2010
Energies by DanielaNob on flickr

Energies by DanielaNob on flickr

This isn’t a very easy question to answer, actually, but we’ll give it a go over the next few lessons.

There is an important distinction between TYPES of energy and SOURCES of energy.  Heat is a type of energy.  The Sun is a source of energy. Electricity is a type of energy.  Oil is a source of energy.  Make sure you are clear on the difference.

We will look at conservation of energy – the idea that energy cannot be created or destroyed, but simply transferred from one form to another.  We will do a number of experiments that illustrate this.

Log on to then science, energy, and you will find a ton of animations to get you going.

Here is a nice powerpoint from Mr Hobbins as well: Introduction to Energy