Archive for April, 2012

Digestion and absorption – OPTION H

Friday, April 13th, 2012

H2 – digestion.  We’ve done the basics, and because you ask good questions, we’ve gone further, so much of this you will have some idea about already.  You have the background, now we need to fill in the details.  Click here.

  • State that digestive juices are secreted into the alimentary canal by glands, including salivary glands, gastric glands in the stomach wall, the pancreas and the wall of the small intestine.
  • Explain the structural features of exocrine gland cells.
  • Compare the chemical composition of salivagastric juice and pancreatic juice.
  • Outline the control of digestive juice secretion by nerves and hormones, using the example of secretion by gastric juice.
  • Outline the role of membrane-bound enzymes on the surface of epithelial cells in the small intestine in digestion.
  • Outline the reasons for cellulose not being digested in the alimentary canal.
  • Explain why pepsin and trypsin are initially synthesized as inactive precursors and how they are subsequently activated.
  • Discuss the roles of gastric acid and Helicobacter pylori in the development of stomach ulcers and stomach cancers.
  • Explain the problem of lipid digestion in a hydrophilic medium and the role of bile in overcoming this.

B0008462 Ileum section by wellcome images on flickr

H3 – absorption of digested foods.  This is a short section, much of which we’ve covered before.  Click here. You need to be able to:-

  • Draw and label a diagram showing a transverse section of the ileum as seen under a light microscope.
  • Explain the structural features of an epithelial cell of a villus as seen in electron micrographs, including microvilli, mitochondria, pinocytotic vesicles and tight junctions.
  • Explain the mechanisms used by the ileum to absorb and transport food, including facilitated diffusion, active transport and endocytosis.
  • List the materials that are not absorbed and are egested.

Group 4 Project 2012

Friday, April 13th, 2012

Here we go – the much anticipated Group 4 Project is upon us.  Please read the following documents carefully so that you know where you have to be and when.  If you are not sure about this, ASK one of the science teachers.

This shows the groups you will be working in for this assignment.  You are mixed up so that you are together with Biologists, Chemists, Physicists and Environmentalists.  TAKE NOTE of your group and group mates, and which teacher you will be working with, and their ROOM NUMBER.  G4 groupings 2012

This booklet contains all the information and rubrics you need to successfully complete this task.  You will have to submit a written reflection at the end.  This will contribute towards your final IB grade. group IV project booklet 2012

Here is the powerpoint that your teachers used in class to introduce the project. Group 4 Project ppt 2012


Or check out this kinetic sculpture 🙂



Mock exam answer scheme

Sunday, April 8th, 2012

exam tactics by Sean MacEntee on flickr

Here is the mark scheme for your recently completed mock exam paper.

HL Higher Mock March 2012 – marker