Thinking Allowed

exam cartoons by Robin Hutton on flickr

So you have all the infomation you need to succeed in the upcoming exams.  Make sure you also know the command terms used by the IB. 

It is no good knowing the syllabus inside out, but then answering an explain question by describing, or a distinguish question by comparing. 

Check out this very helpful presentation by Mr Taylor in Bandung that clarifies these action verbs.  It is an important part of your revision.

And for HL candidates, here’s the syllabus outline for Option H. Option H syllabus guide

You need to get your head around this.  Gas Exchange     The effect of exercise on heart and lungs    And here’s a great presentation to help.

• Define partial pressure.
• Explain the oxygen dissociation curves of adult hemoglobin, fetal hemoglobin and myoglobin.
• Describe how carbon dioxide is carried by the blood. [Include action of carbonic anhydrase, chloride shift, and plasma proteins]
• Explain the role of the Bohr shift in the supply of oxygen to respiring tissues.
• Explain how and why ventilation rate varies with exercise.
• Outline the possible causes of asthma and its effects on the gas exchange system.
• Explain the problem of gas exchange at high altitudes and the way the body acclimatizes.

Cardiac_cycle_pressure_only from wikimedia

Take another look at your notes on blood, blood vessels and the heart from topic 6.  Re-learn your heart diagram.  There is some new vocab to get your head around in this section.  I have highlighted these terms below.  Use this presentation to help you.

• Explain the events of the cardiac cycle. [Talk about atrial and ventricular systole and diastole, and heart sounds]
• Analyse data showing pressure and volume changes in the left atrium, left ventricle and aorta during the cardiac cycle.
• Outline the mechanisms that control heartbeat. [Include role of sinoatrial (SA) node, atrioventricular (AV) node and conducting fibres in the ventricular walls]
• Outline atherosclerosis and the causes of coronary thrombosis.
• Discuss factors that affect the incidence of CHD (coronary heart disease).

Ileum (3) by GreenFlames09 on flickr

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 saliva, gastric 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.

 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.

BIO 120 Liver 010 by djneight on flickr

Here are a couple of presentations for you. Functions of the liver  and this one.  You should be able to:

• Outline the circulation of blood through liver tissue, including the hepatic artery, hepatic portal vein, sinusoids and hepatic vein.
• Explain the role of the liver in regulating levels of nutrients in the blood.
• Outline the role of the liver in the storage of nutrients, including carbohydrate, iron, vitamin A and vitamin D.
• State that the liver synthesizes plasma proteins and cholesterol.
• State that the liver has role in detoxification.
• Describe the process of erythrocyte and hemoglobin breakdown in the liver, including phagocytosis, digestion of globin and bile pigment formation.
• Explain the liver damage caused by excessive alcohol consumption.

As we delve into Option H, we’ll be reviewing human biology concepts at the same time.  This first section is about hormonal control.  Hormones are chemical messengers secreted by endocrine glands into the blood and transported to specific target cells.  They can be steroids (eg progesterone, testosterone, estrogen), proteins (eg insulin, ADH, FSH, LH) and tyrosine derivatives (eg thyroxin).

You need to:-

• Distinguish between the mode of action of steroid and protein hormones.
• Outline the relationship between the hypothalamus and the pituitary gland.
• Explain the control of ADH (vasopressin) secretion by negative feedback.

Another fantastic presentation here.  We’ll use this one too. Hormonal Control

ghosts of semesters passed by foreverdigital on flickr

Here are the syllabus guides for the core (SL) and HL topics for the entire IB Bio course.  The syllabus guides for the options we have studied are in previous posts.

For SL – you need TOPICS 1, 2, 3, 4, 5 and 6 only.

For HL – you need all the above PLUS TOPICS 7, 8, 9, 10 and 11.

Topic 1 – Statistical Analysis 2009 Syllabus   Topic 2 – syllabus outline  Topic 3,7,8 – syllabus outline   Topic 4 – Syllabus outline  Topic 5 – syllabus guide  Topic 6 – syllabus outline  Topic 9 – Syllabus outline  IB Biology HL Topic 10 – syllabus guide  Topic 11 – syllabus guide

Before you know it, mocks will be over, then Easter break, then in a few short weeks it will be May and you’ll start the REAL IB exams… and then graduation and tears of joy and sadness and a new chapter will begin…. One step at a time.  Keep studying.  It will end.

Check out lottolab.  Watch the TED video and then play around the site.  There are loads of optical illusions to keep you entertained.

And now get back to your mock revision….Friday 19th March is looming!

peacock by vigilant20 on flickr

Here’s what we need to cover in this last section of Option E.

1. Honey bees are social organisms.  Describe the organization of a bee colony – who does what.  Find one other example of such social organization and describe it. #1 2 Social Organisms
2. What is the role of natural selection in colonies like this?
3. Give 2 non-human examples of altruistic behaviour and discuss in terms of evolution.  Altruistic Behavior in animals
4. What is foraging?  Bluegill fish forage for Daphnia.  Find one other example, and explain how this type of behaviour optimizes food intake. E6 notes #3 4
5. Peacocks have pretty fancy tail feathers.  Why have they evolved this way? Explain in terms of mate selection. #5 animal behavior   Peacocks #5
6. Animals show rhythmical variations in activity.  Outline 2 examples illustrating this.  Eg, seasonal reproductive behaviour in deer. Rythmical Variations

Here’s a very useful slideshare presentation on this section.

fMRI by nats on flickr

This next section, E5, is all about the human brain, brain function, fMRI, sympathetic and parasympathetic nervous systems, pupil reflex, brain death, and the perception of pain.  Phew!  That’s a lot of concepts. 

We’ll again use click4biology as a good resource, and this presentation from Mr Taylor in Bandung to help us get through it all.  Here are the key questions we need to answer:

• What are the major parts of the human brain, and what are their functions?
• How do animal experiments, lesions and fMRI scanning used in identifying which part of the brain is involved with specific functions?
• How are heart rate, movements of the iris, and blood flow to the gut controlled by the sympathetic and parasympathetic nervous systems?
• What is the pupil reflex and how is it used to determine brain death?
• How is pain perceived and how to endorphins help to alleviate it?

This is also a very useful set of notes, courtesy of Mr Hobbins. Topic E5 The Brain