Archive for March, 2010

How we hear

Friday, March 26th, 2010
Malayan Flying Fox 2 by littleREDelf on flickr

Malayan Flying Fox 2 by littleREDelf on flickr

Sound waves travel through the air, and we are able to detect them, using our ears.  So, let’s start by looking at a diagram of the human ear, and relate the structure to the function.  You don’t need to be able to draw the diagram, just label it, and know what each part plays in allowing us to hear.  Use this site to learn about ear structure and how we hear. 

Now let’s try and answer these questions:-

  • Why do we have two ears?
  • What is perfect pitch?
  • How do cochlear implants work?
  • How is an owl’s face like a satellite dish?
  • What is ultrasound?  How do we use it?
  • What is echo-location?  Bats and dolphins use it all the time. Can humans learn to as well?

Thanks to Mr Boulton for finding these resources.

Earthquake in Manila!

Thursday, March 25th, 2010
location of earthquake from USGS

location of earthquake from USGS

As if we arranged the whole thing… following on from this week’s discussion about earthquakes, seismic waves, epicenters, S and P waves…did you feel it

Could you explain to your parents (assuming they are not seismologists) what happened to cause today’s quake?  Could you explain it to someone in Grade 1?

Was there a tsunami warning after this earthquake?  Why or why not?

Waves on the Earth

Thursday, March 25th, 2010
Tsunami Hazard Zone by hey mr glen on flickr

Tsunami Hazard Zone by hey mr glen on flickr

These are some of the questions we should be able to answer after some research.  Check out these videos that explain a bit about earthquakes.  This one relates sound waves to earthquakes.  This one relates transverse and longitudinal waves to earthquakes. 

  • How are water waves formed?
  • Why are earthquakes so damaging?
  • How are tsunamis created?
  • Why do some indigenous tribes place their ears to the ground to hear if someone is approaching?

Functions of the liver

Thursday, March 25th, 2010
BIO 120 Liver 010 by djneight on flickr

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.

Hormonal control

Thursday, March 25th, 2010

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

Waves questions

Wednesday, March 17th, 2010

The distance between repeating parts of the pattern (the length of each single wave) is known as the wavelength (l).  Wavelengths can be measured from anywhere to the next identical part of the wave.

Frequency is a measure of how often something happens in one second. The symbol of frequency is f and the units are hertz (Hz). The relationship between velocity, frequency and wavelength is:

 Velocity (m/s) = frequency (Hz) x wavelength (m)

Light waves travel much faster than sound waves. The speed of a set of waves can be found by using information about the distance travelled and time taken or from information about the frequency and wavelength.

Distance, speed and time are connected by:

Speed (m/s)   =   Distance (m) / time (s)

Example An echo takes 1.5 s to reflect from the front wall of a school building 250m away. What is the speed of sound in air?

Distance for echo = 2 x 250 m = 500 m                                Time taken   = 1.5 s

Speed = distance/time = 500/1.5 = 333m/s

This method is practical at school only for the measurement of the speed of sound.

Example Capital Radio broadcasts throughout the London area using radio waves of frequency 1548kHz, travelling at 300000km/s. To what wavelength would you tune a radio to receive Capital programmes?

Speed   = 300000km/s = 300000000m/s                  Frequency = 1548 kHz (1 548 000 Hz)

Wavelength = speed/frequency  = 300 000 000/1 548 000 = 194 m 

Using your knowledge of the wave equation, and the relationship between frequency and time [f = 1/T], answer the following questions:-

  1. If the waves in the ocean are timed so that they come to shore every 1.74 seconds, what is the frequency of these waves? (Show your working and don’t forget units).
  2. A radio wave has a frequency of 2 MHz (2 MegaHertz = 2 000 000 Hz). Calculate the time period between successive waves.
  3. A radio station broadcasts with a wavelength of 160m. If the velocity of the radio signal is 3 x 108 m/s, calculate the frequency of the wave. 
  4. If all the 1.2 billion people in China jump up and down at the same time, they will create a shock wave that will travel around the Earth in all directions.  This wave will focus and peak on the other side of the Earth, exactly opposite China (around California).  If the circumference of the Earth is 40 000km and the speed of sound on the Earth’s surface is 2850m/s, calculate how long it will take for California to crumble into the sea due to the shock wave.

Grade 9 Integrated Science 1 docwaves practice questions mark scheme

What are waves?

Tuesday, March 16th, 2010
green sine by bdu on flickr

green sine by bdu on flickr

New topic – yay!  We’ll learn about waves.  Here are some of the points we’ll try and answer:-

  • What is a wave?
  • What is the difference between transverse and longitudinal waves?
  • What are some examples of transverse and longitudinal waves?
  • What are the amplitude, frequency and wavelength of a wave?

Anatomy of Waves

We’ll then take a look at the wave equation       v = f λ

This shows us the relationship between speed of a wave v, the time it takes for a particle to vibrate up and down, and the distance between successive waves λ.  You’ll need your calculators as we practice solving problems in class.

Syllabus guides

Tuesday, March 9th, 2010
ghosts of semesters passed by foreverdigital on flickr

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.

Optical illusions

Wednesday, March 3rd, 2010

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!