Archive for February, 2010

Food chains and food webs

Thursday, February 4th, 2010
fox chasing rabbit 0121 by pixpoils on flickr

fox chasing rabbit 0121 by pixpoils on flickr

What is a food chain?  It is a representation of energy flow through an ecosystem.  All food chains begin with a green plant, that traps energy from the Sun. We’ll look at lots of examples, and get to grips with terms such as producer, consumer, carnivore, herbivore, autotroph, heterotroph. 

Food chains have limited use in looking at the big picture in an ecosystem, since there is usually more than one organism feeding on each food source.  For a more realistic view of what happens in nature we need to consider food webs.  A food web is a number of inter-connected food chains.

Check out this brainpop video.

We’ll discuss the idea of interdependence between all the organisms within a food chain, and look at how disease or a change in the environment affects things.

We need to answer this important question:  why are food chains short (only 3 or 4 organisms long)?

We’ll use explorelearning to help us with these concepts.  Log in using the details given in class, type a search for food chains.  Follow the instructions for the food chain, praire ecosystem and forest ecosystem activities.  Enjoy!

And here are a couple more sites to help reinforce these ideas.  This one is from bbc science and this one allows you to explore a number of food webs.

This booklet by Mr Boulton might be useful for review and notes.Booklet to learn about ecology


Tuesday, February 2nd, 2010

Here are some questions we need to answer:

  1. What is the difference between innate and learned behaviour?  How can the process of learning improve the chance of survival?  Give examples.
  2. What is the difference between taxis and kinesis?  Give examples of each.  How could these be investigated in the lab?
  3. What experiments did Pavlov carry out on dogs?  What is the difference between unconditioned and conditioned stimuli?  What is the difference between unconditioned and conditioned response?
  4. What role do genetics and learning play in the development of birdsong in young birds?

This presentation from Mr Taylor in Bandung is excellent, as is click4biology.

And we’ll finish this section by doing a design lab – you need to design an experiment to investigate innate behaviour by either taxis or kinesis.  This will just be a design exercise – we won’t actually carry out the lab. Here are the criteria: Design lab criteria

How we hear

Tuesday, February 2nd, 2010
All ears by banlon1964 on flickr

All ears by banlon1964 on flickr

You need to be able to label a diagram of the human ear using the following labels:

  • pinna
  • eardrum
  • bones of middle ear
  • oval window
  • round window
  • semicircular canals
  • cochlea
  • auditory nerve
  • Eustachian tube

This animation explains how sound waves are detected by the ear and transmitted to the brain.

This site is useful in explaining how we hear.

Think about these questions – why do we have two ears?  What role does the pinna play in other animals? Can fish hear? What range of sounds can the human ear hear? What is a cochlear implant and how does it work?  What does it mean to be tone deaf or have perfect pitch?