Available online
Description
The programme is largely concerned wioh the home experiment associated with the ecosystem module (i.e. the inter action of populations of the alga chlorella and the water flea daphnia). The wiring-...up of the home kit analogue computer is explained and the mathematical equations which model the home experiment "system" are derived. A larger and more sophisticated analogue computer, equipped with multiplyers, is used to explore the effect of varying parameter values.
The programme is largely concerned wioh the home experiment associated with the ecosystem module (i.e. the inter action of populations of the alga chlorella and the water flea daphnia). The wiring-...up of the home kit analogue computer is explained and the mathematical equations which model the home experiment "system" are derived. A larger and more sophisticated analogue computer, equipped with multiplyers, is used to explore the effect of varying parameter values.
| Module code and title: | T241, Systems behaviour |
|---|---|
| Item code: | T241; 11 |
| First transmission date: | 03-06-1973 |
| Published: | 1973 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:23:08 |
| + Show more... | |
| Producer: | John Groom |
| Contributors: | Richard Morris; Ray Wilson |
| Publisher: | BBC Open University |
| Keyword(s): | Computer management; Daphnia; Ecosystems |
| Footage description: | Still shot of a field of brussel sprouts. Still shot of individual sprout plant. Still shot of the caterpillar of the cabbage white butterfly attacking a brussel sprout plant. Still shot of tractor spraying crops with insecticide. Still shot of caterpillar damaged sprout plant and a healthy one which was treated with DDT. Diagram of a simplified eco-system showing a sprout autotroph and two heterotrophs (man and caterpillar). Still shot of a caterpillar eating a ground beetle. The ground beetle is added to the ecosystem diagram. Commentary explains why spraying crops with insecticides can have a more adverse effect in the long term than not spraying at all. R. Morris explains why models of eco-systems must be extremely accurate if they are to be of any use. He discusses ways in which this accuracy might be achieved but points out that it can only be done at present with very simple eco-systems such as the Daphnia-Chlorella system. Morris explains the components of the eco system which students have been sent and which they can use to model some aspects of the Daphnia-Chlorella ecosystem. Shot of Daphnia feeding on Chlorella. Shot of young hatching from Daphnia. Morris explains that an eco-system such as the one lor Daphnia-Chlorella can be modelled by the use of differential equations rather than by experimenting on the organisms themselves. Graph shows the exponential growth of Chlorella population with no predator other factors limiting growth. Morris gives the algebraic expression of the curve. This linear differential eqution shows the growth of chlorella populations and allows prediction of chlorella population size over any period of time. Morris with an analogue computer which can simulate rate of growth of chlorella population. He wires the computer to solve the equation and relates each step of the wiring to the equation. The growth rate is simulated on the computer's volt meter and then on an oscilloscope screen. Morris explains the shading effect as chlorella population grows and its effect on population size. The equation for this is shown on the screen. Morris discusses growth rate for a Daphnia population and arrives at a linear differential equation for it. This equation shows the death rate factor without consideration of crowding effect. Morris modifies the equation to take crowding into account. Morris adds birth rate variable for Daphnia to equation. The equation now shows how a Daphnia population grows in the presence of Dhlorella. Morris next builds an equation which shows how chlorella grows in the presence Daphnia. With these two equations a complete model of the Daphnia/Chlorella eco-system has been developed on which computer simulations can be carried out. R.A.Wilson uses these equations to simulate the eco-system on an analogue computer. An oscilloscope wired to the computer shows: 1. Chlorella growth in absence of daphnia 2. Chlorella growth with daphnia introduced 3. Curve for both populations. Wilson shows and explains how the simulation variables can be changed on the computer. Morris sums up with a discussion on sensible methods of pest control brought about by accurate simulation of the eco-system. He then asks students to carry out an eco-system experiment at home so that the results can be compared with predictions made by a computer simulations. |
| Master spool number: | 6HT/70938 |
| Production number: | FOUT0938 |
| Videofinder number: | 2716 |
| Available to public: | no |
