B2 Blue light sensing in plants
Link to a web site which explains why plants bend towards blue light.
A nice introduction to the carbon cycle
00.00 Carbon in the ecosystem
This section begins by introducing the element carbon as a finite resource. Carbon is present in the atmosphere, living things and soil.
00.38 Uptake of CO2 from the atmosphere
Radioactive carbon dioxide is used to measure and trace the uptake of CO2. The equation for photosynthesis is given with 14C.
02.23 The return of CO2 to the atmosphere
Carbon passes into animals in food, and is returned to the air through respiration. The change in CO2 level in air is shown with bicarbonate indicator, demonstrating that living things give off this gas.
Nutrients including carbon return to the soil during the breakdown of dead remains by decay organisms. Carbon is also returned to the air when fossil fuels are burned.
00.00 Introduction to photosynthesis
Photosynthesis is responsible for growth in plants. The raw materials are carbon dioxide and water, and light is the energy source transformed by chlorophyll. The products are glucose and oxygen. The rate of photosynthesis can be maximised in a greenhouse by using artificial light and supplying carbon dioxide.
01.25 How does light intensity affect the rate of photosynthesis?
The amount of CO2 used (measured by a gas analyser) indicates the rate of photosynthesis. If the light intensity increases, so does the uptake of CO2 and the rate of photosynthesis.
03.31 How does the supply of carbon dioxide affect the rate of photosynthesis?
This sequence starts with a demonstration of pondweed photosynthesising in water. The amount of oxygen produced (measured in capillary tubing) indicates the rate of photosynthesis. Next a solution of sodium hydrogen carbonate is used to supply CO2. As the supply of CO2 increases so do the production of O2 and the rate of photosynthesis. Data are displayed.
An overview of photosynthesis for A level
Plant growth under coloured lights
Photographs of experiments (designed by students) to look at the effect of light colour on the angle of plant growth. Data from these experiments.
Transport and support in plants
An overview of the main transport and support structures in plants
Xylem and Phloem
The structure and function of the xylem and phloem