Designed for the new specification IGCSE Edexcel course but can be used for other examination boards. Covers: © Cycles within ecosystems 4.10 describe the stages in the carbon cycle, including respiration, photosynthesis, decomposition and combustion 4.11B describe the stages in the nitrogen cycle, including the roles of nitrogen fixing bacteria, decomposers, nitrifying bacteria and denitrifying bacteria (specific names of bacteria are not required)

Designed for the new specification AQA GCSE course but can be modified for other exam boards. 12 slides covering Active transport . By the end of the powerpoint students would have covered: Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). This requires energy from respiration. Active transport allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil. Plants require ions for healthy growth. It also allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration. Sugar molecules are used for cell respiration. Students should be able to: describe how substances are transported into and out of cells by diffusion, osmosis and active transport explain the differences between the three processes.

Designed for the new specification AQA GCSE course but can be modified for other exam boards. 32 slides covering Diffusion. (contains a optional practical) By the end of the powerpoint students would have covered: Substances may move into and out of cells across the cell membranes via diffusion. Diffusion is the spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration. Some of the substances transported in and out of cells by diffusion are oxygen and carbon dioxide in gas exchange, and of the waste product urea from cells into the blood plasma for excretion in the kidney. Students should be able to explain how different factors affect the rate of diffusion. Factors which affect the rate of diffusion are: the difference in concentrations (concentration gradient) the temperature the surface area of the membrane. A single-celled organism has a relatively large surface area to volume ratio. This allows sufficient transport of molecules into and out of the cell to meet the needs of the organism. Students should be able to calculate and compare surface area to volume ratios. Students should be able to explain the need for exchange surfaces and a transport system in multicellular organisms in terms of surface area to volume ratio. Students should be able to explain how the small intestine and lungs in mammals, gills in fish, and the roots and leaves in plants, are adapted for exchanging materials. In multicellular organisms, surfaces and organ systems are specialised for exchanging materials. This is to allow sufficient molecules tobe transported into and out of cells for the organism’s needs. The effectiveness of an exchange surface is increased by: having a large surface area a membrane that is thin, to provide a short diffusion path (in animals) having an efficient blood supply (in animals, for gaseous exchange) being ventilated.

Designed for the new specification International A-level edexcel course but can be modified for other exam boards. 35 slides coveringThe Structure of Neurones By the end of the powerpoint students would have covered: 8.1 know the structure and function of sensory, relay and motor neurones, including Schwann cells and myelination Powerpoint contains exam questions.

Designed for the new specification International A-level edexcel course but can be modified for other exam boards. 17 slides coveringThe Structure of Neurones By the end of the powerpoint students would have covered: 8.5 understand the role of myelination in saltatory conduction. Powerpoint contains exam questions.

Designed for the new specification International A-level edexcel course but can be modified for other exam boards. 26 slides coveringThe Structure of Neurones By the end of the powerpoint students would have covered: 8.6 (i) know the structure and function of synapses in nerve impulse transmission, including the role of neurotransmitters and acetylcholine. Powerpoint contains exam questions.

Designed for the new specification International A-level edexcel course but can be modified for other exam boards. 22 slides covering Lipids By the end of the powerpoint students would have covered: State the importance of lipids. Describe the structure of Triglycerides. Describe the differences between saturated and unsaturated fatty acids. Includes two practical/demo activities

Designed for the new specification International A-level edexcel course but can be modified for other exam boards. 34 slides coveringThe Structure of Neurones By the end of the powerpoint students would have covered: 8.4 understand how a nerve impulse (action potential) is conducted along an axon, including changes in membrane permeability to sodium and potassium ions Powerpoint contains exam questions.