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 AQA GCSE course but can be modified for other exam boards. 15 slides covering animal and plant cells. By the end of the powerpoint students would have covered: **4.1.1.2 Animal and plant cells ** Students should be able to explain how the main sub-cellular structures, including the nucleus, cell membranes, mitochondria, chloroplasts in plant cells and plasmids in bacterial cells are related to their functions. Most animal cells have the following parts: -a nucleus -cytoplasm -a cell membrane -mitochondria -ribosomes. In addition to the parts found in animal cells, plant cells often have: -chloroplasts -a permanent vacuole filled with cell sap. Plant and algal cells also have a cell wall made of cellulose, which strengthens the cell. Students should be able to use estimations and explain when they should be used to judge the relative size or area of sub-cellular structures.

Designed for the new specification AQA GCSE course but can be modified for other exam boards. 15 slides covering Eukaryotic and prokaryotic cells . By the end of the powerpoint students would have covered: **4.1.1.1 Eukaryotes and prokaryotes ** Plant and animal cells (eukaryotic cells) have a cell membrane, cytoplasm and genetic material enclosed in a nucleus. Bacterial cells (prokaryotic cells) are much smaller in comparison. They have cytoplasm and a cell membrane surrounded by a cell wall. The genetic material is not enclosed in a nucleus. It is a single DNA loop and there may be one or more small rings of DNA called plasmids. Students should be able to demonstrate an understanding of the scale and size of cells and be able to make order of magnitude calculations, including the use of standard form.

Designed for the new specification International A-level edexcel course but can be modified for other exam boards. 21 slides covering Fertilisation in plants By the end of the powerpoint students would have covered: 3.13 know the process of fertilisation in flowering plants, starting with the growth of a pollen tube and ending with the fusion of nuclei. Powerpoint contains exam questions.

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. 29 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.