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Intermediate 2 Biology

Intermediate 2 Biology. Course Revision Notes. Living Cells. Unit 1 Revision. What’s in Unit 1. Cell Biology: Cells Diffusion and Osmosis Enzymes Respiration Photosynthesis. Animal Cells. What you need to know: Parts of an animal cell (name and function) Why do we stain cells?.

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Intermediate 2 Biology

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  1. Intermediate 2 Biology Course Revision Notes

  2. Living Cells Unit 1 Revision

  3. What’s in Unit 1 • Cell Biology: • Cells • Diffusion and Osmosis • Enzymes • Respiration • Photosynthesis

  4. Animal Cells • What you need to know: • Parts of an animal cell (name and function) • Why do we stain cells?

  5. Plant Cells • What you need to know: • Parts of a plant cell (name and function) • What do we use to stain cells?

  6. Uses of Cells • Yeast: • Single celled fungus • Used to make beer, bread, wine by fermentation • Glucose Alcohol + Carbon Dioxide

  7. Uses of Cells • Bacteria: • Single celled • Used to make yoghurt • Lactose Lactic Acid • Antibiotics • Antibacterial chemicals • Made from fungi to kill bacteria

  8. Diffusion • The movement of molecules from an area of high concentration to an area of low concentration until they are evenly spread

  9. Diffusion • Movement of substances • Carbon Dioxide moves __________ cells • Oxygen moves ________ cells • Food (glucose) moves ___________ cells

  10. Osmosis • The movement of water from a region of high water concentration to a region of low water concentration through a selectively permeable membrane Water Sugar Low Water Concentration High Water Concentration

  11. Osmosis and Cells

  12. Diffusion and Osmosis • Diffusion and osmosis occur: • Down a concentration gradient • Through a semi permeable membrane

  13. Enzymes • Properties of an enzyme: • Speed up chemical reactions • Remain unchanged • Lower the activation/input energy • Other enzymes facts: • Made of protein • Are specific to one substrate

  14. Enzymes • Types of enzyme • Amylase (SAM) • Catalase (HPCOW) • Phosphorylase (G1PPS) • Lipase (FLAG) • Pepsin (PPP/PPAA)

  15. Enzymes • Affect of temperature and pH: • If above 50°C enzymes are denatured • Optimum temperature is about 37°C • They work in a narrow pH range • Each enzyme has its own optimum pH

  16. Respiration • A chemical process in which energy is released from food molecules in cells • There is energy in all food • Fats - contain the most • Carbohydrate - most commonly used • Protein – only broken down after long periods of starvation

  17. ATP • Adenosine Triphosphate • Stores energy • Made from ADP + Pi with energy • Energy stored in the 3rd bond ADENOSINE Pi Pi Pi

  18. ATP

  19. Aerobic Respiration • With oxygen • Produces 38 ATP (in total) • Controlled by enzymes • 2 Stages • Glycolysis • Breakdown of pyruvic acid • Glucose + Oxygen Water + CO2

  20. Aerobic Respiration • Stage 1: Glycolysis • Breakdown of glucose into pyruvic acid • 2 ATP formed • Doesn’t require oxygen • Stage 2 • Breakdown of pyruvic acid into water and carbon dioxide • 36 ATP formed • Requires oxygen

  21. Anaerobic Respiration • Without oxygen • Produces 2 ATP (in total) • Different final product in animals and plants • Animals • Glucose Lactic Acid • Plants and Yeast • Glucose Ethanol + Carbon Dioxide

  22. Anaerobic Respiration • Glycolysis occurs as before • Stage 2: • In animals Pyruvic Acid is converted to Lactic Acid which causes muscle fatigue. This is reversible • In plants and yeast Pyruvic Acid is broken down into Ethanol and Carbon Dioxide. This is irreversible because carbon dioxide is released

  23. Photosynthesis • Green plants photosynthesise and are known as producers • 2 Stages • Photolysis • Carbon Fixation • They make carbohydrate (glucose) • Water + CO2 Glucose + Oxygen Light + Chlorophyll

  24. Photosynthesis • What is needed • Carbon Dioxide (carbon dioxide concentration) • Water • Light (light intensity) • Chlorophyll • Suitable Temperature • The ones in blue are raw materials

  25. Stages • Stage 1: Photolysis • Light splits water into hydrogen and oxygen • Hydrogen is used in stage 2 • Oxygen is released as a by-product • 1 ATP made (which is used in stage 2) • Stage 2: Carbon Fixation • The hydrogen (from stage 1) is joined with carbon dioxide using the ATP (from stage 1) • Glucose is formed • Controlled by enzymes

  26. What Happens Next • Once the glucose has been made the following can happen: • Used straight away for respiration • Stored as starch • Made into cellulose for cell walls

  27. Limiting Factors • Anything that when in short supply reduces or limits the rate of photosynthesis • There are 3 limiting factors: • Carbon Dioxide Concentration • Light Intensity • Temperature

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