OCR 21st Century Science - Biology B456
- Created by: gera279
- Created on: 05-06-16 17:56
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B4 - The Processes of Life
- Cell structure and function
- Animal cell
- Nucleus - contains DNA, the instructions for proteins
- Cytoplasm - gel substance where proteins like enzymes are made, anaerobic respiration occurs here
- Cell membrane - holds cell together and controls what goes in and out
- Mitochondria - enzymes needed for aerobic respiration found here
- Plant cells
- Rigid cell wall - made of cellulose, supports and strengthens cell
- Vacuole - contains cell sap, weak solution of sugar and salts
- Chloroplasts - contain chlorophyll, place where photosynthesis occurs
- Yeast - single cell microorganisms; nucles, cytoplasm, mitochondria, membrane, cell wall
- Bacteria - no nucleus or mitochondria; cell membrane + wall, cytoplasm, circular DNA
- Animal cell
- Enzymes
- Proteins that speed up chemical reactions
- Have an 'active site' where the substrate (molecule changed) attaches to
- At too high temp, bonds in the enzyme break, changing the shape of the active site
- pH can also denature enzymes and prevent them from working
- Aerobic respiration
- A series of chemical reactions that release energy by breaking down food molecules
- This energy is used for movement, active transport + synthesis of large molecules
- Aerobic respiration needs oxygen, releases more energy than anaerobic
- C6H12H6 + 6O2 --> 6C02 + 6H2O + energy released
- Anaerobic respiration
- Respiration without oxygen
- Happens in humans during vigorous excercise; plants when roots become waterlogged
- Glucose --> Lactic acid + energy released (animal cells/some bacteria)
- Glucose --> Ethanol + carbon dioxide + energy released (plant cells/yeast)
- Fermenting plant and animal waste gives biogas; yeast ferments hydrocarbons in flour making CO2, causing it to rise; yeast ferment sugar to form alcohol
- Fermentation - microorganisms breaking down sugar as they respire anaerobically
- Photosynthesis
- Series of chemical reactions that use sunlight to produce food (glucose)
- Chlorophyll absorbs sunlight and uses the energy to convert the CO2 and H20 into glucose
- 6CO2 + 6H2O --> C6H12O6 + 6O2
- Glucose is used for respiration; making amino acids when combined with nitrogen
- Rate of photosynthesis
- Light and CO2 increase rate up to a point, after which temp is limiting factor - enzymes denature at around 45 degrees
- Investigating photosynthesis
- Transect - measure between two fixed points, move along and colect data you want
- Light meter - measures levels of light
- Quadrat - 10x10 grid, used for percentage cover
- ID Key - series of questions narrowing down options until identification
- Diffusion, osmosis and active transport
- Diffusion - the passive overall movement of particles from an area of high concentration to an area of low concentration
- Osmosis - the overall movement of water particles across a partially permeable membrane from an area of low concentration to and area of high concentration
- Active transport - overall movement of chemicals across a cell membrane from a region of low to high concentration using energy released by respiration
B5 - Growth and Development
- DNA - making proteins
- Structure
- Double helix - two strands coiled…
- Structure
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