B4

B4

1. Cell Structure and function

   • Plant and animal cells
     • animal
       • Nucleus, contains DNA which has instrucions for making proteins. The enzymes used in chemical reactions of respiration (In plant photosythesis)
       • Cytoplasm, where proteins are made and some chemical reactions take place
       • Cell membrane, holds cell together and controls what goes out and in. (Water and gas pass freely)
       • Mitrochondria, where the enzymes needed for the reactions of areobic respiration are found and take place
     • Plant
       • Plant cells have some extra things that animal cells dont
         • Rigid cell wall, made of cellouse. Supports and strengthens cell.
         • Vavuole contains cell sap. A weak sugar/salt solution
         • Chlorpasts, where reaction for photosythesis takes place. Contains green substance called chlorophyll and enzymes for photosynthesis.
   • Yeast Cells and Bacteria
     • Yeast cells used to make bread/wine
     • Bacteria cells are different to the others. They don't have a nucleus or a mitochondria but can still respire aerobically.

2. Enzymes

   • Enzymes are proteins made by living things
     • Enzymes are proteins that speed up a chemical reaction
     • There are 1000's of differnt reactions happening in living things. They are carefully controlled by enzymes
   • Lock and key
     • CR involve things being split or joined together
     • Substrate is a moleculethat is changed in a reaction
     • Each enzyme molecule has and active sits, where the substrate joins on to the enzyme
     • Enzymes speed up one reaction because for the enzyme to work a substrate has to be the correct size/shape to fit the active site.
   • Tempreture and pH
     • Enzymes need to be at a specific constant tempreture/pH to work at their optimium
     • Change in tempreture/pH chages the rate of an enzyme controlled CR
       • High tempreture increases the rate a first but some bonds holding the enzyme begin to break if it gets too hot and this changes the enzymes active site make it denatured.
         • If it is too cold it wil just work a lot slower.
       • If the PH is too high or low the same happens and the enzyme denatures

3. Aerobic Repiration

   • Respiration is not breathing in and out
     • Respiration is a series of CR that release energy by breaking down large food molecules (e.g glucose). It occurs in all living cells
     • Energy released is used to power some chemical reactions
       • Movement: Contract muscles
       • Active transport: Move substance in and out of cells
       • Synthis of large molecules: (Polymers are made by joining smaller molecules together. This requires energy
         • Glucose is joined to make starch/Cellulose in plant cells. (Plant cells
         • Animale cells: Glucose and nitrogen join to make amino acids which join to make proteins.
   • Aerobic repiration needs plenty of Oxygen
     • Means with oxygen and releases more energy per glucose molecule than anerobic repiration. Used most of the time

4. Anaerobic reperaion

   • Anerobic reperation doesnt use oxygen. Takes place when little/no oxygen is available
     • If a plants roots become waerlogged. Bacteria gets stuck under skin or when oraganism have to exersise.
   • In animal and some bacteria cells it produces lactic acid
   • In plants and some, microorganisms they also produce Ethanol and carbon dioxide
     • Fermentation: Microorganisms break down sugars into other products as the AR
       • Biofuel: Microorganisms ferment plant/animal waste wich contains carbohydrates. Product made of methane and co2
       • Bread: Yeast ferment the carbohydrates in flour and release Co2. Bread rises
       • Alcohol: Yeast ferment sugar to form ethanol. Sugar used comes from grapes/barley

5. Photosynthesis

   • Photosythesis produces Glucose
     • Photosynthesis is a series of CR that uses energy from the sun to produce food (glucose)
     • Happens in green parts of plants and some microorganisms (phytoplankton)
     • Chlorophyll is needed for it to happen. Its a green substance that absorbs sunlight and allows the energy to be used to convert CO2 and H20 into glucose
     • Organisms that use Photosynthesis are at the start of the food chain. Makes energy from the sun available to other organisms through being eaten
   • The product glucose is used in three ways
     • The glucose is used for respiration and this releases energy
     • Glucose is used to make chemicals for growth, Converted to cellulose/Combined with nitrogen to make amino acids/ to make chlorophyll
     • Stored as starcg all over the plant to be used as food in winter

6. Rate of photosythesis

   • Three factors affect the rate of photosynthesis
     • Light, Co2 and tempreture
     • Any can be the limitingfactor. Slows photsythesis. Depends on enviromental conditions

7. Investigating photsyntheisis

   • Transect
     • Way of investigating how something changes across an area. Run a tape measure from tow FIXED points, start at one end and collect the data you need, then the other
   • Things that help collect data
     • Light meter
     • Quadrat
       • Used to estimate th percentage cover over a paticular area. (Count if more than half covered)
     • Identification Key
       • Series of questions that are used to figure out what a plant is. You use it to narrow down the possibillities

8. Diffusion, Osmosis, Active transport

   • Diffusion is the passive overall movement of particles from a region of their higher concentration to a region of their lower concentration
   • Osmosis is the overall movement of water from a dilute to a more concentrated solution through a partially permeable membrane
   • Active transport is the overall movement of chemicals across a cell membrane from a region of high concentration using energy released by respiration.

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