GCSE AQA Biology Higher

• The nucleus is the control center of the cell, containing the genetic material.
• parts of the lung

  Trachea, lung, bronchus, bronchioles and alveoli
• Describe how to test a food sample for lipids

  1)Put the sample in a test tube with some distilled water 2)Add a few drops of ethanol OR a few drops of Sudan III stain to the test tube3)Gently shake the test tube4)if lipids are present, a cloudy emulsion forms(ethanol)OR a separate red layer forms at the top (Sudan III stain)
• Describe how to test a food sample for protein

  1)put the food sample in a test tube2)Add 2cm^3 of biuret solution 3)Gently shake the test tube 4)if protein is present, the solution changes from blue to violet or purple
• Describe how to test a food sample for starch

  1)put the food sample in a test tube2)Add a few drops of iodine solution to the test tube3)if starch is present, the solution changes from orangey to blue-black.
• Describe how to test a food sample for sugars

  1)Heat a water bath to 80*C2)Put the food sample in a test tube and add a few drops of Benedict's solution3)Put the test tube in the water bath for around 5 minutes4)if sugars are present, the solution changes from blue to green(some sugar),yellow or brick-red (lots of sugar)
• Bile emulsifies fats what does this mean and why is it important for digestion?

  This means it turns fat into very small droplets.This creates a large surface area for lipase to act on, increasing the rate of lipid breakdown by lipase
• Bile is an alkaline substanceExplain why this is important for digestion


  During digestion, food that's mixed with hydrochloric acid passes from the stomach into the small intestine.Bile is an alkaline substance that neutralises the acid so the digestive enzymes in the small intestine can function at their optimum PH
• where is bile produced and where is it stored?

  produced in the liver and stored in the gallbladder
• give 3 places in the body where lipase are produced

  -mouth -stomach -pancreas
• what do lipase catalyse?

  lipases catalyse the breakdown of lipids into fatty acids by glycerol
• give 2 places in the body where proteases are produced

  -stomach-pancreas
• What do proteases catalyse?

  Proteases catalyse the breakdown of proteins into Amino acids
• give 2 places in the body where amylase is produced

  -Salivary glands-Pancreas
• what does amylase catalyse?

  Amylase catalyses the breakdown of starch into simple sugars
• What are carboghydrases

  Digestive enzyme that catalyse the break down of carbohydrates into simple sugars
• what do digestive enzymes do?

  break down big molecules into smaller ones that will be absorbed into the blood
• Organs of the digestive system

  Salivary glands,Oesophagus,Stomach,Liver,Gall blader,Pancreas,Small intestine and large intestine

  
• Give a brief method for investigating the effector PH on amylase activity


  1)Put a drop of iodine solution in each well of a spotting tile2)Add 2cm^3 starch solution and add 2cm^3 of PH5 buffer solution to a test tube in a water bath at 35*C3)After 10 mins, stir in 2cm^3 of amylase solution and start timing 4)Take a drop from the test tube every 20 seconds and put it in well- repeat until the iodine solution stays orangey and record the time passed.5)Repeat the experiment with a range of PH buffer solutions
• outline how the effect or PH on amylase activity can be investigated

  the effect of PH on amylase activity can be investigated by comparing how long it takes amylase to fully break down a sample of starch solution at different PH levels
• Give the two things that causes enzymes to denature

  -High temperaturesa ph value thats too high to too low
• Enzyme's optimum pH and temp, what's it meant by this?

  The PH and temp at which an enzyme works best are the enzymes optimum temp and PH
• how does changing temp affect the rate of a enzyme catalysed reaction?

  as temp increases, the rate of enzyme catalysed reaction increases.But of the temp gets too high enzymes get denatured and the rate of reaction decreases.
• what does it mean when an enzyme is denatured?

  When an enzyme is denatured, its active site changes shape.This means the substrates won't fit the active site any more, so the enzyme can't catalyse any more reactions.
• describe the lock and key model of enzyme action

  Only a substrate that exactly fits an enzymes active site can bind to the enzyme.once a substrate binds, the enzyme catalyse the reaction
• why do enzymes only catalyse specific reactions?

  an enzymes active site is a specific shapeOnly certain substrates fit the active, so an enzyme can only catalyse specific reactions
• whats an enzymes active site?

  the part of an enzyme that a substrate blinds with
• wha are enzymes?

  proteins that catalyse chemical reactions in an organism
• put these in order (smallest to largest):organ, tissue, organ system, cell

  1)Cell2)Tissue3)organ4)Organ system
• what is an organ system?

  A group of organs working together to perform a particular function
• what Is an organ


  A group of different tissues that work together to perform a certain function.
• what is a tissue?

  A group of cells that act together to perform a specific function.
• give 3 ways that the lamellae in a fish's gills are adapted for exchanging gases with water

  -thin walls-a rich blood supply-blood flows through them in the opposite direction to water flowing over them
• how does the structure of fish gills help it exchange gases with water

  A fishes gills are made up of lots of gill filaments, which are covered in lots of folds called lamellaethis gives the gills a large surface area, which increases rate of diffusion of gases between the fish's blood and water
• give 2 ways that plant leaves are adapted for gas exchange

  -opening in epidermal tissue called stomata let gases in and out of the leaf -air spaces inside leaf tissues allow gases to diffuse in and out of cells
• give 3 ways that alveoli in the lungs are adapted for gas exchange

  -thin walls-a rich blood supply-large surface area
• give 3 ways that the small intestine is adapted for exchanging surfaces

  -walls are folded and have millions of projections called Villi to give a massive surface area-Villi have very thin walls-Villi have a rich blood supply
• give 4 adaptations of exchange surfaces to increase they effectiveness

  -Large surface area(lets more substances diffuse at once)-Thin membrane (speeds up diffusion because diffusion distance is short)-Rich blood supply in animals.(takes things to and from exchange surface efficiently )-gas exchange surfaces are exposed to the air(in animals)
• why do multicellular organisms need exchange surfaces?

  multicellular organisms have relatively small surface are to volume ratio .substances can't diffuse over their surfaces at a level thats high enough to keep all of their cells alive.this means that multi cellular organism need exchange surfaces to transfer substances efficiently.
• why don't single celled organisms need exchange surfaces ?

  single celled organisms have relatively large surface area to volume ratio.this means substances can diffuse over their cell membranes at. rate thats high enough to keep them alive.this means single celled organisms don't need exchange surfaces