key concepts in biology

• What is the first step to use a light microscope?

  Place the slide on the stage
• Why is it important to look through the eyepiece lens?

  To view the specimen clearly
• What should you do after placing the slide on the stage?

  Look through the eyepiece lens
• What is the purpose of the focus wheel?

  To obtain a clear image
• When should you start with the lowest objective lens magnification?

  To ensure a clear initial view
• What should you do after starting with the lowest objective lens magnification?

  Increase the magnification and refocus
• How does increasing the magnification affect the focus process?

  You need to refocus for clarity
• What is the formula for magnification?

  Magnification = measured size / actual size
• What are enzymes classified as?

  Biological catalysts
• What is the role of enzymes in chemical reactions?

  They increase the rate of reaction without being used up
• What is the function of an active site in an enzyme?

  It is where the substrate binds
• How does the shape of an active site relate to enzyme function?

  Each enzyme has a uniquely shaped active site
• Why is the unique shape of an enzyme's active site important?

  It allows specific substrates to bind effectively
• What does the Lock and Key Hypothesis explain?

  How enzymes work
• What forms when a substrate binds to an enzyme's active site?

  An enzyme-substrate complex
• Why can enzymes only catalyze reactions with complementary substrates?

  Because only they fit into the active site
• What is the optimum pH for most enzymes?

  7 (neutral)
• What happens to enzymes if the pH is too high or too low?

  Their active site shape changes
• What is it called when an enzyme can no longer work?

  Denatured
• What enzyme is used to break down carbohydrates?

  Amylase
• What does amylase break down starch into?

  Simple sugars like maltose
• How can you check for the presence of starch in a solution?

  Using iodine solution
• What color does iodine turn when starch is present?

  Blue-black
• What is the procedure to test for starch using amylase?

  1. Heat water to 35°C.
  2. Add iodine to spotting tile.
  3. Mix amylase and starch in a test tube.
  4. Add pH solution to maintain pH.
  5. Place test tube in water bath.
  6. Test drops every 20 seconds for color change.
• What is the formula to calculate the rate of reaction?

  Rate = Change / Time
• What do carbohydrases convert carbohydrates into?

  Simple sugars
• What do proteases convert proteins into?

  Amino acids
• What do lipases convert lipids into?

  Fatty acids and glycerol
• What are reducing sugars?

  A type of simple carbohydrate
• What is calorimetry used for?

  To measure energy in chemical reactions
• How can calorimetry be used with food?

  To measure the calories in food
• What are the steps to measure energy in food using calorimetry?

  1. Take a tube of 50ml cold water.
  2. Record the starting temperature of the water.
  3. Hold a burning food sample beneath the tube at 45 degrees.
  4. Record the final temperature after burning the food.
  5. Calculate energy transferred using:

  • Energy transferred = mass of water x 4.2 x temperature increase
• What is diffusion?

  A form of passive transport
• What is the net movement of molecules during diffusion?

  From high concentration to low concentration
• What is osmosis?

  A form of passive transport for water
• How does osmosis differ from diffusion?

  Osmosis only applies to water
• What is the movement direction in osmosis?

  From dilute solution to concentrated solution
• How can we describe the movement of water in osmosis?

  From high solute concentration to low solute concentration
• What is active transport?

  A transport method that requires energy
• What energy source is used in active transport?

  ATP produced in respiration