Key concepts of Biology

• How are Sperm cells adapted to fit their purpose?

  • Flagellum to swim to egg cell
  • Enzymes in the acrosome that help penetrate the egg
  • Mitochondria in the middle piece to release energy to swim
  • Haploid nucleus in the head to fertilize the egg
• How are egg cells adapted to fit their purpose?

  • Nutrients in the cytoplasm for growth of the embryo
  • Haploid nucleus to fertilize with sperm cell
  • Cell membrane changes after fertilization so that no other sperm can penetrate it
• How are ciliated epithelial cells adapted to their functions?

  • Cilia on the surface beat to move fluids and particles up the trachea.
• Animal cell organelles and functions

  • nucleus- holds DNA
  • cell membrane- controls what moves in and out of the cell
  • mitochondria- needed for aerobic respiration
  • ribosomes- involved in protein synthesis
  • cytoplasm- a ground for chemical reactions to take place
• Plant cell organelles + function

  • nucleus- holds DNA
  • cell membrane- controls what goes in and out of the cell
  • cell wall- strengthens walls of cell
  • chloroplasts- absorbs light energy for photosynthesis
  • mitochondria- needed for aerobic respiration
  • vacuole- filled with "sap" to keep cell turgid
  • ribosomes- involved in protein synthesis
• Bacterial cell organelles and functions

  • Chromosomal DNA- contains DNA and not contained in a nucleus
  • Plasmid DNA- closed circles of DNA that can move from one cell to the next
  • Cell membrane- controls what goes in and out of the cell
  • Ribosomes- involved in protein synthesis
  • Flagella- tail used to move the cell
• Light microscopes through the years

  1590- Scientist experimented by putting lenses in tubes

  1650- Hooke observed and drew cells using a light compound cell

  Late 1600s- Scientist constructed microscope with one spherical lense

  1800- Optical quality of microscope improved
• Quantitative units in relation to cells

  • Milli (10^-3)
  • Micro(10^-6)
  • Nano(10^-9)
  • Pico(10^-12)
• What is the first step in using a microscope?

  Rotate the objective lenses to low power
• Why should you not look through the microscope when adjusting the coarse focus?

  To avoid damaging the slide or lens
• Where should the specimen be positioned on the stage?

  In the center of the stage
• How do you focus the slide towards you?

  By turning the coarse focus adjustment
• What should you do after focusing the slide?

  Draw a low power image of what you see
• How do you bring the slide back into focus after switching to high power?

  Using the fine focus adjustment
• What are the steps to prepare a microscope for viewing a specimen?

  1. Rotate to low power objective
  2. Adjust coarse focus to bring stage close
  3. Place slide on stage, center specimen
  4. Focus slide towards you with coarse focus
  5. Draw low power image
  6. Rotate to high power objective
  7. Use fine focus to bring slide into focus
• What is the next step after drawing the low power image?

  Rotate the objectives to high power
• Drawing the image (practical)

  Draw a diagram at low power (to outline the cell) and high power (to take a closer look at its organelles)
• What are enzymes?


  Biological catalysts. Each one has a specific substrate that fits into the active sites shape. The products produced from an enzyme do not impact its active site.
• How can enzymes be denatured?

  Enzymes are denatured because of changes in high temperature or pH causing the active site to change shape and the substrate to not fit in anymore.
• Factors affecting enzyme rate of reaction

  • Temperature: The enzymes rate of reaction increases with temperature until it reaches its optimum temperature and then denatures
  • pH: Each enzyme works best at a different pH. Same as temperature
  • Substrate concentration: As substrate concentration increases so does enzyme activity, until eventually it reaches a standstill due to not having any more activity
• What equipment is needed to set up the experiment?

  Bunsen burner, heatproof mat, tripod, gauze
• What temperature should the water be maintained at during the experiment?

  About 35°C
• How many drops of iodine solution are added to each spot of the spotting tile?

  Two drops
• How much amylase enzyme solution is added to the test tube?

  2 cm
• How much starch solution is added to the test tube?

  2 cm
• What is the purpose of adding the pH solution to the test tube?

  To keep the pH constant
• What should be done after mixing the solution in the test tube?

  Place it into the beaker of water
• How often should drops of solution be removed from the test tube?

  Every 20 seconds
• What should be done with the drops of solution removed from the test tube?

  Put them into a different well of the spotting tile
• What indicates that the reaction has stopped?

  The iodine solution stops turning black
• What should be recorded at the end of the experiment?

  The time it takes for the reaction
• What should be done after completing the experiment with one pH solution?

  Repeat with different pH solutions
• Enzymes and food

  Carbohydrates, proteins and lipids are large molecules that are needed by the body for growth, repair and metabolism. They are found in our food. These molecules are too large to pass from the intestine into the blood, so digestive enzymes break them down into smaller molecules. Once in the body, different enzymes use these raw materials to synthesise larger molecules.
• Which breaks into which:

  Carbohydrates: glucose

  Proteins: amino acids

  Lipids: fatty acids and glycerol
• Diffusion

  • Diffusion is the movement of a substance from an area of high concentration to an area of lower concentration.
  • Diffusion occurs in liquids and gases when their particles collide randomly and spread out.
  • Is how oxygen leaves a leaf
• Osmosis

  • The movement of water molecules from high concentration to low concentration across a semi permeable membrane
  • The particles move downwards
  • How water keeps plant cells turgid
• Active transport

  The movement of molecules from a low concentration to a high concentration

  Requires energy

  How minerals get into root hair cells
• What is the purpose of the practical investigation described?

  To investigate osmosis in potatoes
• What are the steps involved in the osmosis investigation with potatoes?

  1. Set up 6 boiling tubes with sucrose solutions.
  2. Prepare 6 potato cylinders of equal length.
  3. Dry each cylinder and record its mass.
  4. Place cylinders in boiling tubes for 40 minutes.
  5. Remove cylinders, dry, and record mass again.
  6. Repeat for multiple measurements to calculate mean.