B1

• Define magnification.

  How much larger a displayed image is compared with the original image.
• Define resolution.

  The ability to distinguish between two points.
• Why is staining used?

  • Some specimens are colourless.
  • It is useful to highlight different structures.
  • It increases contrast.
• What is the formula to calculate magnification from image size and actual size?


  Image size = Actual Size x Magnification
• How do you calculate total magnification?

  Total magnification = Eyepiece magnification x Objective lens magnification
• How is a light microscope set up?

  Place the specimen on a slide, cover it with a cover slip, illuminate with a lamp and view using the eyepiece.
• State 5 parts of an animal cell.

  1. Nucleus
  2. Cytoplasm
  3. Mitochondria
  4. Ribosomes
  5. Cell membrane
• State 2 functions of the nucleus.

  • Control the cell.
  • Contains genetic material - found in the form of chromosomes.
• State the function of the cytoplasm.

  It is a 'jelly-like' substance where the chemical reactions of the cell take place.
• State the function of the mitochondria.

  They are the site of aerobic respiration.
• State the function of ribosomes.

  They are the site of protein synthesis.
• State 3 organelles only found in plant cells.

  • Cellulose cell wall
  • Permanent vacuole
  • Chloroplasts
• What is the function of the cell wall and what is it made of?

  It provides strength and support. It is made of cellulose.
• What is the function of the permanent vacuole and what does it contain?

  It supports the cell and contains cell sap (a solution of sugars and salts).
• State the function of chloroplasts.

  They are the site of photosynthesis.
• State the function of the cell membrane.

  It is a selective barrier that controls what enters and exits the cell.
• Give 3 differences between prokaryotic and eukaryotic cells.

  • Prokaryotic cells have no nucleus
  • Prokaryotic cells have plasmid loops of DNA
  • Prokaryotic cells have no mitochondria
• State 4 organelles only found in bacterial cells.

  • Flagella
  • Plasmid
  • Slime capsule
  • Pili
• What is the function of the flagella?

  'Tail like' structures that allow the cell to move through liquids.
• What is the function of the plasmid?

  Circular piece of DNA that are used to store extra DNA. They float in the cytoplasm.
• What is the function of the slime capsule?

  A layer outside the cell wall that protects the cell from drying out and from poisonous substances. Also helps the bacteria to stick to smooth surfaces.
• What is the function of the pili?

  Tiny 'hair-like' structures that enable the cell to attach to structure. Also used to transfer genetic material between bacteria.
• Describe the image produced by an electron microscope.

  The image is black and white, it can be 2D or 3D and it has a very high magnification and resolution.
• Why are electron microscopes better than light microscopes?

  They produce images with enough detail to see structures inside cells.
• Describe the structure of DNA.

  • It has a polymer made of many nucleotide monomers.
  • It is made of 2 strands in the shape of a double helix.
• Describe the structure of a nucleotide.

  A nucleotide contains a 5 carbon sugar, phosphate group and nitrogen base.

  
• Name the 4 bases in DNA.

  1. Adenine (A)
  2. Thymine (T)
  3. Cytosine (C)
  4. Guanine (G)
• How do the bases in DNA pair up?

  Adenine pairs with Thymine (A with T).

  Cytosine pairs with Guanine (C with G).
• Describe transcription.

  1. DNA unzipped.
  2. Complementary mRNA nucleotides bind and are joined together.
  3. mRNA detaches and leaves the nucleus.
• Describe translation.

  1. mRNA travels to a ribosome.
  2. Carrier molecules carry amino acids to the ribosome based on the mRNA sequence.
  3. The amino acids are joined together.
• How does the sequence of DNA affect the protein made in protein synthesis?

  DNA is a triplet code where 3 bases code for one amino acid and the order of amino acids determine the protein produced.
• What are enzymes?

  Enzymes are biological catalysts that speed up the rate of metabolic reactions.
• Describe the structure of enzymes.

  Enzymes are proteins that contain an active site that fits a specific substrate.
• Describe the lock and key hypothesis.

  A substrate that fits the specific active site of the enzyme binds, a reaction occurs (catalysed by the enzyme) and then the products are released.
• State 4 factors that affect enzyme function.

  • Temperature
  • pH
  • Substrate concentration
  • Enzyme concentration
• Describe the effect of temperature on the rate of an enzyme-controlled reaction.

  • As the temperature increases, so does the rate of reaction.
  • Once the temperature exceeds the optimum, the enzyme denatures and the rate of reaction decreases.

  
• What is the purpose of respiration?

  To produce energy in the form ATP from larger molecules (like sugars).
• What type of reaction is respiration?

  Respiration is an exothermic reaction.
• When does aerobic respiration take place?

  When there is plenty of oxygen available.
• What is the word equation for aerobic respiration?

  Glucose + Oxygen ------> Carbon dioxide + Water (+ energy)