QUESTIONS THAT I GET WRONG

• What are three ASEPTIC techniques

  1. Wash surface and hands with ANTIBACTERIAL soap and water
  2. Use a bunsen burner to create a convection current to make AIR FLOW
  3. Flame the neck of the bottle
• What sides of Hydrophobic and hydrophillic molecules allow the travel THROUGH membranes

  Hydrophillic
• Why does cholesterol stop damage to membranes

  1. Cholesterol stabilises the membrane
  2. So the APs can not make channels in the membranes
• How can monoclonal antibodies with gold attached be used in TEMs

  1. The monoclonal antibody is complementary to the sample
  2. It binds to the sample
  3. The gold interacts with the ELECTRONS in the TEM
• Explain how two enzymes with different amino acid sequences can catalyse the same reaction

  1. They have the similar tertiary structures
  2. That are complementary to the substrate
  3. They can form enzyme-substrate complexes
• How could scientists control an ENZYME experiment to measure the affect of pH

  1. Use the SAME volume of buffer and pH solution
  2. Use the SAME concentration of substrate
  3. Use the SAME concentration of denatured enzymes
• What does Kinetic energy do in transpiration

  1. If it INCREASES
  2. There is MORE water loss
• Describe an investigation that you could do to investigate whether the mangrove root cells have a LOWER water potential than sea water

  1. Weigh the mangrove and record the mass
  2. Place into the seawater for 10 minutes
  3. Remove and BLOT dry
  4. Record the final mass
  5. If it has a lower water potential the mass will have INCREASED
• Why will ribosomes with detergent (which dissolves lipids) be less dense than without detergent?

  1. Ribosomes are bound to the rough endoplasmic reticulum
  2. The detergent dissolves the RER so the free ribosomes will be less dense
• Name the property of Arsenic (III) oxide that describes its ability to react in these two ways

  Amphoteric
• What kind of isomerism can occur in Square planar molecules

  Cis-trans
• Explain why copper (I) iodide is white

  1. It has a full 3d subshell
  2. It can not adsorb white light
• Describe how you distinguish between separate samples of the two stereoisomers of CH3CH2CH2CH2CH(OH)CN

  1. Using plane polarised light
  2. The enatiomers will rotate the light in opposite directions
• Explain why the reaction produces a racemic mixture

  • The planar carbonyl group
  • It attacks from both sides
  • With equal probability
• Why would the total volumes of a mixture not need to be measured to allow a correct value for Kc

  Volumes cancel out
• What is more attracted to the solvent

  The polar isomer
• What makes an amine attached to a benzene ring more stronger of a base

  1. The further away it is from the delocalised ring
  2. The electrons are push towards the N group then
  3. Which means more lone pairs are readily available
• State why there is a difference between the theoretical and experimental values

  1. It has covalent character
• Explain why the enthalpy of hydration becomes less exothermic from Li+ and k+

  1. Because it takes less energy to lose an e-
  2. The electrostatic attraction between the metal ion and the O- of the water DECREASES
• Explain why the atomic radius DECREASES across period 3, from Na and Cl

  1. There is an increase in nuclear charge
  2. There is similar shielding throughout the period
• What is the Equation for the burning of Phosphorus in air to give Phosphorus (V)

  4P + 5O2 -> P4O10
• Explain why a solution containing [Al(H2O)6]^3+ has a pH <7

  1. Because its alkaline and can donate protons as its a base
  2. Al^3+ has a smaller size and a high charge
• State what must be done to maintain the EMF of this fuel cell when in use.

  Constantly add reactants
• Explain THREE ways and insect's tracheal system is adapted for efficient gas exchange

  1. Tracheoles have thin walls so there is a SHORT diffusion pathway
  2. There is a large number of tracheoles so a larger surface area for gas exchange
• Suggest two environmental variables that could be changed it increase the rate of growth of these cells

  1. Heat - Increases enzyme activity
  2. Increased glucose - Increased respiration
• Explain why the student used only the first 5 mm from the tip of an onion root

  1. This is where dividing cells are mostly found
• Why would the student press down firmly on the cover slip

  1. It spreads the cells to allow light to pass through
• Suggest ONE explanation for the faster rate of plasmid replication in cells growing in a HIGH amino acid concentration

  1. Amino acids form proteins
  2. There are more enzymes for protein synthesis
• Suggest why a nucleus is not visible in the image

  Not stained
• Name an organelle found in both a chloroplast and a prokaryotic cell

  Ribosomes
• Explain the effect that rinsing the burette with deionised water will have on the value of titre

  1. Titre would INCREASE
  2. It would become more diluted
• The student noticed that some of the liquid injected into the gas syringe did not vaporise. What affect would this have on the calculated Mr

  1. The calculated Mr would be greater
  2. A lower Volume will be recorded
• Suggest how glycogen acts as a source of energy

  1. It is highly branched meaning there is many loose ends which can be hydrolysed to release glucose for energy
  2. Glucose is used in respiration
• Describe how a triglyceride is formed

  1. A glycerol molecule bonded to three fatty acids
  2. Via a condensation reaction removing 3 water molecules
  3. Causing an ester bond to form
• Describe how an ester bond is formed in a phospholipid molecule

  1. Via a condensation reaction
  2. Between glycerol + fatty acid
• How would you test for lipids

  1. Blend and mix the food
  2. Mix with ethanol and water
  3. Gives a white milky emulsion
• Explain the importance of keeping the xylem being kept as a continous tube

  1. It allows a water column
  2. Cohesion is from Hydrogen bonds
  3. Evaporation creates tension in the column
• Explain why amylase produced in the human digestive system does not digest GOS

  1. The active site is complementary to starch
  2. Due to its tertiary structure
• Suggest how GOS can work as a prebiotic

  1. GOS provides galactose
  2. The galactose is used in respiration
  3. The bacteria uses it for binary fission
• Suggest how non-competitive inhibitors cause it to become inactive

  1. It will bind to the allosteric site on the enzyme
  2. This will alter the ACTIVE SITE shape
  3. So the previously complementary substrate will not fit