B3

• What are ribosomes function?


  Protein synthesis.
• What does the number of mitochondria in a cell depend on and why?

  It depends on how active a cell is because respiration occurs in the mitochondria.
• Can ribosomes be seen through a light microscope?

  No - they're too small.
• What does the DNA base code do?

  It determines what amino acid is made - every sequence of 3 bases codes for 1 amino acid
• What did Watson and Crick discover?


  The structure of DNA. They used data from other scientists to build a model.
• What does mRNA do?


  It is a molecule that carries the base code information from the DNA to the ribosomes.
• Why don't new scientific discoveries get rewarded straight away?


  The discoveries need to be tested and repeated by other scientists.
• Give some examples of different protein's functions.

  Collagen, Enzymes, Hormones and Carrier proteins (like haemoglobin).
• How are different proteins given their different functions?


  They have their own number and order of amino acids. This makes each type of protein molecule a different shape.
• What is denaturing?


  At high or low pH's or high temps, the active site of an enzyme changes shape.
• Why is enzyme activity slower at lower temperatures?

  Because the particles are moving more slowly and therefore less likely to collide
• What is the formula for Q10 and what does it measure?

  Rate at higher temp / Rate at lower temp. It works out how temp alters rate of reaction.
• What can gene mutation cause?

  Production of the wrong proteins.
• How do gene mutations cause the production of the wrong proteins?

  They change the base code of the DNA, so change the order of amino acids in the protein.
• What does the 'switching off' of certain genes do?

  It means that different cells can have different functions.
• How does respiration produce energy from food?

  It releases energy from a molecule called ATP.
• What is the formula for Aerobic respiration?

  C6H12O6 + 6O2 -> 6CO2 + 6H2O
• What is oxygen debt?


  The incomplete breakdown of glucose, resulting in build up of lactic acid.
• Why do the breathing and heart rates stay high during recovery?


  -Rapid blood can carry lactic acid to the Liver.

  -extra oxygen can be supplied the liver.
• What is the formula respiratory quotient?


  RQ = CO2 produced / O2 used.
• What is metabolic rate?


  The sum of all reactions occurring in the body.
• How do changes in temperature and pH affect respiration rate?

  By affecting enzymes which control respiration.
• What are the advantages of a multicellular organism?


  - The organism can be larger and more complex.

  - It allows cell differentiation
• What does a multicellular organism need?


  -Communication between all the cells.

  -Nutrients for all the cells.

  -The ability to control exchanges with the environment.
• Define mitosis.


  The process of producing new cells for growth.
• What process produces gametes?

  Meiosis
• What is a diploid cell?

  A cell that has two copies of each chromosome. E.g. Body cells.
• What is a zygote?

  A fertilised egg.
• Give an example of a haploid cell.


  Sperm cell (or gamete).
• How is a sperm cell adapted for it's purpose?


  - Many mitochondria to provide energy.

  - An ACROSOME releases enzymes to digest the egg membrane.
• What is the plasma and what does it do?


  The liquid part of the blood. It transports important substances around the body (e.g. Hormones, CO2 and glucose).
• How does the small size of a red blood cell mean that it's adapted to it's purpose?

  It means that it has a large S/A:Volume ratio so it can exchange oxygen more quickly.
• How is oxyhemoglobin formed?


  When the haemoglobin is red blood cells reacts with the oxygen from the lungs.
• Which blood vessel carries blood back to the heart from the tissues?

  Veins
• What do capillaries do?


  Link arteries to veins and allow materials to pass between the blood and the tissues.
• What type of blood vessel needs a thick elastic wall and why?

  Arteries because they need to resist the high pressure.
• Why do capillaries need to be permeable?

  So that they can transfer substances to the tissues from the blood and vice versa.
• How are veins adapted for their purpose?


  They have large lumen valves to stop back flow in the blood.
• Which blood vessels carry blood away from the heart?

  The aorta (takes blood to the rest of the body) and pulmonary artery (takes blood to the lungs).
• Why does the left ventricle have a thicker muscle wall than the right ventricle?


  It has to pump the blood further than the right ventricle, so needs to be more powerful.