Knowledge to know biology

• Cardiac muscle

  A type of muscle found in the heart that can initiate its own contractions
• Heartbeat recap

  An action potential is initiated by the sinoatrial node (SAN)<br>

  2. The action potential causes an impulse to travel through the walls of the atria to the atrioventricular node (AV node)<br>

  3. The AV node triggers a wave of electrical activity which travels down the Purkyne fibres in the bundle of His to the apex of the heart muscle<br>

  4. The heart muscle contracts from the apex upwards, squeezing the ventricles and pushing blood out at high pressure through the pulmonary artery and the aorta
• Action potential


  A wave of electrical activity that travels through the heart muscle and causes it to contract
• Caecification


  The process of forming a caecum or a pouch-like structure in an organ
• Atrioventricular node


  A group of cells that transmits the action potential from the atria to the ventricles
• Myogenic


  The ability of cardiac muscle to initiate its own contractions
• Atria


  The two upper chambers of the heart
• 1. A Node


  A group of cells in the wall of the right atrium that initiates an action potential
• Purkyne fibres


  Fibres that transmit the action potential from the bundle of His to the apex of the heart muscle
• Heart muscle contraction

  The contraction of the heart muscle that pushes blood through the body
• Sensory neuron


  A type of neuron that detects changes in the environment and transmits the information to the central nervous system
• Bundle of His

  A group of fibres that transmits the action potential from the atrioventricular node to the ventricles
• Parasympathetic nervous system

  A part of the autonomic nervous system that conserves energy by decreasing the heart rate and respiratory rate
• Carotid artery


  A major artery that supplies blood to the head and neck
• Heartbeat

  The contraction of the heart muscle that pushes blood through the body
• Medulla oblongata

  A part of the brain that controls the rate of the firing of action potentials in the sinoatrial node
• Chemical and pressure receptors


  Receptors that detect changes in the levels of chemicals and pressure in the blood
• 1. VM

  A nerve that transmits information from the carotid artery and aorta to the medulla oblongata
• Sympathetic nervous system

  A part of the autonomic nervous system that prepares the body for action by increasing the heart rate and respiratory rate
• Nervous control of heart rate

  The control of the rate of heartbeats by the nervous system through the medulla oblongata
• Aorta


  The largest artery in the body that carries oxygenated blood from the heart to the rest of the body
• Water removed from the reactants joining two molecules together forming a chemical bond

  Condensation
• The addition of water to the reactants to break a chemical bond between 2 molecules

  Hydrolysis
• 1. Add Benedict's reagent. 2. Heat the solution in a water bath for 5 minutes at 95 degrees Celsius. 3. Change from blue to brick red as CuO formed


  Test for Reducing Sugars (3)
• Smaller units from which larger molecules are made

  Monomer
• 1. Add 2cm³ of food sample then add 2cm³ of dilute HCl and heat.

  2. Add 2cm³ of NaHCO3 then do test for reducing sugars.

  Non-Reducing Sugars (2)
• Add drops of iodine to starch solution. Colour change to blue-black


  Test for Starch (1)
• 1. Mix Test solution with ethanol.

  2. Shake for 1 minute then add water.

  3. Cloudy white emulsion

  Test for Lipids (3)
• 1. Obtain equal volumes of test solution and NaOH then add a few drops of biuret solution (dilute copper (II) sulphate solution).

  2. Colour change to mauve/purple

  Test for Proteins (2)
• 1. Very high resolution.

  2. Needs thin and dead specimen.

  3. Artefacts can occur (remnant left on object during prep, such as air bubbles)

  4. Uses magnets to focus on specimen

  5. Uses electrons fired at sample.

  6. Is not in colour

  Transmission Electron Microscope (5)
• 1. Inhibitor is similar in shape to substrate so it impermanently binds to the active site.

  2. Prevents ESC from forming, slowing rate

  Competitive inhibition (2)
• 1. Molecule will bind to allosteric site.

  2. Binding causes a change in active site.

  3. Permanently preventing further ESC.

  Non-competitive inhibition (3)
• 1. DNA helicase breaks the hydrogen bonds between the base pairs

  2. 2 single strands formed as the double helix "unzips".

  3. Free DNA nucleotides in the nucleoplasm bond to the complementary bases on the strand.

  4. DNA polymerase forms phosphodiester bonds between adjacent DNA nucleotides via condensation reaction with the hydrolysis of ATP, forming the phosphate backbone


  DNA Replication: Semiconservative (4)
• 1. ATP stores or releases only a small amount of energy at a time, so no energy is wasted as heat.

  2. Small and soluble so easily transported

  3. Easily broken down, so energy is released instantaneously

  4. Can be quickly re-made

  5. Can make other molecules more reactive via phosphorylation

  6. ATP can't pass out of cell, so the cell always has an immediate supply of energy.


  Describe 6 properties of ATP that make it a good energy source. (6)
• Prevents the cell from drying out. Allows bacteria to stick to each other


  Slime capsule (2)
• Used for attachment of a cell to a surface

  Fimbria
• Involved in bacterial conjugation

  Pilli
• Invagination of cell membrane. Site of cell respiration (prokaryotes)

  Mesosome
• The ability to distinguish two points apart

  Resolution
• 1. Lower resolution than TEM

  2. 3D image

  3. Does not require thin samples


  Scanning Electron Microscope