bio

• Involuntary (Smooth) muscle

  • Non striated
  • One nucleus per cell
  • Not branched
  • Tapered at the ends
  • Slow rhythmic contraction, in the wall of gut and blood vessel not under voluntary control
• Uses of genetically modified plants

  • Golden rice
  • Genetically modified banana, carrot, lettuce producing antigens for vaccines
• Diffusion


  The net movement of molecules and ions from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement (kinetic energy)
• Diffusion

  The random movement of molecules and ions in liquids and gases using kinetic energy
• Factors affecting rate of diffusion

  • Temperature
  • Distance
  • Concentration gradients
  • Surface area to volume ratio
• Osmosis


  The net movement of water molecules from a region of higher water potential (diluted solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane
• Water potential


  A measure of the tendency of water to move from one area to another by osmosis
• Water is an important solvent and most cells contain 75% water
• Water transport substances and allow many chemical reactions to take place
• Partially permeable membrane


  A membrane that effectively has gaps allowing small molecules like water to pass through, while larger molecules cannot
• Importance of water potential and osmosis


  • Maintaining correct osmotic balance inside the body (osmoregulation)
  • Preventing water flow into or out of cells, which could cause them to swell or shrivel
• Active transport


  The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration (against concentration gradient) using energy from respiration
• Carrier protein


  A protein found in the cell membrane that facilitates the movement of particles against their concentration gradient
• Carrier proteins are specific, each one binding to a particular solute
• How carrier proteins work

  The solute binds to the carrier protein's binding site, which then rotates using ATP energy to transfer the solute against the concentration gradient
• Importance of active transport

  • Absorption of food (glucose) through epithelial cells of small intestine
  • Reabsorption of glucose through kidney tubules
  • Absorption of minerals through root hair cells
• Biological molecules

  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic acids
• Carbohydrate


  Molecules containing carbon, hydrogen and oxygen in a 1:2:1 ratio
• Disaccharide

  Sugars with two carbon rings, e.g. maltose, sucrose, lactose

  
• Glycogen

  An insoluble polysaccharide that stores energy in animal cells
• Carbohydrates are a source of energy through respiration, providing 17 kJ/g
• Lipid

  Molecules containing carbon, hydrogen and oxygen, but with a lower oxygen content than carbohydrates
• Proteins have a specific sequence and shape of amino acids, which determines their function

  
• Investigating vitamin C content of lemon juice

  1. Place 2 cm3 of 1% vitamin C solution in a test tube

  2. Add 1% DCPIP drop by drop until the blue colour doesn't disappear

  3. Repeat with 2 cm3 of lemon juice

  4. Compare the volume of DCPIP used to decolorize both the vitamin C solution and the lemon juice

  5. Calculate the concentration of vitamin C in the lemon juice
• Regions of the alimentary canal and their functions

  • Mouth: Ingestion of food, mechanical digestion by teeth, chemical digestion of starch by amylase, formation of a bolus
  • Oesophagus: Transport of food from mouth to stomach
  • Stomach: Storage of food, further mechanical and chemical digestion
  • Small intestine: Absorption of digested food molecules
  • Large intestine: Absorption of water, formation and storage of faeces
  • Anus: Egestion of faeces
• Oxygen debt


  • During vigorous exercise, muscle respires anaerobically because the blood cannot supply enough O2 to maintain aerobic respiration, this leads to formation of lactate in muscles
  • An oxygen debt is created because O2 is needed to convert lactic acid to pyruvic acid, this happens in the liver
  • The heart rate and breathing rate don't return to normal straight away after exercise but there is a recovery period (gradual decrease in heart rate, blood pressure and breathing rate)
  • This is characterised by deeper breathing (an athlete pants for breath)
• Alveoli


  Fine, thin-walled, pouch-like air sacs