Paper 1 bio

• Coronary heart disease


  Layers of fatty material build up inside the coronary arteries and narrow them
• Treatments for coronary heart disease

  1. Stents to keep the coronary arteries open

  2. Statins to reduce blood cholesterol levels and slow down the rate at which fatty materials build up
• Heart valve issues


  May become faulty, developing a leak or not opening fully
• Treatments for heart valve issues

  Heart valves can be replaced
• Treatments for heart failure

  1. Donor heart, or heart and lungs, can be transplanted

  2. Artificial hearts can be used to keep patients alive while waiting for a heart transplant or to allow the heart to recover
• Cancer


  Caused by uncontrolled cell division, can form masses of cells called tumours
• Benign tumours


  • Do not spread around the body
• Malignant tumours


  • Spread, in the blood, to different parts of the body where they form secondary tumours
• Tissue


  A group of cells with a similar structure and function, which all work together to do a job
• Organ


  Groups of different tissues, which all work together to perform a specific job
• Organ system


  Groups of organs working together to do a particular job
• Organ systems


  • Digestive system
• Enzyme


  Biological catalysts that speed up chemical reactions in living organisms
• Enzymes


  • They are all large proteins
  • There is a space within the protein molecule called the active site
  • Each enzyme catalyses a specific reaction
  • They work best at a specific temperature and pH called the optimum
• Lock and key theory

  The chemical that reacts is called the substrate (key) and it fits into the enzyme's active site (lock)
• High temperature and extremes of pH

  Make enzymes change shape (denaturing), the enzyme cannot work once it has been denatured
• Chromosomes


  The nucleus of a cell contains desmosomes made of DNA
• Chromosomes


  • Each chromosome carries hundreds to thousands of genes
• Different genes contain the code to make different proteins and so control the development of different characteristics
• In body cells, the chromosomes are found in pairs, with one chromosome coming from each parent
• Different species have different numbers of pairs of chromosomes, eg humans have 23 pairs and dogs have 39 pairs
• A Section of One Chromosome

  • Gene for eye colour
  • Genes for hair colour
  • Genes for height
• Bacterial cells


  • They have many different shapes-some are round, some are rod-shaped and some are spiral-but they are all prokaryotic cells
• In bacterial cells, the roles of mitochondria and chloroplasts are taken over by the cytoplm
• Plasmids


  Circles of DNA that can be transferred from one cell to another
• Plasmids allow bacterial cells to move genes from one cell to another
• A Typical Bacterial Cell

  • Cell wall provides structural support to the bacteria
  • Plasmid: circular, section of DNA that can replicate independently of chromosomal DNA
  • Flagella: tail-like structures to help some bacteria move
• Osmosis


  The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
• Water may move across cell membranes by osmosis
• Diffusion


  The net movement of particles from an area of higher concentration to an area of lower concentration until they are evenly spread out
• Many substances move into and out of cells, across cell membranes, by diffusion
• Examples of diffusion in living organisms

  • Oxygen and carbon dioxide diffuse during gas exchange in lungs, gills and plant leaves
  • Urea diffuses from cells into the blood plasma for excretion by the kidney
  • Digested food molecules from the small intestine diffuse into the blood
• Digestive enzymes


  • Produced by specialised cells in glands and in the gut lining
  • Pass out of the cells into the digestive system
  • Come into contact with food molecules
  • Catalyse the breakdown of large insoluble food molecules into smaller soluble molecules
• Digestive enzymes


  • Carbohydrase
  • Protease
  • Lipase
• Carbohydrase (amylase)


  • Breaks down starch into sugar (maltose)
  • Produced in the salivary glands and the pancreas
• Protease


  • Breaks down proteins into amino acids
  • Produced in the stomach, pancreas and small intestine
• Lipase


  • Breaks down lipids into fatty acids and glycerol
  • Produced in the pancreas and small intestine
• Organs involved in digestion

  • Liver
  • Stomach
  • Pancreas
  • Small intestine
  • Gall bladder
  • Bile duct
• Stem cells


  Undifferentiated cells that have not yet become specialised and can divide to make different types of cells
• Types of stem cells

  • Embryonic stem cells (from human embryos)
  • Adult stem cells (found in some organs and tissues, e.g. bone marrow)