Exam questions

• Pathogen


  Microorganism that causes disease
• Ways communicable diseases can be transmitted

  • Direct contact: non-sexual, such as shaking hands
  • Dirty water
  • Air OR coughing/sneezing
• Defence systems that prevent microorganisms infecting the human body

  • Hydrochloric acid produced by the stomach
  • The skin is a barrier covering the whole body
• Ways white blood cells protect us from disease


  • Ingest microbes
  • Produce antibodies
  • Produce antitoxins
• Infection with HIV


  Leads to increase in susceptibility to other pathogens
• HIV attacks the immune system OR HIV leads to loss of white blood cells
• Patient is unable to produce antibodies/phagocytes
• HIV becomes AIDS, without an immune response any infection can be fatal
• Human Papillomavirus (HPV) can cause cervical cancer
• Cancer happens when cells divide uncontrollably
• How HPV causes cervical cancer

  1. HPV is spread through sexual contact

  2. Virus infects cells in the cervix

  3. Virus causes mutations in the cell's DNA

  4. Mutations lead to uncontrolled cell division, which lead to cancer
• How the immune system responds to vaccines


  1. Vaccination involves introducing small quantities of dead or inactive forms of HPV

  2. Stimulate the white blood cells

  3. Allow 'lymphocytes' or 'B-cells' to produce antibodies against HPV

  4. Memory cells for the HPV antigen are produced

  5. If infected, antibodies against HPV are produced faster
• Children receive a vaccine for HPV


  Stopping infection with the virus
• Children who get the vaccine


  Are less likely to get cancer
• The HPV vaccine could reduce the incidence of cancer
• Placebo


  A substance that has no therapeutic effect, used as a control in an experiment or trial to determine the effectiveness of a medical treatment
• Double-blind


  A clinical trial design in which neither the participants nor the researchers know which participants are receiving the experimental treatment and which are receiving a placebo or another treatment
• Reasons why double-blind is important


  • To avoid any bias by the patients
  • To avoid any bias by the researchers
  • If patients know they received the drug they may be more likely to report side effects
  • If researchers know who has been given the real drug then they may pay closer attention to those patients
• Photosynthesis


  6CO2 + 6H2O ➔ C6H12O6 + 6O2
• Main uses of glucose in plants


  • Cellular respiration - break down the glucose to release energy
  • Make cellulose - which is used to make strong cell walls
  • Make starch - which is used to store glucose for a later time
  • Make amino acids - which are used to make proteins
  • Make lipids - these store the energy as fats or oils for later use