Paper 1 B5+B6

Paper 1 B5+B6

1. Communicable Diseases

   • Communicable Diseases are cause by pathogens that may be transmitted from one organism to the next.
     • Pathogens are organisms thar cause infectious diseases.
     • Pathogens may be viruses, bacteria, protists or fungi. They can infect plants or animals and can be spread by direct contact, by water or by air
     • Bacteria and viruses reproduce radily inside the body.
       • Bacteria produces poisons (toxins) that damage tissues and make us feel ill
       • Viruses live and reproduce inside cells causing damge to the cell
   • Exaples of Communicable Diseases
     • Salmonella - Bacteria -
       • Symptoms = fever abdominal cramps,vomiting, diarrhoea
       • Spread = bacteria on food, food prepared in unhygenic conditions
       • Preventing = vaccinating chickens, washing hands and surfaces
       • Treatment = normally goes without treatment needed
     • Gonorrhoea - Bacteria
       • Symptoms- yellow or green discharge from the vagina or penis and pain on urination
       • Spread - sexual contact
       • Prevention - Barrier method of contraception
       • Treatment - antibiotics
     • Measles- Virus
       • Symptoms - Fever and red skin rash
       • Spread - inhalation of droplets from sneezes and coughs
       • Prevention - vaccination
       • No way of treating it
     • HIV - Virus
       • Symptoms -Flu like illness to start before immune system becomes weakened
       • Spread - sexual contact or exchange of bogy fluids
       • Preventing - barrier method of contreception and not sharing needles
       • Treating - antiretrovial drugs
     • Black spot - Fungi
       • Symptoms - purple or black spots on leaves
       • Spread - contact on leaves
       • No way of prevention
       • Treatment - remove infected plants
     • Malaria - Protist
       • Symptoms - episodes of fever that can be fatal
       • Spread - Mosquitos (vectors)
       • Prevention - Prevent them from breeding using nests
       • Treatment - antiviral drugs
   • Human Defence System
     • Skin - covers whole body protecting against phsical damage, microbe infection and dehydration. Dead outerlayer cells make it difficult for mictobes to penetrate
     • Nasal hair - keep out dust + large microbes
     • sticky mucus - traps dust + microbes - carried away by cilia
     • Hydrochloric acid in stomch kills microorganisma
     • White blood cells defend against pathogens by antibody production and antitoxin production

2. Preventing and treating disease

   • Bacterial Growth
     • Bacteria multiply by simple cell division as often asonce evry 20 minutes, if they have the nutrients and sustainable temperature.
     • Growing bacteria in a lab
       • Sterilise metal loop in a flame
       • Dip loop in bacteria culture
       • Carefully open lid on sterile agar in petri dish
       • Transfer bacteria to sterile agar
       • Seal petri dish lid using tape
       • This prevents contamination from microbes with air
       • Incubate at 25 degrees in school lab
       • This helps prevent growth of pathogent harmful to humans
     • Bacteria at the end of growth period = bacteria at start of growth period x 2 ((to the power) numver of divisions)
   • Plant disease detection
     • Stunted growth
     • Spots on leaves
     • Leaf discoulouration
     • Presence of pests
     • Areas of decay
     • Growths/ Matlformed stems
   • Plant Disease identifacation
     • Taking plants to labrotory to identify pathogen
     • Reference to a garden manual or website
     • using teating kits to identify monclonal antibodies
   • Phsical plant defences
     • Cellulose cell walls
     • tough waxy cuticle
     • layer of read cells around stem
   • Chemical plant defences
     • Antibacterial chemicals
     • poisons to deter herbivores
   • Mechanical plant defences
     • Thornes and hairs
     • leaves whick drop off or curl when touched
     • mimicry to trick animals
   • Vaccinatons
     • vaccines contain small dead / inactive forms of the pathogen which are injected into us and stimulate the white blood cells to produce antibodies
     • Many vaccines contain more than one disease EG MMR vaccine - mumps + measles + rubella
   • Drugs of the past
     • Heart drug digitalis - from foxglove
     • Painkiller aspirin - from willow
     • Penicillin - from penicillium mould