Biology - B1 - AQA - GCSE - Keeping Healthy and Defending Against Infection

Biology - B1 - AQA - GCSE - Keeping Healthy and Defending Against Infection

1. Diet and Exercise

   • Food Groups
     • Proteins
       • Meat, fish, eggs and cheese.
       • Growth and Repair - Building cells.
     • Fats
       • Cheese, butter, margarine and oils.
       • A source of energy. Cell membranes and insulating the body.
     • Carbohydrates
       • Potatoes, pasta, bread, bananas, sugar and rice.
       • A source of energy.
     • Mineral Ions
     • Vitamins
   • Poor diets can lead to deficiency diseases.
     • Too little vitamin D ---> Rickets (Affects growth of skeleton)
   • Metabolic rate
     • The speed at which chemical reactions take place in the body.
     • Affected by:
       • Age
       • Sex
       • Inherited factors
       • Muscle:Fat proportion
       • Amount of physical activity

2. Defending Against Infection

   • Pathogens
     • Bacteria
       • Multiply rapidly in warm and moist conditions.
       • Microscopic.
       • Living cells.
       • When they enter the body, they release toxins that make humans feel ill.
     • Fungi
       • Larger fungi include moulds and mushrooms
     • Viruses
       • Reproduce inside host cells.
         • Damage cells whilst doing so.
           • Eventually, burst open host cell.
       • Genetic material inside a coat of protein.
       • Passed through bloodstream.
     • Disease-Causing Microbe
   • White Blood Cells
     • Ingest pathogens
       • DO NOT SAY "EATS PATHOGENS"
     • Produce antibodies to destroy pathogens
       • Bind to pathogens and damage/destroy.
       • Coat pathogens to make them easier to ingest.
       • Specific antibodies fit specific antigens.
     • Produce antitoxins to counter the toxin produced by pathogens
   • NOTE
     • Pathogens are not the disease, they CAUSE the disease.
     • White blood cells do not eat pathogens, they INGEST pathogens.
     • Antibodies and antitoxins are not living, they are SPECIALISED PROTEINS.
   • Vaccination
     • Works against bacteria - NOT VIRUSES
       • Bacteria can be resistant to vaccination.
     • Contains weak/dead pathogens to make it easy for the white blood cells to deal with them.