paper 1 biology

• Cell membrane


  Responsible for determining what goes in and out of the cell
• Animal cell


  • Lacks cell wall, vacuole, chloroplasts
• Cytoplasm


  Where most reactions take place
• Ribosomes


  Responsible for protein synthesis
• Mitochondria


  Where energy is produced
• Nucleus


  Contains DNA, control centre of the cell
• There is no typical cell as cells are highly specialised and differentiated
• Microscopy techniques


  Have varied from basic lenses to sophisticated electron microscopes
• Calculating magnification from microscope images


  Magnification = image size / object size
• Producing an uncontaminated bacterial culture


  1. Flame inoculation loop

  2. Open bottles near flame

  3. Transfer sample quickly

  4. Incubate at 37°C or 25°C
• Investigating effect of antibiotics/antiseptics on bacteria


  1. Clean work area and hands

  2. Label agar plates

  3. Add filter paper discs

  4. Incubate at 25°C for 48 hours

  5. Measure clear zones
• DNA


  Long strand of deoxyribonucleic acid, forms double helix, located in nucleus
• Mitosis


  1. DNA condenses into chromosomes

  2. Chromosomes line up

  3. Chromosomes pulled apart

  4. New nuclei form

  5. Cell divides into two identical daughter cells
• Creating stem cells


  1. Take nucleus from patient's cell

  2. Insert into empty egg

  3. Embryo develops

  4. Stem cells removed from embryo
• Diffusion


  Movement of particles from high to low concentration
• Osmosis


  Movement of water through partially permeable membrane from high to low water concentration
• Active transport


  Movement of substances from low to high concentration, against concentration gradient
• Cell membrane


  Responsible for determining what goes in and out of the cell
• Plant cell


  • Cell wall
  • Vacuole
  • Chloroplasts
• Animal cell


  • No cell wall
  • No vacuole
  • No chloroplasts
• There is no typical cell as there is a wide range of differentiated, specialized cells
• Bacteria divide very quickly, roughly every 20 minutes
• Producing an uncontaminated bacterial culture


  1. Flame inoculation loop

  2. Open bottles near flame

  3. Transfer sample quickly

  4. Incubate at 37°C or 25°C
• Investigating effect of antibiotics/antiseptics on bacteria


  1. Clean work area and hands

  2. Label agar plates

  3. Place filter paper discs

  4. Incubate at 25°C for 48 hours

  5. Measure clear zones
• DNA


  • Long strand of deoxyribonucleic acid made of A, T, C, G
  • Twisted into double helix
  • Further twisted into chromosomes in nucleus
• Mitosis


  1. DNA condenses into chromosomes

  2. Chromosomes line up in middle

  3. Chromosomes pulled to opposite ends

  4. New nuclei form

  5. Cell divides into two identical daughter cells
• Diffusion


  Movement of particles from high to low concentration
• Tissue


  One type of cell carrying out one function
• Organ


  Made up from lots of different types of cells carrying out a joint function
• Organ system


  A group of organs that work together to carry out a function
• Hierarchy of biological organisation


  • Cells
  • Tissues
  • Organs
  • Organ systems
• Digestive system


  1. Mouth (mechanical breakdown of food)

  2. Saliva glands (produce enzymes)

  3. Liver (produces bile)

  4. Gallbladder (stores bile)

  5. Small intestine (absorption of nutrients)

  6. Stomach (churns food, produces acid)

  7. Pancreas (produces enzymes)

  8. Large intestine (removes excess water)

  9. Rectum and anus (waste removal)
• Lipase


  Enzyme that breaks down fats into fatty acids and glycerol
• Amylase


  Enzyme that breaks down starch into sugars
• Enzyme mechanism


  1. Enzyme has specifically shaped active site

  2. Substrate binds to active site

  3. Enzyme-substrate complex forms

  4. Catalysis occurs

  5. Products are released

  6. Enzyme is unchanged and can be used again
• Temperature increases


  • Enzyme activity increases (up to optimal temperature)
  • Enzyme becomes denatured (after optimal temperature)
• pH changes


  Enzyme becomes denatured (at very high or very low pH)
• Respiratory system


  1. Air enters through mouth/nose

  2. Travels down trachea

  3. Into bronchi

  4. Into bronchioles

  5. Into alveoli (site of gas exchange)

  6. Diaphragm moves up and down to bring air in and out

  7. Intercostal muscles allow rib cage to expand
• Cardiovascular system


  1. Blood pumped from heart to lungs and back to heart

  2. Then pumped around rest of body

  3. Deoxygenated blood enters right atrium

  4. Flows to right ventricle

  5. Pumped to lungs via pulmonary artery

  6. Oxygenated blood returns to left atrium

  7. Flows to left ventricle

  8. Pumped to body via aorta
• Heart


  • Right side has smaller muscle as only pumps to lungs
  • Left side has larger muscle as pumps to whole body