Organisation- Biology paper 1

• Cells


  Make up all living things
• Tissue


  A group of specialised cells with a similar structure and function, can be made of more than one type of cell
• Tissue examples

  • Muscular tissue
  • Epithelial tissue
• Organs


  Formed from a number of different tissues, working together to produce a specific function
• Organ example

  • Stomach
• Organ systems

  Organs organised to work together to perform a certain function
• Organ system example

  • Digestive system
• Organs in the digestive system

  • Glands (salivary glands, pancreas)
  • Stomach
  • Small intestine
  • Liver
  • Gall bladder
  • Large intestine
  • Rectum
  • Anus
• Enzymes

  Biological catalysts that increase the rate of reaction without being used up
• How enzymes work (Lock and Key Hypothesis)

  1. Substrate binds to active site

  2. Reaction takes place

  3. Products released
• Enzymes

  • They can both break up large molecules and join small ones
  • They are protein molecules and the shape of the enzyme is vital to its function
• Optimum pH and temperature for enzymes

  • Optimum temperature is around 37 degrees celsius (body temperature)
  • Optimum pH for most enzymes is 7, some have a low optimum pH
• When temperature becomes too hot

  Bonds in the structure break, changing the shape of the active site so the substrate can no longer fit in, enzyme is denatured
• If pH is too high or too low


  Forces that hold the amino acid chains that make up the protein will be affected, changing the shape of the active site so the substrate can no longer fit in, enzyme is denatured
• Types of enzymes

  • Carbohydrases
  • Proteases
  • Lipases
• Carbohydrases


  Convert carbohydrates into simple sugars
• Carbohydrase example

  • Amylase breaks down starch into maltose
• Proteases


  Convert proteins into amino acids
• Protease example


  • Pepsin produced in the stomach
• Lipases


  Convert lipids into fatty acids and glycerol
• Soluble glucose, amino acids, fatty acids and glycerol pass into the bloodstream to be carried to all the cells around the body
• Tests for different molecules

  • Benedict's test for sugars
  • Iodine test for starch
  • Biuret test for protein
  • Emulsion test for lipids
  • Sudan III test for lipids
• Bile


  • Produced in the liver and stored in the gallbladder, released into the small intestine
  • Alkaline to neutralise hydrochloric acid
  • Emulsifies large drops of fat into smaller ones to increase surface area for lipase
• Investigating effect of pH on enzyme controlled reaction

  1. Warm amylase, starch and buffer solution

  2. Take drops of solution at regular intervals and test with iodine

  3. Time when starch is completely broken down

  4. Calculate rate from 1000/time
• Heart


  An organ in the circulatory system that pumps blood around the body
• Circulatory system


  Carries oxygen and nutrients to every cell in the body and removes waste products
• Double circulatory system

  Two circuits - deoxygenated blood to lungs, oxygenated blood around body
• Parts of the heart

  • Right atrium
  • Right ventricle
  • Left atrium
  • Left ventricle
  • Muscular walls
  • Valves
  • Coronary arteries
• Blood flow through the heart

  1. Blood flows into right atrium and left atrium

  2. Atria contract, forcing blood into ventricles

  3. Ventricles contract, pushing blood to lungs and around body

  4. Valves close to prevent backflow
• Pacemaker


  Group of cells in the right atrium that provide electrical stimulation to make the heart contract
• Artificial pacemaker


  Electrical device that produces a signal causing the heart to beat at a normal speed
• Types of blood vessels

  • Arteries
  • Veins
  • Capillaries
• Arteries


  • Layers of muscle and elastic fibres to withstand high pressure
  • Carry blood away from the heart
• Veins

  • Wide lumen to allow low pressure blood flow
  • Have valves to ensure blood flows in the right direction
  • Carry blood towards the heart
• Capillaries


  • One cell thick walls for short diffusion pathway
  • Permeable walls to allow substances to move between blood and cells
• Lungs

  Supply oxygen to blood and remove carbon dioxide
• Parts of the gas exchange system

  • Trachea
  • Intercostal muscles
  • Bronchi
  • Bronchioles
  • Alveoli
  • Diaphragm
• Ventilation

  1. Ribcage moves up and out, diaphragm moves down, increasing volume and decreasing pressure, drawing air into lungs

  2. Opposite happens when exhaling
• Gas exchange in alveoli

  1. Oxygen diffuses from alveoli into capillary blood

  2. Carbon dioxide diffuses from capillary blood into alveoli
• Alveoli


  • Very small and arranged in clusters for large surface area
  • Capillaries provide large blood supply
  • Thin walls for short diffusion pathway