Organisation

• Tissue examples


  • Muscular tissue
  • Epithelial tissue
• Organ system


  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
• 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
  • Each enzyme has its own uniquely shaped active site where the substrate binds
• Types of enzymes


  • Carbohydrases (convert carbohydrates into simple sugars)
  • Proteases (convert proteins into amino acids)
  • 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 biological molecules

  • Benedict's test (for sugars, turns brick red)
  • Iodine test (for starch, turns blue-black)
  • Biuret test (for protein, turns purple)
  • Emulsion test (for lipids, adds ethanol resulting in cloudy layer)
  • Sudan III test (for lipids, red layer forms on top)
• Double circulatory system


  Two circuits - deoxygenated blood to lungs, oxygenated blood around body
• Thorax


  Top part of body where the lungs are found, protected by ribcage
• Parts of the gas exchange system

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


  • Small size and clustered arrangement creates large surface area, thin walls for short diffusion pathway, large blood supply maintains concentration gradient
• Calculating breathing rate


  Divide the number of breaths by the number of minutes
• Components of blood


  • Plasma
  • Red blood cells
  • White blood cells
  • Platelets
• Red blood cells


  • Carry oxygen molecules from the lungs to all the cells in the body
  • Biconcave disc shape provides a large surface area
  • No nucleus allowing more room to carry oxygen
  • Contain the red pigment haemoglobin, which binds to oxygen and forms oxyhaemoglobin
• White blood cells


  • Part of the immune system, which is the body's defence against pathogens (microorganisms that can produce disease)
  • Have a nucleus
  • Types: those that produce antibodies against microorganisms, those that engulf and digest pathogens, those that produce antitoxins to neutralise toxins produced by microorganisms
• Coronary heart disease


  When the coronary arteries that provide blood to the heart become blocked with the build up of fatty material, resulting in less blood flowing to the heart and reducing its oxygen supply, which may lead to a heart attack
• Non-communicable diseases


  Diseases that are not infectious, but there are a number of risk factors that increase the likelihood of them occurring
• Cardiovascular disease


  • Diet containing lots of LDL (bad) cholesterol results in arteries becoming blocked, increasing blood pressure
  • Smoking damages the walls of arteries
  • Exercise lowers blood pressure, reducing strain on the heart
• Pregnancy


  • Smoking and alcohol can cause many damaging effects on the unborn child
• Carcinogens


  Substances that can lead to cancers
• Malignant tumours


  • The tumour grows and spreads to other tissues, cancerous, the tumour may split up, resulting in cells being carried in the bloodstream or lymphatic system, they can travel to and stay in another organ, potentially causing secondary tumours, the cancer cells divide more rapidly and have a longer life span in comparison to normal cells
• Plant tissues


  • Epidermal tissue
  • Palisade mesophyll tissue
  • Spongy mesophyll tissue
  • Xylem
  • Phloem
  • Meristematic tissue
• Palisade mesophyll tissue


  • Has lots of chloroplasts, meaning photosynthesis can happen rapidly, positioned at the top of the leaf so they receive lots of light
• Spongy mesophyll tissue


  • Has lots of air spaces, allowing gases to diffuse in and out of cells
• Meristematic tissue


  • Able to differentiate into different types of plant cell, allowing the plant to grow
• The leaf is a plant organ, and has the following tissues: epidermis, palisade, spongy mesophyll, xylem and phloem, and guard cells (these surround the stomata and control the opening and closing of them, depending on the water availability)
• Translocation


  The movement of food substances made in the leaves up or down the phloem, for use immediately or storage
• Factors affecting the rate of transpiration

  • Increase in temperature
  • Increase in relative humidity
  • Increased air movement (wind)
  • Increase in light intensity
• Guard cells


  • Kidney shaped, have thin outer walls and thick inner walls, when lots of water is available they fill and change shape to open stomata, allowing gases to be exchanged and more water to leave the plant via evaporation, more stomata are found on the bottom of the leaf, allowing gases to be exchanged whilst minimising water loss by evaporation as the lower surface is shaded and cooler