Organisation

• Cells make up all living things
• A tissue is a group of specialised cells with a similar structure and function
• Organs are formed from a number of different tissues, working together to produce a specific function
• Organs are organised into organ systems, which work together to perform a certain function
• The digestive system is an organ system made up of organs working together to break down food for absorption
• Organs in the digestive system include glands (salivary glands and pancreas), stomach, small intestine, liver, gall bladder, large intestine, rectum, and anus
• Enzymes are biological catalysts that can break up large molecules and join small ones
• Enzymes are protein molecules with a specific active site where substrates bind
• Enzymes require an optimum pH and temperature to function properly
• Carbohydrases convert carbohydrates into simple sugars, proteases convert proteins into amino acids, and lipases convert lipids into fatty acids and glycerol
• Tests for carbohydrates, starch, proteins, and lipids include Benedict’s test, iodine test, Biuret test, Emulsion test, and Sudan III test
• Bile is alkaline to neutralise stomach acid and emulsifies fats in the small intestine
• The heart is an organ in the circulatory system with a double circulatory system
• The heart has muscular walls, 4 chambers, valves, and coronary arteries
• Blood vessels include arteries, veins, and capillaries with specific functions and structures
• The lungs supply oxygen to the blood and remove carbon dioxide through gas exchange in structures like alveoli
• Blood is made up of plasma, red blood cells, white blood cells, and platelets
• Coronary heart disease is a non-communicable disease caused by blockage in coronary arteries leading to reduced blood flow to the heart
• Solutions for heart issues:

  • Stents (metal mesh tubes inserted in arteries) keep the arteries open to allow blood flow
  • Stents are effective in lowering the risk of a heart attack
  • Stents have a quick recovery time from surgery
  • Risks of stents include heart attack during the procedure, infection following it, and blood clots forming near the stent (thrombosis)
  • Statins are drugs that decrease LDL (bad) cholesterol levels
  • Statins reduce the risk of strokes, coronary heart disease, and heart attacks
  • Statins increase HDL (good) cholesterol levels
• • Cons of statins include the need for continuous intake, potential side effects, and delayed immediate effects
• Faulty heart valves:

  • Replacing with a biological valve (from pigs or cattle) works well but only lasts 12-15 years
  • Replacing with a mechanical valve lasts longer but requires constant medication to prevent blood clotting
• Heart failure can be solved with a heart transplant:

  • Heart transplant requires a donor who has recently died
  • Artificial heart may be used while waiting for a donor
  • Artificial hearts are less likely to be rejected by the immune system
  • Surgery for heart transplant temporarily exposes the body to infection
• Extreme blood loss can be solved by giving artificial blood:

  • Artificial blood is a salt solution that can keep people alive even if they lose ⅔ of their red blood cells
  • Artificial blood gives time for the patient to produce new blood cells
  • Artificial blood can only be used for short periods, then a blood transfusion is needed
• Non-communicable diseases:

  • Health is a state of physical, mental, and social well-being
  • Diseases can be caused by factors like diet, stress, and life situations
  • Communicable diseases are infectious and caused by pathogens
  • Non-communicable diseases are not passed from person to person
  • Diseases can interact with each other, causing one to worsen the effects of another
• Lifestyle factors affecting non-communicable diseases:

  • Risk factors increase the likelihood of non-communicable diseases
  • Risk factors can be aspects of a person's lifestyle, substances in the body, or environmental factors
  • Lifestyle factors like diet, smoking, and exercise can impact diseases like cardiovascular disease, type 2 diabetes, liver and brain function, lung disease, and cancer
• Cancer:

  • Cancer results from changes in cells leading to uncontrollable growth and division, forming a tumour
  • Tumours can be benign or malignant
  • Lifestyle risk factors for cancer include smoking, obesity, UV light exposure, and viral infections
  • Genetic risk factors for cancer can be inherited
• Plant tissues:

  • Epidermal tissue covers the whole plant and helps reduce water loss
  • Palisade mesophyll tissue has many chloroplasts for rapid photosynthesis
  • Spongy mesophyll tissue has air spaces for gas exchange
  • Xylem transports water and mineral ions
  • Phloem transports food substances
  • Meristematic tissue can differentiate into different types of plant cells
• Plant organ system:

  • Roots, stem, and leaves form a plant organ system for substance transport
  • Translocation moves food substances in the phloem
  • Transpiration is the loss of water vapour from leaves and stems
  • Guard cells surround stomata and control their opening and closing
• Factors affecting transpiration rate:

  • Increase in temperature leads to faster evaporation and transpiration
  • Increase in relative humidity reduces the rate of diffusion and transpiration
  • Increased air movement (wind) and light intensity increase the rate of transpiration