Biology EBIs


What I got wrong and why + improved answers

Cells, tissues and organs

  • When a phagocyte engulfs a bacterium, it creates a vacuole and secretes digestive enzymes into this vacuole.
  • The nucleus contains DNA/RNA and controls the cell's activities. That is better than saying "controls cell activities".
  • Blood clotting prevents blood loss pathogens from entering the bodies - "microorganisms" is too vague
  • Right ventricle pumps blood to the lungs
  • Blood vessel with least oxygen is the vena cava

Digestion and diet

  • Bile emulsifies fats and neutralizes digested food from stomach
  • sunlight (not 'playing outdoors) boosts vitamin D levels which reduces the chance of rickets
  • 'exercise' is not a component of a balanced diet. However, protein, carbs and fats (typically 1 mark each) are.
  • Excess fat in a diet can lead to obesity and other problems
    • blood vessels clogged
    • high blood pressure
    • joint damage

Control of internal conditions

  • Smaller SA to vol ratio, less heat is lost
  • If muscles are kept warm, they can still contract, making them useful
  • A arctic penguin's feet are outside its body but the muscles that control them are inside. Feet are controlled by tendons, which have to be strong and not elastic
  • When penguins huddle together to keep warm, the obvious advantages are that they keep warm, protect themselves from the elements (primarily cold wind) and decrease the SA:Vol ratio further

Diseases and disorders

  • Emphisema is a disease that causes the enlargement of the alveoli, where they lose a large amount of surface area and so results in breathlessness (lung transplant required)
  • Coronary failure means the heart can't pump blood at the rate that it is required to (heart transplant required)
  • Diabetes is a metabolic disease in which the pancreas can't produce enough insulin to regulate glucose levels in the blood (pancreas transplant)
  • Hepatitis is a disease characterized by the inflamation of the liver (liver transplant)
  • Poor vision can be fixed / improved with a surgery that involves replacing the cornea.
  • In terms of organ donation, clones are better because they're always available, have no complications with relatives and there's no shortage.
  • Smoking causes cilia to be damaged (not 'covered')
  • Tar contains carcinogens that can


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