Homeostasis

Traps in Homeostasis

• Mismatches hormones and functions
  Insulin (pancreas) lowers blood glucose; ADH (pituitary) reduces urine volume; adrenaline prepares for 'fight or flight'; thyroxine controls metabolic rate.
• Homeostasis misconceptions
  Hot: vasodilation, sweating, hair flat. Cold: vasoconstriction, shivering, hair erect. Dehydration → more ADH → more water reabsorbed → concentrated urine. Liver stores glycogen; insulin lowers, glucagon raises blood glucose.
• Gives the job of a neighbouring structure or stage
  Learn structures as pairs of 'name → one job' and contrast neighbours: ribosome makes protein, mitochondrion releases energy; cochlea hears, semicircular canals balance. When two options sit in the same organ or process, ask which one does exactly the job in the stem.
• Reverses a direction, order or effect
  Before answering, say the process out loud in order with arrows (receptor → sensory → relay → motor → effector; lungs → pulmonary vein → left atrium). Then ask: does my option point the same way? If an option is the mirror image of a fact you know, it is a trap.
• Takes one contributing factor as the whole answer
  Watch for 'only', 'just', 'mainly'. Ask: is this the MAIN reason, or one contributor? If it would need other things to work (plasma proteins need platelets), it is incomplete.
• Confuses excretion and egestion
  Excretion = removing waste made by cell metabolism (urea, CO₂, excess water). Egestion = removing undigested food (faeces) that never entered cells.
• Uses an everyday idea instead of the biology
  Translate everyday words into the textbook definition before choosing. If the only reason an option attracts you is its name or looks, test it against the definition in the stem.
• Over-generalises a rule to all cases
  Absolute words (all, always, every, never) are rarely right in biology. Try to name one exception; if you can, reject the option.