When breathing in, the external intercostal muscles

  1. contract, moving the ribs down
  2. contract, moving the ribs up and out
  3. relax, moving the ribs down
  4. relax, moving the ribs out
Answer

B) contract, moving the ribs up and out

External intercostals raise the ribcage. O Level Biology · Topic 9 Human Gas Exchange · 9.1 Human gas exchange

Biology MCQ · More O Level Biology: Human Gas Exchange MCQs · Practise