When a sarcomere contracts,

  1. all bands shorten
  2. the A band shortens
  3. actin filaments shorten
  4. the I band and H zone shorten but the A band stays the same
Answer

D) the I band and H zone shorten but the A band stays the same

Filaments slide, they do not shorten. AS & A Level Biology · Topic 15 Control and Coordination · 15.1 Control and coordination in mammals

Biology MCQ · More A Level Biology: Control and coordination MCQs · Practise